sha1_file: allow link_alt_odb_entries to handle arbitrary repositories

Actually this also allows read_info_alternates and link_alt_odb_entry to
handle arbitrary repositories, but link_alt_odb_entries is the most
interesting function in this set of functions, hence the commit subject.

These functions span a strongly connected component in the function
graph, i.e. the recursive call chain might look like

  -> link_alt_odb_entries
    -> link_alt_odb_entry
      -> read_info_alternates
        -> link_alt_odb_entries

That is why we need to convert all these functions at the same time.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object-store.h

@@ -18,6 +18,10 @@ struct alternate_object_database {
 	char loose_objects_subdir_seen[256];
 	struct oid_array loose_objects_cache;
 
+	/*
+	 * Path to the alternative object store. If this is a relative path,
+	 * it is relative to the current working directory.
+	 */
 	char path[FLEX_ARRAY];
 };
 #define prepare_alt_odb(r) prepare_alt_odb_##r()

sha1_file.c

@@ -390,11 +390,10 @@ static int alt_odb_usable(struct raw_object_store *o,
  * SHA1, an extra slash for the first level indirection, and the
  * terminating NUL.
  */
-#define read_info_alternates(r, rb, d) read_info_alternates_##r(rb, d)
+static void read_info_alternates(struct repository *r,
-static void read_info_alternates_the_repository(const char *relative_base,
+				 const char *relative_base,
-						int depth);
+				 int depth);
-#define link_alt_odb_entry(r, e, rb, d, n) link_alt_odb_entry_##r(e, rb, d, n)
+static int link_alt_odb_entry(struct repository *r, const char *entry,
-static int link_alt_odb_entry_the_repository(const char *entry,
 	const char *relative_base, int depth, const char *normalized_objdir)
 {
 	struct alternate_object_database *ent;
@@ -420,7 +419,7 @@ static int link_alt_odb_entry_the_repository(const char *entry,
 	while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 		strbuf_setlen(&pathbuf, pathbuf.len - 1);
 
-	if (!alt_odb_usable(the_repository->objects, &pathbuf, normalized_objdir)) {
+	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir)) {
 		strbuf_release(&pathbuf);
 		return -1;
 	}
@@ -428,12 +427,12 @@ static int link_alt_odb_entry_the_repository(const char *entry,
 	ent = alloc_alt_odb(pathbuf.buf);
 
 	/* add the alternate entry */
-	*the_repository->objects->alt_odb_tail = ent;
+	*r->objects->alt_odb_tail = ent;
-	the_repository->objects->alt_odb_tail = &(ent->next);
+	r->objects->alt_odb_tail = &(ent->next);
 	ent->next = NULL;
 
 	/* recursively add alternates */
-	read_info_alternates(the_repository, pathbuf.buf, depth + 1);
+	read_info_alternates(r, pathbuf.buf, depth + 1);
 
 	strbuf_release(&pathbuf);
 	return 0;
@@ -468,12 +467,8 @@ static const char *parse_alt_odb_entry(const char *string,
 	return end;
 }
 
-#define link_alt_odb_entries(r, a, s, rb, d) \
+static void link_alt_odb_entries(struct repository *r, const char *alt,
-	link_alt_odb_entries_##r(a, s, rb, d)
+				 int sep, const char *relative_base, int depth)
-static void link_alt_odb_entries_the_repository(const char *alt,
-						int sep,
-						const char *relative_base,
-						int depth)
 {
 	struct strbuf objdirbuf = STRBUF_INIT;
 	struct strbuf entry = STRBUF_INIT;
@@ -487,7 +482,7 @@ static void link_alt_odb_entries_the_repository(const char *alt,
 		return;
 	}
 
-	strbuf_add_absolute_path(&objdirbuf, get_object_directory());
+	strbuf_add_absolute_path(&objdirbuf, r->objects->objectdir);
 	if (strbuf_normalize_path(&objdirbuf) < 0)
 		die("unable to normalize object directory: %s",
 		    objdirbuf.buf);
@@ -496,15 +491,16 @@ static void link_alt_odb_entries_the_repository(const char *alt,
 		alt = parse_alt_odb_entry(alt, sep, &entry);
 		if (!entry.len)
 			continue;
-		link_alt_odb_entry(the_repository, entry.buf,
+		link_alt_odb_entry(r, entry.buf,
 				   relative_base, depth, objdirbuf.buf);
 	}
 	strbuf_release(&entry);
 	strbuf_release(&objdirbuf);
 }
 
-static void read_info_alternates_the_repository(const char *relative_base,
+static void read_info_alternates(struct repository *r,
-						int depth)
+				 const char *relative_base,
+				 int depth)
 {
 	char *path;
 	struct strbuf buf = STRBUF_INIT;
@@ -516,7 +512,7 @@ static void read_info_alternates_the_repository(const char *relative_base,
 		return;
 	}
 
-	link_alt_odb_entries(the_repository, buf.buf, '\n', relative_base, depth);
+	link_alt_odb_entries(r, buf.buf, '\n', relative_base, depth);
 	strbuf_release(&buf);
 	free(path);
 }