Revert "Make SkPngCodec only read as much of the stream as necessary"

This reverts commit 2c65d5161260f3d45a63dcd92229bd09c8a12d53.

Reason for revert: Causing failures in Google3 (https://test.corp.google.com/ui#cl=153703311&flags=CAMQAg==&id=OCL:153703311:BASE:153703364:1492695824938:4db2240d&t=//chrome/skia/dm_wrapper:dm_wrapper) and differences in Gold. This change was not intended to change the output.

Original change's description:
> Make SkPngCodec only read as much of the stream as necessary
> 
> Previously, SkPngCodec assumed that the stream only contained one
> image, which ended at the end of the stream. It read the stream in
> arbitrarily-sized chunks, and then passed that data to libpng for
> processing.
> 
> If a stream contains more than one image, this may result in reading
> beyond the end of the image, making future reads read the wrong data.
> 
> Now, SkPngCodec starts by reading 8 bytes at a time. After the
> signature, 8 bytes is enough to know which chunk is next and how many
> bytes are in the chunk.
> 
> When decoding the size, we stop when we reach IDAT, and when decoding
> the image, we stop when we reach IEND.
> 
> This manual parsing is necessary to support APNG, which is planned in
> the future. It also allows us to remove the SK_GOOGLE3_PNG_HACK, which
> was a workaround for reading more than necessary at the beginning of
> the image.
> 
> Add a test that simulates the issue, by decoding a special stream that
> reports an error if the codec attempts to read beyond the end.
> 
> Temporarily disable the partial decoding tests for png. A larger change
> will be necessary to get those working again, and no clients are
> currently relying on incrementally decoding PNGs (i.e. decode part of
> an image, then decode further with more data).
> 
> Bug: skia:5368
> BUG:34073812
> 
> Change-Id: If832f7b20565411226fb5be3c305a4d16bf9269d
> Reviewed-on: https://skia-review.googlesource.com/13900
> Commit-Queue: Leon Scroggins <scroggo@google.com>
> Reviewed-by: Matt Sarett <msarett@google.com>
> 

TBR=msarett@google.com,scroggo@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I2f82e9960dda7bf5c646774df84320dadb7b930e
Reviewed-on: https://skia-review.googlesource.com/13971
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>

1 files changed, 0 insertions, 102 deletions

diff --git a/tests/CodecExactReadTest.cpp b/tests/CodecExactReadTest.cpp
deleted file mode 100644
index 7e0d8eaccc..0000000000
--- a/tests/CodecExactReadTest.cpp
+++ /dev/null
@@ -1,102 +0,0 @@
-/*
- * Copyright 2017 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "Resources.h"
-#include "Test.h"
-
-#include "SkBitmap.h"
-#include "SkCodec.h"
-#include "SkData.h"
-#include "SkStream.h"
-
-namespace {
-// This class emits a skiatest failure if a client attempts to read beyond its
-// end. Since it is used with complete, valid images, and contains nothing
-// after the encoded image data, it will emit a failure if the client attempts
-// to read beyond the logical end of the data.
-class MyStream : public SkStream {
-public:
-    static MyStream* Make(const char* path, skiatest::Reporter* r) {
-        SkASSERT(path);
-        sk_sp<SkData> data(GetResourceAsData(path));
-        if (!data) {
-            return nullptr;
-        }
-
-        return new MyStream(path, std::move(data), r);
-    }
-
-    size_t read(void* buf, size_t bytes) override {
-        const size_t remaining = fStream.getLength() - fStream.getPosition();
-        if (bytes > remaining) {
-            ERRORF(fReporter, "Tried to read %lu bytes (only %lu remaining) from %s",
-                   bytes, remaining, fPath);
-        }
-        return fStream.read(buf, bytes);
-    }
-
-    bool rewind() override {
-        return fStream.rewind();
-    }
-
-    bool isAtEnd() const override {
-        return fStream.isAtEnd();
-    }
-private:
-    const char* fPath;
-    SkMemoryStream fStream;
-    skiatest::Reporter* fReporter;  // Unowned
-
-    MyStream(const char* path, sk_sp<SkData> data, skiatest::Reporter* r)
-        : fPath(path)
-        , fStream(std::move(data))
-        , fReporter(r)
-    {}
-};
-} // namespace
-
-// Test that SkPngCodec does not attempt to read its input beyond the logical
-// end of its data. Some other SkCodecs do, but some Android apps rely on not
-// doing so for PNGs.
-DEF_TEST(Codec_end, r) {
-    for (const char* path : { "plane.png",
-                              "yellow_rose.png",
-                              "plane_interlaced.png" }) {
-        std::unique_ptr<MyStream> stream(MyStream::Make(path, r));
-        if (!stream) {
-            continue;
-        }
-
-        std::unique_ptr<SkCodec> codec(SkCodec::NewFromStream(stream.release()));
-        if (!codec) {
-            ERRORF(r, "Failed to create a codec from %s\n", path);
-            continue;
-        }
-
-        auto info = codec->getInfo().makeColorType(kN32_SkColorType);
-        SkBitmap bm;
-        bm.allocPixels(info);
-
-        auto result = codec->getPixels(bm.info(), bm.getPixels(), bm.rowBytes());
-        if (result != SkCodec::kSuccess) {
-            ERRORF(r, "Failed to getPixels from %s. error %i", path, result);
-            continue;
-        }
-
-        // Rewind and do an incremental decode.
-        result = codec->startIncrementalDecode(bm.info(), bm.getPixels(), bm.rowBytes());
-        if (result != SkCodec::kSuccess) {
-            ERRORF(r, "Failed to startIncrementalDecode from %s. error %i", path, result);
-            continue;
-        }
-
-        result = codec->incrementalDecode();
-        if (result != SkCodec::kSuccess) {
-            ERRORF(r, "Failed to incrementalDecode from %s. error %i", path, result);
-        }
-    }
-}