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>
Johannes Schindelin committed
May 8, 2026 at 08:16 UTC
17fa0775966dd9769864768c0fdc76d3cc2a01fb
2 files changed
+36
-11
delta.h
+12
-2
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);
}
packfile.c
+24
-9
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)) {