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Fixes 5315 This is essentially the same fix as PR 5296, but for the tile path (we had only fixed scanline). For CMYK (photometric=separated) files, readspec_photometric() drops m_spec.nchannels to 3 for the CMYK->RGB conversion while m_inputchannels stays 4, and the tiled path was unaware of the difference: - sub-8-bit and 9-15 bit samples were unpacked straight into the caller's 3-channel buffer, writing tile_pixels*4 values into room for tile_pixels*3 (heap buffer overflow write) - planarconfig=separate overflowed the same way in separate_to_contig - at 8 and 16 bits the tile was read into scratch and never copied out, so the caller got back uninitialized heap - 17-31 bit samples were never unpacked at all, likewise leaving the caller's buffer uninitialized Assisted-by: Claude Code / Claude Opus 5 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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Copilot review overview
🟡 Changes recommended
Tiled row-padding handling and regression coverage for CMYK 8/16-bit and 9–15-bit paths remain unresolved.
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Review effort: Lite
Findings: 1
Open (1)
What changed in this PR
Fixes tiled TIFF decoding for CMYK images and non-native bit depths, with regression coverage against strip decoding.
Changes:
- Adds scratch-buffer handling for CMYK and planar tile reads.
- Adds unpacking for supported non-native sample depths.
- Updates tiled/strip regression comparisons and expected outputs.
| File | Summary |
|---|---|
testsuite/tiff-misc/run.py |
Adds tiled-versus-strip regression comparisons. Moderate finding (2 votes): coverage is missing CMYK 8/16-bit and 9–15-bit paths. |
testsuite/tiff-misc/ref/out.txt |
Updates expected test output. |
testsuite/tiff-misc/ref/out-libtiff470.txt |
Updates libtiff 4.7 expected output. |
testsuite/tiff-misc/ref/out-libtiff470-c.txt |
Updates libtiff 4.7 variant output. |
testsuite/tiff-misc/ref/out-libtiff470-b.txt |
Updates libtiff 4.7 variant output. |
testsuite/tiff-misc/ref/out-libtiff430.txt |
Updates libtiff 4.3 expected output. |
testsuite/tiff-misc/ref/out-libtiff410.txt |
Updates libtiff 4.1 expected output. |
testsuite/tiff-misc/ref/out-libtiff409.txt |
Updates libtiff 4.0.9 expected output. |
testsuite/tiff-misc/ref/out-libtiff403.txt |
Updates libtiff 4.0.3 expected output. |
testsuite/tiff-misc/ref/out-libtiff403-c.txt |
Updates libtiff 4.0.3 variant output. |
testsuite/tiff-misc/ref/out-libtiff403-b.txt |
Updates libtiff 4.0.3 variant output. |
src/tiff.imageio/tiffinput.cpp |
Updates tiled decoding and CMYK conversion. Moderate finding (1 vote): packed tile rows require independent row-padding handling. |
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| for base in [ "cmyk-1bit", "cmyk-4bit-planar", "rgb-24bit" ] : | ||
| command += oiiotool ("src/{0}-tiled.tif src/{0}-strip.tif --diff".format(base)) |
The tiled/strip regression matrix was missing two of the four bugs the previous commit fixed: CMYK at native 8 and 16 bits (read into scratch and never copied out) and 9-15 bit samples. Adds cmyk-8bit, cmyk-12bit and cmyk-16bit pairs. All three fail against the pre-fix reader. Assisted-by: Claude Code / Claude Opus 5 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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Fixes #5315
This is essentially the same fix as PR #5296, but for the tile path (we had only fixed scanline).
For CMYK (photometric=separated) files, readspec_photometric() drops m_spec.nchannels to 3 for the CMYK->RGB conversion while m_inputchannels stays 4, and the tiled path was unaware of the difference:
tile_pixels*4values into room fortile_pixels*3(heap buffer overflow write)Assisted-by: Claude Code / Claude Opus 5