glibc/libio/tst-popen-fork.c

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/* Test concurrent popen and fork.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdatomic.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/wait.h>
#include <support/check.h>
#include <support/xthread.h>
#include <support/xunistd.h>
static void
popen_and_pclose (void)
{
FILE *f = popen ("true", "r");
TEST_VERIFY_EXIT (f != NULL);
pclose (f);
return;
}
static atomic_bool done = ATOMIC_VAR_INIT (0);
static void *
popen_and_pclose_forever (__attribute__ ((unused))
void *arg)
{
while (!atomic_load_explicit (&done, memory_order_acquire))
popen_and_pclose ();
return NULL;
}
static int
do_test (void)
{
/* Repeatedly call popen in a loop during the entire test. */
pthread_t t = xpthread_create (NULL, popen_and_pclose_forever, NULL);
/* Repeatedly fork off and reap child processes one-by-one.
Each child calls popen once, then exits, leading to the possibility
that a child forks *during* our own popen call, thus inheriting any
intermediate popen state, possibly including lock state(s). */
for (int i = 0; i < 100; i++)
{
int cpid = xfork ();
if (cpid == 0)
{
popen_and_pclose ();
_exit (0);
}
else
xwaitpid (cpid, NULL, 0);
}
/* Stop calling popen. */
atomic_store_explicit (&done, 1, memory_order_release);
xpthread_join (t);
return 0;
}
#include <support/test-driver.c>