nptl/sysdeps/unix/sysv/linux/getpid.c

   1 /* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <unistd.h>
  21 #include <tls.h>
  22 #include <sysdep.h>
  23
  24
  25 #ifndef NOT_IN_libc
  26 static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
  27
  28 static inline __attribute__((always_inline)) pid_t
  29 really_getpid (pid_t oldval)
  30 {
  31   if (__builtin_expect (oldval == 0, 1))
  32     {
  33       pid_t selftid = THREAD_GETMEM (THREAD_SELF, tid);
  34       if (__builtin_expect (selftid != 0, 1))
  35         return selftid;
  36     }
  37
  38   INTERNAL_SYSCALL_DECL (err);
  39   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
  40
  41   /* We do not set the PID field in the TID here since we might be
  42      called from a signal handler while the thread executes fork.  */
  43   if (oldval == 0)
  44     THREAD_SETMEM (THREAD_SELF, tid, result);
  45   return result;
  46 }
  47 #endif
  48
  49 pid_t
  50 __getpid (void)
  51 {
  52 #ifdef NOT_IN_libc
  53   INTERNAL_SYSCALL_DECL (err);
  54   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
  55 #else
  56   pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
  57   if (__builtin_expect (result <= 0, 0))
  58     result = really_getpid (result);
  59 #endif
  60   return result;
  61 }
  62
  63 libc_hidden_def (__getpid)
  64 weak_alias (__getpid, getpid)
  65 libc_hidden_def (getpid)