glibc/nptl/sysdeps/unix/sysv/linux/getpid.c History
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   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
  26static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
  27
  28static inline __attribute__((always_inline)) pid_t
  29really_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
  49pid_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
  63libc_hidden_def (__getpid)
  64weak_alias (__getpid, getpid)
  65libc_hidden_def (getpid)
  66