lib/md2-stream.c

   1 /* Functions to compute MD2 message digest of files or memory blocks.
   2    according to the definition of MD2 in RFC 1319 from April 1992.
   3    Copyright (C) 1995-1997, 1999-2003, 2005-2006, 2008-2024 Free Software
   4    Foundation, Inc.
   5
   6    This file is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    This file is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* Adapted by Simon Josefsson from public domain Libtomcrypt 1.06 by
  20    Tom St Denis. */
  21
  22 #include <config.h>
  23
  24 /* Specification.  */
  25 #include "md2.h"
  26
  27 #include <stdlib.h>
  28
  29 #if USE_UNLOCKED_IO
  30 # include "unlocked-io.h"
  31 #endif
  32
  33 #define BLOCKSIZE 32768
  34 #if BLOCKSIZE % 64 != 0
  35 # error "invalid BLOCKSIZE"
  36 #endif
  37
  38 /* Compute MD2 message digest for bytes read from STREAM.  The
  39    resulting message digest number will be written into the 16 bytes
  40    beginning at RESBLOCK.  */
  41 int
  42 md2_stream (FILE *stream, void *resblock)
  43 {
  44   struct md2_ctx ctx;
  45   size_t sum;
  46
  47   char *buffer = malloc (BLOCKSIZE + 72);
  48   if (!buffer)
  49     return 1;
  50
  51   /* Initialize the computation context.  */
  52   md2_init_ctx (&ctx);
  53
  54   /* Iterate over full file contents.  */
  55   while (1)
  56     {
  57       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
  58          computation function processes the whole buffer so that with the
  59          next round of the loop another block can be read.  */
  60       size_t n;
  61       sum = 0;
  62
  63       /* Read block.  Take care for partial reads.  */
  64       while (1)
  65         {
  66           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
  67
  68           sum += n;
  69
  70           if (sum == BLOCKSIZE)
  71             break;
  72
  73           if (n == 0)
  74             {
  75               /* Check for the error flag IFF N == 0, so that we don't
  76                  exit the loop after a partial read due to e.g., EAGAIN
  77                  or EWOULDBLOCK.  */
  78               if (ferror (stream))
  79                 {
  80                   free (buffer);
  81                   return 1;
  82                 }
  83               goto process_partial_block;
  84             }
  85
  86           /* We've read at least one byte, so ignore errors.  But always
  87              check for EOF, since feof may be true even though N > 0.
  88              Otherwise, we could end up calling fread after EOF.  */
  89           if (feof (stream))
  90             goto process_partial_block;
  91         }
  92
  93       /* Process buffer with BLOCKSIZE bytes.  Note that
  94          BLOCKSIZE % 64 == 0
  95        */
  96       md2_process_block (buffer, BLOCKSIZE, &ctx);
  97     }
  98
  99 process_partial_block:;
 100
 101   /* Process any remaining bytes.  */
 102   if (sum > 0)
 103     md2_process_bytes (buffer, sum, &ctx);
 104
 105   /* Construct result in desired memory.  */
 106   md2_finish_ctx (&ctx, resblock);
 107   free (buffer);
 108   return 0;
 109 }