| commit | 5143ac07b17e2b025865378fce24cc11ac7bf8b1 | [log] [tgz] |
|---|---|---|
| author | Jason Hatton <jhatton@globalfinishing.com> | Thu Oct 12 16:09:30 2023 +0000 |
| committer | Junio C Hamano <gitster@pobox.com> | Fri Oct 13 13:33:35 2023 -0700 |
| tree | 5a09d65e4fa14273e763d0ec8994a0fe01a1eb09 | |
| parent | 678eb55f5da174fce21f686f0073d56904c081c9 [diff] |
Prevent git from rehashing 4GiB files The index stores file sizes using a uint32_t. This causes any file that is a multiple of 2^32 to have a cached file size of zero. Zero is a special value used by racily clean. This causes git to rehash every file that is a multiple of 2^32 every time git status or git commit is run. This patch mitigates the problem by making all files that are a multiple of 2^32 appear to have a size of 1<<31 instead of zero. The value of 1<<31 is chosen to keep it as far away from zero as possible to help prevent things getting mixed up with unpatched versions of git. An example would be to have a 2^32 sized file in the index of patched git. Patched git would save the file as 2^31 in the cache. An unpatched git would very much see the file has changed in size and force it to rehash the file, which is safe. The file would have to grow or shrink by exactly 2^31 and retain all of its ctime, mtime, and other attributes for old git to not notice the change. This patch does not change the behavior of any file that is not an exact multiple of 2^32. Signed-off-by: Jason D. Hatton <jhatton@globalfinishing.com> Signed-off-by: brian m. carlson <bk2204@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
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