Fix crash when staging lines with the index locked#2771
Merged
lucasderraugh merged 1 commit intogit-up:masterfrom Apr 23, 2026
Merged
Fix crash when staging lines with the index locked#2771lucasderraugh merged 1 commit intogit-up:masterfrom
lucasderraugh merged 1 commit intogit-up:masterfrom
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These error overrides might have worked at some point? But in my quick tests, now, if the function errors, it'll return a null diff. As a result of the override, the null diff unexpectedly goes in the rest of GUK. IIRC, a GCDiff gets created with it, GCDiff._cacheDeltasIfNeeded tries to allocate an array of capacity -1 (which maps to unsigned int 18446744073709551615) because that's the output of git_diff_num_deltas on a null value, and that crashes.
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@Cykelero What happens when this path is hit and GIT_ELOCKED is returned? Do we throw some kind of error UI? |
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Author
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Yeah, the usual dialog: |
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Thanks! |
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Fixes #2768.
Why it crashes
See the linked issue for a LLM-generated attempt at diagnosing the issue; it seems rather correct. (the proposed solutions are pretty terrible though)
In a nutshell: in two spots*, GUK calls
git_diff_index_to_workdir(), and explicitly ignores its returned error if it’sGIT_ELOCKED. The reasoning is that we don’t care about failing to write the index: that’s just an optional, beneficial side-effect to our actual need, which is to get a diff.However, when failing in that way,
git_diff_index_to_workdir()does not return a diff**, it returns null! And so that null value is returned, silently makes its way through GUK, until this causes an array to be allocated with an incorrect size.*
diffWorkingDirectoryWithCommitanddiffWorkingDirectoryWithIndex, onGCRepository.** Presumably it did at some point, explaining why the code is written that way.
Reproducing
To reproduce, I had to patch
git_diff_index_to_workdir()to always write the index:Then, you can trigger the crash by staging an individual line. (that’s what I did in Retcon, anyway, but it should work in GitUp as well)
The fix
I removed the override altogether. When I tested, if
git_diff_index_to_workdir()returnsGIT_ELOCKED, it always returns an empty diff. Maybe that’s not always the case, but it doesn’t feel like we should trust its return value in these cases anyway.