Remove dependency on getLength from webp decoder.
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/src@10848 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/images/SkImageDecoder_libwebp.cpp b/images/SkImageDecoder_libwebp.cpp
index 4691d0d..9f1116e 100644
--- a/images/SkImageDecoder_libwebp.cpp
+++ b/images/SkImageDecoder_libwebp.cpp
@@ -60,16 +60,24 @@
// 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 @@
}
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) {
