sys/fork.c

   1 /*
   2  * Copyright (c) 2010 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <errno.h>
  26 #include <TargetConditionals.h>
  27
  28 #include "libc_private.h"
  29
  30 extern pid_t __fork(void);
  31
  32 static void (*_libSystem_atfork_prepare)(void) = 0;
  33 static void (*_libSystem_atfork_parent)(void) = 0;
  34 static void (*_libSystem_atfork_child)(void) = 0;
  35
  36 __private_extern__
  37 void _libc_fork_init(const struct _libc_functions *funcs)
  38 {
  39         _libSystem_atfork_prepare = funcs->atfork_prepare;
  40         _libSystem_atfork_parent = funcs->atfork_parent;
  41         _libSystem_atfork_child = funcs->atfork_child;
  42 }
  43
  44 /*
  45  * fork stub
  46  */
  47 pid_t
  48 fork(void)
  49 {
  50         int ret;
  51
  52         _libSystem_atfork_prepare();
  53         // Reader beware: this __fork() call is yet another wrapper around the actual syscall
  54         // and lives inside libsyscall. The fork syscall needs some cuddling by asm before it's
  55         // allowed to see the big wide C world.
  56         ret = __fork();
  57         if (-1 == ret)
  58         {
  59                 // __fork already set errno for us
  60                 _libSystem_atfork_parent();
  61                 return ret;
  62         }
  63
  64         if (0 == ret)
  65         {
  66                 // We're the child in this part.
  67                 _libSystem_atfork_child();
  68                 return 0;
  69         }
  70
  71         _libSystem_atfork_parent();
  72         return ret;
  73 }
  74