base64dec.c 2.83 KB
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/* base64dec -- an decoder for base64
 *
 * Copyright (C) 2006, 2012 Jeronimo Pellegrini, Niels Möller
 *
 * This program 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.
 *
 * This program 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
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 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
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 */

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

#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
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#ifdef WIN32
#include <fcntl.h>
#endif
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#include "base64.h"
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#include "io.h"

#define CHUNK_SIZE 16392

/* The maximum number of bytes generated for each chunk: */
#define DECODED_SIZE BASE64_DECODE_LENGTH(CHUNK_SIZE)


/*
 * Reads base-64 encoded from stdin, writes decoded to stdout.
 */
int
main(int argc UNUSED, char **argv UNUSED)
{
  /* "buffer" will hold the bytes from disk: */
  uint8_t * buffer = xalloc (CHUNK_SIZE);

  /* "result" will hold bytes before output: */
  uint8_t * result = xalloc (DECODED_SIZE);

  /* We need a Base64 context for decoding: */
  struct base64_decode_ctx b64_ctx;

  /* Init the context: */
  base64_decode_init(&b64_ctx);

#ifdef WIN32
  _setmode(1, O_BINARY);
#endif

  for (;;)
    {
      int nbytes; /* Number of bytes read frmo disk at each iteration */
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      size_t decoded_bytes; /* Bytes actually generated at each iteration */
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      nbytes = fread(buffer, 1, CHUNK_SIZE, stdin);

      if (nbytes < CHUNK_SIZE && ferror(stdin))
	{
	  werror ("Error reading file: %s\n", strerror(errno));
	  return EXIT_FAILURE;
	}

      decoded_bytes = BASE64_DECODE_LENGTH(nbytes);

      /* Decodes one chunk: */
      if (!base64_decode_update(&b64_ctx, &decoded_bytes, result, nbytes, buffer))
	{
	  werror ("Error decoding input (not base64?)\n");
	  return EXIT_FAILURE;
	}

      if (!write_string (stdout, decoded_bytes, result))
	{
	  werror ("Error writing file: %s\n", strerror(errno));
	  return EXIT_FAILURE;
	}

      if (nbytes < CHUNK_SIZE)
	{
	  /* Check if decoding finalized OK: */
	  if (!base64_decode_final(&b64_ctx))
	    {
	      werror ("Decoding did not finish properly.\n");
	      return EXIT_FAILURE;
	    }
	  break;
	}
    }

  if (fflush (stdout) != 0)
    {
      werror ("Error writing file: %s\n", strerror(errno));
      return EXIT_FAILURE;
    }

  free (buffer);
  free (result);

  return EXIT_SUCCESS;
}