diff: widen textconv_object() size out-param to size_t

Continue the size_t evacuation. textconv_object() fills its
out-parameter from fill_textconv()'s size_t return through an
unsigned long*; widen the API to match, then take advantage of the
new shape where callers can.

cat-file's 'c' and batch-mode 'c' branches lose their size_ul
bridge variables (one site becomes a direct call, the other
collapses an if/else into a single negated condition that reads as
"try textconv, fall back to a raw read").

blame.c likewise drops the file_size_st bridge in fill_origin_blob()
and hoists final_buf_size_st to bracket both branches in
setup_scoreboard(). The latter keeps a cast_size_t_to_ulong() shim
because struct blame_scoreboard.final_buf_size is still unsigned
long; that field is its own topic.

log.c just widens its local from unsigned long to size_t.

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

builtin/cat-file.c

@@ -202,11 +202,9 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 
 	case 'c':
 	{
-		unsigned long size_ul = 0;
 		int textconv_ret = textconv_object(the_repository, path,
 						   obj_context.mode, &oid, 1,
-						   &buf, &size_ul);
-		size = size_ul;
+						   &buf, &size);
 		if (textconv_ret)
 			break;
 	}
@@ -448,12 +446,9 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 					    oid_to_hex(oid), data->rest);
 			} else if (opt->transform_mode == 'c') {
 				enum object_type type;
-				unsigned long size_ul = 0;
-				if (textconv_object(the_repository,
-						    data->rest, 0100644, oid,
-						    1, &contents, &size_ul))
-					size = size_ul;
-				else
+				if (!textconv_object(the_repository,
+						     data->rest, 0100644, oid,
+						     1, &contents, &size))
 					contents = odb_read_object(the_repository->objects,
 								   oid, &type, &size);
 				if (!contents)

builtin/log.c

@@ -584,7 +584,7 @@ static int show_blob_object(const struct object_id *oid, struct rev_info *rev, c
 	struct object_id oidc;
 	struct object_context obj_context = {0};
 	char *buf;
-	unsigned long size;
+	size_t size;
 
 	fflush(rev->diffopt.file);
 	if (!rev->diffopt.flags.textconv_set_via_cmdline ||

lib/blame.c

@@ -240,7 +240,7 @@ static struct commit *fake_working_tree_commit(struct repository *r,
 		struct stat st;
 		const char *read_from;
 		char *buf_ptr;
-		unsigned long buf_len;
+		size_t buf_len;
 
 		if (contents_from) {
 			if (stat(contents_from, &st) < 0)
@@ -1044,20 +1044,17 @@ static void fill_origin_blob(struct diff_options *opt,
 {
 	if (!o->file.ptr) {
 		enum object_type type;
-		unsigned long file_size;
+		size_t file_size;
 
 		(*num_read_blob)++;
 		if (opt->flags.allow_textconv &&
 		    textconv_object(opt->repo, o->path, o->mode,
 				    &o->blob_oid, 1, &file->ptr, &file_size))
 			;
-		else {
-			size_t file_size_st = 0;
+		else
 			file->ptr = odb_read_object(the_repository->objects,
 						    &o->blob_oid, &type,
-						    &file_size_st);
-			file_size = cast_size_t_to_ulong(file_size_st);
-		}
+						    &file_size);
 		file->size = file_size;
 
 		if (!file->ptr)
@@ -2886,22 +2883,20 @@ void setup_scoreboard(struct blame_scoreboard *sb,
 		sb->final_buf_size = o->file.size;
 	}
 	else {
+		size_t final_buf_size_st = 0;
 		o = get_origin(sb->final, sb->path);
 		if (fill_blob_sha1_and_mode(sb->repo, o))
 			die(_("no such path %s in %s"), sb->path, final_commit_name);
 
 		if (sb->revs->diffopt.flags.allow_textconv &&
 		    textconv_object(sb->repo, sb->path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
-				    &sb->final_buf_size))
+				    &final_buf_size_st))
 			;
-		else {
-			size_t final_buf_size_st = 0;
+		else
 			sb->final_buf = odb_read_object(the_repository->objects,
 							&o->blob_oid, &type,
 							&final_buf_size_st);
-			sb->final_buf_size =
-				cast_size_t_to_ulong(final_buf_size_st);
-		}
+		sb->final_buf_size = cast_size_t_to_ulong(final_buf_size_st);
 
 		if (!sb->final_buf)
 			die(_("cannot read blob %s for path %s"),

lib/diff.c

@@ -7997,7 +7997,7 @@ int textconv_object(struct repository *r,
 		    const struct object_id *oid,
 		    int oid_valid,
 		    char **buf,
-		    unsigned long *buf_size)
+		    size_t *buf_size)
 {
 	struct diff_filespec *df;
 	struct userdiff_driver *textconv;

lib/diff.h

@@ -762,7 +762,7 @@ int textconv_object(struct repository *repo,
 		    const char *path,
 		    unsigned mode,
 		    const struct object_id *oid, int oid_valid,
-		    char **buf, unsigned long *buf_size);
+		    char **buf, size_t *buf_size);
 
 int parse_rename_score(const char **cp_p);