Bug#1118385: texlive-binaries: corner-case PDF image nondeterminism

Preuße, Hilmar <[email protected]> Mon, 11 May 2026 09:09:01 +0200

Newsgroups	gmane.linux.debian.devel.tetex
Message-ID	<a3d156a8-d299-414c-80e6-4a3174028473__45923.2083101355$1778483487$gmane$org@web.de>

Am 19.10.2025 um 04:57 schrieb Aaron M. Ucko:

Hello,

> I have found that when a PNG image's row width does not correspond to a
> whole number of bytes, the low-order bits of the last byte in each
> uncompressed row can fluctuate between pdflatex runs, at least when
> libpng can perform SIMD-assisted decompression, yielding
> nondeterministic output even when arranging to supply predetermined
> timestamps.  (Moreover, this fluctuation can affect the length of the
> resulting compressed stream, slightly shifting the file position of
> subsequent content.)
> 

At least I'm able to reproduce the issue by running pdflatex 10 times 
over the same set of input files and getting 10 files having the same 
size but different checksum.

The input files are of course not minimal. As next step I'll contact 
pdfTeX upstream. They should be able to clarify if the code generating 
that alternating content is located on the pdfTeX source code or in one 
of the libraries it is linked with.

Hilmar

hille@rasppi3:~/devel/TeXLive/Upgrade_Test/arm64-sid/home/hille/1118385 
$ ls -l
total 109240
drwxr-xr-x 2 hille hille    36864 May 11 08:55 latex
-rw-rw-r-- 1 hille hille 11178538 May 11 08:55 refman_10.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:18 refman_1.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:22 refman_2.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:26 refman_3.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:31 refman_4.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:35 refman_5.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:39 refman_6.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:43 refman_7.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:47 refman_8.pdf
-rw-rw-r-- 1 hille hille 11178538 May 11 08:51 refman_9.pdf
hille@rasppi3:~/devel/TeXLive/Upgrade_Test/arm64-sid/home/hille/1118385 
$ md5sum refman_*
fad47cf92f41fcee69bcaba215fc54fb  refman_10.pdf
70e2b4061750d4f70089a1571d59bef1  refman_1.pdf
5b897de682ef50f5ac423b60fdedd9b7  refman_2.pdf
c4862f7dd9aba1a41c66577e6cc4908f  refman_3.pdf
2b987c9a15fafe4d83e0e0745d2cd197  refman_4.pdf
a8a28203556c3fd7b261d8a3532b198e  refman_5.pdf
0dc8adff9c21b34633786cf993edd2f3  refman_6.pdf
e3c4783783b132c8b6888d12144d6a58  refman_7.pdf
9c5bc607de841902487556fb4c080746  refman_8.pdf
a50e84bb0d679d778bd6d21980714ebd  refman_9.pdf

-- 
sigfault

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