Introduce GIT_DIR environment variable.

During the mailing list discussion on renaming GIT_ environment
variables, people felt that having one environment that lets the
user (or Porcelain) specify both SHA1_FILE_DIRECTORY (now
GIT_OBJECT_DIRECTORY) and GIT_INDEX_FILE for the default layout
would be handy.  This change introduces GIT_DIR environment
variable, from which the defaults for GIT_INDEX_FILE and
GIT_OBJECT_DIRECTORY are derived.  When GIT_DIR is not defined,
it defaults to ".git".  GIT_INDEX_FILE defaults to
"$GIT_DIR/index" and GIT_OBJECT_DIRECTORY defaults to
"$GIT_DIR/objects".

Special thanks for ideas and discussions go to Petr Baudis and
Daniel Barkalow.  Bugs are mine ;-)

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

1 files changed, 6 insertions, 7 deletions

diff --git a/cache.h b/cache.h
index 1c15b2be08..0901fae8a4 100644
--- a/cache.h
+++ b/cache.h
@@ -106,16 +106,15 @@ static inline unsigned int create_ce_mode(unsigned int mode)
 struct cache_entry **active_cache;
 unsigned int active_nr, active_alloc, active_cache_changed;
 
+#define GIT_DIR_ENVIRONMENT "GIT_DIR"
+#define DEFAULT_GIT_DIR_ENVIRONMENT ".git"
 #define DB_ENVIRONMENT "GIT_OBJECT_DIRECTORY"
-#define DEFAULT_DB_ENVIRONMENT ".git/objects"
-#define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
-
-#define get_object_directory() (gitenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT)
-
 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
-#define DEFAULT_INDEX_ENVIRONMENT ".git/index"
 
-#define get_index_file() (gitenv(INDEX_ENVIRONMENT) ? : DEFAULT_INDEX_ENVIRONMENT)
+extern char *get_object_directory(void);
+extern char *get_index_file(void);
+
+#define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
 #define alloc_nr(x) (((x)+16)*3/2)