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
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