Subject: Re: [PATCH v4 2/5] object-file.c: handle undetermined oid in write_loose_object()

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Fri, 03 Dec 2021 14:41:28 +0100

On Fri, Dec 03 2021, Han Xin wrote:

> From: Han Xin <[email-masked]>
>
> When streaming a large blob object to "write_loose_object()", we have no
> chance to run "write_object_file_prepare()" to calculate the oid in
> advance. So we need to handle undetermined oid in function
> "write_loose_object()".
>
> In the original implementation, we know the oid and we can write the
> temporary file in the same directory as the final object, but for an
> object with an undetermined oid, we don't know the exact directory for
> the object, so we have to save the temporary file in ".git/objects/"
> directory instead.
>
> Helped-by: Jiang Xin <[email-masked]>
> Signed-off-by: Han Xin <[email-masked]>
> ---
>  object-file.c | 30 ++++++++++++++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/object-file.c b/object-file.c
> index 82656f7428..1c41587bfb 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -1892,7 +1892,14 @@ static int write_loose_object(const struct object_id *oid, char *hdr,
>  	const void *buf;
>  	unsigned long len;
>  
> -	loose_object_path(the_repository, &filename, oid);
> +	if (is_null_oid(oid)) {
> +		/* When oid is not determined, save tmp file to odb path. */
> +		strbuf_reset(&filename);

Why re-use this & leak memory? An existing strbuf use in this function
doesn't leak in the same way. Just release it as in the below patch on
top (the ret v.s. err variable naming is a bit confused, maybe could do
with a prep cleanup step.).

> +		strbuf_addstr(&filename, the_repository->objects->odb->path);
> +		strbuf_addch(&filename, '/');

And once we do that this could just become:

	strbuf_addf($filename, "%s/", ...)

Is there's existing uses of this pattern, so mayb e not worth it, but it
allows you to remove the braces on the if/else.

diff --git a/object-file.c b/object-file.c
index 8bd89e7b7ba..2b52f3fc1cc 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1880,7 +1880,7 @@ int write_loose_object(const struct object_id *oid, char *hdr,
 		       int hdrlen, struct input_stream *in_stream,
 		       time_t mtime, unsigned flags)
 {
-	int fd, ret;
+	int fd, ret, err = 0;
 	unsigned char compressed[4096];
 	git_zstream stream;
 	git_hash_ctx c;
@@ -1892,7 +1892,6 @@ int write_loose_object(const struct object_id *oid, char *hdr,
 
 	if (is_null_oid(oid)) {
 		/* When oid is not determined, save tmp file to odb path. */
-		strbuf_reset(&filename);
 		strbuf_addstr(&filename, the_repository->objects->odb->path);
 		strbuf_addch(&filename, '/');
 	} else {
@@ -1902,11 +1901,12 @@ int write_loose_object(const struct object_id *oid, char *hdr,
 	fd = create_tmpfile(&tmp_file, filename.buf);
 	if (fd < 0) {
 		if (flags & HASH_SILENT)
-			return -1;
+			err = -1;
 		else if (errno == EACCES)
-			return error(_("insufficient permission for adding an object to repository database %s"), get_object_directory());
+			err = error(_("insufficient permission for adding an object to repository database %s"), get_object_directory());
 		else
-			return error_errno(_("unable to create temporary file"));
+			err = error_errno(_("unable to create temporary file"));
+		goto cleanup;
 	}
 
 	/* Set it up */
@@ -1968,10 +1968,13 @@ int write_loose_object(const struct object_id *oid, char *hdr,
 			struct strbuf dir = STRBUF_INIT;
 			strbuf_add(&dir, filename.buf, dirlen - 1);
 			if (mkdir(dir.buf, 0777) && errno != EEXIST)
-				return -1;
-			if (adjust_shared_perm(dir.buf))
-				return -1;
-			strbuf_release(&dir);
+				err = -1;
+			else if (adjust_shared_perm(dir.buf))
+				err = -1;
+			else
+				strbuf_release(&dir);
+			if (err < 0)
+				goto cleanup;
 		}
 	}
 
@@ -1984,7 +1987,10 @@ int write_loose_object(const struct object_id *oid, char *hdr,
 			warning_errno(_("failed utime() on %s"), tmp_file.buf);
 	}
 
-	return finalize_object_file(tmp_file.buf, filename.buf);
+	err = finalize_object_file(tmp_file.buf, filename.buf);
+cleanup:
+	strbuf_release(&filename);
+	return err;
 }
 
 static int freshen_loose_object(const struct object_id *oid)