/*
 * 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.
 */

/*
 * Create a large file in small increments.
 *
 * Should work on emufs (emu0:) once the basic system calls are done,
 * and should work on SFS when the file system assignment is
 * done. Sufficiently small files should work on SFS even before that
 * assignment.
 */

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

static char buffer[8192 + 1];

int main(int argc, char *argv[]) {
  const char *filename;
  char *s;
  size_t i, size, chunksize, offset;
  ssize_t len;
  int fd;

  if (argc != 3) {
    warnx("Usage: bigfile <filename> <size>");
    errx(1, "   or: bigfile <filename> <size>/<chunksize>");
  }

  filename = argv[1];
  s = strchr(argv[2], '/');
  if (s != NULL) {
    *s++ = 0;
    chunksize = atoi(s);
    if (chunksize >= sizeof(buffer)) {
      chunksize = sizeof(buffer) - 1;
    }
    if (chunksize == 0) {
      errx(1, "Really?");
    }
  } else {
    chunksize = 10;
  }
  size = atoi(argv[2]);

  /* round size up */
  size = ((size + chunksize - 1) / chunksize) * chunksize;

  printf("Creating a file of size %d in %d-byte chunks\n", size, chunksize);

  fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
  if (fd < 0) {
    err(1, "%s: create", filename);
  }

  i = 0;
  while (i < size) {
    snprintf(buffer, sizeof(buffer), "%d\n", i);
    if (strlen(buffer) < chunksize) {
      offset = chunksize - strlen(buffer);
      memmove(buffer + offset, buffer, strlen(buffer) + 1);
      memset(buffer, ' ', offset);
    }
    len = write(fd, buffer, strlen(buffer));
    if (len < 0) {
      err(1, "%s: write", filename);
    }
    i += len;
  }

  close(fd);

  return 0;
}
