testcases/open_posix_testsuite/conformance/interfaces/shm_open/28-2.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 the state of the shared memory object, including all data
 * associated with the shared memory object, persists until all mapping
 * references are gone even if the shared memory object is unlinked and there
 * is no open reference anymore.
 *
 * Steps:
 *  1. Create a shared memory object, map it and write a string in it.
 *  2. Close the file descriptor and unlink the object.
 *  3. Check that the previously written string is always in the mapped memory.
 */

/* 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 <string.h>
#include <fcntl.h>
#include <errno.h>
#include "posixtest.h"

#define BUF_SIZE 8
#define SHM_NAME "posixtest_28-2"

int main() {
	int fd;
	char str[BUF_SIZE] = "qwerty";
	char *buf;

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

	if (ftruncate(fd, BUF_SIZE) != 0) {
		perror("An error occurs when calling ftruncate()");
		shm_unlink(SHM_NAME);
		return PTS_UNRESOLVED;
	}

	buf = mmap(NULL, BUF_SIZE, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
	if (buf == MAP_FAILED) {
		perror("An error occurs when calling mmap()");
		shm_unlink(SHM_NAME);
		return PTS_UNRESOLVED;
	}

	strcpy(buf, str);

       	if (close(fd) != 0) {
		perror("An error occurs when calling close()");
		shm_unlink(SHM_NAME);
		return PTS_UNRESOLVED;
	}

	if (shm_unlink(SHM_NAME) !=0) {
		perror("An error occurs when calling shm_unlink()");
		return PTS_UNRESOLVED;
	}
        /* Now, SHM_NAME is unlinked and there are no more open references on
	   it but a mapping reference remain */

	if (strcmp(buf, str) == 0) {
		printf("Test PASSED\n");
		return PTS_PASS;
	}
	printf("The content of the shared memory object was removed.\n");
	return PTS_FAIL;
}