Git pack parsing

public_html/libgit/base.php

@@ -23,11 +23,20 @@ function sha1_from_bin($bin)
 	return bin2hex($bin);
 }
 
+function number_from_bin($bin)
+{
+	$c = unpack("N", $bin);
+        return $c[1];
+}
+
 class GitBranchNotFoundException extends Exception {}
 class GitTagNotFoundException extends Exception {}
 class GitInvalidOriginException extends Exception {}
 class GitInvalidElementException extends Exception {}
+class GitInvalidFormatException extends Exception {}
+class GitUnsupportedVersionException extends Exception {}
 class GitPathNotFoundException extends Exception {}
+class GitCorruptIndexException extends Exception {}
 
 require(dirname(__FILE__) . "/class.repository.php");
 require(dirname(__FILE__) . "/class.branch.php");
@@ -38,4 +47,6 @@ require(dirname(__FILE__) . "/class.tree.php");
 require(dirname(__FILE__) . "/class.tree.element.php");
 require(dirname(__FILE__) . "/class.commit.php");
 require(dirname(__FILE__) . "/class.actor.php");
+require(dirname(__FILE__) . "/class.pack.php");
+require(dirname(__FILE__) . "/class.pack.index.php");
 ?>

public_html/libgit/class.pack.index.php

@@ -0,0 +1,74 @@
+<?php
+define("PACK_IDX_SIGNATURE", "\377tOc");
+
+class GitPackIndex
+{
+	public $rawdata = "";
+	public $version = 0;
+	public $index = array();
+	
+	function __construct($data)
+	{
+		$this->rawdata = $data;
+		
+		if(substr($data, 0, 4) == PACK_IDX_SIGNATURE)
+		{
+			$version = number_from_bin(substr($data, 4, 4));
+			
+			if($version == 2)
+			{
+				$this->version = $version;
+				$offset = 8;
+				
+				$indexes = unpack("N*", substr($data, $offset, 256*4));
+				$highest = 0;
+				
+				for($i = 0; $i < 256; $i++)
+				{
+					if(!isset($indexes[$i + 1]))
+					{
+						continue;
+					}
+					
+					$n = $indexes[$i + 1];
+					
+					if($n < $highest)
+					{
+						throw new GitCorruptIndexException("The pack index file is corrupt.");
+					}
+					
+					$highest = $n;
+				}
+				
+				$offset = $offset + (256 * 4);
+				
+				$keys = array();
+				$values = array();
+				
+				for($i = 0; $i < $highest; $i++)
+				{
+					$keys[] = sha1_from_bin(substr($data, $offset, 20));
+					$offset += 20;
+				}
+				
+				$offset += ($highest * 4);
+				
+				for($i = 0; $i < $highest; $i++)
+				{
+					$values[] = number_from_bin(substr($data, $offset, 4));
+					$offset += 4;
+				}
+				
+				$this->index = array_combine($keys, $values);
+			}
+			else
+			{
+				throw new GitUnsupportedVersionException("Version {$version} pack indexes are not supported by this version of the library.");
+			}
+		}
+		else
+		{
+			throw new GitInvalidFormatException("The provided data does not look like a pack index file.");
+		}
+	}
+}

public_html/libgit/class.pack.php

@@ -0,0 +1,16 @@
+<?php
+class GitPack
+{
+	public $repo = null;
+	public $index = array();
+	
+	function __construct($repo, $name)
+	{
+		$this->repo = $repo;
+		
+		$index_filename = "{$repo->path}/objects/pack/{$name}.idx";
+		$pack_filename = "{$repo->path}/objects/pack/{$name}.pack";
+		
+		$this->index = new GitPackIndex(file_get_contents($index_filename));
+	}
+}

public_html/test.php

@@ -2,4 +2,5 @@
 require("libgit/base.php");
 
 $repo = new GitRepository("/home/occupy/testrepo.git");
-pretty_dump($repo->GetObjectForPath($repo->GetBranch("master")->GetTree(), "public_html/css/images/derp"));
+pretty_dump(new GitPack($repo, "pack-8503a2b8cf6e60831dd012afd4d486eb1eddfef8"));
+//pretty_dump($repo->GetObjectForPath($repo->GetBranch("master")->GetTree(), "public_html/css/images/derp"));