From 6cf008cdb981a284e1ecf74a19a077258896c4d2 Mon Sep 17 00:00:00 2001
From: "Kyle J. McKay" <mackyle@gmail.com>
Date: Thu, 23 Apr 2015 10:51:17 -0700
Subject: [PATCH] shlib.sh: add is_git_dir utility function

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
---
 shlib.sh | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/shlib.sh b/shlib.sh
index 9f22fa4..560e1e8 100644
--- a/shlib.sh
+++ b/shlib.sh
@@ -300,6 +300,27 @@ check_interval() {
 	[ $ns -lt $(($os+$2)) ]
 }
 
+# Check to see if the single argument is a Git directory
+is_git_dir() {
+	# Just like Git's test except we ignore GIT_OBJECT_DIRECTORY
+	# And we are slightly more picky (must be refs/.+ not refs/.*)
+	[ -d "$1/objects" -a -x "$1/objects" ] || return 1
+	[ -d "$1/refs" -a -x "$1/refs" ] || return 1
+	if [ -L "$1/HEAD" ]; then
+		_hr="$(readlink "$1/HEAD")"
+		case "$_hr" in "refs/"?*) :;; *) return 1;; esac
+	fi
+	[ -f "$1/HEAD" -a -r "$1/HEAD" ] || return 1
+	read -r _hr <"$1/HEAD" || return 1
+	case "$_hr" in
+		$octet20)
+			return 0;;
+		ref:*)
+			_hr="${_hr##ref:*[[:space:]]}"
+			case "$_hr" in "refs/"?*) return 0;; esac
+	esac
+	return 1
+}
 
 # List all Git repositories, with given prefix if specified, one-per-line
 # All project names starting with _ are always excluded from the result
-- 
2.11.4.GIT