src/TortoiseMerge/libsvn_diff/sha1.c

   1 /*
   2  * sha1.c: SHA1 checksum routines
   3  *
   4  * ====================================================================
   5  *    Licensed to the Apache Software Foundation (ASF) under one
   6  *    or more contributor license agreements.  See the NOTICE file
   7  *    distributed with this work for additional information
   8  *    regarding copyright ownership.  The ASF licenses this file
   9  *    to you under the Apache License, Version 2.0 (the
  10  *    "License"); you may not use this file except in compliance
  11  *    with the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  *    Unless required by applicable law or agreed to in writing,
  16  *    software distributed under the License is distributed on an
  17  *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  18  *    KIND, either express or implied.  See the License for the
  19  *    specific language governing permissions and limitations
  20  *    under the License.
  21  * ====================================================================
  22  */
  23
  24 #include <apr_sha1.h>
  25
  26 #include "sha1.h"
  27
  28 \f
  29
  30 /* The SHA1 digest for the empty string. */
  31 static const unsigned char svn_sha1__empty_string_digest_array[] = {
  32   0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d, 0x32, 0x55,
  33   0xbf, 0xef, 0x95, 0x60, 0x18, 0x90, 0xaf, 0xd8, 0x07, 0x09
  34 };
  35
  36 const unsigned char *
  37 svn_sha1__empty_string_digest(void)
  38 {
  39   return svn_sha1__empty_string_digest_array;
  40 }
  41
  42
  43 const char *
  44 svn_sha1__digest_to_cstring_display(const unsigned char digest[],
  45                                    apr_pool_t *pool)
  46 {
  47   static const char *hex = "0123456789abcdef";
  48   char *str = apr_palloc(pool, (APR_SHA1_DIGESTSIZE * 2) + 1);
  49   int i;
  50
  51   for (i = 0; i < APR_SHA1_DIGESTSIZE; i++)
  52     {
  53       str[i*2]   = hex[digest[i] >> 4];
  54       str[i*2+1] = hex[digest[i] & 0x0f];
  55     }
  56   str[i*2] = '\0';
  57
  58   return str;
  59 }
  60
  61
  62 const char *
  63 svn_sha1__digest_to_cstring(const unsigned char digest[], apr_pool_t *pool)
  64 {
  65   static const unsigned char zeros_digest[APR_SHA1_DIGESTSIZE] = { 0 };
  66
  67   if (memcmp(digest, zeros_digest, APR_SHA1_DIGESTSIZE) != 0)
  68     return svn_sha1__digest_to_cstring_display(digest, pool);
  69   else
  70     return NULL;
  71 }
  72
  73
  74 svn_boolean_t
  75 svn_sha1__digests_match(const unsigned char d1[], const unsigned char d2[])
  76 {
  77   static const unsigned char zeros[APR_SHA1_DIGESTSIZE] = { 0 };
  78
  79   return ((memcmp(d1, zeros, APR_SHA1_DIGESTSIZE) == 0)
  80           || (memcmp(d2, zeros, APR_SHA1_DIGESTSIZE) == 0)
  81           || (memcmp(d1, d2, APR_SHA1_DIGESTSIZE) == 0));
  82 }