lib: Add mlibc

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

1 files changed, 108 insertions, 0 deletions

diff --git a/lib/mlibc/sysdeps/keyronex/generic/entry.cpp b/lib/mlibc/sysdeps/keyronex/generic/entry.cpp
new file mode 100644
index 0000000..ff15c62
--- /dev/null
+++ b/lib/mlibc/sysdeps/keyronex/generic/entry.cpp
@@ -0,0 +1,108 @@
+#include <bits/ensure.h>
+#include <bits/posix/posix_signal.h>
+#include <keyronex/syscall.h>
+#include <mlibc/all-sysdeps.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/elf/startup.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+// defined by the POSIX library
+void __mlibc_initLocale();
+
+extern "C" uintptr_t *__dlapi_entrystack();
+
+extern char **environ;
+static mlibc::exec_stack_data __mlibc_stack_data;
+
+struct LibraryGuard {
+	LibraryGuard();
+};
+
+static LibraryGuard guard;
+
+LibraryGuard::LibraryGuard()
+{
+	__mlibc_initLocale();
+
+	// Parse the exec() stack.
+	mlibc::parse_exec_stack(__dlapi_entrystack(), &__mlibc_stack_data);
+	mlibc::set_startup_data(__mlibc_stack_data.argc,
+	    __mlibc_stack_data.argv, __mlibc_stack_data.envp);
+}
+
+namespace mlibc {
+int
+sys_sigentry(void *sigentry)
+{
+	uintptr_t ret = syscall1(kPXSysSigEntry, (uintptr_t)sigentry, NULL);
+	if (int e = sc_error(ret); e)
+		return e;
+	return 0;
+}
+
+[[noreturn]] int
+sys_sigreturn(ucontext_t *context)
+{
+	syscall1(kPXSysSigReturn, (uintptr_t)context, NULL);
+	__builtin_unreachable();
+}
+}
+
+static void
+do_stacktrace(ucontext_t *ctx)
+{
+	size_t *base_ptr = (size_t *)ctx->uc_mcontext.gregs[REG_RBP];
+
+	mlibc::infoLogger() << "Stacktrace:" << frg::endlog;
+	mlibc::infoLogger() << "  [" << (void *)ctx->uc_mcontext.gregs[REG_RIP]
+			    << "]" << frg::endlog;
+	for (;;) {
+		size_t old_bp = base_ptr[0];
+		size_t ret_addr = base_ptr[1];
+		if (!ret_addr)
+			break;
+		mlibc::infoLogger()
+		    << "  [" << (void *)ret_addr << "]" << frg::endlog;
+		if (!old_bp)
+			break;
+		base_ptr = (size_t *)old_bp;
+	}
+}
+
+static void
+__mlibc_sigentry(int which, siginfo_t *siginfo, void *handler,
+    bool is_sigaction, ucontext_t *ret_context)
+{
+	if ((uintptr_t)handler == (uintptr_t)SIG_DFL) {
+		mlibc::infoLogger()
+		    << "mlibc: Unhandled signal " << which << frg::endlog;
+		do_stacktrace(ret_context);
+		mlibc::sys_exit(128 + which);
+	} else if ((uintptr_t)handler == (uintptr_t)SIG_IGN) {
+		/* epsilon */
+	} else {
+		if (is_sigaction)
+			((void (*)(int, siginfo_t *, void *))handler)(which,
+			    siginfo, ret_context);
+		else
+			((void (*)(int))handler)(which);
+	}
+
+	mlibc::sys_sigreturn(ret_context);
+
+	__builtin_unreachable();
+}
+
+extern "C" void
+__mlibc_entry(int (*main_fn)(int argc, char *argv[], char *env[]))
+{
+	/* communicate the signal handler entry point to the kernel */
+	mlibc::sys_sigentry((void *)__mlibc_sigentry);
+
+	// TODO: call __dlapi_enter, otherwise static builds will break (see
+	// Linux sysdeps)
+	auto result = main_fn(__mlibc_stack_data.argc, __mlibc_stack_data.argv,
+	    environ);
+	exit(result);
+}