Repository format version check.

This adds the repository format version code, first done by
Martin Atukunda.

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

cache.h

@@ -182,6 +182,10 @@ extern int trust_executable_bit;
 extern int only_use_symrefs;
 extern int diff_rename_limit_default;
 
+#define GIT_REPO_VERSION 0
+extern int repository_format_version;
+extern int check_repository_format(void);
+
 #define MTIME_CHANGED	0x0001
 #define CTIME_CHANGED	0x0002
 #define OWNER_CHANGED	0x0004
@@ -388,6 +392,7 @@ extern int git_config_int(const char *, const char *);
 extern int git_config_bool(const char *, const char *);
 extern int git_config_set(const char *, const char *);
 extern int git_config_set_multivar(const char *, const char *, const char *, int);
+extern int check_repository_format_version(const char *var, const char *value);
 
 #define MAX_GITNAME (1000)
 extern char git_default_email[MAX_GITNAME];

environment.c

@@ -13,6 +13,7 @@ char git_default_email[MAX_GITNAME];
 char git_default_name[MAX_GITNAME];
 int trust_executable_bit = 1;
 int only_use_symrefs = 0;
+int repository_format_version = 0;
 
 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
 	*git_graft_file;

setup.c

@@ -154,6 +154,22 @@ static const char *setup_git_directory_1(void)
 	return cwd + offset;
 }
 
+int check_repository_format_version(const char *var, const char *value)
+{
+       if (strcmp(var, "core.repositoryformatversion") == 0)
+               repository_format_version = git_config_int(var, value);
+       return 0;
+}
+
+int check_repository_format(void)
+{
+	git_config(check_repository_format_version);
+	if (GIT_REPO_VERSION < repository_format_version)
+		die ("Expected git repo version <= %d, found %d",
+		     GIT_REPO_VERSION, repository_format_version);
+	return 0;
+}
+
 const char *setup_git_directory(void)
 {
 	const char *retval = setup_git_directory_1();