From 3dc8be4b1eea7f3a45ca6c5035e96fe3e4a0ebe2 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim=20D=C3=BCsterhus?= <duesterhus@woltlab.com>
Date: Sat, 31 Jan 2015 18:40:39 +0100
Subject: [PATCH] Improve locating the central zip directory

---
 .../install/files/lib/system/io/Zip.class.php | 30 ++++++++++++++-----
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/wcfsetup/install/files/lib/system/io/Zip.class.php b/wcfsetup/install/files/lib/system/io/Zip.class.php
index 9332d5dae0..d0fb3c4bea 100644
--- a/wcfsetup/install/files/lib/system/io/Zip.class.php
+++ b/wcfsetup/install/files/lib/system/io/Zip.class.php
@@ -132,14 +132,28 @@ class Zip extends File implements IArchive {
 	 * Moves the file-pointer to the beginning of the Central Directory.
 	 */
 	public function jumpToCentralDirectory() {
-		$this->seek(0);
-		while ($this->isFile()) {
-			$this->skipFile();
-			$offset = $this->tell();
-		}
+		$this->seek(0, SEEK_END);
+		$lastOffset = $this->tell();
+		$this->seek(-4, SEEK_CUR);
+		
+		do {
+			if ($this->read(4) === self::EOF_SIGNATURE) {
+				$eof = unpack('vdiskNo/vdiskWithCentralDirectory/vdiskEntries/vtotalEntries/VcentralDirectorySize/VcentralDirectoryOffset/vcommentLength', $this->read(18));
+				if ($eof['commentLength'] + $this->tell() === $lastOffset) {
+					$this->seek($eof['centralDirectoryOffset']);
+					break;
+				}
+				else {
+					// some part of the comment looked like the EOF_SIGNATURE
+					$this->seek(-18, SEEK_CUR);
+				}
+			}
+			
+			$this->seek(-5, SEEK_CUR);
+		} while(true);
 		
 		if ($this->read(4) !== self::CENTRAL_DIRECTORY_SIGNATURE) throw new SystemException('Unable to locate central directory');
-		$this->seek($offset);
+		$this->seek(-4, SEEK_CUR);
 	}
 	
 	/**
@@ -191,10 +205,10 @@ class Zip extends File implements IArchive {
 		
 		if ($this->read(4) !== self::EOF_SIGNATURE) throw new SystemException('Could not find the end of Central Directory');
 		
-		$eof = unpack('vdiskNo/vdiskWithCentralDirectory/vdiskEntries/vtotalEntries/vcentralDirectorySize', $this->read(12));
+		$eof = unpack('vdiskNo/vdiskWithCentralDirectory/vdiskEntries/vtotalEntries/VcentralDirectorySize', $this->read(12));
 		// check size of Central Directory
 		if ($size !== $eof['centralDirectorySize']) throw new SystemException('Central Directory size does not match');
-		$eof += unpack('vcentralDirectoryOffset/vcommentLength', $this->read(6));
+		$eof += unpack('VcentralDirectoryOffset/vcommentLength', $this->read(6));
 		
 		// read comment
 		if ($eof['commentLength'] > 0) $eof['comment'] = $this->read($eof['commentLength']);
-- 
2.20.1