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delta, packfile: use size_t for delta header sizes 

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
main
Johannes Schindelin 2026-05-08 08:16:42 +00:00 committed by Junio C Hamano
parent 606c192380
commit 17fa077596
2 changed files with 36 additions and 11 deletions
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14
delta.h
View File

@ -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);
}


33
packfile.c
View File

@ -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)) {