From cc81f5bac395dbf49ecf6dfd780e01fed9e4b2c3 Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 12 Jul 2021 13:36:57 +0200
Subject: [PATCH] Fix support for UNC paths in normalizePath, refs #9993

---
 src/Composer/Util/Filesystem.php            | 14 ++++++++++----
 tests/Composer/Test/Util/FilesystemTest.php |  1 +
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/Composer/Util/Filesystem.php b/src/Composer/Util/Filesystem.php
index 2f51920966d4..69f097958c3f 100644
--- a/src/Composer/Util/Filesystem.php
+++ b/src/Composer/Util/Filesystem.php
@@ -544,7 +544,13 @@ public function normalizePath($path)
         $parts = array();
         $path = strtr($path, '\\', '/');
         $prefix = '';
-        $absolute = false;
+        $absolute = '';
+
+        // extract windows UNC paths e.g. \\foo\bar
+        if (strpos($path, '//') === 0 && \strlen($path) > 2) {
+            $absolute = '//';
+            $path = substr($path, 2);
+        }
 
         // extract a prefix being a protocol://, protocol:, protocol://drive: or simply drive:
         if (preg_match('{^( [0-9a-z]{2,}+: (?: // (?: [a-z]: )? )? | [a-z]: )}ix', $path, $match)) {
@@ -553,13 +559,13 @@ public function normalizePath($path)
         }
 
         if (strpos($path, '/') === 0) {
-            $absolute = true;
+            $absolute = '/';
             $path = substr($path, 1);
         }
 
         $up = false;
         foreach (explode('/', $path) as $chunk) {
-            if ('..' === $chunk && ($absolute || $up)) {
+            if ('..' === $chunk && ($absolute !== '' || $up)) {
                 array_pop($parts);
                 $up = !(empty($parts) || '..' === end($parts));
             } elseif ('.' !== $chunk && '' !== $chunk) {
@@ -568,7 +574,7 @@ public function normalizePath($path)
             }
         }
 
-        return $prefix.($absolute ? '/' : '').implode('/', $parts);
+        return $prefix.((string) $absolute).implode('/', $parts);
     }
 
     /**
diff --git a/tests/Composer/Test/Util/FilesystemTest.php b/tests/Composer/Test/Util/FilesystemTest.php
index 0fb4babd828e..7ac013a78d9d 100644
--- a/tests/Composer/Test/Util/FilesystemTest.php
+++ b/tests/Composer/Test/Util/FilesystemTest.php
@@ -220,6 +220,7 @@ public function provideNormalizedPaths()
             array('../src', 'Foo/Bar/../../../src'),
             array('c:../b', 'c:.\\..\\a\\..\\b'),
             array('phar://c:../Foo', 'phar://c:../Foo'),
+            array('//foo/bar', '\\\\foo\\bar'),
         );
     }