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author | Elijah Newren <newren@gmail.com> | 2021-05-20 06:09:37 +0000 |
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committer | Junio C Hamano <gitster@pobox.com> | 2021-05-20 15:40:39 +0900 |
commit | 19ceb486f8dd25fb5782724c454edb2f06f1ed71 (patch) | |
tree | e4835554d8aa3e980aa56ea4f0e4b01901b6d32c /t/t4126-apply-empty.sh | |
parent | merge-ort: add code to check for whether cached renames can be reused (diff) | |
download | tgif-19ceb486f8dd25fb5782724c454edb2f06f1ed71.tar.xz |
merge-ort: avoid accidental API mis-use
Previously, callers of the merge-ort API could have passed an
uninitialized value for struct merge_result *result. However, we want
to check result to see if it has cached renames from a previous merge
that we can reuse; such values would be found behind result->priv.
However, if result->priv is uninitialized, attempting to access behind
it will give a segfault. So, we need result->priv to be NULL (which
will be the case if the caller does a memset(&result, 0)), or be written
by a previous call to the merge-ort machinery. Documenting this
requirement may help, but despite being the person who introduced this
requirement, I still missed it once and it did not fail in a very clear
way and led to a long debugging session.
Add a _properly_initialized field to merge_result; that value will be
0 if the caller zero'ed the merge_result, it will be set to a very
specific value by a previous run by the merge-ort machinery, and if it's
uninitialized it will most likely either be 0 or some value that does
not match the specific one we'd expect allowing us to throw a much more
meaningful error.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 't/t4126-apply-empty.sh')
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