lib/md5-stream.c

   1 /* Functions to compute MD5 message digest of files or memory blocks.
   2    according to the definition of MD5 in RFC 1321 from April 1992.
   3    Copyright (C) 1995-1997, 1999-2001, 2005-2006, 2008-2024 Free Software
   4    Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7    This file is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU Lesser General Public License as
   9    published by the Free Software Foundation; either version 2.1 of the
  10    License, or (at your option) any later version.
  11
  12    This file is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public License
  18    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  19
  20 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */
  21
  22 #include <config.h>
  23
  24 /* Specification.  */
  25 #if HAVE_OPENSSL_MD5
  26 # define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
  27 #endif
  28 #include "md5.h"
  29
  30 #include <stdlib.h>
  31
  32 #if USE_UNLOCKED_IO
  33 # include "unlocked-io.h"
  34 #endif
  35
  36 #include "af_alg.h"
  37
  38 #ifdef _LIBC
  39 # include <endian.h>
  40 # if __BYTE_ORDER == __BIG_ENDIAN
  41 #  define WORDS_BIGENDIAN 1
  42 # endif
  43 /* We need to keep the namespace clean so define the MD5 function
  44    protected using leading __ .  */
  45 # define md5_init_ctx __md5_init_ctx
  46 # define md5_process_block __md5_process_block
  47 # define md5_process_bytes __md5_process_bytes
  48 # define md5_finish_ctx __md5_finish_ctx
  49 # define md5_stream __md5_stream
  50 #endif
  51
  52 #define BLOCKSIZE 32768
  53 #if BLOCKSIZE % 64 != 0
  54 # error "invalid BLOCKSIZE"
  55 #endif
  56
  57 /* Compute MD5 message digest for bytes read from STREAM.  The
  58    resulting message digest number will be written into the 16 bytes
  59    beginning at RESBLOCK.  */
  60 int
  61 md5_stream (FILE *stream, void *resblock)
  62 {
  63   switch (afalg_stream (stream, "md5", resblock, MD5_DIGEST_SIZE))
  64     {
  65     case 0: return 0;
  66     case -EIO: return 1;
  67     }
  68
  69   char *buffer = malloc (BLOCKSIZE + 72);
  70   if (!buffer)
  71     return 1;
  72
  73   struct md5_ctx ctx;
  74   md5_init_ctx (&ctx);
  75   size_t sum;
  76
  77   /* Iterate over full file contents.  */
  78   while (1)
  79     {
  80       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
  81          computation function processes the whole buffer so that with the
  82          next round of the loop another block can be read.  */
  83       size_t n;
  84       sum = 0;
  85
  86       /* Read block.  Take care for partial reads.  */
  87       while (1)
  88         {
  89           /* Either process a partial fread() from this loop,
  90              or the fread() in afalg_stream may have gotten EOF.
  91              We need to avoid a subsequent fread() as EOF may
  92              not be sticky.  For details of such systems, see:
  93              https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
  94           if (feof (stream))
  95             goto process_partial_block;
  96
  97           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
  98
  99           sum += n;
 100
 101           if (sum == BLOCKSIZE)
 102             break;
 103
 104           if (n == 0)
 105             {
 106               /* Check for the error flag IFF N == 0, so that we don't
 107                  exit the loop after a partial read due to e.g., EAGAIN
 108                  or EWOULDBLOCK.  */
 109               if (ferror (stream))
 110                 {
 111                   free (buffer);
 112                   return 1;
 113                 }
 114               goto process_partial_block;
 115             }
 116         }
 117
 118       /* Process buffer with BLOCKSIZE bytes.  Note that
 119          BLOCKSIZE % 64 == 0
 120        */
 121       md5_process_block (buffer, BLOCKSIZE, &ctx);
 122     }
 123
 124 process_partial_block:
 125
 126   /* Process any remaining bytes.  */
 127   if (sum > 0)
 128     md5_process_bytes (buffer, sum, &ctx);
 129
 130   /* Construct result in desired memory.  */
 131   md5_finish_ctx (&ctx, resblock);
 132   free (buffer);
 133   return 0;
 134 }
 135
 136 /*
 137  * Hey Emacs!
 138  * Local Variables:
 139  * coding: utf-8
 140  * End:
 141  */