[PATCH v3 04/11] delta, packfile: use size_t for delta header sizes
- From
Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
- Date
- May 8, 2026, 08:16 UTC
- Message-ID
- <8e87a4e71f8684fbd4331b42b3237ffa4284501c.1778228209.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.2102.v3.git.1778228209.gitgitgadget@gmail.com>
From: Johannes Schindelin <johannes.schindelin@gmx.de>
The delta header decoding functions return unsigned long, which truncates on Windows for objects larger than 4GB. Introduce size_t variants get_delta_hdr_size_sz() and get_size_from_delta_sz() that preserve the full 64-bit size, and use them in packed_object_info() where the size is needed for streaming decisions.
This was originally authored by LordKiRon <https://github.com/LordKiRon>, who preferred not to reveal their real name and therefore agreed that I take over authorship.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> --- delta.h | 14 ++++++++++++-- packfile.c | 33 ++++++++++++++++++++++++--------- 2 files changed, 36 insertions(+), 11 deletions(-)
diff --git a/delta.h b/delta.h index 8a56ec0799..fad68cfc45 100644 --- a/delta.h +++ b/delta.h @@ -86,8 +86,11 @@ void *patch_delta(const void *src_buf, unsigned long src_size, * This must be called twice on the delta data buffer, first to get the * expected source buffer size, and again to get the target buffer size. */ -static inline unsigned long get_delta_hdr_size(const unsigned char **datap, - const unsigned char *top) +/* + * Size_t variant that doesn't truncate - use for >4GB objects on Windows. + */ +static inline size_t get_delta_hdr_size_sz(const unsigned char **datap, + const unsigned char *top) { const unsigned char *data = *datap; size_t cmd, size = 0; @@ -98,6 +101,13 @@ static inline unsigned long get_delta_hdr_size(const unsigned char **datap, i += 7; } while (cmd & 0x80 && data < top); *datap = data; + return size; +} + +static inline unsigned long get_delta_hdr_size(const unsigned char **datap, + const unsigned char *top) +{ + size_t size = get_delta_hdr_size_sz(datap, top); return cast_size_t_to_ulong(size); } diff --git a/packfile.c b/packfile.c index fdae91dd11..4208f53046 100644 --- a/packfile.c +++ b/packfile.c @@ -1161,9 +1161,12 @@ unsigned long unpack_object_header_buffer(const unsigned char *buf, return used; } -unsigned long get_size_from_delta(struct packed_git *p, - struct pack_window **w_curs, - off_t curpos) +/* + * Size_t variant for >4GB delta results on Windows. + */ +static size_t get_size_from_delta_sz(struct packed_git *p, + struct pack_window **w_curs, + off_t curpos) { const unsigned char *data; unsigned char delta_head[20], *in; @@ -1210,10 +1213,18 @@ unsigned long get_size_from_delta(struct packed_git *p, data = delta_head; /* ignore base size */ - get_delta_hdr_size(&data, delta_head+sizeof(delta_head)); + get_delta_hdr_size_sz(&data, delta_head+sizeof(delta_head)); /* Read the result size */ - return get_delta_hdr_size(&data, delta_head+sizeof(delta_head)); + return get_delta_hdr_size_sz(&data, delta_head+sizeof(delta_head)); +} + +unsigned long get_size_from_delta(struct packed_git *p, + struct pack_window **w_curs, + off_t curpos) +{ + size_t size = get_size_from_delta_sz(p, w_curs, curpos); + return cast_size_t_to_ulong(size); } int unpack_object_header(struct packed_git *p, @@ -1618,14 +1629,18 @@ static int packed_object_info_with_index_pos(struct packed_git *p, off_t obj_off ret = -1; goto out; } - *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos); - if (*oi->sizep == 0) { + /* + * Use size_t variant to avoid die() on >4GB deltas. + * oi->sizep is unsigned long, so truncation may occur, + * but streaming code uses its own size_t tracking. + */ + size = get_size_from_delta_sz(p, &w_curs, tmp_pos); + if (size == 0) { ret = -1; goto out; } - } else { - *oi->sizep = size; } + *oi->sizep = (unsigned long)size; } if (oi->disk_sizep || (oi->mtimep && p->is_cruft)) {
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