static void
fresetlockfiles (void)
{
FILE *fp;
#ifdef __USE_STDIO_FUTEXES__
for (fp = _stdio_openlist; fp != NULL; fp = fp->__nextopen)
STDIO_INIT_MUTEX(fp->__lock);
#else
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
for (fp = _stdio_openlist; fp != NULL; fp = fp->__nextopen)
pthread_mutex_init(&fp->__lock, &attr);
pthread_mutexattr_destroy(&attr);
#endif
}
pid_t
__libc_fork (void)
{
pid_t pid;
struct used_handler
{
struct fork_handler *handler;
struct used_handler *next;
} *allp = NULL;
/* Run all the registered preparation handlers. In reverse order.
While doing this we build up a list of all the entries. */
struct fork_handler *runp;
while ((runp = __fork_handlers) != NULL)
{
/* Make sure we read from the current RUNP pointer. */
atomic_full_barrier ();
unsigned int oldval = runp->refcntr;
if (oldval == 0)
/* This means some other thread removed the list just after
the pointer has been loaded. Try again. Either the list
is empty or we can retry it. */
continue;
/* Bump the reference counter. */
if (atomic_compare_and_exchange_bool_acq (&__fork_handlers->refcntr,
oldval + 1, oldval))
/* The value changed, try again. */
continue;
/* We bumped the reference counter for the first entry in the
list. That means that none of the following entries will
just go away. The unloading code works in the order of the
list.
While executing the registered handlers we are building a
list of all the entries so that we can go backward later on. */
while (1)
{
/* Execute the handler if there is one. */
if (runp->prepare_handler != NULL)
runp->prepare_handler ();
/* Create a new element for the list. */
struct used_handler *newp
= (struct used_handler *) alloca (sizeof (*newp));
newp->handler = runp;
newp->next = allp;
allp = newp;
/* Advance to the next handler. */
runp = runp->next;
if (runp == NULL)
break;
/* Bump the reference counter for the next entry. */
atomic_increment (&runp->refcntr);
}
/* We are done. */
break;
}
__UCLIBC_IO_MUTEX_LOCK_CANCEL_UNSAFE(_stdio_openlist_add_lock);
#ifndef NDEBUG
pid_t ppid = THREAD_GETMEM (THREAD_SELF, tid);
#endif
/* We need to prevent the getpid() code to update the PID field so
that, if a signal arrives in the child very early and the signal
handler uses getpid(), the value returned is correct. */
pid_t parentpid = THREAD_GETMEM (THREAD_SELF, pid);
THREAD_SETMEM (THREAD_SELF, pid, -parentpid);
#ifdef ARCH_FORK
pid = ARCH_FORK ();
#else
# error "ARCH_FORK must be defined so that the CLONE_SETTID flag is used"
pid = INLINE_SYSCALL (fork, 0);
#endif
if (pid == 0)
{
struct pthread *self = THREAD_SELF;
assert (THREAD_GETMEM (self, tid) != ppid);
if (__fork_generation_pointer != NULL)
*__fork_generation_pointer += 4;
/* Adjust the PID field for the new process. */
THREAD_SETMEM (self, pid, THREAD_GETMEM (self, tid));
#if HP_TIMING_AVAIL
/* The CPU clock of the thread and process have to be set to zero. */
hp_timing_t now;
HP_TIMING_NOW (now);
THREAD_SETMEM (self, cpuclock_offset, now);
GL(dl_cpuclock_offset) = now;
#endif
/* Reset the file list. These are recursive mutexes. */
fresetlockfiles ();
/* Reset locks in the I/O code. */
STDIO_INIT_MUTEX(_stdio_openlist_add_lock);
/* XXX reset any locks in dynamic loader */
/* Run the handlers registered for the child. */
while (allp != NULL)
{
if (allp->handler->child_handler != NULL)
allp->handler->child_handler ();
/* Note that we do not have to wake any possible waiter.
This is the only thread in the new process. The count
may have been bumped up by other threads doing a fork.
We reset it to 1, to avoid waiting for non-existing
thread(s) to release the count. */
allp->handler->refcntr = 1;
/* XXX We could at this point look through the object pool
and mark all objects not on the __fork_handlers list as
unused. This is necessary in case the fork() happened
while another thread called dlclose() and that call had
to create a new list. */
allp = allp->next;
}
/* Initialize the fork lock. */
__fork_lock = LLL_LOCK_INITIALIZER;
}
else
{
assert (THREAD_GETMEM (THREAD_SELF, tid) == ppid);
/* Restore the PID value. */
THREAD_SETMEM (THREAD_SELF, pid, parentpid);
/* We execute this even if the 'fork' call failed. */
__UCLIBC_IO_MUTEX_UNLOCK_CANCEL_UNSAFE(_stdio_openlist_add_lock);
/* Run the handlers registered for the parent. */
while (allp != NULL)
{
if (allp->handler->parent_handler != NULL)
allp->handler->parent_handler ();
if (atomic_decrement_and_test (&allp->handler->refcntr)
&& allp->handler->need_signal)
lll_futex_wake (allp->handler->refcntr, 1, LLL_PRIVATE);
allp = allp->next;
}
}
return pid;
}
/* We assume here that we are the only remaining thread. */
void _stdio_term(void)
{
#if defined(__STDIO_BUFFERS) || defined(__UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__)
register FILE *ptr;
#ifdef __UCLIBC_HAS_THREADS__
/* First, make sure the open file list is unlocked. If it was
* locked, then I suppose there is a chance that a pointer in the
* chain might be corrupt due to a partial store.
*/
STDIO_INIT_MUTEX(_stdio_openlist_add_lock);
#ifdef __STDIO_BUFFERS
STDIO_INIT_MUTEX(_stdio_openlist_del_lock);
#endif
/* Next we need to worry about the streams themselves. If a stream
* is currently locked, then it may be in an invalid state. So we
* 'disable' it in case a custom stream is stacked on top of it.
* Then we reinitialize the locks.
*/
for (ptr = _stdio_openlist ; ptr ; ptr = ptr->__nextopen ) {
if (__STDIO_ALWAYS_THREADTRYLOCK_CANCEL_UNSAFE(ptr)) {
/* The stream is already locked, so we don't want to touch it.
* However, if we have custom streams, we can't just close it
* or leave it locked since a custom stream may be stacked
* on top of it. So we do unlock it, while also disabling it.
*/
ptr->__modeflags = (__FLAG_READONLY|__FLAG_WRITEONLY);
__STDIO_STREAM_DISABLE_GETC(ptr);
__STDIO_STREAM_DISABLE_PUTC(ptr);
__STDIO_STREAM_INIT_BUFREAD_BUFPOS(ptr);
}
ptr->__user_locking = 1; /* Set locking mode to "by caller". */
STDIO_INIT_MUTEX(ptr->__lock); /* Shouldn't be necessary, but... */
}
#endif
/* Finally, flush all writing streams and shut down all custom streams.
* NOTE: We assume that any stacking by custom streams is done on top
* of streams previously allocated, and hence further down the
* list. Otherwise we have no way of knowing the order in which
* to shut them down.
* Remember that freopen() counts as a new allocation here, even
* though the stream is reused. That's because it moves the
* stream to the head of the list.
*/
for (ptr = _stdio_openlist ; ptr ; ptr = ptr->__nextopen ) {
#ifdef __STDIO_BUFFERS
/* Write any pending buffered chars. */
if (__STDIO_STREAM_IS_WRITING(ptr)) {
__STDIO_COMMIT_WRITE_BUFFER(ptr);
}
#endif
#ifdef __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__
/* Actually close all custom streams to perform any special cleanup. */
if (ptr->__cookie != &ptr->__filedes) {
__CLOSE(ptr);
}
#endif
}
#endif
}
