RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-17 19:15:08 +00:00
Code Issues Activity Actions

LibGfx: Use a FixedArray for the dummy scanline in PNGWriter

Browse source 
PNGWriter sets up one dummy scanline with the same width as the other
scanlines in order to allow addressing the "previous scanline" without
complicating the code.

By using a FixedArray instead of a VLA, we sidestep the risk of stack
overflow and instead get something that can signal OOM.
This commit is contained in:
Andreas Kling 2022-12-07 19:06:41 +01:00 • committed by Sam Atkins
parent e19c8897ee
commit b3b51a5001
1 changed files with 5 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

9
Userland/Libraries/LibGfx/PNGWriter.cpp
View file

@ -8,6 +8,7 @@
#include <AK/Concepts.h>
#include <AK/DeprecatedString.h>
#include <AK/FixedArray.h>
#include <AK/SIMDExtras.h>
#include <LibCompress/Zlib.h>
#include <LibCrypto/Checksum/CRC32.h>
@ -174,8 +175,8 @@ ErrorOr<void> PNGWriter::add_IDAT_chunk(Gfx::Bitmap const& bitmap)
ByteBuffer uncompressed_block_data;
TRY(uncompressed_block_data.try_ensure_capacity(bitmap.size_in_bytes() + bitmap.height()));
Pixel dummy_scanline[bitmap.width()];
auto const* scanline_minus_1 = dummy_scanline;
auto dummy_scanline = TRY(FixedArray<Pixel>::try_create(bitmap.width()));
auto const* scanline_minus_1 = dummy_scanline.data();
for (int y = 0; y < bitmap.height(); ++y) {
auto* scanline = reinterpret_cast<Pixel const*>(bitmap.scanline(y));
@ -217,8 +218,8 @@ ErrorOr<void> PNGWriter::add_IDAT_chunk(Gfx::Bitmap const& bitmap)
Filter paeth_filter { .type = PNG::FilterType::Paeth };
TRY(paeth_filter.buffer.try_ensure_capacity(sizeof(ARGB32) * bitmap.height()));
auto pixel_x_minus_1 = Pixel::gfx_to_png(*dummy_scanline);
auto pixel_xy_minus_1 = Pixel::gfx_to_png(*dummy_scanline);
auto pixel_x_minus_1 = Pixel::gfx_to_png(dummy_scanline[0]);
auto pixel_xy_minus_1 = Pixel::gfx_to_png(dummy_scanline[0]);
for (int x = 0; x < bitmap.width(); ++x) {
auto pixel = Pixel::gfx_to_png(scanline[x]);