musl/src/thread/pthread_self.c

#include "pthread_impl.h"

static struct pthread main_thread;

/* pthread_key_create.c overrides this */
static const void *dummy[1] = { 0 };
weak_alias(dummy, __pthread_tsd_main);

static int *errno_location()
{
	return __pthread_self()->errno_ptr;
}

static int init_main_thread()
{
	if (__set_thread_area(&main_thread) < 0) return -1;
	main_thread.canceldisable = libc.canceldisable;
	main_thread.tsd = (void **)__pthread_tsd_main;
	main_thread.self = libc.main_thread = &main_thread;
	main_thread.errno_ptr = __errno_location();
	libc.errno_location = errno_location;
	main_thread.tid = main_thread.pid = 
		__syscall(SYS_set_tid_address, &main_thread.tid);
	return 0;
}

pthread_t pthread_self()
{
	static int init, failed;
	if (!init) {
		if (failed) return 0;
		if (init_main_thread() < 0) failed = 1;
		if (failed) return 0;
		init = 1;
	}
	return __pthread_self();
}