lib: Add mlibc

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

1 files changed, 55 insertions, 0 deletions

diff --git a/lib/mlibc/tests/posix/sigaltstack.c b/lib/mlibc/tests/posix/sigaltstack.c
new file mode 100644
index 0000000..bebcc30
--- /dev/null
+++ b/lib/mlibc/tests/posix/sigaltstack.c
@@ -0,0 +1,55 @@
+#include <assert.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdlib.h>
+
+static jmp_buf env;
+static char *sigStack;
+
+static void sig_handler(int sig, siginfo_t *info, void *ctx) {
+	(void)sig;
+	(void)info;
+	(void)ctx;
+
+	longjmp(env, 1);
+}
+
+int main() {
+	if (setjmp(env)) {
+		free(sigStack);
+		return 0;
+	}
+
+	sigStack = malloc(SIGSTKSZ);
+
+	stack_t ss;
+	ss.ss_sp = sigStack;
+	ss.ss_size = SIGSTKSZ;
+	ss.ss_flags = 0;
+
+	assert(!sigaltstack(&ss, NULL));
+
+	struct sigaction sa;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
+	sa.sa_sigaction = sig_handler;
+
+	assert(!sigaction(SIGSEGV, &sa, NULL));
+
+	// This is used to trash the stack to ensure sigaltstack actually switched stacks.
+#if defined(__x86_64__)
+	asm volatile ("mov $0, %rsp\n"
+			"\t" "push $0");
+#elif defined(__i386__)
+	asm volatile ("mov $0, %esp\n"
+			"\t" "push $0");
+#elif defined(__aarch64__)
+	asm volatile ("mov sp, %0\n"
+			"\t" "stp x0, x1, [sp, #-16]!" :: "r"((uint64_t)0));
+#elif defined(__riscv) && __riscv_xlen == 64
+	asm volatile ("li sp, 0\n"
+			"\t" "sd zero, 0(sp)");
+#else
+#	error Unknown architecture
+#endif
+}