lib/sha1-stream.c

   1 /* sha1.c - Functions to compute SHA1 message digest of files or
   2    memory blocks according to the NIST specification FIPS-180-1.
   3
   4    Copyright (C) 2000-2001, 2003-2006, 2008-2024 Free Software 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 /* Written by Scott G. Miller
  20    Credits:
  21       Robert Klep <robert@ilse.nl>  -- Expansion function fix
  22 */
  23
  24 #include <config.h>
  25
  26 /* Specification.  */
  27 #if HAVE_OPENSSL_SHA1
  28 # define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
  29 #endif
  30 #include "sha1.h"
  31
  32 #include <stdlib.h>
  33
  34 #if USE_UNLOCKED_IO
  35 # include "unlocked-io.h"
  36 #endif
  37
  38 #include "af_alg.h"
  39
  40 #define BLOCKSIZE 32768
  41 #if BLOCKSIZE % 64 != 0
  42 # error "invalid BLOCKSIZE"
  43 #endif
  44
  45 /* Compute SHA1 message digest for bytes read from STREAM.  The
  46    resulting message digest number will be written into the 20 bytes
  47    beginning at RESBLOCK.  */
  48 int
  49 sha1_stream (FILE *stream, void *resblock)
  50 {
  51   switch (afalg_stream (stream, "sha1", resblock, SHA1_DIGEST_SIZE))
  52     {
  53     case 0: return 0;
  54     case -EIO: return 1;
  55     }
  56
  57   char *buffer = malloc (BLOCKSIZE + 72);
  58   if (!buffer)
  59     return 1;
  60
  61   struct sha1_ctx ctx;
  62   sha1_init_ctx (&ctx);
  63   size_t sum;
  64
  65   /* Iterate over full file contents.  */
  66   while (1)
  67     {
  68       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
  69          computation function processes the whole buffer so that with the
  70          next round of the loop another block can be read.  */
  71       size_t n;
  72       sum = 0;
  73
  74       /* Read block.  Take care for partial reads.  */
  75       while (1)
  76         {
  77           /* Either process a partial fread() from this loop,
  78              or the fread() in afalg_stream may have gotten EOF.
  79              We need to avoid a subsequent fread() as EOF may
  80              not be sticky.  For details of such systems, see:
  81              https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
  82           if (feof (stream))
  83             goto process_partial_block;
  84
  85           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
  86
  87           sum += n;
  88
  89           if (sum == BLOCKSIZE)
  90             break;
  91
  92           if (n == 0)
  93             {
  94               /* Check for the error flag IFF N == 0, so that we don't
  95                  exit the loop after a partial read due to e.g., EAGAIN
  96                  or EWOULDBLOCK.  */
  97               if (ferror (stream))
  98                 {
  99                   free (buffer);
 100                   return 1;
 101                 }
 102               goto process_partial_block;
 103             }
 104         }
 105
 106       /* Process buffer with BLOCKSIZE bytes.  Note that
 107                         BLOCKSIZE % 64 == 0
 108        */
 109       sha1_process_block (buffer, BLOCKSIZE, &ctx);
 110     }
 111
 112  process_partial_block:;
 113
 114   /* Process any remaining bytes.  */
 115   if (sum > 0)
 116     sha1_process_bytes (buffer, sum, &ctx);
 117
 118   /* Construct result in desired memory.  */
 119   sha1_finish_ctx (&ctx, resblock);
 120   free (buffer);
 121   return 0;
 122 }
 123
 124 /*
 125  * Hey Emacs!
 126  * Local Variables:
 127  * coding: utf-8
 128  * End:
 129  */