protocol: introduce protocol extension mechanisms

diff --git a/cache.h b/cache.h
index a916bc79e3c1a77f55764f34f6357478e83b6cb0..c74b7367191ed05717bd22697ad9ac4ca747f714 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -4,6 +4,7 @@
 #include "git-compat-util.h"
 #include "strbuf.h"
 #include "hashmap.h"
+#include "mru.h"
 #include "advice.h"
 #include "gettext.h"
 #include "convert.h"
@@ -444,6 +445,14 @@ static inline enum object_type object_type(unsigned int mode)
 #define GIT_ICASE_PATHSPECS_ENVIRONMENT "GIT_ICASE_PATHSPECS"
 #define GIT_QUARANTINE_ENVIRONMENT "GIT_QUARANTINE_PATH"
 
+/*
+ * Environment variable used in handshaking the wire protocol.
+ * Contains a colon ':' separated list of keys with optional values
+ * 'key[=value]'.  Presence of unknown keys and values must be
+ * ignored.
+ */
+#define GIT_PROTOCOL_ENVIRONMENT "GIT_PROTOCOL"
+
 /*
  * This environment variable is expected to contain a boolean indicating
  * whether we should or should not treat:
@@ -1589,8 +1598,7 @@ extern struct packed_git {
  * A most-recently-used ordered version of the packed_git list, which can
  * be iterated instead of packed_git (and marked via mru_mark).
  */
-struct mru;
-extern struct mru *packed_git_mru;
+extern struct mru packed_git_mru;
 
 struct pack_entry {
        off_t offset;