base: Simplify the construction of MD5Digest.

base/md5.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The original file was copied from sqlite, and was in the public domain.
 
 /*
  * This code implements the MD5 message-digest algorithm.
  * The algorithm is due to Ron Rivest.  This code was
  * written by Colin Plumb in 1993, no copyright is claimed.
@@ skipping 238 matching lines @@
   byteReverse(ctx->in, 14);
 
   /* Append length in bits and transform */
   memcpy(&ctx->in[14 * sizeof(ctx->bits[0])], &ctx->bits[0],
          sizeof(ctx->bits[0]));
   memcpy(&ctx->in[15 * sizeof(ctx->bits[1])], &ctx->bits[1],
          sizeof(ctx->bits[1]));
 
   MD5Transform(ctx->buf, (uint32_t*)ctx->in);
   byteReverse((uint8_t*)ctx->buf, 4);
-  memcpy(digest->a, ctx->buf, 16);
+  memcpy(digest, ctx->buf, 16);
   memset(ctx, 0, sizeof(*ctx)); /* In case it's sensitive */
 }
 
 void MD5IntermediateFinal(MD5Digest* digest, const MD5Context* context) {
   /* MD5Final mutates the MD5Context*. Make a copy for generating the
      intermediate value. */
   MD5Context context_copy;
   memcpy(&context_copy, context, sizeof(context_copy));
   MD5Final(digest, &context_copy);
 }
 
 std::string MD5DigestToBase16(const MD5Digest& digest) {
   static char const zEncode[] = "0123456789abcdef";
 
   std::string ret;
   ret.resize(32);
 
   for (int i = 0, j = 0; i < 16; i++, j += 2) {
-    uint8_t a = digest.a[i];
-    ret[j] = zEncode[(a >> 4) & 0xf];
-    ret[j + 1] = zEncode[a & 0xf];
+    ret[j] = zEncode[(digest[i] >> 4) & 0xf];
+    ret[j + 1] = zEncode[digest[i] & 0xf];
   }
   return ret;
 }
 
 void MD5Sum(const void* data, size_t length, MD5Digest* digest) {
   MD5Context ctx;
   MD5Init(&ctx);
   MD5Update(&ctx, StringPiece(reinterpret_cast<const char*>(data), length));
   MD5Final(digest, &ctx);
 }
 
 std::string MD5String(const StringPiece& str) {
   MD5Digest digest;
   MD5Sum(str.data(), str.length(), &digest);
   return MD5DigestToBase16(digest);
 }
 
 }  // namespace base