Implement normalize_absolute_path

normalize_absolute_path removes several oddities form absolute paths,
giving nice clean paths like "/dir/sub1/sub2".  Also add a test case
for this utility, based on a new test program (in the style of test-sha1).

Signed-off-by: David Reiss <dreiss@facebook.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0060-path-utils.sh

@@ -0,0 +1,40 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 David Reiss
+#
+
+test_description='Test various path utilities'
+
+. ./test-lib.sh
+
+norm_abs() {
+	test_expect_success "normalize absolute" \
+	"test \$(test-path-utils normalize_absolute_path '$1') = '$2'"
+}
+
+norm_abs "" /
+norm_abs / /
+norm_abs // /
+norm_abs /// /
+norm_abs /. /
+norm_abs /./ /
+norm_abs /./.. /
+norm_abs /../. /
+norm_abs /./../.// /
+norm_abs /dir/.. /
+norm_abs /dir/sub/../.. /
+norm_abs /dir /dir
+norm_abs /dir// /dir
+norm_abs /./dir /dir
+norm_abs /dir/. /dir
+norm_abs /dir///./ /dir
+norm_abs /dir//sub/.. /dir
+norm_abs /dir/sub/../ /dir
+norm_abs //dir/sub/../. /dir
+norm_abs /dir/s1/../s2/ /dir/s2
+norm_abs /d1/s1///s2/..//../s3/ /d1/s3
+norm_abs /d1/s1//../s2/../../d2 /d2
+norm_abs /d1/.../d2 /d1/.../d2
+norm_abs /d1/..././../d2 /d1/d2
+
+test_done