Add const to parse_{commit,tag}_buffer()

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -245,10 +245,10 @@ int unregister_shallow(const unsigned char *sha1)
 	return 0;
 }
 
-int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
+int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 {
-	char *tail = buffer;
-	char *bufptr = buffer;
+	const char *tail = buffer;
+	const char *bufptr = buffer;
 	unsigned char parent[20];
 	struct commit_list **pptr;
 	struct commit_graft *graft;

commit.h

@@ -38,7 +38,7 @@ struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
 					      int quiet);
 struct commit *lookup_commit_reference_by_name(const char *name);
 
-int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size);
+int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size);
 int parse_commit(struct commit *item);
 
 /* Find beginning and length of commit subject. */

tag.c

@@ -56,7 +56,7 @@ static unsigned long parse_tag_date(const char *buf, const char *tail)
 	return strtoul(dateptr, NULL, 10);
 }
 
-int parse_tag_buffer(struct tag *item, void *data, unsigned long size)
+int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
 {
 	unsigned char sha1[20];
 	char type[20];

tag.h

@@ -13,7 +13,7 @@ struct tag {
 };
 
 extern struct tag *lookup_tag(const unsigned char *sha1);
-extern int parse_tag_buffer(struct tag *item, void *data, unsigned long size);
+extern int parse_tag_buffer(struct tag *item, const void *data, unsigned long size);
 extern int parse_tag(struct tag *item);
 extern struct object *deref_tag(struct object *, const char *, int);
 extern size_t parse_signature(const char *buf, unsigned long size);