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glibc/linuxthreads/Examples/ex8.c
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/* Tests for fork in multi-threaded environment. | |
Copyright (C) 2000 Free Software Foundation, Inc. | |
Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Library General Public License as | |
published by the Free Software Foundation; either version 2 of the | |
License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Library General Public License for more details. | |
You should have received a copy of the GNU Library General Public | |
License along with the GNU C Library; see the file COPYING.LIB. If not, | |
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
Boston, MA 02111-1307, USA. */ | |
#include <errno.h> | |
#include <error.h> | |
#include <stdlib.h> | |
#include <pthread.h> | |
#include <unistd.h> | |
#include <sys/wait.h> | |
enum | |
{ | |
PREPARE_BIT = 1, | |
PARENT_BIT = 2, | |
CHILD_BIT = 4 | |
}; | |
static int var; | |
static void | |
prepare (void) | |
{ | |
var |= PREPARE_BIT; | |
} | |
static void | |
parent (void) | |
{ | |
var |= PARENT_BIT; | |
} | |
static void | |
child (void) | |
{ | |
var |= CHILD_BIT; | |
} | |
static void *thread (void *arg); | |
int | |
main (void) | |
{ | |
pthread_t th; | |
void *res; | |
pthread_atfork (prepare, parent, child); | |
if (pthread_create (&th, NULL, thread, NULL) != 0) | |
error (EXIT_FAILURE, 0, "cannot create thread"); | |
pthread_join (th, &res); | |
return (int) (long int) res; | |
} | |
static void * | |
thread (void *arg) | |
{ | |
int status; | |
pid_t pid; | |
pid = fork (); | |
if (pid == 0) | |
{ | |
/* We check whether the `prepare' and `child' function ran. */ | |
exit (var != (PREPARE_BIT | CHILD_BIT)); | |
} | |
else if (pid == (pid_t) -1) | |
error (EXIT_FAILURE, errno, "cannot fork"); | |
if (waitpid (pid, &status, 0) != pid) | |
error (EXIT_FAILURE, errno, "wrong child"); | |
if (WTERMSIG (status) != 0) | |
error (EXIT_FAILURE, 0, "Child terminated incorrectly"); | |
status = WEXITSTATUS (status); | |
if (status == 0) | |
status = var != (PREPARE_BIT | PARENT_BIT); | |
return (void *) (long int) status; | |
} |