Fix normalization of relative paths going up a few dirs, fixes #1759

src/Composer/Util/Filesystem.php

@@ -318,10 +318,12 @@ class Filesystem
             $path = substr($path, strlen($prefix));
         }
 
+        $appended = false;
         foreach (explode('/', $path) as $chunk) {
-            if ('..' === $chunk) {
+            if ('..' === $chunk && $appended) {
                 array_pop($parts);
             } elseif ('.' !== $chunk && '' !== $chunk) {
+                $appended = true;
                 $parts[] = $chunk;
             }
         }

tests/Composer/Test/Util/FilesystemTest.php

@@ -139,4 +139,27 @@ class FilesystemTest extends TestCase
         $fs = new Filesystem;
         $this->assertGreaterThanOrEqual(10, $fs->size("$tmp/composer_testdir"));
     }
+
+    /**
+     * @dataProvider provideNormalizedPaths
+     */
+    public function testNormalizePath($expected, $actual)
+    {
+        $fs = new Filesystem;
+        $this->assertEquals($expected, $fs->normalizePath($actual));
+    }
+
+    public function provideNormalizedPaths()
+    {
+        return array(
+            array('../foo', '../foo'),
+            array('c:/foo/bar', 'c:/foo//bar'),
+            array('C:/foo/bar', 'C:/foo/./bar'),
+            array('C:/bar', 'C:/foo/../bar'),
+            array('/bar', '/foo/../bar/'),
+            array('phar://c:/Foo', 'phar://c:/Foo/Bar/..'),
+            array('phar://c:/', 'phar://c:/Foo/Bar/../../../..'),
+            array('/', '/Foo/Bar/../../../..'),
+        );
+    }
 }