src/TortoiseMerge/libsvn_diff/sha1.c

   1 /*
   2  * sha1.c: SHA1 checksum routines
   3  *
   4  * ====================================================================
   5  * Copyright (c) 2008 CollabNet.  All rights reserved.
   6  *
   7  * This software is licensed as described in the file COPYING, which
   8  * you should have received as part of this distribution.  The terms
   9  * are also available at http://subversion.tigris.org/license-1.html.
  10  * If newer versions of this license are posted there, you may use a
  11  * newer version instead, at your option.
  12  *
  13  * This software consists of voluntary contributions made by many
  14  * individuals.  For exact contribution history, see the revision
  15  * history and logs, available at http://subversion.tigris.org/.
  16  * ====================================================================
  17  */
  18
  19 #include <apr_sha1.h>
  20
  21 #include "sha1.h"
  22
  23 \f
  24
  25 /* The SHA1 digest for the empty string. */
  26 static const unsigned char svn_sha1__empty_string_digest_array[] = {
  27   0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d, 0x32, 0x55,
  28   0xbf, 0xef, 0x95, 0x60, 0x18, 0x90, 0xaf, 0xd8, 0x07, 0x09
  29 };
  30
  31 const unsigned char *
  32 svn_sha1__empty_string_digest(void)
  33 {
  34   return svn_sha1__empty_string_digest_array;
  35 }
  36
  37
  38 const char *
  39 svn_sha1__digest_to_cstring_display(const unsigned char digest[],
  40                                    apr_pool_t *pool)
  41 {
  42   static const char *hex = "0123456789abcdef";
  43   char *str = apr_palloc(pool, (APR_SHA1_DIGESTSIZE * 2) + 1);
  44   int i;
  45
  46   for (i = 0; i < APR_SHA1_DIGESTSIZE; i++)
  47     {
  48       str[i*2]   = hex[digest[i] >> 4];
  49       str[i*2+1] = hex[digest[i] & 0x0f];
  50     }
  51   str[i*2] = '\0';
  52
  53   return str;
  54 }
  55
  56
  57 const char *
  58 svn_sha1__digest_to_cstring(const unsigned char digest[], apr_pool_t *pool)
  59 {
  60   static const unsigned char zeros_digest[APR_SHA1_DIGESTSIZE] = { 0 };
  61
  62   if (memcmp(digest, zeros_digest, APR_SHA1_DIGESTSIZE) != 0)
  63     return svn_sha1__digest_to_cstring_display(digest, pool);
  64   else
  65     return NULL;
  66 }
  67
  68
  69 svn_boolean_t
  70 svn_sha1__digests_match(const unsigned char d1[], const unsigned char d2[])
  71 {
  72   static const unsigned char zeros[APR_SHA1_DIGESTSIZE] = { 0 };
  73
  74   return ((memcmp(d1, zeros, APR_SHA1_DIGESTSIZE) == 0)
  75           || (memcmp(d2, zeros, APR_SHA1_DIGESTSIZE) == 0)
  76           || (memcmp(d1, d2, APR_SHA1_DIGESTSIZE) == 0));
  77 }