/*
 * mono-threads-posix.c: Low-level threading, posix version
 *
 * Author:
 *	Rodrigo Kumpera (kumpera@gmail.com)
 *
 * (C) 2011 Novell, Inc
 */

#include <config.h>

#include <mono/utils/mono-compiler.h>
#include <mono/utils/mono-semaphore.h>
#include <mono/utils/mono-threads.h>
#include <mono/utils/mono-tls.h>
#include <mono/utils/mono-mmap.h>
#include <mono/metadata/threads-types.h>
#include <limits.h>

#include <errno.h>

#if defined(PLATFORM_ANDROID) && !defined(TARGET_ARM64) && !defined(TARGET_AMD64)
#define USE_TKILL_ON_ANDROID 1
#endif

#ifdef USE_TKILL_ON_ANDROID
extern int tkill (pid_t tid, int signal);
#endif

#if defined(_POSIX_VERSION) || defined(__native_client__)
#include <sys/resource.h>
#include <signal.h>

#if defined(__native_client__)
void nacl_shutdown_gc_thread(void);
#endif

typedef struct {
	void *(*start_routine)(void*);
	void *arg;
	int flags;
	MonoSemType registered;
	HANDLE handle;
} StartInfo;

#ifdef PLATFORM_ANDROID
static int no_interrupt_signo;
#endif

static void*
inner_start_thread (void *arg)
{
	StartInfo *start_info = arg;
	void *t_arg = start_info->arg;
	int res;
	void *(*start_func)(void*) = start_info->start_routine;
	guint32 flags = start_info->flags;
	void *result;
	HANDLE handle;
	MonoThreadInfo *info;

	/* Register the thread with the io-layer */
	handle = wapi_create_thread_handle ();
	if (!handle) {
		res = MONO_SEM_POST (&(start_info->registered));
		g_assert (!res);
		return NULL;
	}
	start_info->handle = handle;

	info = mono_thread_info_attach (&result);
	info->runtime_thread = TRUE;
	info->handle = handle;

	if (flags & CREATE_SUSPENDED) {
		info->create_suspended = TRUE;
		MONO_SEM_INIT (&info->create_suspended_sem, 0);
	}

	/* start_info is not valid after this */
	res = MONO_SEM_POST (&(start_info->registered));
	g_assert (!res);
	start_info = NULL;

	if (flags & CREATE_SUSPENDED) {
		while (MONO_SEM_WAIT (&info->create_suspended_sem) != 0 &&
			   errno == EINTR);
		MONO_SEM_DESTROY (&info->create_suspended_sem);
	}

	/* Run the actual main function of the thread */
	result = start_func (t_arg);

	/*
	mono_thread_info_detach ();
	*/

#if defined(__native_client__)
	nacl_shutdown_gc_thread();
#endif

	wapi_thread_handle_set_exited (handle, GPOINTER_TO_UINT (result));
	/* This is needed by mono_threads_core_unregister () which is called later */
	info->handle = NULL;

	g_assert (mono_threads_get_callbacks ()->thread_exit);
	mono_threads_get_callbacks ()->thread_exit (NULL);
	g_assert_not_reached ();
	return result;
}

HANDLE
mono_threads_core_create_thread (LPTHREAD_START_ROUTINE start_routine, gpointer arg, guint32 stack_size, guint32 creation_flags, MonoNativeThreadId *out_tid)
{
	pthread_attr_t attr;
	int res;
	pthread_t thread;
	StartInfo start_info;

	res = pthread_attr_init (&attr);
	g_assert (!res);

	if (stack_size == 0) {
#if HAVE_VALGRIND_MEMCHECK_H
		if (RUNNING_ON_VALGRIND)
			stack_size = 1 << 20;
		else
			stack_size = (SIZEOF_VOID_P / 4) * 1024 * 1024;
#else
		stack_size = (SIZEOF_VOID_P / 4) * 1024 * 1024;
#endif
	}

#ifdef PTHREAD_STACK_MIN
	if (stack_size < PTHREAD_STACK_MIN)
		stack_size = PTHREAD_STACK_MIN;
#endif

#ifdef HAVE_PTHREAD_ATTR_SETSTACKSIZE
	res = pthread_attr_setstacksize (&attr, stack_size);
	g_assert (!res);
#endif

	memset (&start_info, 0, sizeof (StartInfo));
	start_info.start_routine = (gpointer)start_routine;
	start_info.arg = arg;
	start_info.flags = creation_flags;
	MONO_SEM_INIT (&(start_info.registered), 0);

	/* Actually start the thread */
	res = mono_threads_get_callbacks ()->mono_gc_pthread_create (&thread, &attr, inner_start_thread, &start_info);
	if (res) {
		MONO_SEM_DESTROY (&(start_info.registered));
		return NULL;
	}

	/* Wait until the thread register itself in various places */
	while (MONO_SEM_WAIT (&(start_info.registered)) != 0) {
		/*if (EINTR != errno) ABORT("sem_wait failed"); */
	}
	MONO_SEM_DESTROY (&(start_info.registered));

	if (out_tid)
		*out_tid = thread;

	return start_info.handle;
}

/*
 * mono_threads_core_resume_created:
 *
 *   Resume a newly created thread created using CREATE_SUSPENDED.
 */
void
mono_threads_core_resume_created (MonoThreadInfo *info, MonoNativeThreadId tid)
{
	MONO_SEM_POST (&info->create_suspended_sem);
}

gboolean
mono_threads_core_yield (void)
{
	return sched_yield () == 0;
}

void
mono_threads_core_exit (int exit_code)
{
	MonoThreadInfo *current = mono_thread_info_current ();

#if defined(__native_client__)
	nacl_shutdown_gc_thread();
#endif

	wapi_thread_handle_set_exited (current->handle, exit_code);

	g_assert (mono_threads_get_callbacks ()->thread_exit);
	mono_threads_get_callbacks ()->thread_exit (NULL);
}

void
mono_threads_core_unregister (MonoThreadInfo *info)
{
	if (info->handle) {
		wapi_thread_handle_set_exited (info->handle, 0);
		info->handle = NULL;
	}
}

HANDLE
mono_threads_core_open_handle (void)
{
	MonoThreadInfo *info;

	info = mono_thread_info_current ();
	g_assert (info);

	if (!info->handle)
		info->handle = wapi_create_thread_handle ();
	else
		wapi_ref_thread_handle (info->handle);
	return info->handle;
}

int
mono_threads_get_max_stack_size (void)
{
	struct rlimit lim;

	/* If getrlimit fails, we don't enforce any limits. */
	if (getrlimit (RLIMIT_STACK, &lim))
		return INT_MAX;
	/* rlim_t is an unsigned long long on 64bits OSX but we want an int response. */
	if (lim.rlim_max > (rlim_t)INT_MAX)
		return INT_MAX;
	return (int)lim.rlim_max;
}

HANDLE
mono_threads_core_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
{
	wapi_ref_thread_handle (handle);

	return handle;
}

gpointer
mono_threads_core_prepare_interrupt (HANDLE thread_handle)
{
	return wapi_prepare_interrupt_thread (thread_handle);
}

void
mono_threads_core_finish_interrupt (gpointer wait_handle)
{
	wapi_finish_interrupt_thread (wait_handle);
}

void
mono_threads_core_self_interrupt (void)
{
	wapi_self_interrupt ();
}

void
mono_threads_core_clear_interruption (void)
{
	wapi_clear_interruption ();
}

int
mono_threads_pthread_kill (MonoThreadInfo *info, int signum)
{
#ifdef USE_TKILL_ON_ANDROID
	int result, old_errno = errno;
	result = tkill (info->native_handle, signum);
	if (result < 0) {
		result = errno;
		errno = old_errno;
	}
	return result;
#elif defined(__native_client__)
	/* Workaround pthread_kill abort() in NaCl glibc. */
	return 0;
#else
	return pthread_kill (mono_thread_info_get_tid (info), signum);
#endif

}

#if !defined (__MACH__)

#if !defined(__native_client__)
static void
suspend_signal_handler (int _dummy, siginfo_t *info, void *context)
{
	MonoThreadInfo *current = mono_thread_info_current ();
	gboolean ret;
	
	if (current->syscall_break_signal) {
		current->syscall_break_signal = FALSE;
		return;
	}

	ret = mono_threads_get_runtime_callbacks ()->thread_state_init_from_sigctx (&current->suspend_state, context);

	/* thread_state_init_from_sigctx return FALSE if the current thread is detaching and suspend can't continue. */
	current->suspend_can_continue = ret;

	MONO_SEM_POST (&current->begin_suspend_semaphore);

	/* This thread is doomed, all we can do is give up and let the suspender recover. */
	if (!ret)
		return;

	while (MONO_SEM_WAIT (&current->resume_semaphore) != 0) {
		/*if (EINTR != errno) ABORT("sem_wait failed"); */
	}

	if (current->async_target) {
#if MONO_ARCH_HAS_MONO_CONTEXT
		MonoContext tmp = current->suspend_state.ctx;
		mono_threads_get_runtime_callbacks ()->setup_async_callback (&tmp, current->async_target, current->user_data);
		current->async_target = current->user_data = NULL;
		mono_monoctx_to_sigctx (&tmp, context);
#else
		g_error ("The new interruption machinery requires a working mono-context");
#endif
	}

	MONO_SEM_POST (&current->finish_resume_semaphore);
}
#endif

static void
mono_posix_add_signal_handler (int signo, gpointer handler, int flags)
{
#if !defined(__native_client__)
	/*FIXME, move the code from mini to utils and do the right thing!*/
	struct sigaction sa;
	struct sigaction previous_sa;
	int ret;

	sa.sa_sigaction = handler;
	sigemptyset (&sa.sa_mask);
	sa.sa_flags = SA_SIGINFO | flags;
	ret = sigaction (signo, &sa, &previous_sa);

	g_assert (ret != -1);
#endif
}

void
mono_threads_init_platform (void)
{
#if !defined(__native_client__)
	int abort_signo;

	/*
	FIXME we should use all macros from mini to make this more portable
	FIXME it would be very sweet if sgen could end up using this too.
	*/
	if (!mono_thread_info_new_interrupt_enabled ())
		return;
	abort_signo = mono_thread_get_abort_signal ();
	mono_posix_add_signal_handler (abort_signo, suspend_signal_handler, 0);

#ifdef PLATFORM_ANDROID
	/*
	 * Lots of android native code can't handle the EINTR caused by
	 * the normal abort signal, so use a different signal for the
	 * no interruption case, which is used by sdb.
	 * FIXME: Use this on all platforms.
	 * SIGUSR1 is used by dalvik/art.
	 */
	no_interrupt_signo = SIGWINCH;
	g_assert (abort_signo != no_interrupt_signo);
	mono_posix_add_signal_handler (no_interrupt_signo, suspend_signal_handler, SA_RESTART);
#endif
#endif
}

void
mono_threads_core_interrupt (MonoThreadInfo *info)
{
	/* Handled in mono_threads_core_suspend () */
}

void
mono_threads_core_abort_syscall (MonoThreadInfo *info)
{
	/*
	We signal a thread to break it from the urrent syscall.
	This signal should not be interpreted as a suspend request.
	*/
	info->syscall_break_signal = TRUE;
	mono_threads_pthread_kill (info, mono_thread_get_abort_signal ());
}

gboolean
mono_threads_core_needs_abort_syscall (void)
{
	return TRUE;
}

gboolean
mono_threads_core_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
{
	/*FIXME, check return value*/
#ifdef PLATFORM_ANDROID
	if (!interrupt_kernel)
		mono_threads_pthread_kill (info, no_interrupt_signo);
	else
		mono_threads_pthread_kill (info, mono_thread_get_abort_signal ());
#else
		mono_threads_pthread_kill (info, mono_thread_get_abort_signal ());
#endif
	while (MONO_SEM_WAIT (&info->begin_suspend_semaphore) != 0) {
		/* g_assert (errno == EINTR); */
	}
	return info->suspend_can_continue;
}

gboolean
mono_threads_core_resume (MonoThreadInfo *info)
{
	MONO_SEM_POST (&info->resume_semaphore);
	while (MONO_SEM_WAIT (&info->finish_resume_semaphore) != 0) {
		/* g_assert (errno == EINTR); */
	}

	return TRUE;
}

void
mono_threads_platform_register (MonoThreadInfo *info)
{
	MONO_SEM_INIT (&info->begin_suspend_semaphore, 0);

#if defined (PLATFORM_ANDROID)
	info->native_handle = gettid ();
#endif
}

void
mono_threads_platform_free (MonoThreadInfo *info)
{
	MONO_SEM_DESTROY (&info->begin_suspend_semaphore);
}

MonoNativeThreadId
mono_native_thread_id_get (void)
{
	return pthread_self ();
}

gboolean
mono_native_thread_id_equals (MonoNativeThreadId id1, MonoNativeThreadId id2)
{
	return pthread_equal (id1, id2);
}

/*
 * mono_native_thread_create:
 *
 *   Low level thread creation function without any GC wrappers.
 */
gboolean
mono_native_thread_create (MonoNativeThreadId *tid, gpointer func, gpointer arg)
{
	return pthread_create (tid, NULL, func, arg) == 0;
}

void
mono_threads_core_set_name (MonoNativeThreadId tid, const char *name)
{
#ifdef HAVE_PTHREAD_SETNAME_NP
	if (!name) {
		pthread_setname_np (tid, "");
	} else {
		char n [16];

		strncpy (n, name, 16);
		n [15] = '\0';
		pthread_setname_np (tid, n);
	}
#endif
}

#endif /*!defined (__MACH__)*/

#endif