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// Copyright 2008 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "third_party/blink/renderer/platform/image-decoders/bmp/bmp_image_decoder.h"
#include "third_party/blink/renderer/platform/image-decoders/bmp/bmp_image_reader.h"
#include "third_party/blink/renderer/platform/image-decoders/fast_shared_buffer_reader.h"
namespace blink {
// Number of bytes in .BMP used to store the file header. This is effectively
// `sizeof(BITMAPFILEHEADER)`, as defined in
// https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapfileheader
static const wtf_size_t kSizeOfFileHeader = 14;
BMPImageDecoder::BMPImageDecoder(AlphaOption alpha_option,
ColorBehavior color_behavior,
wtf_size_t max_decoded_bytes)
: ImageDecoder(alpha_option,
ImageDecoder::kDefaultBitDepth,
color_behavior,
cc::AuxImage::kDefault,
max_decoded_bytes),
decoded_offset_(0) {}
BMPImageDecoder::~BMPImageDecoder() = default;
String BMPImageDecoder::FilenameExtension() const {
return "bmp";
}
const AtomicString& BMPImageDecoder::MimeType() const {
DEFINE_STATIC_LOCAL(const AtomicString, bmp_mime_type, ("image/bmp"));
return bmp_mime_type;
}
void BMPImageDecoder::OnSetData(scoped_refptr<SegmentReader> data) {
if (reader_) {
reader_->SetData(std::move(data));
}
}
bool BMPImageDecoder::SetFailed() {
reader_.reset();
return ImageDecoder::SetFailed();
}
void BMPImageDecoder::DecodeSize() {
Decode(true);
}
void BMPImageDecoder::Decode(wtf_size_t) {
Decode(false);
}
void BMPImageDecoder::Decode(bool only_size) {
if (Failed()) {
return;
}
if (!DecodeHelper(only_size) && IsAllDataReceived()) {
// If we couldn't decode the image but we've received all the data, decoding
// has failed.
SetFailed();
} else if (!frame_buffer_cache_.empty() &&
(frame_buffer_cache_.front().GetStatus() ==
ImageFrame::kFrameComplete)) {
// If we're done decoding the image, we don't need the BMPImageReader
// anymore. (If we failed, |reader_| has already been cleared.)
reader_.reset();
}
}
bool BMPImageDecoder::DecodeHelper(bool only_size) {
wtf_size_t img_data_offset = 0;
if ((decoded_offset_ < kSizeOfFileHeader) &&
!ProcessFileHeader(img_data_offset)) {
return false;
}
if (!reader_) {
reader_ = std::make_unique<BMPImageReader>(this, decoded_offset_,
img_data_offset, false);
reader_->SetData(data_);
}
if (!frame_buffer_cache_.empty()) {
reader_->SetBuffer(&frame_buffer_cache_.front());
}
return reader_->DecodeBMP(only_size);
}
bool BMPImageDecoder::ProcessFileHeader(wtf_size_t& img_data_offset) {
// Read file header.
DCHECK(!decoded_offset_);
FastSharedBufferReader fast_reader(data_);
char buffer[kSizeOfFileHeader];
const char* file_header;
uint16_t file_type;
if (!GetFileType(fast_reader, buffer, file_header, file_type)) {
return false;
}
// See if this is a bitmap filetype we understand.
enum {
BMAP = 0x424D, // "BM"
BITMAPARRAY = 0x4241, // "BA"
// The following additional OS/2 2.x header values (see
// http://www.fileformat.info/format/os2bmp/egff.htm ) aren't widely
// decoded, and are unlikely to be in much use.
/*
ICON = 0x4943, // "IC"
POINTER = 0x5054, // "PT"
COLORICON = 0x4349, // "CI"
COLORPOINTER = 0x4350, // "CP"
*/
};
if (file_type == BITMAPARRAY) {
// Skip initial 14-byte header, try to read the first entry as a BMAP.
decoded_offset_ += kSizeOfFileHeader;
if (!GetFileType(fast_reader, buffer, file_header, file_type)) {
return false;
}
}
if (file_type != BMAP) {
return SetFailed();
}
img_data_offset = BMPImageReader::ReadUint32(&file_header[10]);
decoded_offset_ += kSizeOfFileHeader;
return true;
}
bool BMPImageDecoder::GetFileType(const FastSharedBufferReader& fast_reader,
char* buffer,
const char*& file_header,
uint16_t& file_type) const {
if (data_->size() - decoded_offset_ < kSizeOfFileHeader) {
return false;
}
file_header = fast_reader.GetConsecutiveData(decoded_offset_,
kSizeOfFileHeader, buffer);
file_type = (static_cast<uint16_t>(file_header[0]) << 8) |
static_cast<uint8_t>(file_header[1]);
return true;
}
} // namespace blink
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