[PATCH 1/3] odb: use size_t for the length of objects to write

[Elia Pinto <gitter.spiros@gmail.com>]

c6a4629e32 (odb: use size_t for object_info.sizep and the size APIs,
2026-06-15) widened the read side of the object database API, and the
write_object() callback of odb_source already takes a size_t. But
odb_write_object_ext(), odb_write_object() and odb_source_write_object()
in front of it, as well as write_loose_object() behind it, still take
an "unsigned long", which is only 32 bits wide on Windows.

Most callers hand them a size_t from a strbuf or from odb_read_object(),
which silently gets truncated. The most visible case is index_mem() and
index_stream_convert_blob(): when "git add" or "git hash-object -w"
runs a file over 4GiB through a conversion (core.autocrlf, which is on
by default in Git for Windows, an eol or ident attribute, or a clean
filter), we write a blob made of the first "size mod 2^32" bytes. The
index records it with the stat data of the real file, so "git status"
stays clean and nobody notices until the file is checked out again.
"git hash-object" without "-w" uses hash_object_file(), which takes a
size_t, so the two disagree on the object ID of the same file.

Use size_t throughout, including for the size kept by the in-memory
source.

The existing "hash filtered files over 4GB correctly" test in t1007
only hashes. Running the same with "git hash-object -w" on Windows
shows the problem, but needs another pass over a 5GiB file, so no new
test is added here.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
---
 odb.c                 | 2 +-
 odb.h                 | 4 ++--
 odb/source-inmemory.c | 2 +-
 odb/source-loose.c    | 2 +-
 odb/source.h          | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/odb.c b/odb.c
index 98c5c862f5..6e9daf11e4 100644
--- a/odb.c
+++ b/odb.c
@@ -667,7 +667,7 @@ void odb_assert_oid_type(struct object_database *odb,
 }
 
 int odb_write_object_ext(struct object_database *odb,
-			 const void *buf, unsigned long len,
+			 const void *buf, size_t len,
 			 enum object_type type,
 			 struct object_id *oid,
 			 const struct object_id *compat_oid_in,
diff --git a/odb.h b/odb.h
index 0ccc47ee73..25d02fae75 100644
--- a/odb.h
+++ b/odb.h
@@ -633,14 +633,14 @@ enum odb_write_object_flags {
  * Returns 0 on success, a negative error code otherwise.
  */
 int odb_write_object_ext(struct object_database *odb,
-			 const void *buf, unsigned long len,
+			 const void *buf, size_t len,
 			 enum object_type type,
 			 struct object_id *oid,
 			 const struct object_id *compat_oid,
 			 enum odb_write_object_flags flags);
 
 static inline int odb_write_object(struct object_database *odb,
-				   const void *buf, unsigned long len,
+				   const void *buf, size_t len,
 				   enum object_type type,
 				   struct object_id *oid)
 {
diff --git a/odb/source-inmemory.c b/odb/source-inmemory.c
index 868e723c81..ab7173cd2d 100644
--- a/odb/source-inmemory.c
+++ b/odb/source-inmemory.c
@@ -10,7 +10,7 @@
 struct inmemory_object {
 	enum object_type type;
 	const void *buf;
-	unsigned long size;
+	size_t size;
 };
 
 static const struct inmemory_object *find_cached_object(struct odb_source_inmemory *source,
diff --git a/odb/source-loose.c b/odb/source-loose.c
index 0664634938..fe1a298364 100644
--- a/odb/source-loose.c
+++ b/odb/source-loose.c
@@ -770,7 +770,7 @@ static int end_loose_object_common(struct odb_source_loose *loose,
 
 static int write_loose_object(struct odb_source_loose *loose,
 			      const struct object_id *oid, char *hdr,
-			      int hdrlen, const void *buf, unsigned long len,
+			      int hdrlen, const void *buf, size_t len,
 			      const time_t *mtime, unsigned flags)
 {
 	int fd, ret;
diff --git a/odb/source.h b/odb/source.h
index 1867347dfc..8e6ed96399 100644
--- a/odb/source.h
+++ b/odb/source.h
@@ -469,7 +469,7 @@ static inline int odb_source_freshen_object(struct odb_source *source,
  * object ID and the compatibility object ID, if non-NULL.
  */
 static inline int odb_source_write_object(struct odb_source *source,
-					  const void *buf, unsigned long len,
+					  const void *buf, size_t len,
 					  enum object_type type,
 					  const struct object_id *oid,
 					  const struct object_id *compat_oid,
-- 
2.53.0