testcases/open_posix_testsuite/conformance/interfaces/shm_open/20-2.c

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2.
 *
 *  This program 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 General Public License for more details.
 *
 * Test that shm_open open the shared memory object for writing when calling
 * shm_open with O_RDWR even if the mode don't set write permission.
 *
 * The test use ftruncate to check the object is open for writing.
 */

/* ftruncate was formerly an XOPEN extension. We define _XOPEN_SOURCE here to
   avoid warning if the implementation does not program ftruncate as a base
   interface */
#define _XOPEN_SOURCE 600

#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "posixtest.h"

#define BUF_SIZE 8
#define SHM_NAME "posixtest_20-2"

int main() {
	int fd, result;

	result = shm_unlink(SHM_NAME);
	if (result != 0 && errno != ENOENT) {
		/* The shared memory object exist and shm_unlink can not
		   remove it. */
		perror("An error occurs when calling shm_unlink()");
		return PTS_UNRESOLVED;
	}

	fd = shm_open(SHM_NAME, O_RDWR|O_CREAT, 0);
	if (fd == -1) {
		perror("An error occurs when calling shm_open()");
		return PTS_UNRESOLVED;
	}

	result = ftruncate(fd, BUF_SIZE);
	if (result == 0) {
		printf("Test PASSED\n");
		shm_unlink(SHM_NAME);
		return PTS_PASS;
	} else if (result == -1 && errno == EINVAL) {
		printf("The shared memory object is not opened for writing.\n");
		shm_unlink(SHM_NAME);
		return PTS_FAIL;
	}

	perror("ftruncate");
	shm_unlink(SHM_NAME);
	return PTS_FAIL;
}