os161-assignments/userland/testbin/rmtest/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
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * 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(void) {
  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;
}