packfile,delta: drop the cast_size_t_to_ulong() wrappers

When I started the transition from `unsigned long` to `size_t`, in the
interest of keeping the patches reviewable, I introduced these calls to
prevent data type narrowing from silently failing to handle large object
sizes. I also introduced `*_sz()` variants that would allow most of the
callers to keep using that `unsigned long` that the 90s kindly asked to
be returned.

After the preceding commits, the only places that called the narrow
wrappers either no longer exist or already use the `_sz` form
internally, so the wrappers just narrow values back through
`cast_size_t_to_ulong()` for no reason.

Drop them and rename the `_sz` variants back to the natural names.

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

delta.h

@@ -86,11 +86,8 @@ void *patch_delta(const void *src_buf, size_t 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.
  */
-/*
- * 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)
+static inline size_t get_delta_hdr_size(const unsigned char **datap,
+					const unsigned char *top)
 {
 	const unsigned char *data = *datap;
 	size_t cmd, size = 0;
@@ -104,11 +101,4 @@ static inline size_t get_delta_hdr_size_sz(const unsigned char **datap,
 	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);
-}
-
 #endif

packfile.c

@@ -1164,11 +1164,12 @@ unsigned long unpack_object_header_buffer(const unsigned char *buf,
 }
 
 /*
- * Size_t variant for >4GB delta results on Windows.
+ * Read a delta object's header at curpos in p (already inflated as needed)
+ * and return the size of the result object (the post-application target).
  */
-static size_t get_size_from_delta_sz(struct packed_git *p,
-				     struct pack_window **w_curs,
-				     off_t curpos)
+size_t get_size_from_delta(struct packed_git *p,
+			   struct pack_window **w_curs,
+			   off_t curpos)
 {
 	const unsigned char *data;
 	unsigned char delta_head[20], *in;
@@ -1215,18 +1216,10 @@ static size_t get_size_from_delta_sz(struct packed_git *p,
 	data = delta_head;
 
 	/* ignore base size */
-	get_delta_hdr_size_sz(&data, delta_head+sizeof(delta_head));
+	get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 
 	/* Read the result size */
-	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);
+	return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 }
 
 int unpack_object_header(struct packed_git *p,
@@ -1634,12 +1627,7 @@ static int packed_object_info_with_index_pos(struct packed_git *p, off_t obj_off
 				ret = -1;
 				goto out;
 			}
-			/*
-			 * 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);
+			size = get_size_from_delta(p, &w_curs, tmp_pos);
 			if (size == 0) {
 				ret = -1;
 				goto out;

packfile.h

@@ -458,7 +458,7 @@ int is_pack_valid(struct packed_git *);
 void *unpack_entry(struct repository *r, struct packed_git *, off_t,
 		   enum object_type *, size_t *);
 unsigned long unpack_object_header_buffer(const unsigned char *buf, unsigned long len, enum object_type *type, size_t *sizep);
-unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
+size_t get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
 int unpack_object_header(struct packed_git *, struct pack_window **, off_t *, size_t *);
 off_t get_delta_base(struct packed_git *p, struct pack_window **w_curs,
 		     off_t *curpos, enum object_type type,

patch-delta.c

@@ -27,12 +27,12 @@ void *patch_delta(const void *src_buf, size_t src_size,
 	top = (const unsigned char *) delta_buf + delta_size;
 
 	/* make sure the orig file size matches what we expect */
-	size = get_delta_hdr_size_sz(&data, top);
+	size = get_delta_hdr_size(&data, top);
 	if (size != src_size)
 		return NULL;
 
 	/* now the result size */
-	size = get_delta_hdr_size_sz(&data, top);
+	size = get_delta_hdr_size(&data, top);
 	dst_buf = xmallocz(size);
 
 	out = dst_buf;