/**
* Extracts an object from the pack
*
* @param string $hash hash of object to extract
* @param int $type output parameter, returns the type of the object
* @return string|boolean object content, or false if not found
*/
public function GetObject($hash, &$type = 0)
{
if (!preg_match('/[0-9a-fA-F]{40}/', $hash)) {
return false;
}
if (!$this->packIndex->Valid()) {
throw new Exception('Invalid pack index');
}
if (!$this->packData->Valid()) {
throw new Exception('Unsupported pack file format');
}
$offset = $this->packIndex->FindPackedObject($hash);
if ($offset === false) {
return false;
}
return $this->packData->GetObject($offset, $type);
}
/**
* Applies a binary delta to a base object
*
* @param string $delta delta string
* @param string $base base object data
* @return string patched content
*/
private static function ApplyDelta($delta, $base)
{
/*
* algorithm from patch-delta.c
*/
$pos = 0;
GitPHP_PackData::ParseVarInt($delta, $pos);
// base size
GitPHP_PackData::ParseVarInt($delta, $pos);
// result size
$data = '';
$deltalen = strlen($delta);
while ($pos < $deltalen) {
$opcode = ord($delta[$pos++]);
if ($opcode & 0x80) {
$off = 0;
if ($opcode & 0x1) {
$off = ord($delta[$pos++]);
}
if ($opcode & 0x2) {
$off |= ord($delta[$pos++]) << 8;
}
if ($opcode & 0x4) {
$off |= ord($delta[$pos++]) << 16;
}
if ($opcode & 0x8) {
$off |= ord($delta[$pos++]) << 24;
}
$len = 0;
if ($opcode & 0x10) {
$len = ord($delta[$pos++]);
}
if ($opcode & 0x20) {
$len |= ord($delta[$pos++]) << 8;
}
if ($opcode & 0x40) {
$len |= ord($delta[$pos++]) << 16;
}
if ($len == 0) {
$len = 0x10000;
}
$data .= mb_orig_substr($base, $off, $len);
} else {
if ($opcode > 0) {
$data .= mb_orig_substr($delta, $pos, $opcode);
$pos += $opcode;
}
}
}
return $data;
}
