rmtest.c

/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
 *      The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * rmtest.c
 *
 *      Tests file system synchronization by deleting an open file and
 *      then attempting to read it.
 *
 * This should run correctly when the file system assignment is complete.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <err.h>

#define TEST        "rmdata"
#define TESTDATA    "I wish I was a headlight. -- Jerry Garcia"
#define TESTLEN     (sizeof(TESTDATA)-1)

static
void
dorm(int fd)
{
        /*
         * This used to spawn a copy of /bin/rm, but that's silly.
         * However, we will do the remove() from a subprocess, so
         * that various kinds of improper hacks to make this test
         * run won't work.
         *
         * Close the file in the subprocess, for similar reasons.
         */

        pid_t pid;
        int status;

        pid = fork();
        if (pid<0) {
                err(1, "fork");
        }
        if (pid==0) {
                /* child process */
                close(fd);
                if (remove(TEST)) {
                        err(1, "%s: remove", TEST);
                }
                _exit(0);
        }
        /* parent process */
        if (waitpid(pid, &status, 0)<0) {
                err(1, "waitpid");
        }
        else if (WIFSIGNALED(status)) {
                warn("child process exited with signal %d", WTERMSIG(status));
        }
        else if (WEXITSTATUS(status) != 0) {
                warnx("child process exited with code %d",WEXITSTATUS(status));
        }
}

static
int 
same(const char *a, const char *b, int len)
{
        while (len-- > 0) {
                if (*a++ != *b++) return 0;
        }
        return 1;
}

int
main()
{
        int file, len;
        char buf[TESTLEN];

        /* create test data file */
        file = open(TEST, O_WRONLY | O_CREAT | O_TRUNC, 0664);
        write(file, TESTDATA, TESTLEN);
        close(file);

        /* make sure the data is there */
        file = open(TEST, O_RDONLY);
        len = read(file, buf, TESTLEN);
        if (len < 0) {
                warn("read: before deletion");
        }
        else if (len < (int)TESTLEN) {
                warnx("read: before deletion: short count %d", len);
        }
        if (!same(buf, TESTDATA, TESTLEN)) {
                errx(1, "Failed: data read back was not the same");
        }

        /* rewind the file */
        if (lseek(file, 0, SEEK_SET)) {
                err(1, "lseek");
        }

        /* now spawn our killer and wait for it to do its work */
        dorm(file);

        /* we should be still able to read the data */
        memset(buf, '\0', TESTLEN);
        len = read(file, buf, TESTLEN);
        if (len < 0) {
                warn("read: after deletion");
        }
        else if (len < (int)TESTLEN) {
                warnx("read: after deletion: short count %d", len);
        }

        if (!same(buf, TESTDATA, TESTLEN)) {
                errx(1, "Failed: data read after deletion was not the same");
        }

        /* ok, close the file and it should go away */
        close(file);

        /* try to open it again */
        file = open(TEST, O_RDONLY);
        if (file >= 0) {
                close(file);
                errx(1, "Failed: the file could still be opened");
        }

        if (errno!=ENOENT) {
                err(1, "Unexpected error reopening the file");
        }

        printf("Succeeded!\n");

        return 0;
}