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, 2008-2025 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 #include "sha1.h"
  28
  29 #include <stdlib.h>
  30
  31 #if USE_UNLOCKED_IO
  32 # include "unlocked-io.h"
  33 #endif
  34
  35 #include "af_alg.h"
  36
  37 #define BLOCKSIZE 32768
  38 #if BLOCKSIZE % 64 != 0
  39 # error "invalid BLOCKSIZE"
  40 #endif
  41
  42 /* Compute SHA1 message digest for bytes read from STREAM.  The
  43    resulting message digest number will be written into the 20 bytes
  44    beginning at RESBLOCK.  */
  45 int
  46 sha1_stream (FILE *stream, void *resblock)
  47 {
  48   switch (afalg_stream (stream, "sha1", resblock, SHA1_DIGEST_SIZE))
  49     {
  50     case 0: return 0;
  51     case -EIO: return 1;
  52     }
  53
  54   char *buffer = malloc (BLOCKSIZE + 72);
  55   if (!buffer)
  56     return 1;
  57
  58   struct sha1_ctx ctx;
  59   sha1_init_ctx (&ctx);
  60   size_t sum;
  61
  62   /* Iterate over full file contents.  */
  63   while (1)
  64     {
  65       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
  66          computation function processes the whole buffer so that with the
  67          next round of the loop another block can be read.  */
  68       size_t n;
  69       sum = 0;
  70
  71       /* Read block.  Take care for partial reads.  */
  72       while (1)
  73         {
  74           /* Either process a partial fread() from this loop,
  75              or the fread() in afalg_stream may have gotten EOF.
  76              We need to avoid a subsequent fread() as EOF may
  77              not be sticky.  For details of such systems, see:
  78              https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
  79           if (feof (stream))
  80             goto process_partial_block;
  81
  82           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
  83
  84           sum += n;
  85
  86           if (sum == BLOCKSIZE)
  87             break;
  88
  89           if (n == 0)
  90             {
  91               /* Check for the error flag IFF N == 0, so that we don't
  92                  exit the loop after a partial read due to e.g., EAGAIN
  93                  or EWOULDBLOCK.  */
  94               if (ferror (stream))
  95                 {
  96                   free (buffer);
  97                   return 1;
  98                 }
  99               goto process_partial_block;
 100             }
 101         }
 102
 103       /* Process buffer with BLOCKSIZE bytes.  Note that
 104                         BLOCKSIZE % 64 == 0
 105        */
 106       sha1_process_block (buffer, BLOCKSIZE, &ctx);
 107     }
 108
 109  process_partial_block:;
 110
 111   /* Process any remaining bytes.  */
 112   if (sum > 0)
 113     sha1_process_bytes (buffer, sum, &ctx);
 114
 115   /* Construct result in desired memory.  */
 116   sha1_finish_ctx (&ctx, resblock);
 117   free (buffer);
 118   return 0;
 119 }