nsz Git - musl/blob - src/process/fork.c

   1 #include <unistd.h>
   2 #include <errno.h>
   3 #include "libc.h"
   4 #include "lock.h"
   5 #include "pthread_impl.h"
   6 #include "fork_impl.h"
   7
   8 static volatile int *const dummy_lockptr = 0;
   9
  10 weak_alias(dummy_lockptr, __at_quick_exit_lockptr);
  11 weak_alias(dummy_lockptr, __atexit_lockptr);
  12 weak_alias(dummy_lockptr, __gettext_lockptr);
  13 weak_alias(dummy_lockptr, __locale_lockptr);
  14 weak_alias(dummy_lockptr, __random_lockptr);
  15 weak_alias(dummy_lockptr, __sem_open_lockptr);
  16 weak_alias(dummy_lockptr, __stdio_ofl_lockptr);
  17 weak_alias(dummy_lockptr, __syslog_lockptr);
  18 weak_alias(dummy_lockptr, __timezone_lockptr);
  19 weak_alias(dummy_lockptr, __bump_lockptr);
  20
  21 weak_alias(dummy_lockptr, __vmlock_lockptr);
  22
  23 static volatile int *const *const atfork_locks[] = {
  24         &__at_quick_exit_lockptr,
  25         &__atexit_lockptr,
  26         &__gettext_lockptr,
  27         &__locale_lockptr,
  28         &__random_lockptr,
  29         &__sem_open_lockptr,
  30         &__stdio_ofl_lockptr,
  31         &__syslog_lockptr,
  32         &__timezone_lockptr,
  33         &__bump_lockptr,
  34 };
  35
  36 static void dummy(int x) { }
  37 weak_alias(dummy, __fork_handler);
  38 weak_alias(dummy, __malloc_atfork);
  39 weak_alias(dummy, __ldso_atfork);
  40
  41 static void dummy_0(void) { }
  42 weak_alias(dummy_0, __tl_lock);
  43 weak_alias(dummy_0, __tl_unlock);
  44
  45 pid_t fork(void)
  46 {
  47         sigset_t set;
  48         __fork_handler(-1);
  49         __block_app_sigs(&set);
  50         int need_locks = libc.need_locks > 0;
  51         if (need_locks) {
  52                 __ldso_atfork(-1);
  53                 __inhibit_ptc();
  54                 for (int i=0; i<sizeof atfork_locks/sizeof *atfork_locks; i++)
  55                         if (*atfork_locks[i]) LOCK(*atfork_locks[i]);
  56                 __malloc_atfork(-1);
  57                 __tl_lock();
  58         }
  59         pthread_t self=__pthread_self(), next=self->next;
  60         pid_t ret = _Fork();
  61         int errno_save = errno;
  62         if (need_locks) {
  63                 if (!ret) {
  64                         for (pthread_t td=next; td!=self; td=td->next)
  65                                 td->tid = -1;
  66                         if (__vmlock_lockptr) {
  67                                 __vmlock_lockptr[0] = 0;
  68                                 __vmlock_lockptr[1] = 0;
  69                         }
  70                 }
  71                 __tl_unlock();
  72                 __malloc_atfork(!ret);
  73                 for (int i=0; i<sizeof atfork_locks/sizeof *atfork_locks; i++)
  74                         if (*atfork_locks[i])
  75                                 if (ret) UNLOCK(*atfork_locks[i]);
  76                                 else **atfork_locks[i] = 0;
  77                 __release_ptc();
  78                 __ldso_atfork(!ret);
  79         }
  80         __restore_sigs(&set);
  81         __fork_handler(!ret);
  82         if (ret<0) errno = errno_save;
  83         return ret;
  84 }