sysdeps/unix/sysv/linux/getpid.c

   1 /* Copyright (C) 2003-2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <unistd.h>
  20 #include <tls.h>
  21 #include <sysdep.h>
  22
  23
  24 #if IS_IN (libc)
  25 static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
  26
  27 static inline __attribute__((always_inline)) pid_t
  28 really_getpid (pid_t oldval)
  29 {
  30   if (__glibc_likely (oldval == 0))
  31     {
  32       pid_t selftid = THREAD_GETMEM (THREAD_SELF, tid);
  33       if (__glibc_likely (selftid != 0))
  34         return selftid;
  35     }
  36
  37   INTERNAL_SYSCALL_DECL (err);
  38   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
  39
  40   /* We do not set the PID field in the TID here since we might be
  41      called from a signal handler while the thread executes fork.  */
  42   if (oldval == 0)
  43     THREAD_SETMEM (THREAD_SELF, tid, result);
  44   return result;
  45 }
  46 #endif
  47
  48 pid_t
  49 __getpid (void)
  50 {
  51 #if !IS_IN (libc)
  52   INTERNAL_SYSCALL_DECL (err);
  53   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
  54 #else
  55   pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
  56   if (__glibc_unlikely (result <= 0))
  57     result = really_getpid (result);
  58 #endif
  59   return result;
  60 }
  61
  62 libc_hidden_def (__getpid)
  63 weak_alias (__getpid, getpid)
  64 libc_hidden_def (getpid)