release/src/router/nettle/examples/base16dec.c

   1 /* base16dec -- an decoder for base16
   2  *
   3  * Copyright (C) 2006, 2012 Jeronimo Pellegrini, Niels Möller
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License as published by
   7  * the Free Software Foundation; either version 2.1 of the License, or (at your
   8  * option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  13  * License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public License
  16  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  17  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  18  * MA 02111-1301, USA.
  19  */
  20
  21 #if HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <errno.h>
  26 #include <stdlib.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #ifdef WIN32
  30 #include <fcntl.h>
  31 #endif
  32
  33 #include "base16.h"
  34
  35 #include "io.h"
  36
  37 #define CHUNK_SIZE 16392
  38
  39 /* The maximum number of bytes generated for each chunk: */
  40 #define DECODED_SIZE BASE16_DECODE_LENGTH(CHUNK_SIZE)
  41
  42
  43 /*
  44  * Reads base-16 encoded from stdin, writes decoded to stdout.
  45  */
  46 int
  47 main(int argc UNUSED, char **argv UNUSED)
  48 {
  49   /* "buffer" will hold the bytes from disk: */
  50   uint8_t * buffer = xalloc (CHUNK_SIZE);
  51
  52   /* "result" will hold bytes before output: */
  53   uint8_t * result = xalloc (DECODED_SIZE);
  54
  55   /* We need a Base16 context for decoding: */
  56   struct base16_decode_ctx b16_ctx;
  57
  58   /* Init the context: */
  59   base16_decode_init (&b16_ctx);
  60
  61 #ifdef WIN32
  62   _setmode(1, O_BINARY);
  63 #endif
  64
  65   for (;;)
  66     {
  67       int nbytes; /* Number of bytes read frmo disk at each iteration */
  68       unsigned decoded_bytes; /* Bytes actually generated at each iteration */
  69
  70       nbytes = fread(buffer, 1, CHUNK_SIZE, stdin);
  71
  72       if (nbytes < CHUNK_SIZE && ferror(stdin))
  73         {
  74           werror ("Error reading file: %s\n", strerror(errno));
  75           return EXIT_FAILURE;
  76         }
  77
  78     decoded_bytes = BASE16_DECODE_LENGTH(nbytes);
  79
  80     /* Decodes one chunk: */
  81     if (!base16_decode_update(&b16_ctx, &decoded_bytes, result, nbytes, buffer))
  82       {
  83         werror ("Error decoding input (not base16?)\n");
  84         return EXIT_FAILURE;
  85       }
  86
  87     if (!write_string (stdout, decoded_bytes, result))
  88       {
  89         werror ("Error writing file: %s\n", strerror(errno));
  90         return EXIT_FAILURE;
  91       }
  92     if (nbytes < CHUNK_SIZE)
  93       {
  94         /* Check if decoding finalized OK: */
  95         if (!base16_decode_final(&b16_ctx))
  96           {
  97             werror("Decoding did not finish properly.\n");
  98             return EXIT_FAILURE;
  99           }
 100         break;
 101       }
 102     }
 103
 104   if (fflush (stdout) != 0)
 105     {
 106       werror ("Error writing file: %s\n", strerror(errno));
 107       return EXIT_FAILURE;
 108     }
 109
 110   free (buffer);
 111   free (result);
 112
 113   return EXIT_SUCCESS;
 114 }
 115