src/writemod.c

/*
 * Copyright (c) 2004 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

/*
 * tests out if access checking is done on write path
 * 1. opens with write perms
 * 2. fchmod to turn off write perms
 * 3. writes to file
 */

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <stdio.h>

int 
main(int argc, char* argv[])
{
    char *path;
    int fd;
    char *buf = "hi there";
    ssize_t x;
    int sts;

    if (argc != 2) {
	fprintf(stderr, "%s: requires path argument\n", argv[0]);
        return 1;
    }

    path = argv[1];

    printf("open for write \"%s\" with 777\n", path);
    fd = open(path, O_RDWR, 0777);
    if (fd == -1) {
	perror("open");
        return 1;
    }
    printf("remove perms on file\n");
    sts = fchmod(fd, 0);
    if (sts == -1) {
	perror("fchmod");
        return 1;
    }
    printf("write to the file\n");
    x = write(fd, buf, strlen(buf)+1); 
    if (x == -1) {
	perror("write");
        return 1;
    }
    return 0;
}