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/* Copyright (C) 2002-2025 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 <errno.h>
#include <semaphore.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/wait.h>
int
do_test (void)
{
size_t ps = sysconf (_SC_PAGESIZE);
char tmpfname[] = "/tmp/tst-sem3.XXXXXX";
char data[ps];
void *mem;
int fd;
sem_t *s;
pid_t pid;
char *p;
fd = mkstemp (tmpfname);
if (fd == -1)
{
printf ("cannot open temporary file: %m\n");
return 1;
}
/* Make sure it is always removed. */
unlink (tmpfname);
/* Create one page of data. */
memset (data, '\0', ps);
/* Write the data to the file. */
if (write (fd, data, ps) != (ssize_t) ps)
{
puts ("short write");
return 1;
}
mem = mmap (NULL, ps, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (mem == MAP_FAILED)
{
printf ("mmap failed: %m\n");
return 1;
}
s = (sem_t *) (((uintptr_t) mem + __alignof (sem_t))
& ~(__alignof (sem_t) - 1));
p = (char *) (s + 1);
if (sem_init (s, 1, 1) == -1)
{
puts ("init failed");
return 1;
}
if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
{
puts ("1st wait failed");
return 1;
}
errno = 0;
if (TEMP_FAILURE_RETRY (sem_trywait (s)) != -1)
{
puts ("trywait succeeded");
return 1;
}
else if (errno != EAGAIN)
{
puts ("trywait didn't return EAGAIN");
return 1;
}
*p = 0;
puts ("going to fork now");
pid = fork ();
if (pid == -1)
{
puts ("fork failed");
return 1;
}
else if (pid == 0)
{
/* Play some lock ping-pong. It's our turn to unlock first. */
if ((*p)++ != 0)
{
puts ("child: *p != 0");
return 1;
}
if (sem_post (s) == -1)
{
puts ("child: 1st post failed");
return 1;
}
puts ("child done");
}
else
{
if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1)
{
printf ("parent: 2nd wait failed: %m\n");
return 1;
}
if (*p != 1)
{
puts ("*p != 1");
return 1;
}
puts ("parent done");
}
return 0;
}
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
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