fix(matroska): abort parsing on invalid EBML ID to prevent infinite loop

[pulk17]

[FIX] matroska: Abort parsing on invalid element ID (0xFFFFFFFF) to prevent infinite loops

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Summary

This PR fixes a critical regression where the legacy C Matroska parser (matroska.c) enters an infinite loop when encountering invalid EBML IDs (specifically 0xFFFFFFFF) or EOF conditions inside segment/cluster loops.

The Issue

In parse_segment, parse_segment_cluster, and related functions, the loop structure was:

1. Read EBML ID.
2. If ID is unknown, log warning and skip_bytes.
3. If the ID is 0xFFFFFFFF (EOF/Error), skip_bytes skips 0 bytes.
4. The loop repeats indefinitely, consuming 100% CPU and flooding logs.

The Fix

Added an explicit check for code == 0xFFFFFFFF in the parsing loops. The parser now detects this "Invalid ID" state and aborts the loop gracefully with a specific error message.

Verification

Tested against corrupted/truncated MKV samples that previously caused hangs.

• Before: Infinite loop, process hangs.

• After: Logs "Invalid EBML ID... Aborting segment parsing" and exits successfully.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 4252703...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	6/7
DVD	3/3
DVR-MS	2/2
General	27/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	85/86
Teletext	21/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2...
• ccextractor --out=spupng c83f765c66...

Congratulations: Merging this PR would fix the following tests:

• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed: Never
• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed: Never
• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Check the result page for more info.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results, when compared to test for commit 4252703...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	7/7
DVD	3/3
DVR-MS	2/2
General	27/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	85/86
Teletext	21/21
WTV	13/13
XDS	34/34

NOTE: The following tests have been failing on the master branch as well as the PR:

• ccextractor --out=spupng c83f765c66..., Last passed:

  Test 7741

This PR does not introduce any new test failures. However, some tests are failing on both master and this PR (see above).

Check the result page for more info.

[cfsmp3]

Already fixed (note though that this PR is fixing the symptom but not the underlying problem)