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glibc  2.9
getpid.c
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00001 /* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <unistd.h>
00021 #include <tls.h>
00022 #include <sysdep.h>
00023 
00024 
00025 #ifndef NOT_IN_libc
00026 static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
00027 
00028 static inline __attribute__((always_inline)) pid_t
00029 really_getpid (pid_t oldval)
00030 {
00031   if (__builtin_expect (oldval == 0, 1))
00032     {
00033       pid_t selftid = THREAD_GETMEM (THREAD_SELF, tid);
00034       if (__builtin_expect (selftid != 0, 1))
00035        return selftid;
00036     }
00037 
00038   INTERNAL_SYSCALL_DECL (err);
00039   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
00040 
00041   /* We do not set the PID field in the TID here since we might be
00042      called from a signal handler while the thread executes fork.  */
00043   if (oldval == 0)
00044     THREAD_SETMEM (THREAD_SELF, tid, result);
00045   return result;
00046 }
00047 #endif
00048 
00049 pid_t
00050 __getpid (void)
00051 {
00052 #ifdef NOT_IN_libc
00053   INTERNAL_SYSCALL_DECL (err);
00054   pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
00055 #else
00056   pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
00057   if (__builtin_expect (result <= 0, 0))
00058     result = really_getpid (result);
00059 #endif
00060   return result;
00061 }
00062 
00063 libc_hidden_def (__getpid)
00064 weak_alias (__getpid, getpid)
00065 libc_hidden_def (getpid)