io.c

/* io.c
 *
 * Miscellaneous functions used by the example programs.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2002 Niels Möller
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdarg.h>
#include <stdlib.h>

/* For errno and strerror */
#include <errno.h>
#include <string.h>

#include "io.h"

#define RANDOM_DEVICE "/dev/urandom"
#define BUFSIZE 1000

int quiet_flag = 0;

void *
xalloc(size_t size)
{
  void *p = malloc(size);
  if (!p)
    {
      fprintf(stderr, "Virtual memory exhausted.\n");
      abort();
    }

  return p;
}

void
werror(const char *format, ...)
{
  if (!quiet_flag)
    {
      va_list args;
      va_start(args, format);
      vfprintf(stderr, format, args);
      va_end(args);
    }
}

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

unsigned
read_file(const char *name, unsigned max_size, char **contents)
{
  unsigned size;
  unsigned done;
  char *buffer;
  FILE *f;
    
  f = fopen(name, "rb");
  if (!f)
    {
      werror("Opening `%s' failed: %s\n", name, strerror(errno));
      return 0;
    }
  buffer = NULL;

  if (max_size && max_size < 100)
    size = max_size;
  else
    size = 100;

  /* FIXME: The use of feof and ferror in this loop is a bit confused
     (but I think it is still correct). We should check the return
     value of fread, and call feof and/or ferror when we get a short
     item count. */	

  for (done = 0;
       (!max_size || done < max_size) && !feof(f);
       size *= 2)
    {
      char *p;

      if (max_size && size > max_size)
	size = max_size;

      /* Space for terminating NUL */
      p = realloc(buffer, size + 1);

      if (!p)
	{
	fail:
	  fclose(f);
	  free(buffer);
	  *contents = NULL;
	  return 0;
	}

      buffer = p;
      done += fread(buffer + done, 1, size - done, f);

      if (ferror(f))
	goto fail;
    }
  
  fclose(f);

  /* NUL-terminate the data. */
  buffer[done] = '\0';
  *contents = buffer;
  
  return done;
}

int
write_string(FILE *f, unsigned size, const char *buffer)
{
  size_t res = fwrite(buffer, 1, size, f);

  return res == size;
}

int
write_file(const char *name, unsigned size, const char *buffer)
{
  FILE *f = fopen(name, "wb");
  int res;
  
  if (!f)
    return 0;

  res = write_string(f, size, buffer);
  return fclose(f) == 0 && res;
}

int
simple_random(struct yarrow256_ctx *ctx, const char *name)
{
  unsigned length;
  char *buffer;

  if (name)
    length = read_file(name, 0, &buffer);
  else
    length = read_file(RANDOM_DEVICE, 20, &buffer);
  
  if (!length)
    return 0;

  yarrow256_seed(ctx, length, buffer);

  free(buffer);

  return 1;
}

int
hash_file(const struct nettle_hash *hash, void *ctx, FILE *f)
{
  for (;;)
    {
      char buffer[BUFSIZE];
      size_t res = fread(buffer, 1, sizeof(buffer), f);
      if (ferror(f))
	return 0;
      
      hash->update(ctx, res, buffer);
      if (feof(f))
	return 1;
    }
}