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Remove dependency on getLength from webp decoder.

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In webp_parse_header, continue reading until end of stream is reached,
or we have read WEBP_VP8_HEADER_SIZE bytes. Do not check to see if the
stream was too short, since it may not have a way to report its length,
and WEBP_VP8_HEADER_SIZE is padded slightly. Instead, depend on
WebPGetFeatures to report that the stream did not have enough data.

In webp_idecode, only check length if it is available.

BUG=https://b.corp.google.com/issue?id=8432093
R=djsollen@google.com, vikasa@google.com

Review URL: https://codereview.chromium.org/22841005

git-svn-id: http://skia.googlecode.com/svn/trunk@10848 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
scroggo@google.com 2013-08-21 14:56:09 +00:00
parent af9296e1e9
commit 3c8730a84e
1 changed files with 18 additions and 11 deletions
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29
src/images/SkImageDecoder_libwebp.cpp
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@ -60,16 +60,24 @@ static const size_t WEBP_IDECODE_BUFFER_SZ = (1 << 16);
// Parse headers of RIFF container, and check for valid Webp (VP8) content.
static bool webp_parse_header(SkStream* stream, int* width, int* height, int* alpha) {
unsigned char buffer[WEBP_VP8_HEADER_SIZE];
const uint32_t contentSize = stream->getLength();
const size_t len = stream->read(buffer, WEBP_VP8_HEADER_SIZE);
const uint32_t read_bytes =
(contentSize < WEBP_VP8_HEADER_SIZE) ? contentSize : WEBP_VP8_HEADER_SIZE;
if (len != read_bytes) {
return false; // can't read enough
}
size_t bytesToRead = WEBP_VP8_HEADER_SIZE;
size_t totalBytesRead = 0;
do {
unsigned char* dst = buffer + totalBytesRead;
const size_t bytesRead = stream->read(dst, bytesToRead);
if (0 == bytesRead) {
// Could not read any bytes. Check to see if we are at the end (exit
// condition), and continue reading if not. Important for streams
// that do not have all the data ready.
continue;
}
bytesToRead -= bytesRead;
totalBytesRead += bytesRead;
SkASSERT(bytesToRead + totalBytesRead == WEBP_VP8_HEADER_SIZE);
} while (!stream->isAtEnd() && bytesToRead > 0);
WebPBitstreamFeatures features;
VP8StatusCode status = WebPGetFeatures(buffer, read_bytes, &features);
VP8StatusCode status = WebPGetFeatures(buffer, totalBytesRead, &features);
if (VP8_STATUS_OK != status) {
return false; // Invalid WebP file.
}
@ -192,9 +200,8 @@ static bool webp_idecode(SkStream* stream, WebPDecoderConfig* config) {
}
stream->rewind();
const uint32_t contentSize = stream->getLength();
const uint32_t readBufferSize = (contentSize < WEBP_IDECODE_BUFFER_SZ) ?
contentSize : WEBP_IDECODE_BUFFER_SZ;
const size_t readBufferSize = stream->hasLength() ?
SkTMin(stream->getLength(), WEBP_IDECODE_BUFFER_SZ) : WEBP_IDECODE_BUFFER_SZ;
SkAutoMalloc srcStorage(readBufferSize);
unsigned char* input = (uint8_t*)srcStorage.get();
if (NULL == input) {