From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Sixt <j.sixt@viscovery.net>
Subject: Re: [PATCH] Handle double slashes in make_relative_path()
Date: Fri, 22 Jan 2010 09:36:13 +0100
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Cc: Thomas Rast <trast@student.ethz.ch>, git@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>
To: Junio C Hamano <gitster@pobox.com>
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Junio C Hamano schrieb:
> Credit for test script, motivation and initial patch goes to Thomas Rast,
> but the bugs in the implementation of this patch are mine..

And with this squashed in it has fewer of them ;-) and is more portable.
The bug was that /foo was incorrectly stripped from /foobar.

-- Hannes

diff --git a/path.c b/path.c
index 78ab54a..3cb19c7 100644
--- a/path.c
+++ b/path.c
@@ -396,15 +396,15 @@ const char *make_relative_path(const char *abs, const char *base)
 	static char buf[PATH_MAX + 1];
 	int i = 0, j = 0;

-	if (!base)
+	if (!base || !base[0])
 		return abs;
 	while (base[i]) {
-		if (base[i] == '/') {
-			if (abs[j] != '/')
+		if (is_dir_sep(base[i])) {
+			if (!is_dir_sep(abs[j]))
 				return abs;
-			while (base[i] == '/')
+			while (is_dir_sep(base[i]))
 				i++;
-			while (abs[j] == '/')
+			while (is_dir_sep(abs[j]))
 				j++;
 			continue;
 		} else if (abs[j] != base[i]) {
@@ -413,7 +413,14 @@ const char *make_relative_path(const char *abs, const char *base)
 		i++;
 		j++;
 	}
-	while (abs[j] == '/')
+	if (
+	    /* "/foo" is a prefix of "/foo" */
+	    abs[j] &&
+	    /* "/foo" is not a prefix of "/foobar" */
+	    !is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
+	   )
+		return abs;
+	while (is_dir_sep(abs[j]))
 		j++;
 	if (!abs[j])
 		strcpy(buf, ".");