io.c

/*
 * Copyright (c) 2000 Satoru Takabayashi <satoru@namazu.org>
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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 REGENTS 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 REGENTS 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.
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <errno.h>

#include "ttyrec.h"

#define SWAP_ENDIAN(val) ((unsigned int) ( \
    (((unsigned int) (val) & (unsigned int) 0x000000ffU) << 24) | \
    (((unsigned int) (val) & (unsigned int) 0x0000ff00U) <<  8) | \
    (((unsigned int) (val) & (unsigned int) 0x00ff0000U) >>  8) | \
    (((unsigned int) (val) & (unsigned int) 0xff000000U) >> 24)))

static int
is_little_endian ()
{
  static int retval = -1;

  if (retval == -1)
    {
      int n = 1;
      char *p = (char *) &n;
      char x[] = { 1, 0, 0, 0 };

      assert (sizeof (int) == 4);

      if (memcmp (p, x, 4) == 0)
        {
          retval = 1;
        }
      else
        {
          retval = 0;
        }
    }

  return retval;
}

static int
convert_to_little_endian (int x)
{
  if (is_little_endian ())
    {
      return x;
    }
  else
    {
      return SWAP_ENDIAN (x);
    }
}

int
read_header (FILE * fp, Header * h)
{
  int buf[3];
  int numread;
  long offset;

  offset = ftell (fp);
  numread = fread (buf, sizeof (int), 3, fp);

  /* odd but possible race condition when full header isn't read because
   * it isn't there yet. */
  if (numread < 3)
    {
      fseek (fp, offset, SEEK_SET);
      return 0;
    }

  h->tv.tv_sec = convert_to_little_endian (buf[0]);
  h->tv.tv_usec = convert_to_little_endian (buf[1]);
  h->len = convert_to_little_endian (buf[2]);

  return 1;
}

int
write_header (FILE * fp, Header * h)
{
  int buf[3];

  buf[0] = convert_to_little_endian (h->tv.tv_sec);
  buf[1] = convert_to_little_endian (h->tv.tv_usec);
  buf[2] = convert_to_little_endian (h->len);

  if (fwrite (buf, sizeof (int), 3, fp) == 0)
    {
      return 0;
    }

  return 1;
}

static char *progname = "";
void
set_progname (const char *name)
{
  progname = strdup (name);
}

FILE *
efopen (const char *path, const char *mode)
{
  FILE *fp = fopen (path, mode);
  if (fp == NULL)
    {
      fprintf (stderr, "%s: %s: %s\n", progname, path, strerror (errno));
      exit (EXIT_FAILURE);
    }
  return fp;
}