Make SkSHA1 and SkM5 use common SkDigestHash result type

src/utils/SkSHA1.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * The following code is based on the description in RFC 3174.
  * http://www.ietf.org/rfc/rfc3174.txt
  */
 
@@ skipping 40 matching lines @@
         bufferIndex = 0;
     } else {
         inputIndex = 0;
     }
 
     memcpy(&this->buffer[bufferIndex], &input[inputIndex], inputLength - inputIndex);
 
     this->byteCount += inputLength;
 }
 
-void SkSHA1::finish(Digest& digest) {
+void SkSHA1::finish(SkHashDigest& digest) {
     // Get the number of bits before padding.
     uint8_t bits[8];
     encode(bits, this->byteCount << 3);
 
     // Pad out to 56 mod 64.
     unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
     unsigned int paddingLength = (bufferIndex < 56) ? (56 - bufferIndex) : (120 - bufferIndex);
     static uint8_t PADDING[64] = {
         0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     };
     this->update(PADDING, paddingLength);
 
     // Append length (length before padding, will cause final update).
     this->update(bits, 8);
 
     // Write out digest.
-    encode(digest.data, this->state);
+    // TODO(epoger): eliminate the extra 20-byte copy, by writing directly into digest.data???
+    // NO, we can't do that, because digest.data is immutable (wrapped in SkData).
+    // Or:
+    //  1. malloc 20 bytes here (wrapped in an SkData object),
+    //  2. write the digest into the SkData-wrapped 20 bytes,
+    //  3. bump the ref counter on that SkData-wrapped 20 bytes,
+    //  4. replace digest's fSkDataPtr with the new one
+    size_t digestSize = 20;
+    uint8_t tempDigestData[digestSize];
+    encode(tempDigestData, this->state);
+    digest.copyFrom(tempDigestData, digestSize);
 
 #if defined(SK_SHA1_CLEAR_DATA)
     // Clear state.
     memset(this, 0, sizeof(*this));
 #endif
 }
 
 struct F1 { uint32_t operator()(uint32_t B, uint32_t C, uint32_t D) {
     return (B & C) | ((~B) & D);
     //return D ^ (B & (C ^ D));
@@ skipping 167 matching lines @@
 static void encode(uint8_t output[8], const uint64_t input) {
     output[0] = (uint8_t)((input >> 56) & 0xff);
     output[1] = (uint8_t)((input >> 48) & 0xff);
     output[2] = (uint8_t)((input >> 40) & 0xff);
     output[3] = (uint8_t)((input >> 32) & 0xff);
     output[4] = (uint8_t)((input >> 24) & 0xff);
     output[5] = (uint8_t)((input >> 16) & 0xff);
     output[6] = (uint8_t)((input >>  8) & 0xff);
     output[7] = (uint8_t)((input      ) & 0xff);
 }