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LibGfx/JPEG: Factorize chunk size reading

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This commit is contained in:
Lucas CHOLLET 2023-04-22 13:16:44 -04:00 • committed by Andreas Kling
parent 105a40f4f6
commit ddbe65e2f8
1 changed files with 17 additions and 10 deletions
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27
Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
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@ -700,6 +700,15 @@ static inline ErrorOr<Marker> read_marker_at_cursor(Stream& stream)
return is_supported_marker(marker) ? marker : JPEG_INVALID; return is_supported_marker(marker) ? marker : JPEG_INVALID;
} }
static ErrorOr<u16> read_effective_chunk_size(Stream& stream)
{
// The stored chunk size includes the size of `stored_size` itself.
u16 const stored_size = TRY(stream.read_value<BigEndian<u16>>());
if (stored_size < 2)
return Error::from_string_literal("Stored chunk size is too small");
return stored_size - 2;
}
static ErrorOr<void> read_start_of_scan(Stream& stream, JPEGLoadingContext& context) static ErrorOr<void> read_start_of_scan(Stream& stream, JPEGLoadingContext& context)
{ {
// B.2.3 - Scan header syntax // B.2.3 - Scan header syntax
@ -707,7 +716,7 @@ static ErrorOr<void> read_start_of_scan(Stream& stream, JPEGLoadingContext& cont
if (context.state < JPEGLoadingContext::State::FrameDecoded) if (context.state < JPEGLoadingContext::State::FrameDecoded)
return Error::from_string_literal("SOS found before reading a SOF"); return Error::from_string_literal("SOS found before reading a SOF");
[[maybe_unused]] u16 const bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2; [[maybe_unused]] u16 const bytes_to_read = TRY(read_effective_chunk_size(stream));
u8 const component_count = TRY(stream.read_value<u8>()); u8 const component_count = TRY(stream.read_value<u8>());
Scan current_scan; Scan current_scan;
@ -774,7 +783,7 @@ static ErrorOr<void> read_start_of_scan(Stream& stream, JPEGLoadingContext& cont
static ErrorOr<void> read_restart_interval(Stream& stream, JPEGLoadingContext& context) static ErrorOr<void> read_restart_interval(Stream& stream, JPEGLoadingContext& context)
{ {
// B.2.4.4 - Restart interval definition syntax // B.2.4.4 - Restart interval definition syntax
u16 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2; u16 bytes_to_read = TRY(read_effective_chunk_size(stream));
if (bytes_to_read != 2) { if (bytes_to_read != 2) {
dbgln_if(JPEG_DEBUG, "Malformed DRI marker found!"); dbgln_if(JPEG_DEBUG, "Malformed DRI marker found!");
return Error::from_string_literal("Malformed DRI marker found"); return Error::from_string_literal("Malformed DRI marker found");
@ -785,8 +794,8 @@ static ErrorOr<void> read_restart_interval(Stream& stream, JPEGLoadingContext& c
static ErrorOr<void> read_huffman_table(Stream& stream, JPEGLoadingContext& context) static ErrorOr<void> read_huffman_table(Stream& stream, JPEGLoadingContext& context)
{ {
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()); u16 bytes_to_read = TRY(read_effective_chunk_size(stream));
bytes_to_read -= 2;
while (bytes_to_read > 0) { while (bytes_to_read > 0) {
HuffmanTableSpec table; HuffmanTableSpec table;
u8 table_info = TRY(stream.read_value<u8>()); u8 table_info = TRY(stream.read_value<u8>());
@ -940,11 +949,8 @@ static ErrorOr<void> read_colour_encoding(Stream& stream, [[maybe_unused]] JPEGL
static ErrorOr<void> read_app_marker(Stream& stream, JPEGLoadingContext& context, int app_marker_number) static ErrorOr<void> read_app_marker(Stream& stream, JPEGLoadingContext& context, int app_marker_number)
{ {
// B.2.4.6 - Application data syntax // B.2.4.6 - Application data syntax
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>());
if (bytes_to_read <= 2) u16 bytes_to_read = TRY(read_effective_chunk_size(stream));
return Error::from_string_literal("app marker size too small");
bytes_to_read -= 2;
StringBuilder builder; StringBuilder builder;
for (;;) { for (;;) {
@ -1008,7 +1014,7 @@ static ErrorOr<void> read_start_of_frame(Stream& stream, JPEGLoadingContext& con
return Error::from_string_literal("SOF repeated"); return Error::from_string_literal("SOF repeated");
} }
[[maybe_unused]] u16 const bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()); [[maybe_unused]] u16 const bytes_to_read = TRY(read_effective_chunk_size(stream));
context.frame.precision = TRY(stream.read_value<u8>()); context.frame.precision = TRY(stream.read_value<u8>());
if (context.frame.precision != 8) { if (context.frame.precision != 8) {
@ -1075,7 +1081,8 @@ static ErrorOr<void> read_quantization_table(Stream& stream, JPEGLoadingContext&
{ {
// B.2.4.1 - Quantization table-specification syntax // B.2.4.1 - Quantization table-specification syntax
u16 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2; u16 bytes_to_read = TRY(read_effective_chunk_size(stream));
while (bytes_to_read > 0) { while (bytes_to_read > 0) {
u8 const info_byte = TRY(stream.read_value<u8>()); u8 const info_byte = TRY(stream.read_value<u8>());
u8 const element_unit_hint = info_byte >> 4; u8 const element_unit_hint = info_byte >> 4;