[PATCH 3/3] read-cache: add index.version config variable

[Thomas Gummerer <t.gummerer@gmail.com>]

Add a config variable that allows setting the default index version when
initializing a new index file.  Similar to the GIT_INDEX_VERSION
environment variable this only affects new index files.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 Documentation/config.txt |  4 ++++
 read-cache.c             | 27 ++++++++++++++++++++++-----
 t/t1600-index.sh         | 27 +++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 1655455..033939a 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1591,6 +1591,10 @@ imap::
 	The configuration variables in the 'imap' section are described
 	in linkgit:git-imap-send[1].
 
+index.version::
+	Specify the version with which new index files should be
+	initialized.  This does not affect existing repositories.
+
 init.templatedir::
 	Specify the directory from which templates will be copied.
 	(See the "TEMPLATE DIRECTORY" section of linkgit:git-init[1].)
diff --git a/read-cache.c b/read-cache.c
index 3993e12..ca9b68c 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1223,20 +1223,37 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
 
 #define INDEX_FORMAT_DEFAULT 3
 
+static int index_format_config(const char *var, const char *value, void *cb)
+{
+	unsigned int *version = cb;
+	if (!strcmp(var, "index.version")) {
+		*version = git_config_int(var, value);
+		return 0;
+	}
+	return 1;
+}
+
+
 static unsigned int get_index_format_default()
 {
 	char *envversion = getenv("GIT_INDEX_VERSION");
+	unsigned int version = INDEX_FORMAT_DEFAULT;
 	if (!envversion) {
-		return INDEX_FORMAT_DEFAULT;
-	} else {
-		unsigned int version = strtol(envversion, NULL, 10);
+		git_config(index_format_config, &version);
 		if (version < INDEX_FORMAT_LB || version > INDEX_FORMAT_UB) {
-			warning(_("GIT_INDEX_VERSION set, but the value is invalid.\n"
+			warning(_("index.version set, but the value is invalid.\n"
 				  "Using version %i"), INDEX_FORMAT_DEFAULT);
-			version = INDEX_FORMAT_DEFAULT;
+			return INDEX_FORMAT_DEFAULT;
 		}
 		return version;
 	}
+	version = strtol(envversion, NULL, 10);
+	if (version < INDEX_FORMAT_LB || version > INDEX_FORMAT_UB) {
+		warning(_("GIT_INDEX_VERSION set, but the value is invalid.\n"
+			  "Using version %i"), INDEX_FORMAT_DEFAULT);
+		version = INDEX_FORMAT_DEFAULT;
+	}
+	return version;
 }
 
 /*
diff --git a/t/t1600-index.sh b/t/t1600-index.sh
index 37fd84d..bf34985 100755
--- a/t/t1600-index.sh
+++ b/t/t1600-index.sh
@@ -21,4 +21,31 @@ test_expect_success 'out of bounds GIT_INDEX_VERSION issues warning' '
 	)
 '
 
+test_expect_success 'out of bounds index.version issuses warning' '
+	(
+		unset GIT_INDEX_VERSION &&
+		rm .git/index &&
+		git config --add index.version 1 &&
+		git add a 2>&1 | sed "s/[0-9]//" >actual.err &&
+		sed -e "s/ Z$/ /" <<-\EOF >expect.err &&
+			warning: index.version set, but the value is invalid.
+			Using version Z
+		EOF
+		test_i18ncmp expect.err actual.err
+	)
+'
+
+test_expect_success 'GIT_INDEX_VERSION takes precedence over config' '
+	(
+		rm .git/index &&
+		GIT_INDEX_VERSION=4 &&
+		export GIT_INDEX_VERSION &&
+		git config --add index.version 2 &&
+		git add a 2>&1 &&
+		echo 4 >expect &&
+		test-index-version <.git/index >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
1.8.5.2.300.ge613be6.dirty