[PATCH v3 12/13] git-zlib: widen `git_deflate_bound()` to `size_t`
From: Johannes Schindelin via GitGitGadget <hidden>
Date: 2026-08-13 14:56:15
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Johannes Schindelin <redacted> All four `unsigned long`/`int`/`ssize_t` receivers across archive-zip, diff, http-push and t/helper/test-pack-deltas were widened to `size_t` in the prior commits, and remote-curl and fast-import were already there. With every caller prepared, both the parameter and the return type can now move without introducing any silent narrowing. For inputs above zlib's `uLong` range (i.e. >4 GiB on platforms where `uLong` is 32-bit, notably 64-bit Windows), defer to zlib's stored-block formula (the same fallback it would itself use, see https://github.com/madler/zlib/blob/v1.3.2/deflate.c#L832-L928 keeping in mind that for large sizes, the `storelen` would be relevant, also compare with https://github.com/madler/zlib/issues/549 for a fuller story) plus the worst-case wrapper overhead. The existing path through `deflateBound()` is unchanged for inputs that fit. Assisted-by: Opus 4.7 Signed-off-by: Johannes Schindelin <redacted> --- git-zlib.c | 16 ++++++++++++++-- git-zlib.h | 2 +- 2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/git-zlib.c b/git-zlib.c
index a3b32d9a86..1c94f90497 100644
--- a/git-zlib.c
+++ b/git-zlib.c@@ -167,9 +167,21 @@ int git_inflate(git_zstream *strm, int flush) return status; } -unsigned long git_deflate_bound(git_zstream *strm, unsigned long size) +size_t git_deflate_bound(git_zstream *strm, size_t size) { - return deflateBound(&strm->z, size); +#if SIZE_MAX > ULONG_MAX + if (size > maximum_unsigned_value_of_type(uLong)) + /* + * deflateBound() takes uLong, which is 32-bit on + * Windows. For inputs above that range, return zlib's + * stored-block formula (the conservative path it would + * itself use for an unknown stream state) plus the + * worst-case wrapper overhead. + */ + return size + (size >> 5) + (size >> 7) + (size >> 11) + + 7 + 18; +#endif + return deflateBound(&strm->z, (uLong)size); } void git_deflate_init(git_zstream *strm, int level)
diff --git a/git-zlib.h b/git-zlib.h
index 0b24b15bd0..9248d11ca9 100644
--- a/git-zlib.h
+++ b/git-zlib.h@@ -25,6 +25,6 @@ void git_deflate_end(git_zstream *); int git_deflate_abort(git_zstream *); int git_deflate_end_gently(git_zstream *); int git_deflate(git_zstream *, int flush); -unsigned long git_deflate_bound(git_zstream *, unsigned long); +size_t git_deflate_bound(git_zstream *, size_t); #endif /* GIT_ZLIB_H */
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