From 12b9096b23587720f015fa61b8a65de2cf1ba656 Mon Sep 17 00:00:00 2001
From: Steve Clay <steve@mrclay.org>
Date: Wed, 18 Jan 2017 18:48:15 -0500
Subject: [PATCH] URI rewriter passes through empty URLs

Fixes #561
---
 lib/Minify/CSS/UriRewriter.php                     | 5 +++++
 tests/_test_files/css_uriRewriter/exp.css          | 2 ++
 tests/_test_files/css_uriRewriter/exp_prepend.css  | 2 ++
 tests/_test_files/css_uriRewriter/exp_prepend2.css | 2 ++
 tests/_test_files/css_uriRewriter/in.css           | 2 ++
 5 files changed, 13 insertions(+)

diff --git a/lib/Minify/CSS/UriRewriter.php b/lib/Minify/CSS/UriRewriter.php
index 248875c..acd1a2c 100644
--- a/lib/Minify/CSS/UriRewriter.php
+++ b/lib/Minify/CSS/UriRewriter.php
@@ -294,6 +294,11 @@ class Minify_CSS_UriRewriter
 
             $uri = ($quoteChar === '') ? $m[1] : substr($m[1], 1, strlen($m[1]) - 2);
         }
+
+        if ($uri === '') {
+            return $m[0];
+        }
+
         // if not root/scheme relative and not starts with scheme
         if (!preg_match('~^(/|[a-z]+\:)~', $uri)) {
             // URI is file-relative: rewrite depending on options
diff --git a/tests/_test_files/css_uriRewriter/exp.css b/tests/_test_files/css_uriRewriter/exp.css
index 3296c26..5ce7667 100644
--- a/tests/_test_files/css_uriRewriter/exp.css
+++ b/tests/_test_files/css_uriRewriter/exp.css
@@ -8,6 +8,7 @@
 @import url("/css/foo.css"); /* abs, should not alter */
 @import url(/css2/foo.css); /* abs, should not alter */
 @import url(foo:bar); /* scheme, should not alter */
+@import url(); /* empty, should not alter */
 foo {clip-path:url(#c1)} /* inline clip path, should not alter */
 foo {clip-path:url(/_test_files/css_uriRewriter/foo.svg#c1)}
 foo {mask: url(#c1)} /* should not alter */
@@ -17,5 +18,6 @@ foo {background:url('http://foo.com/css/foo.css');} /* scheme, should not alter
 foo {background:url("//foo.com/css/foo.css");} /* protocol relative, should not alter */
 foo {background:url(foo:bar);} /* scheme, should not alter */
 foo {background:url("/_test_files/css_uriRewriter/foo bar.jpg");}
+foo {background:url("");} /* empty, should not alter */
 @import url('/_test_files/css_uriRewriter/foo bar.css');
 @import "/_test_files/css_uriRewriter/foo bar.css";
diff --git a/tests/_test_files/css_uriRewriter/exp_prepend.css b/tests/_test_files/css_uriRewriter/exp_prepend.css
index bc09c44..a56103d 100644
--- a/tests/_test_files/css_uriRewriter/exp_prepend.css
+++ b/tests/_test_files/css_uriRewriter/exp_prepend.css
@@ -8,6 +8,7 @@
 @import url("/css/foo.css"); /* abs, should not alter */
 @import url(/css2/foo.css); /* abs, should not alter */
 @import url(foo:bar); /* scheme, should not alter */
+@import url(); /* empty, should not alter */
 foo {clip-path:url(#c1)} /* inline clip path, should not alter */
 foo {clip-path:url(http://cnd.com/A/B/foo.svg#c1)}
 foo {mask: url(#c1)} /* should not alter */
@@ -17,5 +18,6 @@ foo {background:url('http://foo.com/css/foo.css');} /* scheme, should not alter
 foo {background:url("//foo.com/css/foo.css");} /* protocol relative, should not alter */
 foo {background:url(foo:bar);} /* scheme, should not alter */
 foo {background:url("http://cnd.com/A/B/foo bar.jpg");}
+foo {background:url("");} /* empty, should not alter */
 @import url('http://cnd.com/A/B/foo bar.css');
 @import "http://cnd.com/A/B/foo bar.css";
diff --git a/tests/_test_files/css_uriRewriter/exp_prepend2.css b/tests/_test_files/css_uriRewriter/exp_prepend2.css
index c8f7c61..f9398a5 100644
--- a/tests/_test_files/css_uriRewriter/exp_prepend2.css
+++ b/tests/_test_files/css_uriRewriter/exp_prepend2.css
@@ -8,6 +8,7 @@
 @import url("/css/foo.css"); /* abs, should not alter */
 @import url(/css2/foo.css); /* abs, should not alter */
 @import url(foo:bar); /* scheme, should not alter */
+@import url(); /* empty, should not alter */
 foo {clip-path:url(#c1)} /* inline clip path, should not alter */
 foo {clip-path:url(//cnd.com/A/B/foo.svg#c1)}
 foo {mask: url(#c1)} /* should not alter */
@@ -17,5 +18,6 @@ foo {background:url('http://foo.com/css/foo.css');} /* scheme, should not alter
 foo {background:url("//foo.com/css/foo.css");} /* protocol relative, should not alter */
 foo {background:url(foo:bar);} /* scheme, should not alter */
 foo {background:url("//cnd.com/A/B/foo bar.jpg");}
+foo {background:url("");} /* empty, should not alter */
 @import url('//cnd.com/A/B/foo bar.css');
 @import "//cnd.com/A/B/foo bar.css";
diff --git a/tests/_test_files/css_uriRewriter/in.css b/tests/_test_files/css_uriRewriter/in.css
index 0200450..e5c4858 100644
--- a/tests/_test_files/css_uriRewriter/in.css
+++ b/tests/_test_files/css_uriRewriter/in.css
@@ -8,6 +8,7 @@
 @import url("/css/foo.css"); /* abs, should not alter */
 @import url(/css2/foo.css); /* abs, should not alter */
 @import url(foo:bar); /* scheme, should not alter */
+@import url(); /* empty, should not alter */
 foo {clip-path:url(#c1)} /* inline clip path, should not alter */
 foo {clip-path:url(foo.svg#c1)}
 foo {mask: url( #c1 )} /* should not alter */
@@ -17,5 +18,6 @@ foo {background:url('http://foo.com/css/foo.css');} /* scheme, should not alter
 foo {background:url("//foo.com/css/foo.css");} /* protocol relative, should not alter */
 foo {background:url(foo:bar);} /* scheme, should not alter */
 foo {background:url("foo bar.jpg");}
+foo {background:url("");} /* empty, should not alter */
 @import url('foo bar.css');
 @import "foo bar.css";