Alternate object pool mechanism updates.

It was a mistake to use GIT_ALTERNATE_OBJECT_DIRECTORIES
environment variable to specify what alternate object pools to
look for missing objects when working with an object database.
It is not a property of the process running the git commands,
but a property of the object database that is partial and needs
other object pools to complete the set of objects it lacks.

This patch allows you to have $GIT_OBJECT_DIRECTORY/info/alternates
whose contents is in exactly the same format as the environment
variable, to let an object database name alternate object pools
it depends on.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/cache.h b/cache.h
index efd2a2c59..dbde95a0b 100644
--- a/cache.h
+++ b/cache.h
@@ -278,9 +278,10 @@ struct checkout {
 extern int checkout_entry(struct cache_entry *ce, struct checkout *state);
 
 extern struct alternate_object_database {
-	char *base;
+	struct alternate_object_database *next;
 	char *name;
-} *alt_odb;
+	char base[0]; /* more */
+} *alt_odb_list;
 extern void prepare_alt_odb(void);
 
 extern struct packed_git {