Fix/hardsubx error handling

[SuvidhJ]

[FIX] Fix resource leaks, missing NULL checks, and missing return in hardsubx.c

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What does this PR do?

Fixes several error-handling issues in src/lib_ccx/hardsubx.c across both _init_hardsubx() and hardsubx_process_data().

Changes in _init_hardsubx()

• Added NULL check for TessBaseAPICreate(): The return value was never validated. If it returned NULL, every subsequent Tesseract call would hit undefined behavior.

• Added NULL checks for both strdup() calls: pars_vec and pars_values were used without checking if strdup() succeeded. On memory allocation failure these would be NULL pointers passed into TessBaseAPIInit4().

• Added TessBaseAPIDelete() in error paths: When tessdata_path lookup failed or TessBaseAPIInit4() returned non-zero, the code called free(ctx) without first deleting the Tesseract handle that was already created. This leaked the handle every time one of these error paths was hit.

Changes in hardsubx_process_data()

• Added missing return statement: The function is declared as returning int but never actually returned a value, which is undefined behavior per the C standard.

• Added NULL checks for av_malloc(), sws_getContext(), and init_encoder(): All three can return NULL on failure, but the results were being used directly without any validation.

• Replaced per-error cleanup with goto cleanup pattern: Previously, each fatal() call would exit without freeing any of the FFmpeg resources allocated up to that point (codec context, format context, frames, buffers, etc.). Now all error paths jump to a centralized cleanup section that safely frees everything that was allocated.

Issues Fixed

Fixes #2158
Fixes #2160
Fixes #2161

Testing

• Changes are limited to error-handling paths only . The normal execution flow is completely unchanged
• All cleanup uses NULL-safe functions (free(NULL) is a no-op per the C standard, av_frame_free() and avcodec_free_context() handle NULL pointers )
• No new dependencies or behavioral changes introduced

[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 f377be9...:

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	86/86
Teletext	21/21
WTV	13/13
XDS	34/34

Congratulations: Merging this PR would fix the following tests:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed: Never
• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed: Never
• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed: Never
• ccextractor --out=spupng c83f765c66..., 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

All tests passed completely.

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 f377be9...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	6/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	80/86
Teletext	21/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2...
• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65...
• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b...
• ccextractor --out=spupng c83f765c66...
• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...

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.

[cfsmp3]

The real fixes here are good (missing return, TessBaseAPIDelete leaks in _init_hardsubx, NULL checks for av_malloc/sws_getContext/init_encoder). But the PR introduces a lot of dead code.

fatal() calls exit() — it never returns. Every goto cleanup placed after a fatal() call is unreachable dead code. Same for the return NULL statements placed after fatal() in _init_hardsubx(). Please remove all of that.

For the new NULL checks (av_malloc, sws_getContext, init_encoder), just use fatal() directly like the rest of the function does — no goto needed.

Also:

• Squash the 4 commits into one.
• Remove the CHANGES.TXT entry — this is an internal code quality fix, not a user-facing change.