lib: Add mlibc

Signed-off-by: Ian Moffett <ian@osmora.org>

80 files changed, 4826 insertions, 0 deletions

diff --git a/lib/mlibc/options/internal/aarch64-include/mlibc/arch-defs.hpp b/lib/mlibc/options/internal/aarch64-include/mlibc/arch-defs.hpp
new file mode 100644
index 0000000..0a4789f
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64-include/mlibc/arch-defs.hpp
@@ -0,0 +1,12 @@
+#ifndef MLIBC_ARCH_DEFS_HPP
+#define MLIBC_ARCH_DEFS_HPP
+
+#include <stddef.h>
+
+namespace mlibc {
+
+inline constexpr size_t page_size = 0x1000;
+
+} // namespace mlibc
+
+#endif // MLIBC_ARCH_DEFS_HPP
diff --git a/lib/mlibc/options/internal/aarch64-include/mlibc/thread.hpp b/lib/mlibc/options/internal/aarch64-include/mlibc/thread.hpp
new file mode 100644
index 0000000..b62d832
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64-include/mlibc/thread.hpp
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <stdint.h>
+#include <mlibc/tcb.hpp>
+
+namespace mlibc {
+
+inline Tcb *get_current_tcb() {
+	// On AArch64, TPIDR_EL0 points to 0x10 bytes before the first TLS block.
+	uintptr_t ptr;
+	asm ("mrs %0, tpidr_el0" : "=r"(ptr));
+	return reinterpret_cast<Tcb *>(ptr + 0x10 - sizeof(Tcb));
+}
+
+inline uintptr_t get_sp() {
+	uintptr_t sp;
+	asm ("mov %0, sp" : "=r"(sp));
+	return sp;
+}
+
+} // namespace mlibc
diff --git a/lib/mlibc/options/internal/aarch64/fenv.S b/lib/mlibc/options/internal/aarch64/fenv.S
new file mode 100644
index 0000000..1b02e87
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64/fenv.S
@@ -0,0 +1,69 @@
+# The functions below are taken from musl.
+.global fegetround
+.type fegetround,%function
+fegetround:
+	mrs x0, fpcr
+	and w0, w0, #0xc00000
+	ret
+
+.global __fesetround
+.hidden __fesetround
+.type __fesetround,%function
+__fesetround:
+	mrs x1, fpcr
+	bic w1, w1, #0xc00000
+	orr w1, w1, w0
+	msr fpcr, x1
+	mov w0, #0
+	ret
+
+.global fetestexcept
+.type fetestexcept,%function
+fetestexcept:
+	and w0, w0, #0x1f
+	mrs x1, fpsr
+	and w0, w0, w1
+	ret
+
+.global feclearexcept
+.type feclearexcept,%function
+feclearexcept:
+	and w0, w0, #0x1f
+	mrs x1, fpsr
+	bic w1, w1, w0
+	msr fpsr, x1
+	mov w0, #0
+	ret
+
+.global feraiseexcept
+.type feraiseexcept,%function
+feraiseexcept:
+	and w0, w0, #0x1f
+	mrs x1, fpsr
+	orr w1, w1, w0
+	msr fpsr, x1
+	mov w0, #0
+	ret
+
+.global fegetenv
+.type fegetenv,%function
+fegetenv:
+	mrs x1, fpcr
+	mrs x2, fpsr
+	stp w1, w2, [x0]
+	mov w0, #0
+	ret
+
+// TODO preserve some bits
+.global fesetenv
+.type fesetenv,%function
+fesetenv:
+	mov x1, #0
+	mov x2, #0
+	cmn x0, #1
+	b.eq 1f
+	ldp w1, w2, [x0]
+1:	msr fpcr, x1
+	msr fpsr, x2
+	mov w0, #0
+	ret
diff --git a/lib/mlibc/options/internal/aarch64/mlibc_crtbegin.S b/lib/mlibc/options/internal/aarch64/mlibc_crtbegin.S
new file mode 100644
index 0000000..b99748b
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64/mlibc_crtbegin.S
@@ -0,0 +1,29 @@
+
+.section .data
+.hidden __dso_handle
+.global __dso_handle
+__dso_handle:
+	.quad __dso_handle
+
+.section .init
+.hidden _init
+.global _init
+_init:
+
+.section .fini
+.hidden _fini
+.global _fini
+_fini:
+
+.section .ctors
+.hidden __CTOR_LIST__
+.global __CTOR_LIST__
+__CTOR_LIST__:
+
+.section .dtors
+.hidden __DTOR_LIST__
+.global __DTOR_LIST__
+__DTOR_LIST__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/aarch64/mlibc_crtend.S b/lib/mlibc/options/internal/aarch64/mlibc_crtend.S
new file mode 100644
index 0000000..2bf6254
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64/mlibc_crtend.S
@@ -0,0 +1,22 @@
+
+.hidden __mlibc_do_ctors
+.hidden __mlibc_do_dtors
+
+.section .init
+	b __mlibc_do_ctors
+
+.section .fini
+	b __mlibc_do_dtors
+
+.section .ctors
+.hidden __CTOR_END__
+.global __CTOR_END__
+__CTOR_END__:
+
+.section .dtors
+.hidden __DTOR_END__
+.global __DTOR_END__
+__DTOR_END__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/aarch64/setjmp.S b/lib/mlibc/options/internal/aarch64/setjmp.S
new file mode 100644
index 0000000..9dddaa8
--- /dev/null
+++ b/lib/mlibc/options/internal/aarch64/setjmp.S
@@ -0,0 +1,63 @@
+// vim: ft=arm64asm
+
+.extern __sigsetjmp
+
+.type __setjmp, "function"
+__setjmp:
+	stp x19, x20, [x0, #0]
+	stp x21, x22, [x0, #16]
+	stp x23, x24, [x0, #24]
+	stp x25, x26, [x0, #32]
+	stp x27, x28, [x0, #48]
+	stp x29, x30, [x0, #64]
+	stp x29, x30, [x0, #80]
+	mov x4, sp
+	str x4, [x0, #96]
+
+	stp d8, d9, [x0, #112]
+	stp d10, d11, [x0, #128]
+	stp d12, d13, [x0, #144]
+	stp d14, d15, [x0, #160]
+
+	cbnz x2, 1f
+
+	mov x0, xzr
+	ret
+1:
+	b __sigsetjmp
+
+.global setjmp
+.type setjmp, "function"
+setjmp:
+	mov x2, xzr
+	b __setjmp
+
+.global sigsetjmp
+.type sigsetjmp, "function"
+sigsetjmp:
+	mov x2, #1
+	b __setjmp
+
+.global longjmp
+.type longjmp, "function"
+longjmp:
+	ldp x19, x20, [x0, #0]
+	ldp x21, x22, [x0, #16]
+	ldp x23, x24, [x0, #24]
+	ldp x25, x26, [x0, #32]
+	ldp x27, x28, [x0, #48]
+	ldp x29, x30, [x0, #64]
+	ldp x29, x30, [x0, #80]
+	ldr x4, [x0, #96]
+	mov sp, x4
+
+	ldp d8, d9, [x0, #112]
+	ldp d10, d11, [x0, #128]
+	ldp d12, d13, [x0, #144]
+	ldp d14, d15, [x0, #160]
+
+	cmp w1, 0
+	csinc w0, w1, wzr, ne
+	br x30
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/gcc-extra/cxxabi.cpp b/lib/mlibc/options/internal/gcc-extra/cxxabi.cpp
new file mode 100644
index 0000000..c5bd92f
--- /dev/null
+++ b/lib/mlibc/options/internal/gcc-extra/cxxabi.cpp
@@ -0,0 +1,20 @@
+
+#include <bits/ensure.h>
+
+// The cxxabi needs operator delete for *deleting* destructors, i.e., destructors that
+// are called by delete expressions. We never use such expressions in mlibc.
+// Note that G++ complains if we make the operator hidden,
+// thus we use it's mangled name as a workaround.
+#if defined(__clang__)
+	extern "C" [[gnu::visibility("hidden")]] void _ZdlPv() { // operator delete (void *, size_t)
+		__ensure(!"operator delete called! delete expressions cannot be used in mlibc.");
+	}
+#else
+	extern "C" [[gnu::visibility("hidden")]] void _ZdlPvj() { // operator delete (void *, unsigned int)
+		__ensure(!"operator delete called! delete expressions cannot be used in mlibc.");
+	}
+
+	extern "C" [[gnu::visibility("hidden")]] void _ZdlPvm() { // operator delete (void *, size_t)
+		__ensure(!"operator delete called! delete expressions cannot be used in mlibc.");
+	}
+#endif
\ No newline at end of file
diff --git a/lib/mlibc/options/internal/gcc/guard-abi.cpp b/lib/mlibc/options/internal/gcc/guard-abi.cpp
new file mode 100644
index 0000000..945582a
--- /dev/null
+++ b/lib/mlibc/options/internal/gcc/guard-abi.cpp
@@ -0,0 +1,68 @@
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <mlibc/debug.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+
+namespace {
+
+// Itanium ABI static initialization guard.
+struct Guard {
+	// bit of the mutex member variable.
+	// indicates that the mutex is locked.
+	static constexpr int32_t locked = 1;
+
+	void lock() {
+		uint32_t v = 0;
+		if(__atomic_compare_exchange_n(&mutex, &v, Guard::locked, false,
+				__ATOMIC_ACQUIRE, __ATOMIC_RELAXED))
+			return;
+
+		mlibc::sys_libc_log("__cxa_guard_acquire contention");
+		__builtin_trap();
+	}
+
+	void unlock() {
+		__atomic_store_n(&mutex, 0, __ATOMIC_RELEASE);
+	}
+
+	// the first byte's meaning is fixed by the ABI.
+	// it indicates whether initialization has already been completed.
+	uint8_t complete;
+
+	// we use some of the remaining bytes to implement a mutex.
+	uint32_t mutex;
+};
+
+static_assert(sizeof(Guard) == sizeof(int64_t));
+
+} // namespace { }
+
+extern "C" [[ gnu::visibility("hidden") ]] void __cxa_pure_virtual() {
+	mlibc::panicLogger() << "mlibc: Pure virtual function called from IP "
+			<< (void *)__builtin_return_address(0) << frg::endlog;
+}
+
+extern "C" [[ gnu::visibility("hidden") ]] int __cxa_guard_acquire(int64_t *ptr) {
+	auto guard = reinterpret_cast<Guard *>(ptr);
+	guard->lock();
+	// relaxed ordering is sufficient because
+	// Guard::complete is only modified while the mutex is held.
+	if(__atomic_load_n(&guard->complete, __ATOMIC_RELAXED)) {
+		guard->unlock();
+		return 0;
+	}else{
+		return 1;
+	}
+}
+
+extern "C" [[ gnu::visibility("hidden") ]] void __cxa_guard_release(int64_t *ptr) {
+	auto guard = reinterpret_cast<Guard *>(ptr);
+	// do a store-release so that compiler generated code can skip calling
+	// __cxa_guard_acquire by doing a load-acquire on Guard::complete.
+	__atomic_store_n(&guard->complete, 1, __ATOMIC_RELEASE);
+	guard->unlock();
+}
+
diff --git a/lib/mlibc/options/internal/gcc/initfini.cpp b/lib/mlibc/options/internal/gcc/initfini.cpp
new file mode 100644
index 0000000..b329f38
--- /dev/null
+++ b/lib/mlibc/options/internal/gcc/initfini.cpp
@@ -0,0 +1,23 @@
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <mlibc/internal-sysdeps.hpp>
+#include <mlibc/debug.hpp>
+
+typedef void (*InitPtr)();
+
+extern InitPtr __CTOR_LIST__ [[ gnu::visibility("hidden") ]];
+extern InitPtr __CTOR_END__ [[ gnu::visibility("hidden") ]];
+
+extern "C" [[ gnu::visibility("hidden") ]] void __mlibc_do_ctors() {
+	auto it = &__CTOR_LIST__;
+	while(it != &__CTOR_END__)
+		(*it++)();
+}
+
+extern "C" [[ gnu::visibility("hidden") ]] void __mlibc_do_dtors() {
+	mlibc::sys_libc_log("__mlibc_do_dtors() called");
+}
+
diff --git a/lib/mlibc/options/internal/gcc/stack_protector.cpp b/lib/mlibc/options/internal/gcc/stack_protector.cpp
new file mode 100644
index 0000000..e5e50f0
--- /dev/null
+++ b/lib/mlibc/options/internal/gcc/stack_protector.cpp
@@ -0,0 +1,31 @@
+#include <stdint.h>
+#include <string.h>
+#include <mlibc/debug.hpp>
+#include <mlibc/stack_protector.hpp>
+
+uintptr_t __stack_chk_guard = 0;
+
+namespace mlibc {
+
+void initStackGuard(void *entropy) {
+	if(entropy != nullptr) {
+		memcpy(&__stack_chk_guard, entropy, sizeof(__stack_chk_guard));
+	} else {
+		// If no entropy is available, set it to the terminator canary
+		__stack_chk_guard = 0;
+		__stack_chk_guard |= ('\n' << 16);
+		__stack_chk_guard |= (255 << 24);
+	}
+}
+
+} // namespace mlibc
+
+extern "C" [[noreturn]] void __stack_chk_fail() {
+	mlibc::panicLogger() << "Stack smashing detected!" << frg::endlog;
+	__builtin_unreachable();
+}
+
+extern "C" [[noreturn, gnu::visibility("hidden")]] void __stack_chk_fail_local() {
+	__stack_chk_fail();
+};
+
diff --git a/lib/mlibc/options/internal/generic/allocator.cpp b/lib/mlibc/options/internal/generic/allocator.cpp
new file mode 100644
index 0000000..d738212
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/allocator.cpp
@@ -0,0 +1,196 @@
+
+#include <string.h>
+
+#include <bits/ensure.h>
+#include <frg/eternal.hpp>
+#include <mlibc/allocator.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+#include <internal-config.h>
+
+#if !MLIBC_DEBUG_ALLOCATOR
+
+// --------------------------------------------------------
+// Globals
+// --------------------------------------------------------
+
+MemoryAllocator &getAllocator() {
+	// use frg::eternal to prevent a call to __cxa_atexit().
+	// this is necessary because __cxa_atexit() call this function.
+	static frg::eternal<VirtualAllocator> virtualAllocator;
+	static frg::eternal<MemoryPool> heap{virtualAllocator.get()};
+	static frg::eternal<MemoryAllocator> singleton{&heap.get()};
+	return singleton.get();
+}
+
+// --------------------------------------------------------
+// VirtualAllocator
+// --------------------------------------------------------
+
+uintptr_t VirtualAllocator::map(size_t length) {
+	void *ptr;
+	__ensure(!mlibc::sys_anon_allocate(length, &ptr));
+	return (uintptr_t)ptr;
+}
+
+void VirtualAllocator::unmap(uintptr_t address, size_t length) {
+	__ensure(!mlibc::sys_anon_free((void *)address, length));
+}
+
+#else
+
+namespace {
+	struct AllocatorMeta {
+		size_t allocatedSize;
+		size_t pagesSize;
+		frg::array<uint64_t, 4> magic;
+	};
+
+	constexpr frg::array<uint64_t, 4> allocatorMagic {
+		0x6d4bbb9f3446e83f, 0x25e213a7a7f9f954,
+		0x1a3c667586538bef, 0x994f34ff71c090bc
+	};
+} // namespace anonymous
+
+// Turn vm_unmap calls in free into vm_map(..., PROT_NONE, ...) calls to prevent
+// those addresses from being reused. This is useful for detecting situations like this:
+// 1. Allocate object X at address Y
+// 2. Do some computation using object X
+// 3. Free object X at address Y
+// 4. Allocate object Z at address W, and it so happens that W == Y
+// 5. Try to use object X, but the memory which was backing it now contains object Z
+constexpr bool neverReleaseVa = false;
+constexpr bool logAllocations = false;
+
+// Area before the returned allocated block (which exists due to us offseting
+// the block to be as close to the edge of a page).
+constexpr uint8_t offsetAreaValue = 'A';
+// Area which we return a pointer to in allocate and reallocate.
+constexpr uint8_t allocatedAreaValue = 'B';
+// Area after the allocated block, which exists due to the alignment constraints.
+constexpr uint8_t alignmentAreaValue = 'C';
+// Remaining area within the metadata page after the metadata.
+constexpr uint8_t metaAreaValue = 'D';
+
+// Alignment of the returned memory.
+// TODO(qookie): Eventually accept alignment as an argument of allocate.
+constexpr size_t pointerAlignment = 16;
+
+// TODO(qookie): Support this. Perhaps by overallocating by 2x and then picking
+// an offset that guarantees the desired alignment.
+static_assert(pointerAlignment <= 4096, "Pointer aligment of more than 4096 bytes is unsupported");
+static_assert(!(pointerAlignment & (pointerAlignment - 1)),
+		"Pointer aligment must be a power of 2");
+
+constexpr size_t pageSize = 0x1000;
+
+void *MemoryAllocator::allocate(size_t size) {
+	size_t pg_size = (size + size_t{pageSize - 1}) & ~size_t{pageSize - 1};
+	size_t offset = (pg_size - size) & ~size_t{pointerAlignment - 1};
+
+	void *ptr;
+
+	// Two extra pages for metadata in front and guard page at the end
+	// Reserve the whole region as PROT_NONE...
+	if (int e = mlibc::sys_vm_map(nullptr, pg_size + pageSize * 2, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0, &ptr))
+		mlibc::panicLogger() << "sys_vm_map failed in MemoryAllocator::allocate (errno " << e << ")" << frg::endlog;
+
+	// ...Then replace pages to make them accessible, excluding the guard page
+	if (int e = mlibc::sys_vm_map(ptr, pg_size + pageSize, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0, &ptr))
+		mlibc::panicLogger() << "sys_vm_map failed in MemoryAllocator::allocate (errno " << e << ")" << frg::endlog;
+
+	void *meta = ptr;
+	void *out_page = reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(ptr) + pageSize);
+	void *out = reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(out_page) + offset);
+	void *out_align_area = reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(out) + size);
+
+	AllocatorMeta metaData{size, pg_size, allocatorMagic};
+
+	memset(meta, metaAreaValue, pageSize);
+	memcpy(meta, &metaData, sizeof(AllocatorMeta));
+
+	memset(out_page, offsetAreaValue, offset);
+	memset(out, allocatedAreaValue, size);
+	memset(out_align_area, alignmentAreaValue, pg_size - offset - size);
+
+	if constexpr (logAllocations)
+		mlibc::infoLogger() << "MemoryAllocator::allocate(" << size << ") = " << out << frg::endlog;
+
+	return out;
+}
+
+void MemoryAllocator::free(void *ptr) {
+	if (!ptr)
+		return;
+
+	if constexpr (logAllocations)
+		mlibc::infoLogger() << "MemoryAllocator::free(" << ptr << ")" << frg::endlog;
+
+	uintptr_t page_addr = reinterpret_cast<uintptr_t>(ptr) & ~size_t{pageSize - 1};
+	AllocatorMeta *meta = reinterpret_cast<AllocatorMeta *>(page_addr - pageSize);
+
+	if (meta->magic != allocatorMagic)
+		mlibc::panicLogger() << "Invalid allocator metadata magic in MemoryAllocator::free" << frg::endlog;
+
+	deallocate(ptr, meta->allocatedSize);
+}
+
+void MemoryAllocator::deallocate(void *ptr, size_t size) {
+	if (!ptr)
+		return;
+
+	if constexpr (logAllocations)
+		mlibc::infoLogger() << "MemoryAllocator::deallocate(" << ptr << ", " << size << ")" << frg::endlog;
+
+	uintptr_t page_addr = reinterpret_cast<uintptr_t>(ptr) & ~size_t{pageSize - 1};
+	AllocatorMeta *meta = reinterpret_cast<AllocatorMeta *>(page_addr - pageSize);
+
+	if (meta->magic != allocatorMagic)
+		mlibc::panicLogger() << "Invalid allocator metadata magic in MemoryAllocator::deallocate" << frg::endlog;
+
+	if (size != meta->allocatedSize)
+		mlibc::panicLogger() << "Invalid allocated size in metadata in MemoryAllocator::deallocate (given " << size << ", stored " << meta->allocatedSize << ")" << frg::endlog;
+
+	if constexpr (neverReleaseVa) {
+		void *unused;
+		if (int e = mlibc::sys_vm_map(meta, meta->pagesSize + pageSize * 2, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0, &unused))
+			mlibc::panicLogger() << "sys_vm_map failed in MemoryAllocator::deallocate (errno " << e << ")" << frg::endlog;
+	} else {
+		if (int e = mlibc::sys_vm_unmap(meta, meta->pagesSize + pageSize * 2))
+			mlibc::panicLogger() << "sys_vm_unmap failed in MemoryAllocator::deallocate (errno " << e << ")" << frg::endlog;
+	}
+}
+
+void *MemoryAllocator::reallocate(void *ptr, size_t size) {
+	if (!size) {
+		free(ptr);
+		return nullptr;
+	}
+
+	void *newArea = allocate(size);
+
+	if (ptr) {
+		uintptr_t page_addr = reinterpret_cast<uintptr_t>(ptr) & ~size_t{pageSize - 1};
+		AllocatorMeta *meta = reinterpret_cast<AllocatorMeta *>(page_addr - pageSize);
+
+		if (meta->magic != allocatorMagic)
+			mlibc::panicLogger() << "Invalid allocator metadata magic in MemoryAllocator::reallocate" << frg::endlog;
+
+		memcpy(newArea, ptr, frg::min(meta->allocatedSize, size));
+
+		deallocate(ptr, meta->allocatedSize);
+	}
+
+	if constexpr (logAllocations)
+		mlibc::infoLogger() << "MemoryAllocator::reallocate(" << ptr << ", " << size << ") = " << newArea << frg::endlog;
+
+	return newArea;
+}
+
+MemoryAllocator &getAllocator() {
+	// use frg::eternal to prevent a call to __cxa_atexit().
+	// this is necessary because __cxa_atexit() call this function.
+	static frg::eternal<MemoryAllocator> singleton{};
+	return singleton.get();
+}
+
+#endif /* !MLIBC_DEBUG_ALLOCATOR */
diff --git a/lib/mlibc/options/internal/generic/charcode.cpp b/lib/mlibc/options/internal/generic/charcode.cpp
new file mode 100644
index 0000000..e09d5cd
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/charcode.cpp
@@ -0,0 +1,244 @@
+
+#include <bits/ensure.h>
+#include <frg/string.hpp>
+#include <mlibc/charcode.hpp>
+#include <mlibc/debug.hpp>
+
+namespace mlibc {
+
+struct utf8_charcode {
+	static constexpr bool preserves_7bit_units = true;
+	static constexpr bool has_shift_states = false;
+
+	struct decode_state {
+		decode_state()
+		: _progress{0}, _cpoint{0} { }
+
+		auto progress() { return _progress; }
+		auto cpoint() { return _cpoint; }
+
+		charcode_error operator() (code_seq<const char> &seq) {
+			auto uc = static_cast<unsigned char>(*seq.it);
+			if(!_progress) {
+				if(!(uc & 0b1000'0000)) {
+					// ASCII-compatible.
+					_cpoint = uc;
+				}else if((uc & 0b1110'0000) == 0b1100'0000) {
+					_cpoint = uc & 0b1'1111;
+					_progress = 1;
+				}else if((uc & 0b1111'0000) == 0b1110'0000) {
+					_cpoint = uc & 0b1111;
+					_progress = 2;
+				}else if((uc & 0b1111'1000) == 0b1111'0000) {
+					_cpoint = uc & 0b111;
+					_progress = 3;
+				}else{
+					// If the highest two bits are 0b10, this is the second (or later) unit.
+					// Units with highest five bits = 0b11111 do not occur in valid UTF-8.
+					__ensure((uc & 0b1100'0000) == 0b1000'0000
+							|| (uc & 0b1111'1000) == 0b1111'1000);
+					return charcode_error::illegal_input;
+				}
+			}else{
+				// TODO: Return an error.
+				__ensure((uc & 0b1100'0000) == 0b1000'0000);
+				_cpoint = (_cpoint << 6) | (uc & 0x3F);
+				--_progress;
+			}
+			++seq.it;
+			return charcode_error::null;
+		}
+
+	private:
+		int _progress;
+		codepoint _cpoint;
+	};
+
+	struct encode_state {
+		// Encodes a single character from wseq + the current state and stores it in nseq.
+		// TODO: Convert decode_state to the same strategy.
+		charcode_error operator() (code_seq<char> &nseq, code_seq<const codepoint> &wseq) {
+			auto wc = *wseq.it;
+			__ensure(wc <= 0x7F && "utf8_charcode cannot encode multibyte chars yet");
+			*nseq.it = wc;
+			++wseq.it;
+			++nseq.it;
+			return charcode_error::null;
+		}
+	};
+};
+
+polymorphic_charcode::~polymorphic_charcode() = default;
+
+// For *decoding, this class assumes that:
+// - G::decode_state has members progress() and cpoint().
+// - G::decode_state::progress() >= 0 at all times.
+//   TODO: This will be needed on platforms like Windows, where wchar_t is UTF-16.
+//   TODO: There, we can use negative __mlibc_mbstate::progress to represent encoding to UTF-16.
+// - If G::decode_state::progress() == 0, the code point (given by cpoint())
+//   was decoded successfully.
+template<typename G>
+struct polymorphic_charcode_adapter : polymorphic_charcode {
+	polymorphic_charcode_adapter()
+	: polymorphic_charcode{G::preserves_7bit_units, G::has_shift_states} { }
+
+	charcode_error decode(code_seq<const char> &nseq, code_seq<codepoint> &wseq,
+			__mlibc_mbstate &st) override {
+		__ensure(!st.__progress); // TODO: Update st with ds.progress() and ds.cpoint().
+
+		code_seq<const char> decode_nseq = nseq;
+		typename G::decode_state ds;
+
+		while(decode_nseq && wseq) {
+			// Consume the next code unit.
+			if(auto e = ds(decode_nseq); e != charcode_error::null)
+				return e;
+
+			// Produce a new code point.
+			if(!ds.progress()) {
+				// "Commit" consumed code units (as there was no decode error).
+				nseq.it = decode_nseq.it;
+				if(!ds.cpoint()) // Stop on null characters.
+					return charcode_error::null;
+				*wseq.it = ds.cpoint();
+				++wseq.it;
+			}
+		}
+
+		if(ds.progress())
+			return charcode_error::input_underflow;
+		return charcode_error::null;
+	}
+
+	charcode_error decode_wtranscode(code_seq<const char> &nseq, code_seq<wchar_t> &wseq,
+			__mlibc_mbstate &st) override {
+		__ensure(!st.__progress); // TODO: Update st with ds.progress() and ds.cpoint().
+
+		code_seq<const char> decode_nseq = nseq;
+		typename G::decode_state ds;
+
+		while(decode_nseq && wseq) {
+			// Consume the next code unit.
+			if(auto e = ds(decode_nseq); e != charcode_error::null)
+				return e;
+
+			// Produce a new code point.
+			if(!ds.progress()) {
+				nseq.it = decode_nseq.it;
+				// "Commit" consumed code units (as there was no decode error).
+				if(!ds.cpoint()) // Stop on null characters.
+					return charcode_error::null;
+				*wseq.it = ds.cpoint();
+				++wseq.it;
+			}
+		}
+
+		if(ds.progress())
+			return charcode_error::input_underflow;
+		return charcode_error::null;
+	}
+
+	charcode_error decode_wtranscode_length(code_seq<const char> &nseq, size_t *n,
+			__mlibc_mbstate &st) override {
+		__ensure(!st.__progress); // TODO: Update st with ds.progress() and ds.cpoint().
+
+		code_seq<const char> decode_nseq = nseq;
+		typename G::decode_state ds;
+
+		*n = 0;
+		while(decode_nseq) {
+			// Consume the next code unit.
+			if(auto e = ds(decode_nseq); e != charcode_error::null)
+				return e;
+
+			if(!ds.progress()) {
+				nseq.it = decode_nseq.it;
+				// "Commit" consumed code units (as there was no decode error).
+				if(!ds.cpoint()) // Stop on null code points.
+					return charcode_error::null;
+				++(*n);
+			}
+		}
+
+		if(ds.progress())
+			return charcode_error::input_underflow;
+		return charcode_error::null;
+	}
+
+	charcode_error encode_wtranscode(code_seq<char> &nseq, code_seq<const wchar_t> &wseq,
+			__mlibc_mbstate &st) override {
+		__ensure(!st.__progress); // TODO: Update st with es.progress() and es.cpoint().
+
+		code_seq<char> encode_nseq = nseq;
+		typename G::encode_state es;
+
+		while(encode_nseq && wseq) {
+			codepoint cp = *wseq.it;
+			if(!cp)
+				return charcode_error::null;
+
+			code_seq<const codepoint> cps{&cp, &cp + 1};
+			if(auto e = es(encode_nseq, cps); e == charcode_error::dirty) {
+				continue;
+			}else if(e != charcode_error::null) {
+				return e;
+			}
+			__ensure(cps.it == cps.end);
+			++wseq.it;
+
+			// "Commit" produced code units (as there was no encode error).
+			nseq.it = encode_nseq.it;
+		}
+
+		if(encode_nseq.it != nseq.it)
+			return charcode_error::output_overflow;
+		return charcode_error::null;
+	}
+
+	charcode_error encode_wtranscode_length(code_seq<const wchar_t> &wseq, size_t *n,
+			__mlibc_mbstate &st) override {
+		__ensure(!st.__progress); // TODO: Update st with es.progress() and es.cpoint().
+
+		typename G::encode_state es;
+
+		*n = 0;
+		while(wseq) {
+			char temp[4];
+			code_seq<char> encode_nseq{temp, temp + 4};
+			codepoint cp = *wseq.it;
+			if(!cp)
+				return charcode_error::null;
+			// Consume the next code unit.
+			code_seq<const codepoint> cps{&cp, &cp + 1};
+			if(auto e = es(encode_nseq, cps); e == charcode_error::dirty) {
+				continue;
+			}else if(e != charcode_error::null) {
+				return e;
+			}
+
+			++(*n);
+			++wseq.it;
+		}
+
+		return charcode_error::null;
+	}
+};
+
+polymorphic_charcode *current_charcode() {
+	static polymorphic_charcode_adapter<utf8_charcode> global_charcode;
+	return &global_charcode;
+}
+
+charcode_error wide_charcode::promote(wchar_t nc, codepoint &wc) {
+	// TODO: Allow non-identity encodings of wchar_t.
+	wc = nc;
+	return charcode_error::null;
+}
+
+wide_charcode *platform_wide_charcode() {
+	static wide_charcode global_wide_charcode;
+	return &global_wide_charcode;
+}
+
+} // namespace mlibc
+
diff --git a/lib/mlibc/options/internal/generic/charset.cpp b/lib/mlibc/options/internal/generic/charset.cpp
new file mode 100644
index 0000000..c42b4f4
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/charset.cpp
@@ -0,0 +1,144 @@
+
+#include <bits/ensure.h>
+#include <mlibc/charset.hpp>
+#include <mlibc/debug.hpp>
+
+namespace mlibc {
+
+bool charset::is_ascii_superset() {
+	// TODO: For locales that change the meaning of ASCII chars, this needs to be changed.
+	return true;
+}
+
+bool charset::is_alpha(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_alpha() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_digit(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c >= '0' && c <= '9';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_digit() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_xdigit(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_xdigit() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_alnum(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_alnum() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_punct(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c == '!' || c == '"' || c == '#' || c == '$' || c == '%' || c == '&'
+				|| c == '\'' || c == '(' || c == ')' || c == '*' || c == '+' || c == ','
+				|| c == '-' || c == '.' || c == '/'
+				|| c == ':' || c == ';' || c == '<' || c == '=' || c == '>' || c == '?'
+				|| c == '@'
+				|| c == '[' || c == '\\' || c == ']' || c == '^' || c == '_' || c == '`'
+				|| c == '{' || c == '|' || c == '}' || c == '~';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_punct() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_graph(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c >= 0x21 && c <= 0x7E;
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_graph() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_blank(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c == ' ' || c == '\t';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_blank() is not implemented"
+				" for the full Unicode charset " << c << frg::endlog;
+	return false;
+}
+
+bool charset::is_space(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c == ' ' || c == '\t' || c == '\n' || c == '\v' || c == '\f' || c == '\r';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_space() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_print(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return c >= 0x20 && c <= 0x7E;
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_print() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_lower(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return (c >= 'a' && c <= 'z');
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_print() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+bool charset::is_upper(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		return (c >= 'A' && c <= 'Z');
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::is_print() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return false;
+}
+
+codepoint charset::to_lower(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		if(c >= 'A' && c <= 'Z')
+			return c - 'A' + 'a';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::to_lower() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return c;
+}
+
+codepoint charset::to_upper(codepoint c) {
+	if(c <= 0x7F && is_ascii_superset())
+		if(c >= 'a' && c <= 'z')
+			return c - 'a' + 'A';
+	if(c > 0x7F)
+		mlibc::infoLogger() << "mlibc: charset::to_upper() is not implemented"
+				" for the full Unicode charset" << frg::endlog;
+	return c;
+}
+
+charset *current_charset() {
+	static charset global_charset;
+	return &global_charset;
+}
+
+} // namespace mlibc
+
diff --git a/lib/mlibc/options/internal/generic/debug.cpp b/lib/mlibc/options/internal/generic/debug.cpp
new file mode 100644
index 0000000..19427c8
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/debug.cpp
@@ -0,0 +1,22 @@
+
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+
+namespace mlibc {
+
+frg::stack_buffer_logger<InfoSink, 512> infoLogger;
+frg::stack_buffer_logger<PanicSink, 512> panicLogger;
+
+void InfoSink::operator() (const char *message) {
+	sys_libc_log(message);
+}
+
+void PanicSink::operator() (const char *message) {
+//	sys_libc_log("mlibc: Write to PanicSink");
+	sys_libc_log(message);
+	sys_libc_panic();
+}
+
+} // namespace mlibc
+
diff --git a/lib/mlibc/options/internal/generic/ensure.cpp b/lib/mlibc/options/internal/generic/ensure.cpp
new file mode 100644
index 0000000..57c953a
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/ensure.cpp
@@ -0,0 +1,18 @@
+
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+
+void __ensure_fail(const char *assertion, const char *file, unsigned int line,
+		const char *function) {
+	mlibc::panicLogger() << "In function " << function
+			<< ", file " << file << ":" << line << "\n"
+			<< "__ensure(" << assertion << ") failed" << frg::endlog;
+}
+
+void __ensure_warn(const char *assertion, const char *file, unsigned int line,
+		const char *function) {
+	mlibc::infoLogger() << "In function " << function
+			<< ", file " << file << ":" << line << "\n"
+			<< "__ensure(" << assertion << ") failed" << frg::endlog;
+}
+
diff --git a/lib/mlibc/options/internal/generic/essential.cpp b/lib/mlibc/options/internal/generic/essential.cpp
new file mode 100644
index 0000000..d00df1e
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/essential.cpp
@@ -0,0 +1,217 @@
+#include <string.h>
+#include <stdint.h>
+
+namespace {
+	// Needed since we cannot declare a templated enum.
+	template<typename T>
+	struct word_helper {
+		using underlying [[gnu::aligned(1)]] = T;
+		enum class [[gnu::may_alias]] word_enum : underlying { };
+	};
+
+	template<typename T>
+	using word = typename word_helper<T>::word_enum;
+
+	template<typename T>
+	[[gnu::always_inline]]
+	inline word<T> alias_load(const unsigned char *&p) {
+		word<T> value = *reinterpret_cast<const word<T> *>(p);
+		p += sizeof(T);
+		return value;
+	}
+
+	template<typename T>
+	[[gnu::always_inline]]
+	inline void alias_store(unsigned char *&p, word<T> value) {
+		*reinterpret_cast<word<T> *>(p) = value;
+		p += sizeof(T);
+	}
+
+#ifdef __LP64__
+	void *forward_copy(void *__restrict dest, const void *__restrict src, size_t n) {
+		auto curDest = reinterpret_cast<unsigned char *>(dest);
+		auto curSrc = reinterpret_cast<const unsigned char *>(src);
+
+		while(n >= 8 * 8) {
+			auto w1 = alias_load<uint64_t>(curSrc);
+			auto w2 = alias_load<uint64_t>(curSrc);
+			auto w3 = alias_load<uint64_t>(curSrc);
+			auto w4 = alias_load<uint64_t>(curSrc);
+			auto w5 = alias_load<uint64_t>(curSrc);
+			auto w6 = alias_load<uint64_t>(curSrc);
+			auto w7 = alias_load<uint64_t>(curSrc);
+			auto w8 = alias_load<uint64_t>(curSrc);
+			alias_store<uint64_t>(curDest, w1);
+			alias_store<uint64_t>(curDest, w2);
+			alias_store<uint64_t>(curDest, w3);
+			alias_store<uint64_t>(curDest, w4);
+			alias_store<uint64_t>(curDest, w5);
+			alias_store<uint64_t>(curDest, w6);
+			alias_store<uint64_t>(curDest, w7);
+			alias_store<uint64_t>(curDest, w8);
+			n -= 8 * 8;
+		}
+		if(n >= 4 * 8) {
+			auto w1 = alias_load<uint64_t>(curSrc);
+			auto w2 = alias_load<uint64_t>(curSrc);
+			auto w3 = alias_load<uint64_t>(curSrc);
+			auto w4 = alias_load<uint64_t>(curSrc);
+			alias_store<uint64_t>(curDest, w1);
+			alias_store<uint64_t>(curDest, w2);
+			alias_store<uint64_t>(curDest, w3);
+			alias_store<uint64_t>(curDest, w4);
+			n -= 4 * 8;
+		}
+		if(n >= 2 * 8) {
+			auto w1 = alias_load<uint64_t>(curSrc);
+			auto w2 = alias_load<uint64_t>(curSrc);
+			alias_store<uint64_t>(curDest, w1);
+			alias_store<uint64_t>(curDest, w2);
+			n -= 2 * 8;
+		}
+		if(n >= 8) {
+			auto w = alias_load<uint64_t>(curSrc);
+			alias_store<uint64_t>(curDest, w);
+			n -= 8;
+		}
+		if(n >= 4) {
+			auto w = alias_load<uint32_t>(curSrc);
+			alias_store<uint32_t>(curDest, w);
+			n -= 4;
+		}
+		if(n >= 2) {
+			auto w = alias_load<uint16_t>(curSrc);
+			alias_store<uint16_t>(curDest, w);
+			n -= 2;
+		}
+		if(n)
+			*curDest = *curSrc;
+		return dest;
+	}
+#else // !__LP64__
+	void *forward_copy(void *dest, const void *src, size_t n) {
+		for(size_t i = 0; i < n; i++)
+			((char *)dest)[i] = ((const char *)src)[i];
+		return dest;
+	}
+#endif // __LP64__ / !__LP64__
+}
+
+// --------------------------------------------------------------------------------------
+// memcpy() implementation.
+// --------------------------------------------------------------------------------------
+
+
+void *memcpy(void *__restrict dest, const void *__restrict src, size_t n) {
+	return forward_copy(dest, src, n);
+}
+
+
+// --------------------------------------------------------------------------------------
+// memset() implementation.
+// --------------------------------------------------------------------------------------
+
+#ifdef __LP64__
+
+void *memset(void *dest, int val, size_t n) {
+	auto curDest = reinterpret_cast<unsigned char *>(dest);
+	unsigned char byte = val;
+
+	// Get rid of misalignment.
+	while(n && (reinterpret_cast<uintptr_t>(curDest) & 7)) {
+		*curDest++ = byte;
+		--n;
+	}
+
+	auto pattern64 = static_cast<word<uint64_t>>(
+			static_cast<uint64_t>(byte)
+			| (static_cast<uint64_t>(byte) << 8)
+			| (static_cast<uint64_t>(byte) << 16)
+			| (static_cast<uint64_t>(byte) << 24)
+			| (static_cast<uint64_t>(byte) << 32)
+			| (static_cast<uint64_t>(byte) << 40)
+			| (static_cast<uint64_t>(byte) << 48)
+			| (static_cast<uint64_t>(byte) << 56));
+
+	auto pattern32 = static_cast<word<uint32_t>>(
+			static_cast<uint32_t>(byte)
+			| (static_cast<uint32_t>(byte) << 8)
+			| (static_cast<uint32_t>(byte) << 16)
+			| (static_cast<uint32_t>(byte) << 24));
+
+	auto pattern16 = static_cast<word<uint16_t>>(
+			static_cast<uint16_t>(byte)
+			| (static_cast<uint16_t>(byte) << 8));
+
+	while(n >= 8 * 8) {
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		n -= 8 * 8;
+	}
+	if(n >= 4 * 8) {
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		n -= 4 * 8;
+	}
+	if(n >= 2 * 8) {
+		alias_store<uint64_t>(curDest, pattern64);
+		alias_store<uint64_t>(curDest, pattern64);
+		n -= 2 * 8;
+	}
+	if(n >= 8) {
+		alias_store<uint64_t>(curDest, pattern64);
+		n -= 8;
+	}
+	if(n >= 4) {
+		alias_store<uint32_t>(curDest, pattern32);
+		n -= 4;
+	}
+	if(n >= 2) {
+		alias_store<uint16_t>(curDest, pattern16);
+		n -= 2;
+	}
+	if(n)
+		*curDest = byte;
+	return dest;
+}
+
+#else // !__LP64__
+
+void *memset(void *dest, int byte, size_t count) {
+	for(size_t i = 0; i < count; i++)
+		((char *)dest)[i] = (char)byte;
+	return dest;
+}
+
+#endif // __LP64__ / !__LP64__
+
+// --------------------------------------------------------------------------------------
+// "Non-optimized" functions.
+// --------------------------------------------------------------------------------------
+
+void *memmove(void *dest, const void *src, size_t size) {
+	char *dest_bytes = (char *)dest;
+	char *src_bytes = (char *)src;
+	if(dest_bytes < src_bytes) {
+		return forward_copy(dest, src, size);
+	}else if(dest_bytes > src_bytes) {
+		for(size_t i = 0; i < size; i++)
+			dest_bytes[size - i - 1] = src_bytes[size - i - 1];
+	}
+	return dest;
+}
+
+size_t strlen(const char *s) {
+	size_t len = 0;
+	for(size_t i = 0; s[i]; i++)
+		len++;
+	return len;
+}
diff --git a/lib/mlibc/options/internal/generic/frigg.cpp b/lib/mlibc/options/internal/generic/frigg.cpp
new file mode 100644
index 0000000..7575c9c
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/frigg.cpp
@@ -0,0 +1,14 @@
+
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+
+extern "C" void frg_panic(const char *mstr) {
+//	mlibc::sys_libc_log("mlibc: Call to frg_panic");
+	mlibc::sys_libc_log(mstr);
+	mlibc::sys_libc_panic();
+}
+
+extern "C" void frg_log(const char *mstr) {
+	mlibc::sys_libc_log(mstr);
+}
diff --git a/lib/mlibc/options/internal/generic/global-config.cpp b/lib/mlibc/options/internal/generic/global-config.cpp
new file mode 100644
index 0000000..264a984
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/global-config.cpp
@@ -0,0 +1,27 @@
+#include <stdlib.h>
+#include <string.h>
+#include <mlibc/global-config.hpp>
+
+namespace mlibc {
+
+struct GlobalConfigGuard {
+	GlobalConfigGuard();
+};
+
+GlobalConfigGuard guard;
+
+GlobalConfigGuard::GlobalConfigGuard() {
+	// Force the config to be created during initialization of libc.so.
+	mlibc::globalConfig();
+}
+
+static bool envEnabled(const char *env) {
+	auto value = getenv(env);
+	return value && *value && *value != '0';
+}
+
+GlobalConfig::GlobalConfig() {
+	debugMalloc = envEnabled("MLIBC_DEBUG_MALLOC");
+}
+
+}
diff --git a/lib/mlibc/options/internal/generic/inline-emitter.cpp b/lib/mlibc/options/internal/generic/inline-emitter.cpp
new file mode 100644
index 0000000..bf81c0b
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/inline-emitter.cpp
@@ -0,0 +1,16 @@
+// This translation unit provides symbols for functions marked with __MLIBC_INLINE_DEFINITION.
+// All headers with such functions must be included here.
+
+#define __MLIBC_EMIT_INLINE_DEFINITIONS
+
+#include <mlibc-config.h>
+
+#include <elf.h>
+
+#if __MLIBC_LINUX_OPTION
+#include <sys/sysmacros.h>
+#endif /* __MLIBC_LINUX_OPTION */
+
+#ifndef MLIBC_BUILDING_RTDL
+#include <math.h>
+#endif
diff --git a/lib/mlibc/options/internal/generic/locale.cpp b/lib/mlibc/options/internal/generic/locale.cpp
new file mode 100644
index 0000000..7ba040f
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/locale.cpp
@@ -0,0 +1,87 @@
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+#include <mlibc/locale.hpp>
+
+namespace mlibc {
+
+char *nl_langinfo(nl_item item) {
+	if(item == CODESET) {
+		return const_cast<char *>("UTF-8");
+	} else if(item >= ABMON_1 && item <= ABMON_12) {
+		switch(item) {
+			case ABMON_1: return const_cast<char *>("Jan");
+			case ABMON_2: return const_cast<char *>("Feb");
+			case ABMON_3: return const_cast<char *>("Mar");
+			case ABMON_4: return const_cast<char *>("Apr");
+			case ABMON_5: return const_cast<char *>("May");
+			case ABMON_6: return const_cast<char *>("Jun");
+			case ABMON_7: return const_cast<char *>("Jul");
+			case ABMON_8: return const_cast<char *>("Aug");
+			case ABMON_9: return const_cast<char *>("Sep");
+			case ABMON_10: return const_cast<char *>("Oct");
+			case ABMON_11: return const_cast<char *>("Nov");
+			case ABMON_12: return const_cast<char *>("Dec");
+			default:
+				__ensure(!"ABMON_* constants don't seem to be contiguous!");
+				__builtin_unreachable();
+		}
+	} else if(item >= MON_1 && item <= MON_12) {
+		switch(item) {
+			case MON_1: return const_cast<char *>("January");
+			case MON_2: return const_cast<char *>("Feburary");
+			case MON_3: return const_cast<char *>("March");
+			case MON_4: return const_cast<char *>("April");
+			case MON_5: return const_cast<char *>("May");
+			case MON_6: return const_cast<char *>("June");
+			case MON_7: return const_cast<char *>("July");
+			case MON_8: return const_cast<char *>("August");
+			case MON_9: return const_cast<char *>("September");
+			case MON_10: return const_cast<char *>("October");
+			case MON_11: return const_cast<char *>("November");
+			case MON_12: return const_cast<char *>("December");
+			default:
+				__ensure(!"MON_* constants don't seem to be contiguous!");
+				__builtin_unreachable();
+		}
+	} else if(item == AM_STR) {
+		return const_cast<char *>("AM");
+	} else if(item == PM_STR) {
+		return const_cast<char *>("PM");
+	} else if(item >= DAY_1 && item <= DAY_7) {
+		switch(item) {
+			case DAY_1: return const_cast<char *>("Sunday");
+			case DAY_2: return const_cast<char *>("Monday");
+			case DAY_3: return const_cast<char *>("Tuesday");
+			case DAY_4: return const_cast<char *>("Wednesday");
+			case DAY_5: return const_cast<char *>("Thursday");
+			case DAY_6: return const_cast<char *>("Friday");
+			case DAY_7: return const_cast<char *>("Saturday");
+			default:
+				__ensure(!"DAY_* constants don't seem to be contiguous!");
+				__builtin_unreachable();
+		}
+	} else if(item >= ABDAY_1 && item <= ABDAY_7) {
+		switch(item) {
+			case ABDAY_1: return const_cast<char *>("Sun");
+			case ABDAY_2: return const_cast<char *>("Mon");
+			case ABDAY_3: return const_cast<char *>("Tue");
+			case ABDAY_4: return const_cast<char *>("Wed");
+			case ABDAY_5: return const_cast<char *>("Thu");
+			case ABDAY_6: return const_cast<char *>("Fri");
+			case ABDAY_7: return const_cast<char *>("Sat");
+			default:
+				__ensure(!"ABDAY_* constants don't seem to be contiguous!");
+				__builtin_unreachable();
+		}
+	}else if(item == D_FMT) {
+		return const_cast<char *>("%m/%d/%y");
+	}else if(item == T_FMT) {
+		return const_cast<char *>("%H:%M:%S");
+	}else{
+		mlibc::infoLogger() << "mlibc: nl_langinfo item "
+				<< item << " is not implemented properly" << frg::endlog;
+		return const_cast<char *>("");
+	}
+}
+
+}
diff --git a/lib/mlibc/options/internal/generic/sigset.cpp b/lib/mlibc/options/internal/generic/sigset.cpp
new file mode 100644
index 0000000..134277d
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/sigset.cpp
@@ -0,0 +1,37 @@
+#include <bits/sigset_t.h>
+#include <bits/ensure.h>
+
+int sigemptyset(sigset_t *sigset) {
+	*sigset = 0;
+	return 0;
+}
+
+int sigfillset(sigset_t *sigset) {
+	*sigset = ~sigset_t(0);
+	return 0;
+}
+
+// TODO: Return EINVAL instead of __ensure()ing.
+
+int sigaddset(sigset_t *sigset, int sig) {
+	int signo = sig - 1;
+	// TODO: do not hard code CHAR_BITS
+	__ensure((unsigned int)signo < sizeof(sigset_t) * 8);
+	*sigset |= sigset_t(1) << signo;
+	return 0;
+}
+
+int sigdelset(sigset_t *sigset, int sig) {
+	int signo = sig - 1;
+	// TODO: do not hard code CHAR_BITS
+	__ensure((unsigned int)signo < sizeof(sigset_t) * 8);
+	*sigset &= ~(sigset_t(1) << signo);
+	return 0;
+}
+
+int sigismember(const sigset_t *set, int sig) {
+	int signo = sig - 1;
+	// TODO: do not hard code CHAR_BITS
+	__ensure((unsigned int)signo < sizeof(sigset_t) * 8);
+	return (*set) & (sigset_t(1) << signo);
+}
diff --git a/lib/mlibc/options/internal/generic/strings.cpp b/lib/mlibc/options/internal/generic/strings.cpp
new file mode 100644
index 0000000..ce4f84b
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/strings.cpp
@@ -0,0 +1,22 @@
+#include <ctype.h>
+
+#include <mlibc/strings.hpp>
+
+namespace mlibc {
+
+int strncasecmp(const char *a, const char *b, size_t size) {
+	for(size_t i = 0; i < size; i++) {
+		unsigned char a_byte = tolower(a[i]);
+		unsigned char b_byte = tolower(b[i]);
+		if(!a_byte && !b_byte)
+			return 0;
+		// If only one char is null, one of the following cases applies.
+		if(a_byte < b_byte)
+			return -1;
+		if(a_byte > b_byte)
+			return 1;
+	}
+	return 0;
+}
+
+}
diff --git a/lib/mlibc/options/internal/generic/threads.cpp b/lib/mlibc/options/internal/generic/threads.cpp
new file mode 100644
index 0000000..5f1168c
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/threads.cpp
@@ -0,0 +1,342 @@
+#include <abi-bits/errno.h>
+#include <bits/threads.h>
+#include <bits/ensure.h>
+#include <mlibc/all-sysdeps.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/lock.hpp>
+#include <mlibc/threads.hpp>
+#include <mlibc/tcb.hpp>
+
+extern "C" Tcb *__rtdl_allocateTcb();
+
+namespace mlibc {
+
+int thread_create(struct __mlibc_thread_data **__restrict thread, const struct __mlibc_threadattr *__restrict attrp, void *entry, void *__restrict user_arg, bool returns_int) {
+	auto new_tcb = __rtdl_allocateTcb();
+	pid_t tid;
+	struct __mlibc_threadattr attr = {};
+	if (!attrp)
+		thread_attr_init(&attr);
+	else
+		attr = *attrp;
+
+	if (attr.__mlibc_cpuset)
+		mlibc::infoLogger() << "pthread_create(): cpuset is ignored!" << frg::endlog;
+	if (attr.__mlibc_sigmaskset)
+		mlibc::infoLogger() << "pthread_create(): sigmask is ignored!" << frg::endlog;
+
+	// TODO: due to alignment guarantees, the stackaddr and stacksize might change
+	// when the stack is allocated. Currently this isn't propagated to the TCB,
+	// but it should be.
+	void *stack = attr.__mlibc_stackaddr;
+	if (!mlibc::sys_prepare_stack) {
+		MLIBC_MISSING_SYSDEP();
+		return ENOSYS;
+	}
+	int ret = mlibc::sys_prepare_stack(&stack, entry,
+			user_arg, new_tcb, &attr.__mlibc_stacksize, &attr.__mlibc_guardsize, &new_tcb->stackAddr);
+	if (ret)
+		return ret;
+
+	if (!mlibc::sys_clone) {
+		MLIBC_MISSING_SYSDEP();
+		return ENOSYS;
+	}
+	new_tcb->stackSize = attr.__mlibc_stacksize;
+	new_tcb->guardSize = attr.__mlibc_guardsize;
+	new_tcb->returnValueType = (returns_int) ? TcbThreadReturnValue::Integer : TcbThreadReturnValue::Pointer;
+	mlibc::sys_clone(new_tcb, &tid, stack);
+	*thread = reinterpret_cast<struct __mlibc_thread_data *>(new_tcb);
+
+	__atomic_store_n(&new_tcb->tid, tid, __ATOMIC_RELAXED);
+	mlibc::sys_futex_wake(&new_tcb->tid);
+
+	return 0;
+}
+
+int thread_join(struct __mlibc_thread_data *thread, void *ret) {
+	auto tcb = reinterpret_cast<Tcb *>(thread);
+
+	if (!__atomic_load_n(&tcb->isJoinable, __ATOMIC_ACQUIRE))
+		return EINVAL;
+
+	while (!__atomic_load_n(&tcb->didExit, __ATOMIC_ACQUIRE)) {
+		mlibc::sys_futex_wait(&tcb->didExit, 0, nullptr);
+	}
+
+	if(ret && tcb->returnValueType == TcbThreadReturnValue::Pointer)
+		*reinterpret_cast<void **>(ret) = tcb->returnValue.voidPtr;
+	else if(ret && tcb->returnValueType == TcbThreadReturnValue::Integer)
+		*reinterpret_cast<int *>(ret) = tcb->returnValue.intVal;
+
+	// FIXME: destroy tcb here, currently we leak it
+
+	return 0;
+}
+
+static constexpr size_t default_stacksize = 0x200000;
+static constexpr size_t default_guardsize = 4096;
+
+int thread_attr_init(struct __mlibc_threadattr *attr) {
+	*attr = __mlibc_threadattr{};
+	attr->__mlibc_stacksize = default_stacksize;
+	attr->__mlibc_guardsize = default_guardsize;
+	attr->__mlibc_detachstate = __MLIBC_THREAD_CREATE_JOINABLE;
+	return 0;
+}
+
+static constexpr unsigned int mutexRecursive = 1;
+static constexpr unsigned int mutexErrorCheck = 2;
+
+// TODO: either use uint32_t or determine the bit based on sizeof(int).
+static constexpr unsigned int mutex_owner_mask = (static_cast<uint32_t>(1) << 30) - 1;
+static constexpr unsigned int mutex_waiters_bit = static_cast<uint32_t>(1) << 31;
+
+// Only valid for the internal __mlibc_m mutex of wrlocks.
+static constexpr unsigned int mutex_excl_bit = static_cast<uint32_t>(1) << 30;
+
+int thread_mutex_init(struct __mlibc_mutex *__restrict mutex,
+		const struct __mlibc_mutexattr *__restrict attr) {
+	auto type = attr ? attr->__mlibc_type : __MLIBC_THREAD_MUTEX_DEFAULT;
+	auto robust = attr ? attr->__mlibc_robust : __MLIBC_THREAD_MUTEX_STALLED;
+	auto protocol = attr ? attr->__mlibc_protocol : __MLIBC_THREAD_PRIO_NONE;
+	auto pshared = attr ? attr->__mlibc_pshared : __MLIBC_THREAD_PROCESS_PRIVATE;
+
+	mutex->__mlibc_state = 0;
+	mutex->__mlibc_recursion = 0;
+	mutex->__mlibc_flags = 0;
+	mutex->__mlibc_prioceiling = 0; // TODO: We don't implement this.
+
+	if(type == __MLIBC_THREAD_MUTEX_RECURSIVE) {
+		mutex->__mlibc_flags |= mutexRecursive;
+	}else if(type == __MLIBC_THREAD_MUTEX_ERRORCHECK) {
+		mutex->__mlibc_flags |= mutexErrorCheck;
+	}else{
+		__ensure(type == __MLIBC_THREAD_MUTEX_NORMAL);
+	}
+
+	// TODO: Other values aren't supported yet.
+	__ensure(robust == __MLIBC_THREAD_MUTEX_STALLED);
+	__ensure(protocol == __MLIBC_THREAD_PRIO_NONE);
+	__ensure(pshared == __MLIBC_THREAD_PROCESS_PRIVATE);
+
+	return 0;
+}
+
+int thread_mutex_destroy(struct __mlibc_mutex *mutex) {
+	__ensure(!mutex->__mlibc_state);
+	return 0;
+}
+
+int thread_mutex_lock(struct __mlibc_mutex *mutex) {
+	unsigned int this_tid = mlibc::this_tid();
+	unsigned int expected = 0;
+	while(true) {
+		if(!expected) {
+			// Try to take the mutex here.
+			if(__atomic_compare_exchange_n(&mutex->__mlibc_state,
+					&expected, this_tid, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
+				__ensure(!mutex->__mlibc_recursion);
+				mutex->__mlibc_recursion = 1;
+				return 0;
+			}
+		}else{
+			// If this (recursive) mutex is already owned by us, increment the recursion level.
+			if((expected & mutex_owner_mask) == this_tid) {
+				if(!(mutex->__mlibc_flags & mutexRecursive)) {
+					if (mutex->__mlibc_flags & mutexErrorCheck)
+						return EDEADLK;
+					else
+						mlibc::panicLogger() << "mlibc: pthread_mutex deadlock detected!"
+							<< frg::endlog;
+				}
+				++mutex->__mlibc_recursion;
+				return 0;
+			}
+
+			// Wait on the futex if the waiters flag is set.
+			if(expected & mutex_waiters_bit) {
+				int e = mlibc::sys_futex_wait((int *)&mutex->__mlibc_state, expected, nullptr);
+
+				// If the wait returns EAGAIN, that means that the mutex_waiters_bit was just unset by
+				// some other thread. In this case, we should loop back around.
+				if (e && e != EAGAIN)
+					mlibc::panicLogger() << "sys_futex_wait() failed with error code " << e << frg::endlog;
+
+				// Opportunistically try to take the lock after we wake up.
+				expected = 0;
+			}else{
+				// Otherwise we have to set the waiters flag first.
+				unsigned int desired = expected | mutex_waiters_bit;
+				if(__atomic_compare_exchange_n((int *)&mutex->__mlibc_state,
+						reinterpret_cast<int*>(&expected), desired, false, __ATOMIC_RELAXED, __ATOMIC_RELAXED))
+					expected = desired;
+			}
+		}
+	}
+}
+
+int thread_mutex_unlock(struct __mlibc_mutex *mutex) {
+	// Decrement the recursion level and unlock if we hit zero.
+	__ensure(mutex->__mlibc_recursion);
+	if(--mutex->__mlibc_recursion)
+		return 0;
+
+	auto flags = mutex->__mlibc_flags;
+
+	// Reset the mutex to the unlocked state.
+	auto state = __atomic_exchange_n(&mutex->__mlibc_state, 0, __ATOMIC_RELEASE);
+
+	// After this point the mutex is unlocked, and therefore we cannot access its contents as it
+	// may have been destroyed by another thread.
+
+	unsigned int this_tid = mlibc::this_tid();
+	if ((flags & mutexErrorCheck) && (state & mutex_owner_mask) != this_tid)
+		return EPERM;
+
+	if ((flags & mutexErrorCheck) && !(state & mutex_owner_mask))
+		return EINVAL;
+
+	__ensure((state & mutex_owner_mask) == this_tid);
+
+	if(state & mutex_waiters_bit) {
+		// Wake the futex if there were waiters. Since the mutex might not exist at this location
+		// anymore, we must conservatively ignore EACCES and EINVAL which may occur as a result.
+		int e = mlibc::sys_futex_wake((int *)&mutex->__mlibc_state);
+		__ensure(e >= 0 || e == EACCES || e == EINVAL);
+	}
+
+	return 0;
+}
+
+int thread_mutexattr_init(struct __mlibc_mutexattr *attr) {
+	attr->__mlibc_type = __MLIBC_THREAD_MUTEX_DEFAULT;
+	attr->__mlibc_robust = __MLIBC_THREAD_MUTEX_STALLED;
+	attr->__mlibc_pshared = __MLIBC_THREAD_PROCESS_PRIVATE;
+	attr->__mlibc_protocol = __MLIBC_THREAD_PRIO_NONE;
+	return 0;
+}
+
+int thread_mutexattr_destroy(struct __mlibc_mutexattr *attr) {
+	memset(attr, 0, sizeof(*attr));
+	return 0;
+}
+
+int thread_mutexattr_gettype(const struct __mlibc_mutexattr *__restrict attr, int *__restrict type) {
+	*type = attr->__mlibc_type;
+	return 0;
+}
+
+int thread_mutexattr_settype(struct __mlibc_mutexattr *attr, int type) {
+	if (type != __MLIBC_THREAD_MUTEX_NORMAL && type != __MLIBC_THREAD_MUTEX_ERRORCHECK
+			&& type != __MLIBC_THREAD_MUTEX_RECURSIVE)
+		return EINVAL;
+
+	attr->__mlibc_type = type;
+	return 0;
+}
+
+int thread_cond_init(struct __mlibc_cond *__restrict cond, const struct __mlibc_condattr *__restrict attr) {
+	auto clock = attr ? attr->__mlibc_clock : CLOCK_REALTIME;
+	auto pshared = attr ? attr->__mlibc_pshared : __MLIBC_THREAD_PROCESS_PRIVATE;
+
+	cond->__mlibc_clock = clock;
+	cond->__mlibc_flags = pshared;
+
+	__atomic_store_n(&cond->__mlibc_seq, 1, __ATOMIC_RELAXED);
+
+	return 0;
+}
+
+int thread_cond_destroy(struct __mlibc_cond *) {
+	return 0;
+}
+
+int thread_cond_broadcast(struct __mlibc_cond *cond) {
+	__atomic_fetch_add(&cond->__mlibc_seq, 1, __ATOMIC_RELEASE);
+	if(int e = mlibc::sys_futex_wake((int *)&cond->__mlibc_seq); e)
+		__ensure(!"sys_futex_wake() failed");
+
+	return 0;
+}
+
+int thread_cond_timedwait(struct __mlibc_cond *__restrict cond, __mlibc_mutex *__restrict mutex,
+		const struct timespec *__restrict abstime) {
+	// TODO: pshared isn't supported yet.
+	__ensure(cond->__mlibc_flags == 0);
+
+	constexpr long nanos_per_second = 1'000'000'000;
+	if (abstime && (abstime->tv_nsec < 0 || abstime->tv_nsec >= nanos_per_second))
+		return EINVAL;
+
+	auto seq = __atomic_load_n(&cond->__mlibc_seq, __ATOMIC_ACQUIRE);
+
+	// TODO: handle locking errors and cancellation properly.
+	while (true) {
+		if (thread_mutex_unlock(mutex))
+			__ensure(!"Failed to unlock the mutex");
+
+		int e;
+		if (abstime) {
+			// Adjust for the fact that sys_futex_wait accepts a *timeout*, but
+			// pthread_cond_timedwait accepts an *absolute time*.
+			// Note: mlibc::sys_clock_get is available unconditionally.
+			struct timespec now;
+			if (mlibc::sys_clock_get(cond->__mlibc_clock, &now.tv_sec, &now.tv_nsec))
+				__ensure(!"sys_clock_get() failed");
+
+			struct timespec timeout;
+			timeout.tv_sec = abstime->tv_sec - now.tv_sec;
+			timeout.tv_nsec = abstime->tv_nsec - now.tv_nsec;
+
+			// Check if abstime has already passed.
+			if (timeout.tv_sec < 0 || (timeout.tv_sec == 0 && timeout.tv_nsec < 0)) {
+				if (thread_mutex_lock(mutex))
+					__ensure(!"Failed to lock the mutex");
+				return ETIMEDOUT;
+			} else if (timeout.tv_nsec >= nanos_per_second) {
+				timeout.tv_nsec -= nanos_per_second;
+				timeout.tv_sec++;
+				__ensure(timeout.tv_nsec < nanos_per_second);
+			} else if (timeout.tv_nsec < 0) {
+				timeout.tv_nsec += nanos_per_second;
+				timeout.tv_sec--;
+				__ensure(timeout.tv_nsec >= 0);
+			}
+
+			e = mlibc::sys_futex_wait((int *)&cond->__mlibc_seq, seq, &timeout);
+		} else {
+			e = mlibc::sys_futex_wait((int *)&cond->__mlibc_seq, seq, nullptr);
+		}
+
+		if (thread_mutex_lock(mutex))
+			__ensure(!"Failed to lock the mutex");
+
+		// There are four cases to handle:
+		//   1. e == 0: this indicates a (potentially spurious) wakeup. The value of
+		//      seq *must* be checked to distinguish these two cases.
+		//   2. e == EAGAIN: this indicates that the value of seq changed before we
+		//      went to sleep. We don't need to check seq in this case.
+		//   3. e == EINTR: a signal was delivered. The man page allows us to choose
+		//      whether to go to sleep again or to return 0, but we do the former
+		//      to match other libcs.
+		//   4. e == ETIMEDOUT: this should only happen if abstime is set.
+		if (e == 0) {
+			auto cur_seq = __atomic_load_n(&cond->__mlibc_seq, __ATOMIC_ACQUIRE);
+			if (cur_seq > seq)
+				return 0;
+		} else if (e == EAGAIN) {
+			__ensure(__atomic_load_n(&cond->__mlibc_seq, __ATOMIC_ACQUIRE) > seq);
+			return 0;
+		} else if (e == EINTR) {
+			continue;
+		} else if (e == ETIMEDOUT) {
+			__ensure(abstime);
+			return ETIMEDOUT;
+		} else {
+			mlibc::panicLogger() << "sys_futex_wait() failed with error " << e << frg::endlog;
+		}
+	}
+}
+
+} // namespace mlibc
diff --git a/lib/mlibc/options/internal/generic/ubsan.cpp b/lib/mlibc/options/internal/generic/ubsan.cpp
new file mode 100644
index 0000000..3491729
--- /dev/null
+++ b/lib/mlibc/options/internal/generic/ubsan.cpp
@@ -0,0 +1,254 @@
+#include <limits.h>
+#include <mlibc/debug.hpp>
+
+#define FMT(obj) format_object((obj), opts, formatter)
+
+#define LOG_NAME_LOC(name, loc) "ubsan: " name " at " << loc << "\n  "
+#define LOG_LHS_RHS(lhs, rhs) "LHS = " << (lhs) << ", RHS = " << (rhs)
+
+struct SourceLocation {
+	const char *filename;
+	uint32_t line;
+	uint32_t column;
+};
+
+template<class F>
+void format_object(const SourceLocation &loc, frg::format_options opts, F &formatter) {
+	FMT(loc.filename);
+	FMT(":");
+	FMT(loc.line);
+	FMT(":");
+	FMT(loc.column);
+}
+
+using ValueHandle = uintptr_t;
+
+struct TypeDescriptor {
+	enum class Kind : uint16_t {
+		Integer = 0x0000,
+		Float = 0x0001,
+		Unknown = 0xffff
+	} kind;
+
+	uint16_t info;
+	char name[];
+
+	unsigned bitWidthInt() const {
+		return 1 << (info >> 1);
+	}
+
+	bool isInlineInt() const {
+		if (kind != Kind::Integer)
+			return false;
+
+		auto inlineBits = sizeof(ValueHandle) * CHAR_BIT;
+		auto valueBits = bitWidthInt();
+		return inlineBits <= valueBits;
+	}
+
+	bool isSigned() const {
+		return info & 1;
+	}
+};
+
+template<class F>
+void format_object(const TypeDescriptor &type, frg::format_options opts, F &formatter) {
+	FMT(type.name);
+}
+
+struct Value {
+	const TypeDescriptor &type;
+	ValueHandle val;
+
+	Value(const TypeDescriptor &type, ValueHandle val) : type(type), val(val) {}
+};
+
+template<class F>
+void format_object(const Value &val, frg::format_options opts, F &formatter) {
+	if (val.type.isInlineInt() && val.type.isSigned()) {
+		auto signedValue = static_cast<int64_t>(val.val);
+		FMT(signedValue);
+	} else if (val.type.isInlineInt() && !val.type.isSigned()) {
+		auto unsignedValue = static_cast<uint64_t>(val.val);
+		FMT(unsignedValue);
+	}
+
+	FMT(" (");
+	FMT(val.type);
+	FMT(")");
+}
+
+
+// --- Hook implementations ---
+
+struct TypeMismatch {
+	SourceLocation loc;
+	const TypeDescriptor &type;
+	unsigned char logAlignment;
+	unsigned char kind;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_type_mismatch_v1(TypeMismatch *tm, ValueHandle pointer) {
+	// TODO: Make this print more information.
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("type mismatch", tm->loc)
+		<< "accessed address " << (void *)pointer << " but type "
+		<< tm->type << " requires alignment " << (1 << tm->logAlignment)
+		<< frg::endlog;
+}
+
+struct PointerOverflowData {
+	SourceLocation loc;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_pointer_overflow(PointerOverflowData *pod, ValueHandle base, ValueHandle result) {
+	(void)base;
+	(void)result;
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("pointer overflow", pod->loc)
+		<< frg::endlog;
+}
+
+struct InvalidValueData {
+	SourceLocation loc;
+	const TypeDescriptor &type;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_load_invalid_value(InvalidValueData *ivd, ValueHandle value) {
+	(void)value;
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("load of invalid value", ivd->loc)
+		<< frg::endlog;
+}
+
+struct OverflowData {
+	SourceLocation loc;
+	const TypeDescriptor &type;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_add_overflow(OverflowData *od, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("add overflowed ", od->loc)
+		<< LOG_LHS_RHS(Value(od->type, lhs), Value(od->type, rhs))
+		<< frg::endlog;
+}
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_sub_overflow(OverflowData *od, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("sub overflowed", od->loc)
+		<< LOG_LHS_RHS(Value(od->type, lhs), Value(od->type, rhs))
+		<< frg::endlog;
+}
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_mul_overflow(OverflowData *od, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("mul overflowed", od->loc)
+		<< LOG_LHS_RHS(Value(od->type, lhs), Value(od->type, rhs))
+		<< frg::endlog;
+}
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_divrem_overflow(OverflowData *od, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("divrem overflowed", od->loc)
+		<< LOG_LHS_RHS(Value(od->type, lhs), Value(od->type, rhs))
+		<< frg::endlog;
+}
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_negate_overflow(OverflowData *od, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("negate overflowed", od->loc)
+		<< LOG_LHS_RHS(Value(od->type, lhs), Value(od->type, rhs))
+		<< frg::endlog;
+}
+
+struct ShiftOutOfBoundsData {
+	SourceLocation loc;
+	const TypeDescriptor &lhsType;
+	const TypeDescriptor &rhsType;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_shift_out_of_bounds(ShiftOutOfBoundsData *soob, ValueHandle lhs, ValueHandle rhs) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("shift out of bounds", soob->loc)
+		<< LOG_LHS_RHS(Value(soob->lhsType, lhs), Value(soob->rhsType, rhs))
+		<< frg::endlog;
+}
+
+struct OutOfBoundsData {
+	SourceLocation loc;
+	const TypeDescriptor &arrayType;
+	const TypeDescriptor &indexType;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_out_of_bounds(OutOfBoundsData *oobd, ValueHandle data) {
+	(void)data;
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("out of bounds access", oobd->loc)
+		<< frg::endlog;
+}
+
+struct UnreachableData {
+	SourceLocation loc;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_builtin_unreachable(UnreachableData *ubd) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("reached __builtin_unreachable()", ubd->loc)
+		<< frg::endlog;
+}
+
+struct InvalidBuiltinData {
+	SourceLocation loc;
+	unsigned char kind;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_invalid_builtin(InvalidBuiltinData *ibd) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("reached invalid builtin", ibd->loc)
+		<< frg::endlog;
+}
+
+struct VLABoundData {
+	SourceLocation loc;
+	const TypeDescriptor &type;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_vla_bound_not_positive(VLABoundData *vlabd) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("VLA bound not positive", vlabd->loc)
+		<< frg::endlog;
+}
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_missing_return(UnreachableData *data) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("reached end of a value-returning function without returning a value", data->loc)
+		<< frg::endlog;
+}
+
+struct NonNullArgData {
+	SourceLocation loc;
+	SourceLocation attr_loc;
+	int arg_index;
+};
+
+extern "C" [[gnu::visibility("hidden")]]
+void __ubsan_handle_nonnull_arg(NonNullArgData *data) {
+	mlibc::panicLogger()
+		<< LOG_NAME_LOC("null pointer passed to non-null argument", data->loc)
+		<< "argument " << data->arg_index << " is required to be non-null in "
+		<< data->attr_loc << frg::endlog;
+}
diff --git a/lib/mlibc/options/internal/include/bits/cpu_set.h b/lib/mlibc/options/internal/include/bits/cpu_set.h
new file mode 100644
index 0000000..69f6923
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/cpu_set.h
@@ -0,0 +1,13 @@
+#ifndef _MLIBC_INTERNAL_CPU_SET_H
+#define _MLIBC_INTERNAL_CPU_SET_H
+
+typedef unsigned long __cpu_mask;
+
+#define CPU_SETSIZE 1024
+#define __NCPUBITS (8 * sizeof(__cpu_mask))
+
+typedef struct {
+	__cpu_mask __bits[CPU_SETSIZE / __NCPUBITS];
+} cpu_set_t;
+
+#endif /* _MLIBC_INTERNAL_CPU_SET_H */
diff --git a/lib/mlibc/options/internal/include/bits/ensure.h b/lib/mlibc/options/internal/include/bits/ensure.h
new file mode 100644
index 0000000..f75a2e9
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/ensure.h
@@ -0,0 +1,45 @@
+
+#ifndef MLIBC_ENSURE_H
+#define MLIBC_ENSURE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef __MLIBC_ABI_ONLY
+
+void __ensure_fail(const char *assertion, const char *file, unsigned int line,
+		const char *function);
+
+void __ensure_warn(const char *assertion, const char *file, unsigned int line,
+		const char *function);
+
+#endif /* !__MLIBC_ABI_ONLY */
+
+#define __ensure(assertion) do { if(!(assertion)) \
+		__ensure_fail(#assertion, __FILE__, __LINE__, __func__); } while(0)
+
+#define MLIBC_UNIMPLEMENTED() __ensure_fail("Functionality is not implemented", \
+		__FILE__, __LINE__, __func__)
+
+#define MLIBC_MISSING_SYSDEP() __ensure_warn("Library function fails due to missing sysdep", \
+		__FILE__, __LINE__, __func__)
+
+#define MLIBC_CHECK_OR_ENOSYS(sysdep, ret) ({ \
+			if (!(sysdep)) { \
+				__ensure_warn("Library function fails due to missing sysdep", \
+					__FILE__, __LINE__, __func__); \
+				errno = ENOSYS; \
+				return (ret); \
+			} \
+			sysdep; \
+		})
+
+#define MLIBC_STUB_BODY { MLIBC_UNIMPLEMENTED(); __builtin_unreachable(); }
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // MLIBC_ENSURE_H
+
diff --git a/lib/mlibc/options/internal/include/bits/ether_addr.h b/lib/mlibc/options/internal/include/bits/ether_addr.h
new file mode 100644
index 0000000..1631e98
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/ether_addr.h
@@ -0,0 +1,10 @@
+#ifndef MLIBC_ETHER_ADDR_H
+#define MLIBC_ETHER_ADDR_H
+
+#include <stdint.h>
+
+struct ether_addr {
+	uint8_t ether_addr_octet[6];
+} __attribute__((__packed__));
+
+#endif // MLIBC_ETHER_ADDR_H
diff --git a/lib/mlibc/options/internal/include/bits/inline-definition.h b/lib/mlibc/options/internal/include/bits/inline-definition.h
new file mode 100644
index 0000000..ec4c4da
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/inline-definition.h
@@ -0,0 +1,19 @@
+#ifndef MLIBC_INLINE_DEFINITION_H
+#define MLIBC_INLINE_DEFINITION_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __MLIBC_EMIT_INLINE_DEFINITIONS
+#define __MLIBC_INLINE_DEFINITION
+#else
+#define __MLIBC_INLINE_DEFINITION __attribute__((__gnu_inline__)) extern __inline__
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // MLIBC_INLINE_DEFINITION_H
+
diff --git a/lib/mlibc/options/internal/include/bits/machine.h b/lib/mlibc/options/internal/include/bits/machine.h
new file mode 100644
index 0000000..371a94b
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/machine.h
@@ -0,0 +1,86 @@
+
+#ifndef MLIBC_MACHINE_H
+#define MLIBC_MACHINE_H
+
+#include <stdint.h>
+
+#if defined (__i386__)
+struct __mlibc_jmpbuf_register_state {
+	uint32_t ebx;
+	uint32_t ebp;
+	uint32_t esi;
+	uint32_t edi;
+	uint32_t esp;
+	uint32_t eip;
+};
+#elif defined (__x86_64__)
+struct __mlibc_jmpbuf_register_state {
+	uint64_t rbx;
+	uint64_t rbp;
+	uint64_t r12;
+	uint64_t r13;
+	uint64_t r14;
+	uint64_t r15;
+	uint64_t rsp;
+	uint64_t rip;
+};
+#elif defined (__aarch64__)
+struct __mlibc_jmpbuf_register_state {
+	uint64_t x19;
+	uint64_t x20;
+	uint64_t x21;
+	uint64_t x22;
+	uint64_t x23;
+	uint64_t x24;
+	uint64_t x25;
+	uint64_t x26;
+	uint64_t x27;
+	uint64_t x28;
+	uint64_t x29;
+	uint64_t x30;
+	uint64_t sp;
+	uint64_t pad;
+	uint64_t d8;
+	uint64_t d9;
+	uint64_t d10;
+	uint64_t d11;
+	uint64_t d12;
+	uint64_t d13;
+	uint64_t d14;
+	uint64_t d15;
+};
+#elif defined (__riscv) && __riscv_xlen == 64
+struct __mlibc_jmpbuf_register_state {
+	uint64_t ra;
+	uint64_t s0;
+	uint64_t s1;
+	uint64_t s2;
+	uint64_t s3;
+	uint64_t s4;
+	uint64_t s5;
+	uint64_t s6;
+	uint64_t s7;
+	uint64_t s8;
+	uint64_t s9;
+	uint64_t s10;
+	uint64_t s11;
+	uint64_t sp;
+	double fs0;
+	double fs1;
+	double fs2;
+	double fs3;
+	double fs4;
+	double fs5;
+	double fs6;
+	double fs7;
+	double fs8;
+	double fs9;
+	double fs10;
+	double fs11;
+};
+#else
+#  error "Missing architecture specific code"
+#endif
+
+#endif // MLIBC_MACHINE_H
+
diff --git a/lib/mlibc/options/internal/include/bits/mbstate.h b/lib/mlibc/options/internal/include/bits/mbstate.h
new file mode 100644
index 0000000..2bfb3eb
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/mbstate.h
@@ -0,0 +1,12 @@
+#ifndef MLIBC_MBSTATE_H
+#define MLIBC_MBSTATE_H
+
+struct __mlibc_mbstate {
+	short __progress;
+	short __shift;
+	unsigned int __cpoint;
+};
+
+#define __MLIBC_MBSTATE_INITIALIZER {0, 0, 0}
+
+#endif // MLIBC_MBSTATE_H
diff --git a/lib/mlibc/options/internal/include/bits/nl_item.h b/lib/mlibc/options/internal/include/bits/nl_item.h
new file mode 100644
index 0000000..dc882dc
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/nl_item.h
@@ -0,0 +1,82 @@
+
+#ifndef _NL_ITEM_H
+#define _NL_ITEM_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int nl_item;
+
+#define ABDAY_1 0x60000
+#define ABDAY_2 0x60001
+#define ABDAY_3 0x60002
+#define ABDAY_4 0x60003
+#define ABDAY_5 0x60004
+#define ABDAY_6 0x60005
+#define ABDAY_7 0x60006
+
+#define DAY_1 0x60007
+#define DAY_2 0x60008
+#define DAY_3 0x60009
+#define DAY_4 0x6000A
+#define DAY_5 0x6000B
+#define DAY_6 0x6000C
+#define DAY_7 0x6000D
+
+#define ABMON_1 0x6000E
+#define ABMON_2 0x6000F
+#define ABMON_3 0x60010
+#define ABMON_4 0x60011
+#define ABMON_5 0x60012
+#define ABMON_6 0x60013
+#define ABMON_7 0x60014
+#define ABMON_8 0x60015
+#define ABMON_9 0x60016
+#define ABMON_10 0x60017
+#define ABMON_11 0x60018
+#define ABMON_12 0x60019
+
+#define MON_1 0x6001A
+#define MON_2 0x6001B
+#define MON_3 0x6001C
+#define MON_4 0x6001D
+#define MON_5 0x6001E
+#define MON_6 0x6001F
+#define MON_7 0x60020
+#define MON_8 0x60021
+#define MON_9 0x60022
+#define MON_10 0x60023
+#define MON_11 0x60024
+#define MON_12 0x60025
+
+#define AM_STR 0x60026
+#define PM_STR 0x60027
+
+#define D_T_FMT 0x60028
+#define D_FMT 0x60029
+#define T_FMT 0x6002A
+#define T_FMT_AMPM 0x6002B
+
+#define ERA 0x6002C
+#define ERA_D_FMT 0x6002D
+#define ALT_DIGITS 0x6002E
+#define ERA_D_T_FMT 0x6002F
+#define ERA_T_FMT 0x60030
+
+#define CODESET 0x30000
+
+#define CRNCYSTR 0x40000
+
+#define RADIXCHAR 0x50000
+#define THOUSEP 0x50001
+
+#define YESEXPR 0x70000
+#define NOEXPR 0x70001
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _NL_ITEM_H
+
diff --git a/lib/mlibc/options/internal/include/bits/null.h b/lib/mlibc/options/internal/include/bits/null.h
new file mode 100644
index 0000000..7d3fa7b
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/null.h
@@ -0,0 +1,16 @@
+
+#ifndef MLIBC_NULL_H
+#define MLIBC_NULL_H
+
+#ifdef NULL
+#undef NULL
+#endif
+
+#ifndef __cplusplus
+#  define NULL ((void *)0)
+#else
+#  define NULL 0
+#endif
+
+#endif // MLIBC_NULL_H
+
diff --git a/lib/mlibc/options/internal/include/bits/off_t.h b/lib/mlibc/options/internal/include/bits/off_t.h
new file mode 100644
index 0000000..929fae9
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/off_t.h
@@ -0,0 +1,8 @@
+#ifndef MLIBC_OFF_T_H
+#define MLIBC_OFF_T_H
+
+// TODO: use something like int64_t instead?
+typedef long off_t;
+typedef long off64_t;
+
+#endif // MLIBC_OFF_T_H
diff --git a/lib/mlibc/options/internal/include/bits/sigset_t.h b/lib/mlibc/options/internal/include/bits/sigset_t.h
new file mode 100644
index 0000000..bb86848
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/sigset_t.h
@@ -0,0 +1,25 @@
+#ifndef MLIBC_BITS_SIGSET_T_H
+#define MLIBC_BITS_SIGSET_T_H
+
+#include <abi-bits/signal.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef __MLIBC_ABI_ONLY
+
+// functions to manage sigset_t
+int sigemptyset(sigset_t *);
+int sigfillset(sigset_t *);
+int sigaddset(sigset_t *, int);
+int sigdelset(sigset_t *, int);
+int sigismember(const sigset_t *set, int sig);
+
+#endif /* !__MLIBC_ABI_ONLY */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif //MLIBC_BITS_SIGSET_T_H
diff --git a/lib/mlibc/options/internal/include/bits/size_t.h b/lib/mlibc/options/internal/include/bits/size_t.h
new file mode 100644
index 0000000..46d7486
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/size_t.h
@@ -0,0 +1,6 @@
+#ifndef MLIBC_SIZE_T_H
+#define MLIBC_SIZE_T_H
+
+typedef __SIZE_TYPE__ size_t;
+
+#endif // MLIBC_SIZE_T_H
diff --git a/lib/mlibc/options/internal/include/bits/ssize_t.h b/lib/mlibc/options/internal/include/bits/ssize_t.h
new file mode 100644
index 0000000..c450233
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/ssize_t.h
@@ -0,0 +1,15 @@
+
+#ifndef MLIBC_SSIZE_T_H
+#define MLIBC_SSIZE_T_H
+
+// TODO: use ptrdiff_t instead?
+#if __UINTPTR_MAX__ == __UINT64_MAX__
+typedef long ssize_t;
+#elif __UINTPTR_MAX__ == __UINT32_MAX__
+typedef int ssize_t;
+#else
+#error "unsupported architecture"
+#endif
+
+#endif // MLIBC_SSIZE_T_H
+
diff --git a/lib/mlibc/options/internal/include/bits/threads.h b/lib/mlibc/options/internal/include/bits/threads.h
new file mode 100644
index 0000000..3feb4c3
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/threads.h
@@ -0,0 +1,79 @@
+#ifndef _INTERNAL_THREADS_H
+#define _INTERNAL_THREADS_H
+
+#include <abi-bits/clockid_t.h>
+#include <bits/size_t.h>
+#include <bits/cpu_set.h>
+#include <bits/sigset_t.h>
+
+// values for pthread_attr_{get,set}detachstate().
+#define __MLIBC_THREAD_CREATE_JOINABLE 0
+#define __MLIBC_THREAD_CREATE_DETACHED 1
+
+// values for pthread_mutexattr_{get,set}type().
+#define __MLIBC_THREAD_MUTEX_DEFAULT 0
+#define __MLIBC_THREAD_MUTEX_NORMAL 0
+#define __MLIBC_THREAD_MUTEX_ERRORCHECK 1
+#define __MLIBC_THREAD_MUTEX_RECURSIVE 2
+
+// values for pthread_mutexattr_{get,set}pshared().
+#define __MLIBC_THREAD_PROCESS_PRIVATE 0
+#define __MLIBC_THREAD_PROCESS_SHARED 1
+
+// values for pthread_mutexattr_{get,set}robust().
+#define __MLIBC_THREAD_MUTEX_STALLED 0
+#define __MLIBC_THREAD_MUTEX_ROBUST 1
+
+// Values for pthread_mutexattr_{get,set}protocol()
+#define __MLIBC_THREAD_PRIO_NONE 0
+#define __MLIBC_THREAD_PRIO_INHERIT 1
+#define __MLIBC_THREAD_PRIO_PROTECT 2
+
+struct sched_param {
+	int sched_priority;
+};
+
+struct __mlibc_thread_data;
+
+struct __mlibc_threadattr {
+	size_t __mlibc_guardsize;
+	size_t __mlibc_stacksize;
+	void *__mlibc_stackaddr;
+	int __mlibc_detachstate;
+	int __mlibc_scope;
+	int __mlibc_inheritsched;
+	struct sched_param __mlibc_schedparam;
+	int __mlibc_schedpolicy;
+	cpu_set_t *__mlibc_cpuset;
+	size_t __mlibc_cpusetsize;
+	sigset_t __mlibc_sigmask;
+	int __mlibc_sigmaskset;
+};
+
+struct __mlibc_mutex {
+	unsigned int __mlibc_state;
+	unsigned int __mlibc_recursion;
+	unsigned int __mlibc_flags;
+	int __mlibc_prioceiling;
+};
+
+struct __mlibc_mutexattr {
+	int __mlibc_type;
+	int __mlibc_robust;
+	int __mlibc_protocol;
+	int __mlibc_pshared;
+	int __mlibc_prioceiling;
+};
+
+struct __mlibc_cond {
+	unsigned int __mlibc_seq;
+	unsigned int __mlibc_flags;
+	clockid_t __mlibc_clock;
+};
+
+struct __mlibc_condattr {
+	int __mlibc_pshared;
+	clockid_t __mlibc_clock;
+};
+
+#endif /* _INTERNAL_THREADS_H */
diff --git a/lib/mlibc/options/internal/include/bits/types.h b/lib/mlibc/options/internal/include/bits/types.h
new file mode 100644
index 0000000..935c5e0
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/types.h
@@ -0,0 +1,319 @@
+#ifndef _MLIBC_INTERNAL_TYPES_H
+#define _MLIBC_INTERNAL_TYPES_H
+
+typedef __UINT8_TYPE__  __mlibc_uint8;
+typedef __UINT16_TYPE__ __mlibc_uint16;
+typedef __UINT32_TYPE__ __mlibc_uint32;
+typedef __UINT64_TYPE__ __mlibc_uint64;
+
+typedef __INT8_TYPE__  __mlibc_int8;
+typedef __INT16_TYPE__ __mlibc_int16;
+typedef __INT32_TYPE__ __mlibc_int32;
+typedef __INT64_TYPE__ __mlibc_int64;
+
+// Clang and GCC have different mechanisms for INT32_C and friends.
+#ifdef __clang__
+#	define __MLIBC_C_EXPAND_JOIN(x, suffix) x ## suffix
+#	define __MLIBC_C_JOIN(x, suffix) __MLIBC_C_EXPAND_JOIN(x, suffix)
+
+#	define __MLIBC_INT8_C(x)  __MLIBC_C_JOIN(x, __INT8_C_SUFFIX__)
+#	define __MLIBC_INT16_C(x) __MLIBC_C_JOIN(x, __INT16_C_SUFFIX__)
+#	define __MLIBC_INT32_C(x) __MLIBC_C_JOIN(x, __INT32_C_SUFFIX__)
+#	define __MLIBC_INT64_C(x) __MLIBC_C_JOIN(x, __INT64_C_SUFFIX__)
+
+#	define __MLIBC_UINT8_C(x)  __MLIBC_C_JOIN(x, __UINT8_C_SUFFIX__)
+#	define __MLIBC_UINT16_C(x) __MLIBC_C_JOIN(x, __UINT16_C_SUFFIX__)
+#	define __MLIBC_UINT32_C(x) __MLIBC_C_JOIN(x, __UINT32_C_SUFFIX__)
+#	define __MLIBC_UINT64_C(x) __MLIBC_C_JOIN(x, __UINT64_C_SUFFIX__)
+
+#	define __MLIBC_INTMAX_C(x) __MLIBC_C_JOIN(x, __INTMAX_C_SUFFIX__)
+#	define __MLIBC_UINTMAX_C(x) __MLIBC_C_JOIN(x, __UINTMAX_C_SUFFIX__)
+#else
+#	define __MLIBC_INT8_C(x)  __INT8_C(x)
+#	define __MLIBC_INT16_C(x) __INT16_C(x)
+#	define __MLIBC_INT32_C(x) __INT32_C(x)
+#	define __MLIBC_INT64_C(x) __INT64_C(x)
+
+#	define __MLIBC_UINT8_C(x)  __UINT8_C(x)
+#	define __MLIBC_UINT16_C(x) __UINT16_C(x)
+#	define __MLIBC_UINT32_C(x) __UINT32_C(x)
+#	define __MLIBC_UINT64_C(x) __UINT64_C(x)
+
+#	define __MLIBC_INTMAX_C(x) __INTMAX_C(x)
+#	define __MLIBC_UINTMAX_C(x) __UINTMAX_C(x)
+#endif
+
+#define __MLIBC_INT8_MAX  __INT8_MAX__
+#define __MLIBC_INT16_MAX __INT16_MAX__
+#define __MLIBC_INT32_MAX __INT32_MAX__
+#define __MLIBC_INT64_MAX __INT64_MAX__
+
+#define __MLIBC_INT8_MIN  (-__MLIBC_INT8_MAX - 1)
+#define __MLIBC_INT16_MIN (-__MLIBC_INT16_MAX - 1)
+#define __MLIBC_INT32_MIN (-__MLIBC_INT32_MAX - 1)
+#define __MLIBC_INT64_MIN (-__MLIBC_INT64_MAX - 1)
+
+#define __MLIBC_UINT8_MAX  __UINT8_MAX__
+#define __MLIBC_UINT16_MAX __UINT16_MAX__
+#define __MLIBC_UINT32_MAX __UINT32_MAX__
+#define __MLIBC_UINT64_MAX __UINT64_MAX__
+
+// Fast types (signed).
+
+#if defined (__i386__)
+
+typedef __mlibc_int8 __mlibc_int_fast8;
+#define __MLIBC_INT_FAST8_C(x) __MLIBC_INT8_C(x)
+#define __MLIBC_INT_FAST8_MAX __MLIBC_INT8_MAX
+#define __MLIBC_INT_FAST8_MIN __MLIBC_INT8_MIN
+
+typedef __mlibc_int32 __mlibc_int_fast16;
+#define __MLIBC_INT_FAST16_C(x) __MLIBC_INT32_C(x)
+#define __MLIBC_INT_FAST16_MAX __MLIBC_INT32_MAX
+#define __MLIBC_INT_FAST16_MIN __MLIBC_INT32_MIN
+
+typedef __mlibc_int32 __mlibc_int_fast32;
+#define __MLIBC_INT_FAST32_C(x) __MLIBC_INT32_C(x)
+#define __MLIBC_INT_FAST32_MAX __MLIBC_INT32_MAX
+#define __MLIBC_INT_FAST32_MIN __MLIBC_INT32_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast64;
+#define __MLIBC_INT_FAST64_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST64_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST64_MIN __MLIBC_INT64_MIN
+
+#elif defined (__x86_64__)
+
+typedef __mlibc_int8 __mlibc_int_fast8;
+#define __MLIBC_INT_FAST8_C(x) __MLIBC_INT8_C(x)
+#define __MLIBC_INT_FAST8_MAX __MLIBC_INT8_MAX
+#define __MLIBC_INT_FAST8_MIN __MLIBC_INT8_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast16;
+#define __MLIBC_INT_FAST16_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST16_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST16_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast32;
+#define __MLIBC_INT_FAST32_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST32_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST32_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast64;
+#define __MLIBC_INT_FAST64_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST64_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST64_MIN __MLIBC_INT64_MIN
+
+#elif defined (__aarch64__)
+
+typedef __mlibc_int8 __mlibc_int_fast8;
+#define __MLIBC_INT_FAST8_C(x) __MLIBC_INT8_C(x)
+#define __MLIBC_INT_FAST8_MAX __MLIBC_INT8_MAX
+#define __MLIBC_INT_FAST8_MIN __MLIBC_INT8_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast16;
+#define __MLIBC_INT_FAST16_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST16_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST16_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast32;
+#define __MLIBC_INT_FAST32_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST32_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST32_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast64;
+#define __MLIBC_INT_FAST64_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST64_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST64_MIN __MLIBC_INT64_MIN
+
+#elif defined (__riscv) && __riscv_xlen == 64
+
+typedef __mlibc_int8 __mlibc_int_fast8;
+#define __MLIBC_INT_FAST8_C(x) __MLIBC_INT8_C(x)
+#define __MLIBC_INT_FAST8_MAX __MLIBC_INT8_MAX
+#define __MLIBC_INT_FAST8_MIN __MLIBC_INT8_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast16;
+#define __MLIBC_INT_FAST16_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST16_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST16_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast32;
+#define __MLIBC_INT_FAST32_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST32_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST32_MIN __MLIBC_INT64_MIN
+
+typedef __mlibc_int64 __mlibc_int_fast64;
+#define __MLIBC_INT_FAST64_C(x) __MLIBC_INT64_C(x)
+#define __MLIBC_INT_FAST64_MAX __MLIBC_INT64_MAX
+#define __MLIBC_INT_FAST64_MIN __MLIBC_INT64_MIN
+
+#else
+#  error "Missing architecture specific code"
+#endif
+
+// Fast types (unsigned).
+
+#if defined (__i386__)
+
+typedef __mlibc_uint8 __mlibc_uint_fast8;
+#define __MLIBC_UINT_FAST8_C(x) __MLIBC_UINT8_C(x)
+#define __MLIBC_UINT_FAST8_MAX __MLIBC_UINT8_MAX
+#define __MLIBC_UINT_FAST8_MIN __MLIBC_UINT8_MIN
+
+typedef __mlibc_uint32 __mlibc_uint_fast16;
+#define __MLIBC_UINT_FAST16_C(x) __MLIBC_UINT32_C(x)
+#define __MLIBC_UINT_FAST16_MAX __MLIBC_UINT32_MAX
+#define __MLIBC_UINT_FAST16_MIN __MLIBC_UINT32_MIN
+
+typedef __mlibc_uint32 __mlibc_uint_fast32;
+#define __MLIBC_UINT_FAST32_C(x) __MLIBC_UINT32_C(x)
+#define __MLIBC_UINT_FAST32_MAX __MLIBC_UINT32_MAX
+#define __MLIBC_UINT_FAST32_MIN __MLIBC_UINT32_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast64;
+#define __MLIBC_UINT_FAST64_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST64_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST64_MIN __MLIBC_UINT64_MIN
+
+#elif defined (__x86_64__)
+
+typedef __mlibc_uint8 __mlibc_uint_fast8;
+#define __MLIBC_UINT_FAST8_C(x) __MLIBC_UINT8_C(x)
+#define __MLIBC_UINT_FAST8_MAX __MLIBC_UINT8_MAX
+#define __MLIBC_UINT_FAST8_MIN __MLIBC_UINT8_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast16;
+#define __MLIBC_UINT_FAST16_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST16_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST16_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast32;
+#define __MLIBC_UINT_FAST32_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST32_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST32_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast64;
+#define __MLIBC_UINT_FAST64_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST64_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST64_MIN __MLIBC_UINT64_MIN
+
+#elif defined (__aarch64__)
+
+typedef __mlibc_uint8 __mlibc_uint_fast8;
+#define __MLIBC_UINT_FAST8_C(x) __MLIBC_UINT8_C(x)
+#define __MLIBC_UINT_FAST8_MAX __MLIBC_UINT8_MAX
+#define __MLIBC_UINT_FAST8_MIN __MLIBC_UINT8_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast16;
+#define __MLIBC_UINT_FAST16_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST16_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST16_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast32;
+#define __MLIBC_UINT_FAST32_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST32_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST32_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast64;
+#define __MLIBC_UINT_FAST64_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST64_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST64_MIN __MLIBC_UINT64_MIN
+
+#elif defined (__riscv) && __riscv_xlen == 64
+
+typedef __mlibc_uint8 __mlibc_uint_fast8;
+#define __MLIBC_UINT_FAST8_C(x) __MLIBC_UINT8_C(x)
+#define __MLIBC_UINT_FAST8_MAX __MLIBC_UINT8_MAX
+#define __MLIBC_UINT_FAST8_MIN __MLIBC_UINT8_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast16;
+#define __MLIBC_UINT_FAST16_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST16_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST16_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast32;
+#define __MLIBC_UINT_FAST32_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST32_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST32_MIN __MLIBC_UINT64_MIN
+
+typedef __mlibc_uint64 __mlibc_uint_fast64;
+#define __MLIBC_UINT_FAST64_C(x) __MLIBC_UINT64_C(x)
+#define __MLIBC_UINT_FAST64_MAX __MLIBC_UINT64_MAX
+#define __MLIBC_UINT_FAST64_MIN __MLIBC_UINT64_MIN
+
+#else
+#  error "Missing architecture specific code"
+#endif
+
+// Special types.
+
+typedef __INTMAX_TYPE__  __mlibc_intmax;
+typedef __INTPTR_TYPE__  __mlibc_intptr;
+typedef __PTRDIFF_TYPE__ __mlibc_ptrdiff;
+#define __MLIBC_INTMAX_MAX __INTMAX_MAX__
+#define __MLIBC_INTMAX_MIN (-__INTMAX_MAX__ - 1)
+#define __MLIBC_INTPTR_MAX __INTPTR_MAX__
+#define __MLIBC_INTPTR_MIN (-__INTPTR_MAX__ - 1)
+#define __MLIBC_PTRDIFF_MAX __PTRDIFF_MAX__
+#define __MLIBC_PTRDIFF_MIN (-__PTRDIFF_MAX__ - 1)
+
+typedef __UINTMAX_TYPE__ __mlibc_uintmax;
+typedef __UINTPTR_TYPE__ __mlibc_uintptr;
+typedef __SIZE_TYPE__    __mlibc_size;
+#define __MLIBC_UINTMAX_MAX __UINTMAX_MAX__
+#define __MLIBC_UINTPTR_MAX __UINTPTR_MAX__
+#define __MLIBC_SIZE_MAX __SIZE_MAX__
+
+// Other limits.
+
+#define __MLIBC_WCHAR_MAX __WCHAR_MAX__
+#define __MLIBC_WCHAR_MIN __WCHAR_MIN__
+
+#define __MLIBC_WINT_MAX __WINT_MAX__
+#define __MLIBC_WINT_MIN __WINT_MIN__
+
+#define __MLIBC_SIG_ATOMIC_MAX __SIG_ATOMIC_MAX__
+#define __MLIBC_SIG_ATOMIC_MIN __SIG_ATOMIC_MIN__
+
+// ----------------------------------------------------------------------------
+// Sanity checking. Make sure that we agree with the compiler's ABI.
+// ----------------------------------------------------------------------------
+
+#if defined(__cpp_static_assert)
+#	define __MLIBC_STATIC_ASSERT(c, text) static_assert(c, text)
+#elif !defined(__cplusplus)
+#	define __MLIBC_STATIC_ASSERT(c, text) _Static_assert(c, text)
+#else
+#	define __MLIBC_STATIC_ASSERT(c, text)
+#endif
+
+#define __MLIBC_CHECK_TYPE(T1, T2) __MLIBC_STATIC_ASSERT(sizeof(T1) == sizeof(T2),\
+	#T1 " != " #T2);
+
+// Least-width.
+__MLIBC_CHECK_TYPE(__mlibc_int8,  __INT_LEAST8_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_int16, __INT_LEAST16_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_int32, __INT_LEAST32_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_int64, __INT_LEAST64_TYPE__);
+
+__MLIBC_CHECK_TYPE(__mlibc_uint8,  __UINT_LEAST8_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_uint16, __UINT_LEAST16_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_uint32, __UINT_LEAST32_TYPE__);
+__MLIBC_CHECK_TYPE(__mlibc_uint64, __UINT_LEAST64_TYPE__);
+
+// Fast-width.
+// Unfortunately, GCC and Clang disagree about fast types.
+#ifndef __clang__
+	__MLIBC_CHECK_TYPE(__mlibc_int_fast8,  __INT_FAST8_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_int_fast16, __INT_FAST16_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_int_fast32, __INT_FAST32_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_int_fast64, __INT_FAST64_TYPE__);
+
+	__MLIBC_CHECK_TYPE(__mlibc_uint_fast8,  __UINT_FAST8_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_uint_fast16, __UINT_FAST16_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_uint_fast32, __UINT_FAST32_TYPE__);
+	__MLIBC_CHECK_TYPE(__mlibc_uint_fast64, __UINT_FAST64_TYPE__);
+#endif
+
+#endif // _MLIBC_INTERNAL_TYPES_H
diff --git a/lib/mlibc/options/internal/include/bits/wchar.h b/lib/mlibc/options/internal/include/bits/wchar.h
new file mode 100644
index 0000000..a422ef7
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/wchar.h
@@ -0,0 +1,9 @@
+#ifndef MLIBC_WCHAR_H
+#define MLIBC_WCHAR_H
+
+#include <bits/types.h>
+
+#define WCHAR_MAX      __MLIBC_WCHAR_MAX
+#define WCHAR_MIN      __MLIBC_WCHAR_MIN
+
+#endif // MLIBC_WCHAR_H
diff --git a/lib/mlibc/options/internal/include/bits/wchar_t.h b/lib/mlibc/options/internal/include/bits/wchar_t.h
new file mode 100644
index 0000000..4eb4e9c
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/wchar_t.h
@@ -0,0 +1,12 @@
+
+#ifndef MLIBC_WCHAR_T_H
+#define MLIBC_WCHAR_T_H
+
+#ifndef __cplusplus
+
+typedef __WCHAR_TYPE__ wchar_t;
+
+#endif
+
+#endif // MLIBC_WCHAR_T_H
+
diff --git a/lib/mlibc/options/internal/include/bits/winsize.h b/lib/mlibc/options/internal/include/bits/winsize.h
new file mode 100644
index 0000000..7b3006a
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/winsize.h
@@ -0,0 +1,13 @@
+
+#ifndef MLIBC_WINSIZE_H
+#define MLIBC_WINSIZE_H
+
+struct winsize {
+	unsigned short ws_row;
+	unsigned short ws_col;
+	unsigned short ws_xpixel;
+	unsigned short ws_ypixel;
+};
+
+#endif // MLIBC_WINSIZE_H
+
diff --git a/lib/mlibc/options/internal/include/bits/wint_t.h b/lib/mlibc/options/internal/include/bits/wint_t.h
new file mode 100644
index 0000000..b4f57bf
--- /dev/null
+++ b/lib/mlibc/options/internal/include/bits/wint_t.h
@@ -0,0 +1,6 @@
+#ifndef MLIBC_WINT_T_H
+#define MLIBC_WINT_T_H
+
+typedef __WINT_TYPE__ wint_t;
+
+#endif // MLIBC_WINT_T_H
diff --git a/lib/mlibc/options/internal/include/mlibc/all-sysdeps.hpp b/lib/mlibc/options/internal/include/mlibc/all-sysdeps.hpp
new file mode 100644
index 0000000..7189286
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/all-sysdeps.hpp
@@ -0,0 +1,33 @@
+#ifndef MLIBC_ALL_SYSDEPS
+#define MLIBC_ALL_SYSDEPS
+
+#include <mlibc-config.h>
+#include <internal-config.h>
+
+#if __MLIBC_ANSI_OPTION
+#	include <mlibc/ansi-sysdeps.hpp>
+#endif /* __MLIBC_ANSI_OPTION */
+
+#if __MLIBC_POSIX_OPTION
+#	include <mlibc/posix-sysdeps.hpp>
+#endif /* __MLIBC_POSIX_OPTION */
+
+#if __MLIBC_LINUX_OPTION
+#	include <mlibc/linux-sysdeps.hpp>
+#endif /* __MLIBC_LINUX_OPTION */
+
+#if __MLIBC_GLIBC_OPTION
+#	include <mlibc/glibc-sysdeps.hpp>
+#endif /* __MLIBC_GLIBC_OPTION */
+
+#if __MLIBC_BSD_OPTION
+#	include <mlibc/bsd-sysdeps.hpp>
+#endif /* __MLIBC_BSD_OPTION */
+
+#if MLIBC_BUILDING_RTDL
+#	include <mlibc/rtdl-sysdeps.hpp>
+#endif /* MLIBC_BUILDING_RTDL */
+
+#include <mlibc/internal-sysdeps.hpp>
+
+#endif /* MLIBC_ALL_SYSDEPS */
diff --git a/lib/mlibc/options/internal/include/mlibc/allocator.hpp b/lib/mlibc/options/internal/include/mlibc/allocator.hpp
new file mode 100644
index 0000000..5f9617e
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/allocator.hpp
@@ -0,0 +1,37 @@
+#ifndef MLIBC_FRIGG_ALLOC
+#define MLIBC_FRIGG_ALLOC
+
+#include <mlibc/lock.hpp>
+#include <bits/ensure.h>
+#include <frg/slab.hpp>
+#include <internal-config.h>
+
+#if !MLIBC_DEBUG_ALLOCATOR
+
+struct VirtualAllocator {
+public:
+	uintptr_t map(size_t length);
+
+	void unmap(uintptr_t address, size_t length);
+};
+
+typedef frg::slab_pool<VirtualAllocator, FutexLock> MemoryPool;
+
+typedef frg::slab_allocator<VirtualAllocator, FutexLock> MemoryAllocator;
+
+MemoryAllocator &getAllocator();
+
+#else
+
+struct MemoryAllocator {
+	void *allocate(size_t size);
+	void free(void *ptr);
+	void deallocate(void *ptr, size_t size);
+	void *reallocate(void *ptr, size_t size);
+};
+
+MemoryAllocator &getAllocator();
+
+#endif // !MLIBC_DEBUG_ALLOCATOR
+
+#endif // MLIBC_FRIGG_ALLOC
diff --git a/lib/mlibc/options/internal/include/mlibc/bitutil.hpp b/lib/mlibc/options/internal/include/mlibc/bitutil.hpp
new file mode 100644
index 0000000..6d2b25e
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/bitutil.hpp
@@ -0,0 +1,34 @@
+#ifndef MLIBC_BITUTIL
+#define MLIBC_BITUTIL
+
+#include <stdint.h>
+
+namespace mlibc {
+
+template<typename T>
+struct bit_util;
+
+template<>
+struct bit_util<uint64_t> {
+	static uint64_t byteswap(uint64_t x) {
+		return __builtin_bswap64(x);
+	}
+};
+
+template<>
+struct bit_util<uint32_t> {
+	static uint32_t byteswap(uint32_t x) {
+		return __builtin_bswap32(x);
+	}
+};
+
+template<>
+struct bit_util<uint16_t> {
+	static uint16_t byteswap(uint16_t x) {
+		return __builtin_bswap16(x);
+	}
+};
+
+} // namespace mlibc
+
+#endif // MLIBC_BITUTIL
diff --git a/lib/mlibc/options/internal/include/mlibc/charcode.hpp b/lib/mlibc/options/internal/include/mlibc/charcode.hpp
new file mode 100644
index 0000000..67bd03d
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/charcode.hpp
@@ -0,0 +1,124 @@
+#ifndef MLIBC_CHARCODE_HPP
+#define MLIBC_CHARCODE_HPP
+
+#include <stddef.h>
+#include <stdint.h>
+#include <bits/ensure.h>
+#include <bits/mbstate.h>
+#include <mlibc/debug.hpp>
+
+namespace mlibc {
+
+enum class charcode_error {
+	null,
+	dirty,
+	illegal_input,
+	input_underflow,
+	output_overflow
+};
+
+template<typename C>
+struct code_seq {
+	C *it;
+	const C *end;
+
+	explicit operator bool () {
+		return it != end;
+	}
+};
+
+// Some encodings (e.g. the one defined in RFC 1843) have "shift states",
+// i.e. escape sequences that switch between different encodings (e.g. between single-byte ASCII
+// and 2-byte encoding of Chinese characters).
+// TODO: Implement that using the __shift member of __mlibc_mbstate.
+
+typedef uint32_t codepoint;
+
+// The following class deals with decoding/encoding "code units" (of type char)
+// to "code points" that are defined by unicode (of type codepoint).
+// It also offers convenience functions to transcode to wchar_t, char16_t and char32_t.
+// We assume that the encoding of wchar_t (and char16_t, char32_t) is fixed.
+// char is allowed to have an arbitrary encoding.
+// TODO: char16_t and char32_t variants are missing.
+// TODO: For iconv(), first decode and then encode to the destination encoding.
+struct polymorphic_charcode {
+	virtual ~polymorphic_charcode();
+
+	// Helper function to decode a single char.
+	charcode_error promote(char nc, codepoint &wc) {
+		auto uc = static_cast<unsigned char>(nc);
+		if(uc <= 0x7F && preserves_7bit_units) {
+			wc = uc;
+			return charcode_error::null;
+		}
+
+		code_seq<const char> nseq{&nc, &nc + 1};
+		code_seq<codepoint> wseq{&wc, &wc + 1};
+		__mlibc_mbstate st = __MLIBC_MBSTATE_INITIALIZER;
+
+		if(auto e = decode(nseq, wseq, st); e != charcode_error::null)
+			return e;
+		// This should have read/written exactly one code unit/code point.
+		__ensure(nseq.it == nseq.end);
+		__ensure(wseq.it == wseq.end);
+		return charcode_error::null;
+	}
+
+	// Helper function to decode a single char.
+	charcode_error promote_wtranscode(char nc, wchar_t &wc) {
+		auto uc = static_cast<unsigned char>(nc);
+		if(uc <= 0x7F && preserves_7bit_units) { // TODO: Use "wtranscode_preserves_7bit_units".
+			wc = uc;
+			return charcode_error::null;
+		}
+
+		code_seq<const char> nseq{&nc, &nc + 1};
+		code_seq<wchar_t> wseq{&wc, &wc + 1};
+		__mlibc_mbstate st = __MLIBC_MBSTATE_INITIALIZER;
+
+		if(auto e = decode_wtranscode(nseq, wseq, st); e != charcode_error::null)
+			return e;
+		// This should have read/written exactly one code unit/code point.
+		__ensure(nseq.it == nseq.end);
+		__ensure(wseq.it == wseq.end);
+		return charcode_error::null;
+	}
+
+	polymorphic_charcode(bool preserves_7bit_units_, bool has_shift_states_)
+	: preserves_7bit_units{preserves_7bit_units_}, has_shift_states{has_shift_states_} { }
+
+	virtual charcode_error decode(code_seq<const char> &nseq, code_seq<codepoint> &wseq,
+			__mlibc_mbstate &st) = 0;
+
+	virtual charcode_error decode_wtranscode(code_seq<const char> &nseq, code_seq<wchar_t> &wseq,
+			__mlibc_mbstate &st) = 0;
+
+	virtual charcode_error decode_wtranscode_length(code_seq<const char> &nseq, size_t *n,
+			__mlibc_mbstate &st) = 0;
+
+	virtual charcode_error encode_wtranscode(code_seq<char> &nseq, code_seq<const wchar_t> &wseq,
+			__mlibc_mbstate &st) = 0;
+
+	virtual charcode_error encode_wtranscode_length(code_seq<const wchar_t> &wseq, size_t *n,
+			__mlibc_mbstate &st) = 0;
+
+	// True if promotion only zero-extends units below 0x7F.
+	const bool preserves_7bit_units;
+
+	// Whether the encoding has shift states.
+	const bool has_shift_states;
+};
+
+polymorphic_charcode *current_charcode();
+
+// Similar to polymorphic_charcode but for wchar_t. Note that this encoding is fixed per-platform;
+// thus, it does not need to be polymorphic.
+struct wide_charcode {
+	charcode_error promote(wchar_t nc, codepoint &wc);
+};
+
+wide_charcode *platform_wide_charcode();
+
+} // namespace mlibc
+
+#endif // MLIBC_CHARCODE_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/charset.hpp b/lib/mlibc/options/internal/include/mlibc/charset.hpp
new file mode 100644
index 0000000..a068f05
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/charset.hpp
@@ -0,0 +1,40 @@
+#ifndef MLIBC_CHARSET_HPP
+#define MLIBC_CHARSET_HPP
+
+#include <mlibc/charcode.hpp>
+
+namespace mlibc {
+
+// Represents the charset of a certain locale. We define the charset as
+// a set of characters, together with their properties and conversion rules
+// *but not* their encoding (e.g. to UTF-8 or UTF-16).
+struct charset {
+	// Returns true iif the meaning of the first 0x7F characters matches ASCII.
+	bool is_ascii_superset();
+
+	bool is_alpha(codepoint c);
+	bool is_digit(codepoint c);
+	bool is_xdigit(codepoint c);
+	bool is_alnum(codepoint c);
+	bool is_punct(codepoint c);
+	bool is_graph(codepoint c);
+	bool is_blank(codepoint c);
+	bool is_space(codepoint c);
+	bool is_print(codepoint c);
+
+	bool is_lower(codepoint c);
+	bool is_upper(codepoint c);
+	codepoint to_lower(codepoint c);
+	codepoint to_upper(codepoint c);
+};
+
+charset *current_charset();
+
+// The property if a character is a control character is locale-independent.
+inline bool generic_is_control(codepoint c) {
+	return (c <= 0x1F) || (c == 0x7F) || (c >= 0x80 && c <= 0x9F);
+}
+
+} // namespace mlibc
+
+#endif // MLIBC_CHARSET_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/debug.hpp b/lib/mlibc/options/internal/include/mlibc/debug.hpp
new file mode 100644
index 0000000..7067039
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/debug.hpp
@@ -0,0 +1,27 @@
+#ifndef MLIBC_DEBUG_HPP
+#define MLIBC_DEBUG_HPP
+
+#include <frg/logging.hpp>
+
+namespace mlibc {
+
+struct InfoSink {
+	// constexpr so that this can be initialized statically.
+	constexpr InfoSink() = default;
+
+	void operator() (const char *message);
+};
+
+struct PanicSink {
+	// constexpr so that this can be initialized statically.
+	constexpr PanicSink() = default;
+
+	void operator() (const char *message);
+};
+
+extern frg::stack_buffer_logger<InfoSink, 512> infoLogger;
+extern frg::stack_buffer_logger<PanicSink, 512> panicLogger;
+
+} // namespace mlibc
+
+#endif // MLIBC_DEBUG_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/file-window.hpp b/lib/mlibc/options/internal/include/mlibc/file-window.hpp
new file mode 100644
index 0000000..68c3ebf
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/file-window.hpp
@@ -0,0 +1,64 @@
+#ifndef MLIBC_FILE_WINDOW
+#define MLIBC_FILE_WINDOW
+
+#include <abi-bits/fcntl.h>
+#include <mlibc/allocator.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+#include <internal-config.h>
+
+struct file_window {
+	file_window(const char *path) {
+		int fd;
+		if(mlibc::sys_open("/etc/localtime", O_RDONLY, 0, &fd))
+			mlibc::panicLogger() << "mlibc: Error opening file_window to "
+					<< path << frg::endlog;
+
+		if(!mlibc::sys_stat) {
+			MLIBC_MISSING_SYSDEP();
+			__ensure(!"cannot proceed without sys_stat");
+		}
+		struct stat info;
+		if(mlibc::sys_stat(mlibc::fsfd_target::fd, fd, "", 0, &info))
+			mlibc::panicLogger() << "mlibc: Error getting TZinfo stats" << frg::endlog;
+
+#if MLIBC_MAP_FILE_WINDOWS
+		if(mlibc::sys_vm_map(nullptr, (size_t)info.st_size, PROT_READ, MAP_PRIVATE,
+				fd, 0, &_ptr))
+			mlibc::panicLogger() << "mlibc: Error mapping TZinfo" << frg::endlog;
+#else
+		_ptr = getAllocator().allocate(info.st_size);
+		__ensure(_ptr);
+
+		size_t progress = 0;
+		size_t st_size = static_cast<size_t>(info.st_size);
+		while(progress < st_size) {
+			ssize_t chunk;
+			if(int e = mlibc::sys_read(fd, reinterpret_cast<char *>(_ptr) + progress,
+					st_size - progress, &chunk); e)
+				mlibc::panicLogger() << "mlibc: Read from file_window failed" << frg::endlog;
+			if(!chunk)
+				break;
+			progress += chunk;
+		}
+		if(progress != st_size)
+			mlibc::panicLogger() << "stat reports " << info.st_size << " but we only read "
+					<< progress << " bytes" << frg::endlog;
+#endif
+
+		if(mlibc::sys_close(fd))
+			mlibc::panicLogger() << "mlibc: Error closing TZinfo" << frg::endlog;
+	}
+
+	// TODO: Write destructor to deallocate/unmap memory.
+
+	void *get() {
+		return _ptr;
+	}
+
+private:
+	void *_ptr;
+};
+
+#endif // MLIBC_FILE_WINDOW
+
diff --git a/lib/mlibc/options/internal/include/mlibc/fsfd_target.hpp b/lib/mlibc/options/internal/include/mlibc/fsfd_target.hpp
new file mode 100644
index 0000000..b577325
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/fsfd_target.hpp
@@ -0,0 +1,15 @@
+#ifndef MLIBC_FSFD_TARGET
+#define MLIBC_FSFD_TARGET
+
+namespace mlibc {
+
+enum class fsfd_target {
+	none,
+	path,
+	fd,
+	fd_path
+};
+
+} // namespace mlibc
+
+#endif // MLIBC_FSFD_TARGET
diff --git a/lib/mlibc/options/internal/include/mlibc/global-config.hpp b/lib/mlibc/options/internal/include/mlibc/global-config.hpp
new file mode 100644
index 0000000..7eaed3c
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/global-config.hpp
@@ -0,0 +1,19 @@
+#ifndef MLIBC_GLOBAL_CONFIG
+#define MLIBC_GLOBAL_CONFIG
+
+namespace mlibc {
+
+struct GlobalConfig {
+	GlobalConfig();
+	
+	bool debugMalloc;
+};
+
+inline const GlobalConfig &globalConfig() {
+	static GlobalConfig cached;
+	return cached;
+}
+
+}
+
+#endif // MLIBC_GLOBAL_CONFIG
diff --git a/lib/mlibc/options/internal/include/mlibc/internal-sysdeps.hpp b/lib/mlibc/options/internal/include/mlibc/internal-sysdeps.hpp
new file mode 100644
index 0000000..02df713
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/internal-sysdeps.hpp
@@ -0,0 +1,41 @@
+#ifndef MLIBC_INTERNAL_SYSDEPS
+#define MLIBC_INTERNAL_SYSDEPS
+
+#include <stddef.h>
+
+#include <abi-bits/seek-whence.h>
+#include <abi-bits/vm-flags.h>
+#include <bits/off_t.h>
+#include <bits/ssize_t.h>
+#include <abi-bits/stat.h>
+#include <mlibc/fsfd_target.hpp>
+
+namespace [[gnu::visibility("hidden")]] mlibc {
+
+void sys_libc_log(const char *message);
+[[noreturn]] void sys_libc_panic();
+
+int sys_tcb_set(void *pointer);
+
+[[gnu::weak]] int sys_futex_tid();
+int sys_futex_wait(int *pointer, int expected, const struct timespec *time);
+int sys_futex_wake(int *pointer);
+
+int sys_anon_allocate(size_t size, void **pointer);
+int sys_anon_free(void *pointer, size_t size);
+
+int sys_open(const char *pathname, int flags, mode_t mode, int *fd);
+int sys_read(int fd, void *buf, size_t count, ssize_t *bytes_read);
+int sys_seek(int fd, off_t offset, int whence, off_t *new_offset);
+int sys_close(int fd);
+
+[[gnu::weak]] int sys_stat(fsfd_target fsfdt, int fd, const char *path, int flags,
+		struct stat *statbuf);
+// mlibc assumes that anonymous memory returned by sys_vm_map() is zeroed by the kernel / whatever is behind the sysdeps
+int sys_vm_map(void *hint, size_t size, int prot, int flags, int fd, off_t offset, void **window);
+int sys_vm_unmap(void *pointer, size_t size);
+[[gnu::weak]] int sys_vm_protect(void *pointer, size_t size, int prot);
+
+} //namespace mlibc
+
+#endif // MLIBC_INTERNAL_SYSDEPS
diff --git a/lib/mlibc/options/internal/include/mlibc/locale.hpp b/lib/mlibc/options/internal/include/mlibc/locale.hpp
new file mode 100644
index 0000000..a46a2c3
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/locale.hpp
@@ -0,0 +1,12 @@
+#ifndef MLIBC_LOCALE
+#define MLIBC_LOCALE
+
+#include <bits/nl_item.h>
+
+namespace mlibc {
+
+char *nl_langinfo(nl_item item);
+
+} // namespace mlibc
+
+#endif // MLIBC_LOCALE
diff --git a/lib/mlibc/options/internal/include/mlibc/lock.hpp b/lib/mlibc/options/internal/include/mlibc/lock.hpp
new file mode 100644
index 0000000..aa05079
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/lock.hpp
@@ -0,0 +1,124 @@
+#ifndef MLIBC_LOCK_HPP
+#define MLIBC_LOCK_HPP
+
+#include <errno.h>
+#include <stdint.h>
+#include <mlibc/internal-sysdeps.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/tid.hpp>
+#include <bits/ensure.h>
+
+template<bool Recursive>
+struct FutexLockImpl {
+	FutexLockImpl() : _state{0}, _recursion{0} { }
+
+	FutexLockImpl(const FutexLockImpl &) = delete;
+
+	FutexLockImpl &operator= (const FutexLockImpl &) = delete;
+
+	static constexpr uint32_t waitersBit = (1 << 31);
+	static constexpr uint32_t ownerMask = (static_cast<uint32_t>(1) << 30) - 1;
+
+	void lock() {
+		unsigned int this_tid = mlibc::this_tid();
+		unsigned int expected = 0;
+
+		while(true) {
+			if(!expected) {
+				// Try to take the mutex here.
+				if(__atomic_compare_exchange_n(&_state,
+						&expected, this_tid, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
+					if constexpr (Recursive) {
+						__ensure(!_recursion);
+						_recursion = 1;
+					}
+					return;
+				}
+			}else{
+				// If this (recursive) mutex is already owned by us, increment the recursion level.
+				if((expected & ownerMask) == this_tid) {
+					if constexpr (Recursive)
+						++_recursion;
+					else
+						mlibc::panicLogger() << "mlibc: FutexLock deadlock detected!" << frg::endlog;
+					return;
+				}
+
+				// Wait on the futex if the waiters flag is set.
+				if(expected & waitersBit) {
+					int e = mlibc::sys_futex_wait((int *)&_state, expected, nullptr);
+
+					// If the wait returns EAGAIN, that means that the waitersBit was just unset by
+					// some other thread. In this case, we should loop back around.
+					if (e && e != EAGAIN)
+						mlibc::panicLogger() << "sys_futex_wait() failed with error code " << e << frg::endlog;
+
+					// Opportunistically try to take the lock after we wake up.
+					expected = 0;
+				}else{
+					// Otherwise we have to set the waiters flag first.
+					unsigned int desired = expected | waitersBit;
+					if(__atomic_compare_exchange_n((int *)&_state,
+							reinterpret_cast<int*>(&expected), desired, false, __ATOMIC_RELAXED, __ATOMIC_RELAXED))
+						expected = desired;
+				}
+			}
+		}
+	}
+
+	bool try_lock() {
+		unsigned int this_tid = mlibc::this_tid();
+		unsigned int expected = __atomic_load_n(&_state, __ATOMIC_RELAXED);
+
+		if(!expected) {
+			// Try to take the mutex here.
+			if(__atomic_compare_exchange_n(&_state,
+							&expected, this_tid, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
+				if constexpr (Recursive)
+					_recursion = 1;
+				return true;
+			}
+		} else {
+			// If this (recursive) mutex is already owned by us, increment the recursion level.
+			if((expected & ownerMask) == this_tid) {
+				if constexpr (Recursive) {
+					__ensure(!_recursion);
+					++_recursion;
+					return true;
+				} else {
+					return false;
+				}
+			}
+		}
+
+		return false;
+	}
+
+	void unlock() {
+		// Decrement the recursion level and unlock if we hit zero.
+		if constexpr (Recursive) {
+			__ensure(_recursion);
+			if(--_recursion)
+				return;
+		}
+
+		// Reset the mutex to the unlocked state.
+		auto state = __atomic_exchange_n(&_state, 0, __ATOMIC_RELEASE);
+		__ensure((state & ownerMask) == mlibc::this_tid());
+
+		if(state & waitersBit) {
+			// Wake the futex if there were waiters. Since the mutex might not exist at this location
+			// anymore, we must conservatively ignore EACCES and EINVAL which may occur as a result.
+			int e = mlibc::sys_futex_wake((int *)&_state);
+			__ensure(e >= 0 || e == EACCES || e == EINVAL);
+		}
+	}
+private:
+	uint32_t _state;
+	uint32_t _recursion;
+};
+
+using FutexLock = FutexLockImpl<false>;
+using RecursiveFutexLock = FutexLockImpl<true>;
+
+#endif
diff --git a/lib/mlibc/options/internal/include/mlibc/stack_protector.hpp b/lib/mlibc/options/internal/include/mlibc/stack_protector.hpp
new file mode 100644
index 0000000..47290fc
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/stack_protector.hpp
@@ -0,0 +1,10 @@
+#ifndef MLIBC_STACK_PROTECTOR_HPP
+#define MLIBC_STACK_PROTECTOR_HPP
+
+namespace mlibc {
+
+void initStackGuard(void *);
+
+} // namespace mlibc
+
+#endif // MLIBC_STACK_PROTECTOR_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/strings.hpp b/lib/mlibc/options/internal/include/mlibc/strings.hpp
new file mode 100644
index 0000000..5a93c7c
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/strings.hpp
@@ -0,0 +1,12 @@
+#ifndef MLIBC_STRINGS
+#define MLIBC_STRINGS
+
+#include <bits/size_t.h>
+
+namespace mlibc {
+
+int strncasecmp(const char *a, const char *b, size_t size);
+
+} // namespace mlibc
+
+#endif // MLIBC_STRINGS
diff --git a/lib/mlibc/options/internal/include/mlibc/strtofp.hpp b/lib/mlibc/options/internal/include/mlibc/strtofp.hpp
new file mode 100644
index 0000000..f9c5e20
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/strtofp.hpp
@@ -0,0 +1,165 @@
+#ifndef MLIBC_STRTOFP_HPP
+#define MLIBC_STRTOFP_HPP
+
+#include <string.h>
+#include <bits/ensure.h>
+#include <type_traits>
+
+namespace mlibc {
+
+template<typename T>
+T strtofp(const char *str, char **endptr) {
+	if (strcmp(str, "INF") == 0 || strcmp(str, "inf") == 0) {
+		if (endptr)
+			*endptr = (char *)str + 3;
+		if constexpr (std::is_same_v<T, float>)
+			return __builtin_inff();
+		else if constexpr (std::is_same_v<T, double>)
+			return __builtin_inf();
+		else
+			return __builtin_infl();
+	} else if (strcmp(str, "INFINITY") == 0 || strcmp(str, "infinity") == 0) {
+	if (endptr)
+		*endptr = (char *)str + 8;
+	if constexpr (std::is_same_v<T, float>)
+		return __builtin_inff();
+	else if constexpr (std::is_same_v<T, double>)
+		return __builtin_inf();
+	else
+		return __builtin_infl();
+	} else if (strncmp(str, "NAN", 3) == 0 || strncmp(str, "nan", 3) == 0) {
+		if (endptr)
+			*endptr = (char *)str + 3;
+		if constexpr (std::is_same_v<T, float>)
+			return __builtin_nanf("");
+		else if constexpr (std::is_same_v<T, double>)
+			return __builtin_nan("");
+		else
+			return __builtin_nanl("");
+	}
+
+	bool negative = *str == '-';
+	if (*str == '+' || *str == '-')
+		str++;
+
+	bool hex = false;
+	if (*str == '0' && (*(str + 1) == 'x' || *(str + 1) == 'X')) {
+		str += 2;
+		hex = true;
+	}
+
+	T result = static_cast<T>(0);
+
+	const char *tmp = str;
+
+	if (!hex) {
+		while (true) {
+			if (!isdigit(*tmp))
+				break;
+			result *= static_cast<T>(10);
+			result += static_cast<T>(*tmp - '0');
+			tmp++;
+		}
+	} else {
+		while (true) {
+			if (!isxdigit(*tmp))
+				break;
+			result *= static_cast<T>(16);
+			result += static_cast<T>(*tmp <= '9' ? (*tmp - '0') : (tolower(*tmp) - 'a' + 10));
+			tmp++;
+		}
+	}
+
+	if (*tmp == '.') {
+		tmp++;
+
+		if (!hex) {
+			T d = static_cast<T>(10);
+
+			while (true) {
+				if (!isdigit(*tmp))
+					break;
+				result += static_cast<T>(*tmp - '0') / d;
+				d *= static_cast<T>(10);
+				tmp++;
+			}
+		} else {
+			T d = static_cast<T>(16);
+
+			while (true) {
+				if (!isxdigit(*tmp))
+					break;
+				result += static_cast<T>(*tmp <= '9' ? (*tmp - '0') : (tolower(*tmp) - 'a' + 10)) / d;
+				d *= static_cast<T>(16);
+				tmp++;
+			}
+		}
+	}
+
+	if (!hex) {
+		if (*tmp == 'e' || *tmp == 'E') {
+			tmp++;
+
+			bool exp_negative = *tmp == '-';
+			if (*tmp == '+' || *tmp == '-')
+				tmp++;
+
+			int exp = 0;
+			while (true) {
+				if (!isdigit(*tmp))
+					break;
+				exp *= 10;
+				exp += *tmp - '0';
+				tmp++;
+			}
+
+			if (!exp_negative) {
+				for (int i = 0; i < exp; ++i) {
+					result *= static_cast<T>(10);
+				}
+			} else {
+				for (int i = 0; i < exp; ++i) {
+					result /= static_cast<T>(10);
+				}
+			}
+		}
+	} else {
+		if (*tmp == 'p' || *tmp == 'P') {
+			tmp++;
+
+			bool exp_negative = *tmp == '-';
+			if (*tmp == '+' || *tmp == '-')
+				tmp++;
+
+			int exp = 0;
+			while (true) {
+				if (!isdigit(*tmp))
+					break;
+				exp *= 10;
+				exp += *tmp - '0';
+				tmp++;
+			}
+
+			if (!exp_negative) {
+				for (int i = 0; i < exp; ++i) {
+					result *= static_cast<T>(2);
+				}
+			} else {
+				for (int i = 0; i < exp; ++i) {
+					result /= static_cast<T>(2);
+				}
+			}
+		}
+	}
+
+	if (endptr)
+		*endptr = const_cast<char *>(tmp);
+	if (negative)
+		result = -result;
+
+	return result;
+}
+
+}
+
+#endif // MLIBC_STRTOFP_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/strtol.hpp b/lib/mlibc/options/internal/include/mlibc/strtol.hpp
new file mode 100644
index 0000000..3b8fca9
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/strtol.hpp
@@ -0,0 +1,159 @@
+#ifndef MLIBC_STRTOL_HPP
+#define MLIBC_STRTOL_HPP
+
+#include <type_traits>
+#include <ctype.h>
+#include <wctype.h>
+#include <limits.h>
+
+namespace mlibc {
+
+template<typename T> struct int_limits {};
+
+template<>
+struct int_limits<long> {
+	static long max() { return LONG_MAX; }
+	static long min() { return LONG_MIN; }
+};
+
+template<>
+struct int_limits<unsigned long> {
+	static unsigned long max() { return ULONG_MAX; }
+	static unsigned long min() { return 0; }
+};
+
+template<>
+struct int_limits<long long> {
+	static long long max() { return LLONG_MAX; }
+	static long long min() { return LLONG_MIN; }
+};
+
+template<>
+struct int_limits<unsigned long long> {
+	static unsigned long long max() { return ULLONG_MAX; }
+	static unsigned long long min() { return 0; }
+};
+
+template<typename T> struct char_detail {};
+
+template<>
+struct char_detail<char> {
+	static bool isSpace(char c) { return isspace(c); }
+	static bool isDigit(char c) { return isdigit(c); }
+	static bool isHexDigit(char c) { return isxdigit(c); }
+	static bool isLower(char c) { return islower(c); }
+	static bool isUpper(char c) { return isupper(c); }
+};
+
+template<>
+struct char_detail<wchar_t> {
+	static bool isSpace(wchar_t c) { return iswspace(c); }
+	static bool isDigit(wchar_t c) { return iswdigit(c); }
+	static bool isHexDigit(wchar_t c) { return iswxdigit(c); }
+	static bool isLower(wchar_t c) { return iswlower(c); }
+	static bool isUpper(wchar_t c) { return iswupper(c); }
+};
+
+template<typename Char> Char widen(char c) { return static_cast<Char>(c); }
+
+template<typename Return, typename Char>
+Return stringToInteger(const Char *__restrict nptr, Char **__restrict endptr, int baseInt) {
+	using UnsignedReturn = std::make_unsigned_t<Return>;
+
+	auto base = static_cast<Return>(baseInt);
+	auto s = nptr;
+
+	if (base < 0 || base == 1) {
+		if (endptr)
+			*endptr = const_cast<Char *>(nptr);
+		return 0;
+	}
+
+	while (char_detail<Char>::isSpace(*s))
+		s++;
+
+	bool negative = false;
+	if (*s == widen<Char>('-')) {
+		negative = true;
+		s++;
+	} else if (*s == widen<Char>('+')) {
+		s++;
+	}
+
+
+	bool hasOctalPrefix = s[0] == widen<Char>('0');
+	bool hasHexPrefix = hasOctalPrefix && (s[1] == widen<Char>('x') || s[1] == widen<Char>('X'));
+
+	// There's two tricky cases we need to keep in mind here:
+	//   1. We should interpret "0x5" as hex 5 rather than octal 0.
+	//   2. We should interpret "0x" as octal 0 (and set endptr correctly).
+	// To deal with 2, we check the charcacter following the hex prefix.
+	if ((base == 0 || base == 16) && hasHexPrefix && char_detail<Char>::isHexDigit(s[2])) {
+		s += 2;
+		base = 16;
+	} else if ((base == 0 || base == 8) && hasOctalPrefix) {
+		base = 8;
+	} else if (base == 0) { 
+		base = 10;
+	}
+
+	// Compute the range of acceptable values.
+	UnsignedReturn cutoff, cutlim;
+	if (std::is_unsigned_v<Return>) {
+		cutoff = int_limits<Return>::max() / base;
+		cutlim = int_limits<Return>::max() % base;
+	} else {
+		Return co = negative ? int_limits<Return>::min() : int_limits<Return>::max();
+		cutlim = negative ? -(co % base) : co % base;
+		co /= negative ? -base : base;
+		cutoff = co;
+	}
+
+	UnsignedReturn totalValue = 0;
+	bool convertedAny = false;
+	bool outOfRange = false;
+	for (Char c = *s; c != widen<Char>('\0'); c = *++s) {
+		UnsignedReturn digitValue;
+		if (char_detail<Char>::isDigit(c))
+			digitValue = c - widen<Char>('0');
+		else if (char_detail<Char>::isUpper(c))
+			digitValue = c - widen<Char>('A') + 10;
+		else if (char_detail<Char>::isLower(c))
+			digitValue = c - widen<Char>('a') + 10;
+		else
+			break;
+
+		if (digitValue >= static_cast<UnsignedReturn>(base))
+			break;
+
+		if (outOfRange) {
+			// The value is already known to be out of range, but we need to keep
+			// consuming characters until we can't (to set endptr correctly).
+		} else if (totalValue > cutoff || (totalValue == cutoff && digitValue > cutlim)) {
+			// The value will be out of range if we accumulate digitValue.
+			outOfRange = true;
+		} else {
+			totalValue = (totalValue * base) + digitValue;
+			convertedAny = true;
+		}
+	}
+
+	if (endptr)
+		*endptr = const_cast<Char *>(convertedAny ? s : nptr);
+
+	if (outOfRange) {
+		errno = ERANGE;
+
+		if (std::is_unsigned_v<Return>) {
+			return int_limits<Return>::max();
+		} else {
+			return negative ? int_limits<Return>::min() : int_limits<Return>::max();
+		}
+	}
+
+	return negative ? -totalValue : totalValue;
+}
+
+}
+
+#endif // MLIBC_STRTOL_HPP
diff --git a/lib/mlibc/options/internal/include/mlibc/tcb.hpp b/lib/mlibc/options/internal/include/mlibc/tcb.hpp
new file mode 100644
index 0000000..92aad7a
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/tcb.hpp
@@ -0,0 +1,180 @@
+#pragma once
+
+#include <stdint.h>
+#include <limits.h>
+#include <bits/size_t.h>
+#include <frg/array.hpp>
+
+#include "elf.hpp"
+
+/*
+ * Explanation of cancellation bits:
+ *
+ * tcbCancelEnableBit and tcbCancelAsyncBit should be self-explanatory,
+ * they are set if cancellation is enabled, or asynchronous, respectively.
+ *
+ * tcbCancelTriggerBit is set whenever a cancellation is triggered, which is
+ * in pthread_cancel() or in the signal handler. This bit is used by
+ * pthread_testcancel() to check whether a cancellation has been requested,
+ * and also by cancellable syscalls.
+ *
+ * tcbCancelingBit is set when a cancellation is currently being handled. This
+ * is to avoid a situation in which a cancellation handler gets interrupted by
+ * a SIGCANCEL and a second cancellation handler gets executed on top of the
+ * previous one. Right now this cannot happen, since we stay in signal handler
+ * context when canceling/exiting. In the future this might be done outside
+ * of a signal handler, in which case we shouldn't restart the cancellation process.
+ *
+ * tcbExitingBit is set when the thread starts the exit procedure. Currently
+ * this is just an exit, but in the future this will be a stack unwinding
+ * procedure, which shouldn't be reentered. Not currently set anywhere,
+ * may be done so in the future.
+ *
+ * TODO(geert): update this comment when we do unwinding in the exit procedure.
+ */
+
+namespace {
+	// Set when the cancellation is enabled
+	constexpr unsigned int tcbCancelEnableBit = 1 << 0;
+	// 1 - cancellation is asynchronous, 0 - cancellation is deferred
+	constexpr unsigned int tcbCancelAsyncBit = 1 << 1;
+	// Set when the thread has been cancelled
+	constexpr unsigned int tcbCancelTriggerBit = 1 << 2;
+	// Set when the thread is in the process of being cancelled.
+	constexpr unsigned int tcbCancelingBit = 1 << 3;
+	// Set when the thread is exiting.
+	constexpr unsigned int tcbExitingBit = 1 << 4;
+}
+
+namespace mlibc {
+	// Returns true when bitmask indicates thread has been asynchronously
+	// cancelled.
+	static constexpr bool tcb_async_cancelled(int value) {
+		return (value & (tcbCancelEnableBit | tcbCancelAsyncBit
+				| tcbCancelTriggerBit)) == (tcbCancelEnableBit
+					| tcbCancelAsyncBit | tcbCancelTriggerBit);
+	}
+
+	// Returns true when bitmask indicates async cancellation is enabled.
+	static constexpr bool tcb_async_cancel(int value) {
+		return (value & (tcbCancelEnableBit | tcbCancelAsyncBit))
+			== (tcbCancelEnableBit | tcbCancelAsyncBit);
+	}
+
+	// Returns true when bitmask indicates cancellation is enabled.
+	static constexpr bool tcb_cancel_enabled(int value) {
+		return (value & tcbCancelEnableBit);
+	}
+
+	// Returns true when bitmask indicates threas has been cancelled.
+	static constexpr bool tcb_cancelled(int value) {
+		return (value & (tcbCancelEnableBit | tcbCancelTriggerBit))
+		       == (tcbCancelEnableBit | tcbCancelTriggerBit);
+	}
+
+#if !MLIBC_STATIC_BUILD && !MLIBC_BUILDING_RTDL
+	// In non-static builds, libc.so always has a TCB available.
+	constexpr bool tcb_available_flag = true;
+#else
+	// Otherwise this will be set to true after RTDL has initialized the TCB.
+	extern bool tcb_available_flag;
+#endif
+}
+
+enum class TcbThreadReturnValue {
+	Pointer,
+	Integer,
+};
+
+struct Tcb {
+	Tcb *selfPointer;
+	size_t dtvSize;
+	void **dtvPointers;
+	int tid;
+	int didExit;
+#if defined(__x86_64__)
+	uint8_t padding[8];
+#endif
+	uintptr_t stackCanary;
+	int cancelBits;
+
+	union {
+		void *voidPtr;
+		int intVal;
+	} returnValue;
+	TcbThreadReturnValue returnValueType;
+
+	struct AtforkHandler {
+		void (*prepare)(void);
+		void (*parent)(void);
+		void (*child)(void);
+
+		AtforkHandler *next;
+		AtforkHandler *prev;
+	};
+
+	AtforkHandler *atforkBegin;
+	AtforkHandler *atforkEnd;
+
+	struct CleanupHandler {
+		void (*func)(void *);
+		void *arg;
+
+		CleanupHandler *next;
+		CleanupHandler *prev;
+	};
+
+	CleanupHandler *cleanupBegin;
+	CleanupHandler *cleanupEnd;
+	int isJoinable;
+
+	struct LocalKey {
+		void *value;
+		uint64_t generation;
+	};
+	frg::array<LocalKey, PTHREAD_KEYS_MAX> *localKeys;
+
+	size_t stackSize;
+	void *stackAddr;
+	size_t guardSize;
+
+	inline void invokeThreadFunc(void *entry, void *user_arg) {
+		if(returnValueType == TcbThreadReturnValue::Pointer) {
+			auto func = reinterpret_cast<void *(*)(void *)>(entry);
+			returnValue.voidPtr = func(user_arg);
+		} else {
+			auto func = reinterpret_cast<int (*)(void *)>(entry);
+			returnValue.intVal = func(user_arg);
+		}
+	}
+};
+
+// There are a few places where we assume the layout of the TCB:
+#if defined(__x86_64__)
+// GCC expects the stack canary to be at fs:0x28.
+static_assert(offsetof(Tcb, stackCanary) == 0x28);
+// sysdeps/linux/x86_64/cp_syscall.S uses the offset of cancelBits.
+static_assert(offsetof(Tcb, cancelBits) == 0x30);
+#elif defined(__i386__)
+// GCC expects the stack canary to be at gs:0x14.
+// The offset differs from x86_64 due to the change in the pointer size
+// and removed padding before the stack canary.
+static_assert(offsetof(Tcb, stackCanary) == 0x14);
+// sysdeps/linux/x86/cp_syscall.S uses the offset of cancelBits.
+// It differs from x86_64 for the same reasons as the stack canary.
+static_assert(offsetof(Tcb, cancelBits) == 0x18);
+#elif defined(__aarch64__)
+// The thread pointer on AArch64 points to 16 bytes before the end of the TCB.
+// options/linker/aarch64/runtime.S uses the offset of dtvPointers.
+static_assert(sizeof(Tcb) - offsetof(Tcb, dtvPointers) - TP_TCB_OFFSET == 104);
+// sysdeps/linux/aarch64/cp_syscall.S uses the offset of cancelBits.
+static_assert(sizeof(Tcb) - offsetof(Tcb, cancelBits) - TP_TCB_OFFSET == 80);
+#elif defined(__riscv) && __riscv_xlen == 64
+// The thread pointer on RISC-V points to *after* the TCB, and since
+// we need to access specific fields that means that the value in
+// sysdeps/linux/riscv64/cp_syscall.S needs to be updated whenever
+// the struct is expanded.
+static_assert(sizeof(Tcb) - offsetof(Tcb, cancelBits) == 96);
+#else
+#error "Missing architecture specific code."
+#endif
diff --git a/lib/mlibc/options/internal/include/mlibc/threads.hpp b/lib/mlibc/options/internal/include/mlibc/threads.hpp
new file mode 100644
index 0000000..989a8e5
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/threads.hpp
@@ -0,0 +1,27 @@
+#pragma once
+
+#include <bits/ansi/timespec.h>
+#include <bits/threads.h>
+
+namespace mlibc {
+
+int thread_create(struct __mlibc_thread_data **__restrict thread, const struct __mlibc_threadattr *__restrict attrp, void *entry, void *__restrict user_arg, bool returns_int);
+int thread_attr_init(struct __mlibc_threadattr *attr);
+int thread_join(struct __mlibc_thread_data *thread, void *res);
+
+int thread_mutex_init(struct __mlibc_mutex *__restrict mutex, const struct __mlibc_mutexattr *__restrict attr);
+int thread_mutex_destroy(struct __mlibc_mutex *mutex);
+int thread_mutex_lock(struct __mlibc_mutex *mutex);
+int thread_mutex_unlock(struct __mlibc_mutex *mutex);
+
+int thread_mutexattr_init(struct __mlibc_mutexattr *attr);
+int thread_mutexattr_destroy(struct __mlibc_mutexattr *attr);
+int thread_mutexattr_gettype(const struct __mlibc_mutexattr *__restrict attr, int *__restrict type);
+int thread_mutexattr_settype(struct __mlibc_mutexattr *attr, int type);
+
+int thread_cond_init(struct __mlibc_cond *__restrict cond, const struct __mlibc_condattr *__restrict attr);
+int thread_cond_destroy(struct __mlibc_cond *cond);
+int thread_cond_broadcast(struct __mlibc_cond *cond);
+int thread_cond_timedwait(struct __mlibc_cond *__restrict cond, __mlibc_mutex *__restrict mutex, const struct timespec *__restrict abstime);
+
+}
diff --git a/lib/mlibc/options/internal/include/mlibc/tid.hpp b/lib/mlibc/options/internal/include/mlibc/tid.hpp
new file mode 100644
index 0000000..e85c19f
--- /dev/null
+++ b/lib/mlibc/options/internal/include/mlibc/tid.hpp
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <mlibc/thread.hpp>
+#include <mlibc/internal-sysdeps.hpp>
+
+namespace mlibc {
+	inline unsigned int this_tid() {
+		// During RTDL initialization, we don't have a TCB.
+		if (mlibc::tcb_available_flag) {
+			auto tcb = get_current_tcb();
+			return tcb->tid;
+		} else if (mlibc::sys_futex_tid) {
+			return mlibc::sys_futex_tid();
+		} else {
+			return 1;
+		}
+	}
+}
diff --git a/lib/mlibc/options/internal/include/stdint.h b/lib/mlibc/options/internal/include/stdint.h
new file mode 100644
index 0000000..4d8df66
--- /dev/null
+++ b/lib/mlibc/options/internal/include/stdint.h
@@ -0,0 +1,150 @@
+#ifndef _MLIBC_STDINT_H
+#define _MLIBC_STDINT_H
+
+#include <bits/types.h>
+#include <bits/wchar.h>
+
+// ----------------------------------------------------------------------------
+// Type definitions.
+// ----------------------------------------------------------------------------
+
+// Fixed-width (signed).
+typedef __mlibc_int8  int8_t;
+typedef __mlibc_int16 int16_t;
+typedef __mlibc_int32 int32_t;
+typedef __mlibc_int64 int64_t;
+
+// Fixed-width (unsigned).
+typedef __mlibc_uint8  uint8_t;
+typedef __mlibc_uint16 uint16_t;
+typedef __mlibc_uint32 uint32_t;
+typedef __mlibc_uint64 uint64_t;
+
+// Least-width (signed).
+typedef __mlibc_int8  int_least8_t;
+typedef __mlibc_int16 int_least16_t;
+typedef __mlibc_int32 int_least32_t;
+typedef __mlibc_int64 int_least64_t;
+
+// Least-width (unsigned).
+typedef __mlibc_uint8  uint_least8_t;
+typedef __mlibc_uint16 uint_least16_t;
+typedef __mlibc_uint32 uint_least32_t;
+typedef __mlibc_uint64 uint_least64_t;
+
+// Fast-width (signed).
+typedef __mlibc_int_fast8  int_fast8_t;
+typedef __mlibc_int_fast16 int_fast16_t;
+typedef __mlibc_int_fast32 int_fast32_t;
+typedef __mlibc_int_fast64 int_fast64_t;
+
+// Fast-width (unsigned).
+typedef __mlibc_uint_fast8  uint_fast8_t;
+typedef __mlibc_uint_fast16 uint_fast16_t;
+typedef __mlibc_uint_fast32 uint_fast32_t;
+typedef __mlibc_uint_fast64 uint_fast64_t;
+
+// Miscellaneous (signed).
+typedef __mlibc_intmax intmax_t;
+typedef __mlibc_intptr intptr_t;
+
+// Miscellaneous (unsigned).
+typedef __mlibc_uintmax uintmax_t;
+typedef __mlibc_uintptr uintptr_t;
+
+// ----------------------------------------------------------------------------
+// Constants.
+// ----------------------------------------------------------------------------
+
+// Fixed-width (signed).
+#define INT8_C(x)  __MLIBC_INT8_C(x)
+#define INT16_C(x) __MLIBC_INT16_C(x)
+#define INT32_C(x) __MLIBC_INT32_C(x)
+#define INT64_C(x) __MLIBC_INT64_C(x)
+#define INTMAX_C(x) __MLIBC_INTMAX_C(x)
+
+// Fixed-width (unsigned).
+#define UINT8_C(x)  __MLIBC_UINT8_C(x)
+#define UINT16_C(x) __MLIBC_UINT16_C(x)
+#define UINT32_C(x) __MLIBC_UINT32_C(x)
+#define UINT64_C(x) __MLIBC_UINT64_C(x)
+#define UINTMAX_C(x) __MLIBC_UINTMAX_C(x)
+
+// ----------------------------------------------------------------------------
+// Limits.
+// ----------------------------------------------------------------------------
+
+// Fixed-width (signed).
+#define INT8_MAX  __MLIBC_INT8_MAX
+#define INT16_MAX __MLIBC_INT16_MAX
+#define INT32_MAX __MLIBC_INT32_MAX
+#define INT64_MAX __MLIBC_INT64_MAX
+
+#define INT8_MIN  __MLIBC_INT8_MIN
+#define INT16_MIN __MLIBC_INT16_MIN
+#define INT32_MIN __MLIBC_INT32_MIN
+#define INT64_MIN __MLIBC_INT64_MIN
+
+// Fixed-width (unsigned).
+#define UINT8_MAX  __MLIBC_UINT8_MAX
+#define UINT16_MAX __MLIBC_UINT16_MAX
+#define UINT32_MAX __MLIBC_UINT32_MAX
+#define UINT64_MAX __MLIBC_UINT64_MAX
+
+// Least-width (signed).
+#define INT_LEAST8_MAX  __MLIBC_INT8_MAX
+#define INT_LEAST16_MAX __MLIBC_INT16_MAX
+#define INT_LEAST32_MAX __MLIBC_INT32_MAX
+#define INT_LEAST64_MAX __MLIBC_INT64_MAX
+
+#define INT_LEAST8_MIN  __MLIBC_INT8_MIN
+#define INT_LEAST16_MIN __MLIBC_INT16_MIN
+#define INT_LEAST32_MIN __MLIBC_INT32_MIN
+#define INT_LEAST64_MIN __MLIBC_INT64_MIN
+
+// Least-width (unsigned).
+#define UINT_LEAST8_MAX  __MLIBC_UINT8_MAX
+#define UINT_LEAST16_MAX __MLIBC_UINT16_MAX
+#define UINT_LEAST32_MAX __MLIBC_UINT32_MAX
+#define UINT_LEAST64_MAX __MLIBC_UINT64_MAX
+
+// Fast-width (signed).
+#define INT_FAST8_MAX  __MLIBC_INT_FAST8_MAX
+#define INT_FAST16_MAX __MLIBC_INT_FAST16_MAX
+#define INT_FAST32_MAX __MLIBC_INT_FAST32_MAX
+#define INT_FAST64_MAX __MLIBC_INT_FAST64_MAX
+
+#define INT_FAST8_MIN  __MLIBC_INT_FAST8_MIN
+#define INT_FAST16_MIN __MLIBC_INT_FAST16_MIN
+#define INT_FAST32_MIN __MLIBC_INT_FAST32_MIN
+#define INT_FAST64_MIN __MLIBC_INT_FAST64_MIN
+
+// Fast-width (unsigned).
+#define UINT_FAST8_MAX  __MLIBC_UINT_FAST8_MAX
+#define UINT_FAST16_MAX __MLIBC_UINT_FAST16_MAX
+#define UINT_FAST32_MAX __MLIBC_UINT_FAST32_MAX
+#define UINT_FAST64_MAX __MLIBC_UINT_FAST64_MAX
+
+// Miscellaneous (signed).
+#define INTMAX_MAX __MLIBC_INTMAX_MAX
+#define INTPTR_MAX __MLIBC_INTPTR_MAX
+
+#define INTMAX_MIN __MLIBC_INTMAX_MIN
+#define INTPTR_MIN __MLIBC_INTPTR_MIN
+
+// Miscellaneous (unsigned).
+#define UINTMAX_MAX __MLIBC_UINTMAX_MAX
+#define UINTPTR_MAX __MLIBC_UINTPTR_MAX
+
+// Other limits (signed).
+#define PTRDIFF_MAX    __MLIBC_PTRDIFF_MAX
+#define PTRDIFF_MIN    __MLIBC_PTRDIFF_MIN
+#define SIG_ATOMIC_MAX __MLIBC_SIG_ATOMIC_MAX
+#define SIG_ATOMIC_MIN __MLIBC_SIG_ATOMIC_MIN
+#define WINT_MAX       __MLIBC_WINT_MAX
+#define WINT_MIN       __MLIBC_WINT_MIN
+
+// Other limits (unsigned).
+#define SIZE_MAX __MLIBC_SIZE_MAX
+
+#endif // _MLIBC_STDINT_H
diff --git a/lib/mlibc/options/internal/riscv64-include/mlibc/arch-defs.hpp b/lib/mlibc/options/internal/riscv64-include/mlibc/arch-defs.hpp
new file mode 100644
index 0000000..0a4789f
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64-include/mlibc/arch-defs.hpp
@@ -0,0 +1,12 @@
+#ifndef MLIBC_ARCH_DEFS_HPP
+#define MLIBC_ARCH_DEFS_HPP
+
+#include <stddef.h>
+
+namespace mlibc {
+
+inline constexpr size_t page_size = 0x1000;
+
+} // namespace mlibc
+
+#endif // MLIBC_ARCH_DEFS_HPP
diff --git a/lib/mlibc/options/internal/riscv64-include/mlibc/thread.hpp b/lib/mlibc/options/internal/riscv64-include/mlibc/thread.hpp
new file mode 100644
index 0000000..7428b75
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64-include/mlibc/thread.hpp
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <stdint.h>
+#include <mlibc/tcb.hpp>
+#include <bits/ensure.h>
+
+namespace mlibc {
+
+inline Tcb *get_current_tcb() {
+	// On RISC-V, the TCB is below the thread pointer.
+	uintptr_t tp = (uintptr_t)__builtin_thread_pointer();
+	auto tcb = reinterpret_cast<Tcb *>(tp - sizeof(Tcb));
+	__ensure(tcb == tcb->selfPointer);
+	return tcb;
+}
+
+inline uintptr_t get_sp() {
+	uintptr_t sp;
+	asm ("mv %0, sp" : "=r"(sp));
+	return sp;
+}
+
+} // namespace mlibc
diff --git a/lib/mlibc/options/internal/riscv64/fenv.S b/lib/mlibc/options/internal/riscv64/fenv.S
new file mode 100644
index 0000000..c62ea36
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64/fenv.S
@@ -0,0 +1,57 @@
+
+#ifdef __riscv_flen
+
+.global feclearexcept
+.type feclearexcept, %function
+feclearexcept:
+	csrc fflags, a0
+	li a0, 0
+	ret
+
+.global feraiseexcept
+.type feraiseexcept, %function
+feraiseexcept:
+	csrs fflags, a0
+	li a0, 0
+	ret
+
+.global fetestexcept
+.type fetestexcept, %function
+fetestexcept:
+	frflags t0
+	and a0, t0, a0
+	ret
+
+.global fegetround
+.type fegetround, %function
+fegetround:
+	frrm a0
+	ret
+
+.global __fesetround
+.type __fesetround, %function
+__fesetround:
+	fsrm t0, a0
+	li a0, 0
+	ret
+
+.global fegetenv
+.type fegetenv, %function
+fegetenv:
+	frcsr t0
+	sw t0, 0(a0)
+	li a0, 0
+	ret
+
+.global fesetenv
+.type fesetenv, %function
+fesetenv:
+	li t2, -1
+	li t1, 0
+	beq a0, t2, 1f
+	lw t1, 0(a0)
+1:	fscsr t1
+	li a0, 0
+	ret
+
+#endif
\ No newline at end of file
diff --git a/lib/mlibc/options/internal/riscv64/mlibc_crtbegin.S b/lib/mlibc/options/internal/riscv64/mlibc_crtbegin.S
new file mode 100644
index 0000000..b99748b
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64/mlibc_crtbegin.S
@@ -0,0 +1,29 @@
+
+.section .data
+.hidden __dso_handle
+.global __dso_handle
+__dso_handle:
+	.quad __dso_handle
+
+.section .init
+.hidden _init
+.global _init
+_init:
+
+.section .fini
+.hidden _fini
+.global _fini
+_fini:
+
+.section .ctors
+.hidden __CTOR_LIST__
+.global __CTOR_LIST__
+__CTOR_LIST__:
+
+.section .dtors
+.hidden __DTOR_LIST__
+.global __DTOR_LIST__
+__DTOR_LIST__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/riscv64/mlibc_crtend.S b/lib/mlibc/options/internal/riscv64/mlibc_crtend.S
new file mode 100644
index 0000000..bd0cebc
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64/mlibc_crtend.S
@@ -0,0 +1,21 @@
+.hidden __mlibc_do_ctors
+.hidden __mlibc_do_dtors
+
+.section .init
+	tail __mlibc_do_ctors
+
+.section .fini
+	tail __mlibc_do_dtors
+
+.section .ctors
+.hidden __CTOR_END__
+.global __CTOR_END__
+__CTOR_END__:
+
+.section .dtors
+.hidden __DTOR_END__
+.global __DTOR_END__
+__DTOR_END__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/riscv64/setjmp.S b/lib/mlibc/options/internal/riscv64/setjmp.S
new file mode 100644
index 0000000..51568f7
--- /dev/null
+++ b/lib/mlibc/options/internal/riscv64/setjmp.S
@@ -0,0 +1,71 @@
+.global setjmp
+.type setjmp, "function"
+setjmp:
+	sd ra, 0(a0)
+	sd s0, 8(a0)
+	sd s1, 16(a0)
+	sd s2, 24(a0)
+	sd s3, 32(a0)
+	sd s4, 40(a0)
+	sd s5, 48(a0)
+	sd s6, 56(a0)
+	sd s7, 64(a0)
+	sd s8, 72(a0)
+	sd s9, 80(a0)
+	sd s10, 88(a0)
+	sd s11, 96(a0)
+	sd sp, 104(a0)
+	fsd fs0, 112(a0)
+	fsd fs1, 120(a0)
+	fsd fs2, 128(a0)
+	fsd fs3, 136(a0)
+	fsd fs4, 144(a0)
+	fsd fs5, 152(a0)
+	fsd fs6, 160(a0)
+	fsd fs7, 168(a0)
+	fsd fs8, 176(a0)
+	fsd fs9, 184(a0)
+	fsd fs10, 192(a0)
+	fsd fs11, 200(a0)
+	li a0, 0
+	ret
+
+.global sigsetjmp
+.type sigsetjmp, "function"
+sigsetjmp:
+	unimp // TODO
+
+.global longjmp
+.type longjmp, "function"
+longjmp:
+	ld ra,0(a0)
+	ld s0,8(a0)
+	ld s1,16(a0)
+	ld s2,24(a0)
+	ld s3,32(a0)
+	ld s4,40(a0)
+	ld s5,48(a0)
+	ld s6,56(a0)
+	ld s7,64(a0)
+	ld s8,72(a0)
+	ld s9,80(a0)
+	ld s10,88(a0)
+	ld s11,96(a0)
+	ld sp,104(a0)
+	fld fs0,112(a0)
+	fld fs1,120(a0)
+	fld fs2,128(a0)
+	fld fs3,136(a0)
+	fld fs4,144(a0)
+	fld fs5,152(a0)
+	fld fs6,160(a0)
+	fld fs7,168(a0)
+	fld fs8,176(a0)
+	fld fs9,184(a0)
+	fld fs10,192(a0)
+	fld fs11,200(a0)
+	seqz a0,a1
+	add a0,a0,a1
+	ret
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86-include/mlibc/arch-defs.hpp b/lib/mlibc/options/internal/x86-include/mlibc/arch-defs.hpp
new file mode 100755
index 0000000..aa8fe38
--- /dev/null
+++ b/lib/mlibc/options/internal/x86-include/mlibc/arch-defs.hpp
@@ -0,0 +1,13 @@
+#ifndef MLIBC_ARCH_DEFS_HPP
+#define MLIBC_ARCH_DEFS_HPP
+
+#include <stddef.h>
+
+namespace mlibc {
+
+inline constexpr size_t page_size = 0x1000;
+
+} // namespace mlibc
+
+#endif // MLIBC_ARCH_DEFS_HPP
+
diff --git a/lib/mlibc/options/internal/x86-include/mlibc/thread.hpp b/lib/mlibc/options/internal/x86-include/mlibc/thread.hpp
new file mode 100755
index 0000000..3475fb4
--- /dev/null
+++ b/lib/mlibc/options/internal/x86-include/mlibc/thread.hpp
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <stdint.h>
+#include <mlibc/tcb.hpp>
+
+namespace mlibc {
+
+inline Tcb *get_current_tcb() {
+	uintptr_t ptr;
+	asm ("movl %%gs:0, %0" : "=r"(ptr));
+	return reinterpret_cast<Tcb *>(ptr);
+}
+
+inline uintptr_t get_sp() {
+	uintptr_t esp;
+	asm ("mov %%esp, %0" : "=r"(esp));
+	return esp;
+}
+
+} // namespace mlibc
+
diff --git a/lib/mlibc/options/internal/x86/fenv.S b/lib/mlibc/options/internal/x86/fenv.S
new file mode 100644
index 0000000..a46b5fa
--- /dev/null
+++ b/lib/mlibc/options/internal/x86/fenv.S
@@ -0,0 +1,168 @@
+# The functions below are taken from musl.
+
+.hidden __hwcap
+
+.global feclearexcept
+.type feclearexcept,@function
+feclearexcept:
+	mov 4(%esp),%ecx
+	and $0x3f,%ecx
+	fnstsw %ax
+		# consider sse fenv as well if the cpu has XMM capability
+	call 1f
+1:	addl $__hwcap-1b,(%esp)
+	pop %edx
+	testl $0x02000000,(%edx)
+	jz 2f
+		# maintain exceptions in the sse mxcsr, clear x87 exceptions
+	test %eax,%ecx
+	jz 1f
+	fnclex
+1:	push %edx
+	stmxcsr (%esp)
+	pop %edx
+	and $0x3f,%eax
+	or %eax,%edx
+	test %edx,%ecx
+	jz 1f
+	not %ecx
+	and %ecx,%edx
+	push %edx
+	ldmxcsr (%esp)
+	pop %edx
+1:	xor %eax,%eax
+	ret
+		# only do the expensive x87 fenv load/store when needed
+2:	test %eax,%ecx
+	jz 1b
+	not %ecx
+	and %ecx,%eax
+	test $0x3f,%eax
+	jz 1f
+	fnclex
+	jmp 1b
+1:	sub $32,%esp
+	fnstenv (%esp)
+	mov %al,4(%esp)
+	fldenv (%esp)
+	add $32,%esp
+	xor %eax,%eax
+	ret
+
+.global feraiseexcept
+.type feraiseexcept,@function
+feraiseexcept:
+	mov 4(%esp),%eax
+	and $0x3f,%eax
+	sub $32,%esp
+	fnstenv (%esp)
+	or %al,4(%esp)
+	fldenv (%esp)
+	add $32,%esp
+	xor %eax,%eax
+	ret
+
+.global __fesetround
+.hidden __fesetround
+.type __fesetround,@function
+__fesetround:
+	mov 4(%esp),%ecx
+	push %eax
+	xor %eax,%eax
+	fnstcw (%esp)
+	andb $0xf3,1(%esp)
+	or %ch,1(%esp)
+	fldcw (%esp)
+		# consider sse fenv as well if the cpu has XMM capability
+	call 1f
+1:	addl $__hwcap-1b,(%esp)
+	pop %edx
+	testl $0x02000000,(%edx)
+	jz 1f
+	stmxcsr (%esp)
+	shl $3,%ch
+	andb $0x9f,1(%esp)
+	or %ch,1(%esp)
+	ldmxcsr (%esp)
+1:	pop %ecx
+	ret
+
+.global fegetround
+.type fegetround,@function
+fegetround:
+	push %eax
+	fnstcw (%esp)
+	pop %eax
+	and $0xc00,%eax
+	ret
+
+.global fegetenv
+.type fegetenv,@function
+fegetenv:
+	mov 4(%esp),%ecx
+	xor %eax,%eax
+	fnstenv (%ecx)
+		# consider sse fenv as well if the cpu has XMM capability
+	call 1f
+1:	addl $__hwcap-1b,(%esp)
+	pop %edx
+	testl $0x02000000,(%edx)
+	jz 1f
+	push %eax
+	stmxcsr (%esp)
+	pop %edx
+	and $0x3f,%edx
+	or %edx,4(%ecx)
+1:	ret
+
+.global fesetenv
+.type fesetenv,@function
+fesetenv:
+	mov 4(%esp),%ecx
+	xor %eax,%eax
+	inc %ecx
+	jz 1f
+	fldenv -1(%ecx)
+	movl -1(%ecx),%ecx
+	jmp 2f
+1:	push %eax
+	push %eax
+	push %eax
+	push %eax
+	pushl $0xffff
+	push %eax
+	pushl $0x37f
+	fldenv (%esp)
+	add $28,%esp
+		# consider sse fenv as well if the cpu has XMM capability
+2:	call 1f
+1:	addl $__hwcap-1b,(%esp)
+	pop %edx
+	testl $0x02000000,(%edx)
+	jz 1f
+		# mxcsr := same rounding mode, cleared exceptions, default mask
+	and $0xc00,%ecx
+	shl $3,%ecx
+	or $0x1f80,%ecx
+	mov %ecx,4(%esp)
+	ldmxcsr 4(%esp)
+1:	ret
+
+.global fetestexcept
+.type fetestexcept,@function
+fetestexcept:
+	mov 4(%esp),%ecx
+	and $0x3f,%ecx
+	fnstsw %ax
+		# consider sse fenv as well if the cpu has XMM capability
+	call 1f
+1:	addl $__hwcap-1b,(%esp)
+	pop %edx
+	testl $0x02000000,(%edx)
+	jz 1f
+	stmxcsr 4(%esp)
+	or 4(%esp),%eax
+1:	and %ecx,%eax
+	ret
+
+.section .note.GNU-stack,"",%progbits
diff --git a/lib/mlibc/options/internal/x86/mlibc_crtbegin.S b/lib/mlibc/options/internal/x86/mlibc_crtbegin.S
new file mode 100644
index 0000000..d317451
--- /dev/null
+++ b/lib/mlibc/options/internal/x86/mlibc_crtbegin.S
@@ -0,0 +1,29 @@
+
+.section .data
+.hidden __dso_handle
+.global __dso_handle
+__dso_handle:
+	.long __dso_handle
+
+.section .init
+.hidden _init
+.global _init
+_init:
+
+.section .fini
+.hidden _fini
+.global _fini
+_fini:
+
+.section .ctors
+.hidden __CTOR_LIST__
+.global __CTOR_LIST__
+__CTOR_LIST__:
+
+.section .dtors
+.hidden __DTOR_LIST__
+.global __DTOR_LIST__
+__DTOR_LIST__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86/mlibc_crtend.S b/lib/mlibc/options/internal/x86/mlibc_crtend.S
new file mode 100644
index 0000000..e9d9136
--- /dev/null
+++ b/lib/mlibc/options/internal/x86/mlibc_crtend.S
@@ -0,0 +1,24 @@
+
+.hidden __mlibc_do_ctors
+.hidden __mlibc_do_dtors
+
+.section .init
+	call __mlibc_do_ctors
+	ret
+
+.section .fini
+	call __mlibc_do_dtors
+	ret
+
+.section .ctors
+.hidden __CTOR_END__
+.global __CTOR_END__
+__CTOR_END__:
+
+.section .dtors
+.hidden __DTOR_END__
+.global __DTOR_END__
+__DTOR_END__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86/setjmp.S b/lib/mlibc/options/internal/x86/setjmp.S
new file mode 100644
index 0000000..fa6644c
--- /dev/null
+++ b/lib/mlibc/options/internal/x86/setjmp.S
@@ -0,0 +1,53 @@
+
+.type __setjmp, "function"
+__setjmp:
+	mov 4(%esp), %eax       # Save argument (buffer) in edi
+	mov %ebx, 0x00(%eax)
+	mov %ebp, 0x04(%eax)
+	mov %esi, 0x08(%eax)
+	mov %edi, 0x0c(%eax)
+
+	lea 4(%esp), %ecx       # esp before return eip is pushed
+	mov %ecx, 0x10(%eax)
+	mov (%esp), %ecx        # Return eip
+	mov %ecx, 0x14(%eax)
+
+	test %edx, %edx
+	jnz 1f
+	xor %eax, %eax
+	ret
+
+1:
+	jmp __sigsetjmp@PLT
+
+.global setjmp
+.type setjmp, "function"
+setjmp:
+	xor %edx, %edx
+	jmp __setjmp
+
+.global sigsetjmp
+.type sigsetjmp, "function"
+sigsetjmp:
+	mov $1, %edx
+	jmp __setjmp
+
+.global longjmp
+.type longjmp, "function"
+longjmp:
+	mov 4(%esp), %ecx
+	mov 0x00(%ecx), %ebx
+	mov 0x04(%ecx), %ebp
+	mov 0x08(%ecx), %esi
+	mov 0x0c(%ecx), %edi
+
+	mov 8(%esp), %eax
+	test %eax, %eax
+	jnz 1f
+	inc %eax
+1:
+	mov 0x10(%ecx), %esp
+	jmp *0x14(%ecx)
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86_64-include/mlibc/arch-defs.hpp b/lib/mlibc/options/internal/x86_64-include/mlibc/arch-defs.hpp
new file mode 100644
index 0000000..0a4789f
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64-include/mlibc/arch-defs.hpp
@@ -0,0 +1,12 @@
+#ifndef MLIBC_ARCH_DEFS_HPP
+#define MLIBC_ARCH_DEFS_HPP
+
+#include <stddef.h>
+
+namespace mlibc {
+
+inline constexpr size_t page_size = 0x1000;
+
+} // namespace mlibc
+
+#endif // MLIBC_ARCH_DEFS_HPP
diff --git a/lib/mlibc/options/internal/x86_64-include/mlibc/thread.hpp b/lib/mlibc/options/internal/x86_64-include/mlibc/thread.hpp
new file mode 100644
index 0000000..ed02b67
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64-include/mlibc/thread.hpp
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <stdint.h>
+#include <mlibc/tcb.hpp>
+
+namespace mlibc {
+
+inline Tcb *get_current_tcb() {
+	uintptr_t ptr;
+	asm ("movq %%fs:0, %0" : "=r"(ptr));
+	return reinterpret_cast<Tcb *>(ptr);
+}
+
+inline uintptr_t get_sp() {
+	uintptr_t rsp;
+	asm ("mov %%rsp, %0" : "=r"(rsp));
+	return rsp;
+}
+
+} // namespace mlibc
diff --git a/lib/mlibc/options/internal/x86_64/fenv.S b/lib/mlibc/options/internal/x86_64/fenv.S
new file mode 100644
index 0000000..3748988
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64/fenv.S
@@ -0,0 +1,102 @@
+# The functions below are taken from musl.
+.global feclearexcept
+.type feclearexcept,@function
+feclearexcept:
+	# maintain exceptions in the sse mxcsr, clear x87 exceptions
+	mov %edi,%ecx
+	and $0x3f,%ecx
+	fnstsw %ax
+	test %eax,%ecx
+	jz 1f
+	fnclex
+1:	stmxcsr -8(%rsp)
+	and $0x3f,%eax
+	or %eax,-8(%rsp)
+	test %ecx,-8(%rsp)
+	jz 1f
+	not %ecx
+	and %ecx,-8(%rsp)
+	ldmxcsr -8(%rsp)
+1:	xor %eax,%eax
+	ret
+
+.global feraiseexcept
+.type feraiseexcept,@function
+feraiseexcept:
+	and $0x3f,%edi
+	stmxcsr -8(%rsp)
+	or %edi,-8(%rsp)
+	ldmxcsr -8(%rsp)
+	xor %eax,%eax
+	ret
+
+.global __fesetround
+.hidden __fesetround
+.type __fesetround,@function
+__fesetround:
+	push %rax
+	xor %eax,%eax
+	mov %edi,%ecx
+	fnstcw (%rsp)
+	andb $0xf3,1(%rsp)
+	or %ch,1(%rsp)
+	fldcw (%rsp)
+	stmxcsr (%rsp)
+	shl $3,%ch
+	andb $0x9f,1(%rsp)
+	or %ch,1(%rsp)
+	ldmxcsr (%rsp)
+	pop %rcx
+	ret
+
+.global fegetround
+.type fegetround,@function
+fegetround:
+	push %rax
+	stmxcsr (%rsp)
+	pop %rax
+	shr $3,%eax
+	and $0xc00,%eax
+	ret
+
+.global fegetenv
+.type fegetenv,@function
+fegetenv:
+	xor %eax,%eax
+	fnstenv (%rdi)
+	stmxcsr 28(%rdi)
+	ret
+
+.global fesetenv
+.type fesetenv,@function
+fesetenv:
+	xor %eax,%eax
+	inc %rdi
+	jz 1f
+	fldenv -1(%rdi)
+	ldmxcsr 27(%rdi)
+	ret
+1:	push %rax
+	push %rax
+	pushq $0xffff
+	pushq $0x37f
+	fldenv (%rsp)
+	pushq $0x1f80
+	ldmxcsr (%rsp)
+	add $40,%rsp
+	ret
+
+.global fetestexcept
+.type fetestexcept,@function
+fetestexcept:
+	and $0x3f,%edi
+	push %rax
+	stmxcsr (%rsp)
+	pop %rsi
+	fnstsw %ax
+	or %esi,%eax
+	and %edi,%eax
+	ret
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86_64/mlibc_crtbegin.S b/lib/mlibc/options/internal/x86_64/mlibc_crtbegin.S
new file mode 100644
index 0000000..b99748b
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64/mlibc_crtbegin.S
@@ -0,0 +1,29 @@
+
+.section .data
+.hidden __dso_handle
+.global __dso_handle
+__dso_handle:
+	.quad __dso_handle
+
+.section .init
+.hidden _init
+.global _init
+_init:
+
+.section .fini
+.hidden _fini
+.global _fini
+_fini:
+
+.section .ctors
+.hidden __CTOR_LIST__
+.global __CTOR_LIST__
+__CTOR_LIST__:
+
+.section .dtors
+.hidden __DTOR_LIST__
+.global __DTOR_LIST__
+__DTOR_LIST__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86_64/mlibc_crtend.S b/lib/mlibc/options/internal/x86_64/mlibc_crtend.S
new file mode 100644
index 0000000..e9d9136
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64/mlibc_crtend.S
@@ -0,0 +1,24 @@
+
+.hidden __mlibc_do_ctors
+.hidden __mlibc_do_dtors
+
+.section .init
+	call __mlibc_do_ctors
+	ret
+
+.section .fini
+	call __mlibc_do_dtors
+	ret
+
+.section .ctors
+.hidden __CTOR_END__
+.global __CTOR_END__
+__CTOR_END__:
+
+.section .dtors
+.hidden __DTOR_END__
+.global __DTOR_END__
+__DTOR_END__:
+
+.section .note.GNU-stack,"",%progbits
+
diff --git a/lib/mlibc/options/internal/x86_64/setjmp.S b/lib/mlibc/options/internal/x86_64/setjmp.S
new file mode 100644
index 0000000..aa8a134
--- /dev/null
+++ b/lib/mlibc/options/internal/x86_64/setjmp.S
@@ -0,0 +1,54 @@
+
+.type __setjmp, "function"
+__setjmp:
+	mov %rbx, 0x00(%rdi)
+	mov %rbp, 0x08(%rdi)
+	mov %r12, 0x10(%rdi)
+	mov %r13, 0x18(%rdi)
+	mov %r14, 0x20(%rdi)
+	mov %r15, 0x28(%rdi)
+
+	lea 8(%rsp), %rax # rsp before return rip is pushed
+	mov %rax, 0x30(%rdi)
+	mov (%rsp), %rax # return rip
+	mov %rax, 0x38(%rdi)
+
+	test %rdx, %rdx
+	jnz 1f
+	xor %rax, %rax
+	ret
+
+1:
+	jmp __sigsetjmp
+
+.global setjmp
+.type setjmp, "function"
+setjmp:
+	xor %rdx, %rdx
+	jmp __setjmp
+
+.global sigsetjmp
+.type sigsetjmp, "function"
+sigsetjmp:
+	mov $1, %rdx
+	jmp __setjmp
+
+.global longjmp
+.type longjmp, "function"
+longjmp:
+	mov 0x00(%rdi), %rbx
+	mov 0x08(%rdi), %rbp
+	mov 0x10(%rdi), %r12
+	mov 0x18(%rdi), %r13
+	mov 0x20(%rdi), %r14
+	mov 0x28(%rdi), %r15
+
+	mov  %rsi, %rax
+	test %rax, %rax
+	jnz 1f
+	inc %rax
+1:
+	mov  0x30(%rdi), %rsp
+	jmp  *0x38(%rdi)
+.section .note.GNU-stack,"",%progbits
+