lib/sha512-stream.c

   1 /* sha512.c - Functions to compute SHA512 and SHA384 message digest of files or
   2    memory blocks according to the NIST specification FIPS-180-2.
   3
   4    Copyright (C) 2005-2006, 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 David Madore, considerably copypasting from
  20    Scott G. Miller's sha1.c
  21 */
  22
  23 #include <config.h>
  24
  25 /* Specification.  */
  26 #include "sha512.h"
  27
  28 #include <stdlib.h>
  29
  30 #if USE_UNLOCKED_IO
  31 # include "unlocked-io.h"
  32 #endif
  33
  34 #include "af_alg.h"
  35
  36 #define BLOCKSIZE 32768
  37 #if BLOCKSIZE % 128 != 0
  38 # error "invalid BLOCKSIZE"
  39 #endif
  40
  41 /* Compute message digest for bytes read from STREAM using algorithm ALG.
  42    Write the message digest into RESBLOCK, which contains HASHLEN bytes.
  43    The initial and finishing operations are INIT_CTX and FINISH_CTX.
  44    Return zero if and only if successful.  */
  45 static int
  46 shaxxx_stream (FILE *stream, char const *alg, void *resblock,
  47                ssize_t hashlen, void (*init_ctx) (struct sha512_ctx *),
  48                void *(*finish_ctx) (struct sha512_ctx *, void *))
  49 {
  50   switch (afalg_stream (stream, alg, resblock, hashlen))
  51     {
  52     case 0: return 0;
  53     case -EIO: return 1;
  54     }
  55
  56   char *buffer = malloc (BLOCKSIZE + 72);
  57   if (!buffer)
  58     return 1;
  59
  60   struct sha512_ctx ctx;
  61   init_ctx (&ctx);
  62   size_t sum;
  63
  64   /* Iterate over full file contents.  */
  65   while (1)
  66     {
  67       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
  68          computation function processes the whole buffer so that with the
  69          next round of the loop another block can be read.  */
  70       size_t n;
  71       sum = 0;
  72
  73       /* Read block.  Take care for partial reads.  */
  74       while (1)
  75         {
  76           /* Either process a partial fread() from this loop,
  77              or the fread() in afalg_stream may have gotten EOF.
  78              We need to avoid a subsequent fread() as EOF may
  79              not be sticky.  For details of such systems, see:
  80              https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
  81           if (feof (stream))
  82             goto process_partial_block;
  83
  84           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
  85
  86           sum += n;
  87
  88           if (sum == BLOCKSIZE)
  89             break;
  90
  91           if (n == 0)
  92             {
  93               /* Check for the error flag IFF N == 0, so that we don't
  94                  exit the loop after a partial read due to e.g., EAGAIN
  95                  or EWOULDBLOCK.  */
  96               if (ferror (stream))
  97                 {
  98                   free (buffer);
  99                   return 1;
 100                 }
 101               goto process_partial_block;
 102             }
 103         }
 104
 105       /* Process buffer with BLOCKSIZE bytes.  Note that
 106                         BLOCKSIZE % 128 == 0
 107        */
 108       sha512_process_block (buffer, BLOCKSIZE, &ctx);
 109     }
 110
 111  process_partial_block:;
 112
 113   /* Process any remaining bytes.  */
 114   if (sum > 0)
 115     sha512_process_bytes (buffer, sum, &ctx);
 116
 117   /* Construct result in desired memory.  */
 118   finish_ctx (&ctx, resblock);
 119   free (buffer);
 120   return 0;
 121 }
 122
 123 int
 124 sha512_stream (FILE *stream, void *resblock)
 125 {
 126   return shaxxx_stream (stream, "sha512", resblock, SHA512_DIGEST_SIZE,
 127                         sha512_init_ctx, sha512_finish_ctx);
 128 }
 129
 130 int
 131 sha384_stream (FILE *stream, void *resblock)
 132 {
 133   return shaxxx_stream (stream, "sha384", resblock, SHA384_DIGEST_SIZE,
 134                         sha384_init_ctx, sha384_finish_ctx);
 135 }
 136
 137 /*
 138  * Hey Emacs!
 139  * Local Variables:
 140  * coding: utf-8
 141  * End:
 142  */