config: expand tildes in include.path variable

You can already use relative paths in include.path, which
means that including "foo" from your global "~/.gitconfig"
will look in your home directory. However, you might want to
do something clever like putting "~/.gitconfig-foo" in a
specific repository's config file.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -95,7 +95,9 @@ included file is expanded immediately, as if its contents had been
 found at the location of the include directive. If the value of the
 `include.path` variable is a relative path, the path is considered to be
 relative to the configuration file in which the include directive was
-found. See below for examples.
+found. The value of `include.path` is subject to tilde expansion: `{tilde}/`
+is expanded to the value of `$HOME`, and `{tilde}user/` to the specified
+user's home directory. See below for examples.
 
 Example
 ~~~~~~~
@@ -122,6 +124,7 @@ Example
 	[include]
 		path = /path/to/foo.inc ; include by absolute path
 		path = foo ; expand "foo" relative to the current file
+		path = ~/foo ; expand "foo" in your $HOME directory
 
 Variables
 ~~~~~~~~~

config.c

@@ -37,6 +37,11 @@ static int handle_path_include(const char *path, struct config_include_data *inc
 {
 	int ret = 0;
 	struct strbuf buf = STRBUF_INIT;
+	char *expanded = expand_user_path(path);
+
+	if (!expanded)
+		return error("Could not expand include path '%s'", path);
+	path = expanded;
 
 	/*
 	 * Use an absolute path as-is, but interpret relative paths
@@ -63,6 +68,7 @@ static int handle_path_include(const char *path, struct config_include_data *inc
 		inc->depth--;
 	}
 	strbuf_release(&buf);
+	free(expanded);
 	return ret;
 }
 

t/t1305-config-include.sh

@@ -29,6 +29,14 @@ test_expect_success 'chained relative paths' '
 	test_cmp expect actual
 '
 
+test_expect_success 'include paths get tilde-expansion' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = ~/one" >.gitconfig &&
+	echo 1 >expect &&
+	git config test.one >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'include options can still be examined' '
 	echo "[test]one = 1" >one &&
 	echo "[include]path = one" >.gitconfig &&