extern "C" __LIBC_HIDDEN__ pid_t __nacl_clone(int (*fn)(void*),
void* ignored_child_stack,
uint32_t flags,
void* arg,
int* parent_tid,
void** tls,
int* child_tid) {
int tid;
#if !defined(BARE_METAL_BIONIC)
tid = __allocate_tid();
if (tid < 0) {
errno = ENOMEM;
return -1;
}
#endif
// The stack will be put before TLS.
// See the comment of pthread_create in
// libc/bionic/pthread_create.cpp for detail.
void **child_stack = (void **)(((uintptr_t)tls & ~15));
// Pass |fn| and |arg| using TLS.
tls[TLS_SLOT_THREAD_FUNC] = (void*)fn;
tls[TLS_SLOT_THREAD_ARGS] = (void*)arg;
#if defined(BARE_METAL_BIONIC)
nacl_irt_tid_t assigned_tid;
int result = __nacl_irt_thread_create_v0_2(&run_thread, child_stack, tls,
&assigned_tid);
if (result == 0) {
// Set the child thread's signal mask. This should not be racy since
// pthread_create sets a mutex that blocks the child thread from continuing
// until it is fully initialized.
__nacl_signal_thread_init(assigned_tid);
tid = assigned_tid;
}
#else
int result = __nacl_irt_thread_create(&run_thread, child_stack, tls);
#endif
if (result != 0) {
errno = result;
return -1;
}
if (flags & CLONE_PARENT_SETTID)
*parent_tid = tid;
return tid;
}
static int
do_clone (struct pthread *pd, const struct pthread_attr *attr,
int clone_flags, int (*fct) (void *), STACK_VARIABLES_PARMS,
int stopped)
{
#if 0
PREPARE_CREATE;
#endif
if (__builtin_expect (stopped != 0, 0))
/* We make sure the thread does not run far by forcing it to get a
lock. We lock it here too so that the new thread cannot continue
until we tell it to. */
lll_lock (pd->lock, LLL_PRIVATE);
/* One more thread. We cannot have the thread do this itself, since it
might exist but not have been scheduled yet by the time we've returned
and need to check the value to behave correctly. We must do it before
creating the thread, in case it does get scheduled first and then
might mistakenly think it was the only thread. In the failure case,
we momentarily store a false value; this doesn't matter because there
is no kosher thing a signal handler interrupting us right here can do
that cares whether the thread count is correct. */
atomic_increment (&__nptl_nthreads);
#if !defined(__native_client__) && !defined(__ZRT_HOST)
#error "This code was changed to work only in Native Client"
#endif
/* Native Client does not have a notion of a thread ID, so we make
one up. This must be small enough to leave space for number identifying
the clock. Use CLOCK_IDFIELD_SIZE to guarantee that. */
pd->tid = ((unsigned int) pd) >> CLOCK_IDFIELD_SIZE;
/* Native Client syscall thread_create does not push return address onto stack
as opposed to the kernel. We emulate this behavior on x86-64 to meet the
ABI requirement ((%rsp + 8) mod 16 == 0). On x86-32 the attribute
'force_align_arg_pointer' does the same for start_thread (). */
#ifdef __x86_64__
STACK_VARIABLES_ARGS -= 8;
#endif
if (__nacl_irt_thread_create (fct, STACK_VARIABLES_ARGS, pd) != 0)
{
pd->tid = 0;
atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */
/* Failed. If the thread is detached, remove the TCB here since
the caller cannot do this. The caller remembered the thread
as detached and cannot reverify that it is not since it must
not access the thread descriptor again. */
if (IS_DETACHED (pd))
__deallocate_stack (pd);
/* We have to translate error codes. */
return errno == ENOMEM ? EAGAIN : errno;
}
/* Now we have the possibility to set scheduling parameters etc. */
if (__builtin_expect (stopped != 0, 0))
{
INTERNAL_SYSCALL_DECL (err);
int res = 0;
/* Set the affinity mask if necessary. */
if (attr->cpuset != NULL)
{
res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid,
attr->cpusetsize, attr->cpuset);
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
{
/* The operation failed. We have to kill the thread. First
send it the cancellation signal. */
INTERNAL_SYSCALL_DECL (err2);
err_out:
#if __ASSUME_TGKILL
(void) INTERNAL_SYSCALL (tgkill, err2, 3,
THREAD_GETMEM (THREAD_SELF, pid),
pd->tid, SIGCANCEL);
#else
(void) INTERNAL_SYSCALL (tkill, err2, 2, pd->tid, SIGCANCEL);
#endif
return (INTERNAL_SYSCALL_ERROR_P (res, err)
? INTERNAL_SYSCALL_ERRNO (res, err)
: 0);
}
}
/* Set the scheduling parameters. */
if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)
{
res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid,
pd->schedpolicy, &pd->schedparam);
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
goto err_out;
}
}
/* We now have for sure more than one thread. The main thread might
not yet have the flag set. No need to set the global variable
again if this is what we use. */
THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
return 0;
}