function Archive_Tar::_readHeader

Parameters

mixed $v_binary_data:

mixed $v_header:

Return value

bool

File

modules/system/system.tar.inc, line 1740

Class

Archive_Tar

Code

public function _readHeader($v_binary_data, &$v_header) {
    if (strlen($v_binary_data) == 0) {
        $v_header['filename'] = '';
        return true;
    }
    if (strlen($v_binary_data) != 512) {
        $v_header['filename'] = '';
        $this->_error('Invalid block size : ' . strlen($v_binary_data));
        return false;
    }
    if (!is_array($v_header)) {
        $v_header = array();
    }
    // ----- Calculate the checksum
    $v_checksum = 0;
    // ..... First part of the header
    $v_binary_split = str_split($v_binary_data);
    $v_checksum += array_sum(array_map('ord', array_slice($v_binary_split, 0, 148)));
    $v_checksum += array_sum(array_map('ord', array(
        ' ',
        ' ',
        ' ',
        ' ',
        ' ',
        ' ',
        ' ',
        ' ',
    )));
    $v_checksum += array_sum(array_map('ord', array_slice($v_binary_split, 156, 512)));
    $v_data = unpack($this->_fmt, $v_binary_data);
    if (strlen($v_data["prefix"]) > 0) {
        $v_data["filename"] = "{$v_data['prefix']}/{$v_data['filename']}";
    }
    // ----- Extract the checksum
    $v_data_checksum = trim($v_data['checksum']);
    if (!preg_match('/^[0-7]*$/', $v_data_checksum)) {
        $this->_error('Invalid checksum for file "' . $v_data['filename'] . '" : ' . $v_data_checksum . ' extracted');
        return false;
    }
    $v_header['checksum'] = OctDec($v_data_checksum);
    if ($v_header['checksum'] != $v_checksum) {
        $v_header['filename'] = '';
        // ----- Look for last block (empty block)
        if ($v_checksum == 256 && $v_header['checksum'] == 0) {
            return true;
        }
        $this->_error('Invalid checksum for file "' . $v_data['filename'] . '" : ' . $v_checksum . ' calculated, ' . $v_header['checksum'] . ' expected');
        return false;
    }
    // ----- Extract the properties
    $v_header['filename'] = rtrim($v_data['filename'], "\x00");
    if ($this->_isMaliciousFilename($v_header['filename'])) {
        $this->_error('Malicious .tar detected, file "' . $v_header['filename'] . '" will not install in desired directory tree');
        return false;
    }
    $v_header['mode'] = OctDec(trim($v_data['mode']));
    $v_header['uid'] = OctDec(trim($v_data['uid']));
    $v_header['gid'] = OctDec(trim($v_data['gid']));
    $v_header['size'] = $this->_tarRecToSize($v_data['size']);
    $v_header['mtime'] = OctDec(trim($v_data['mtime']));
    if (($v_header['typeflag'] = $v_data['typeflag']) == "5") {
        $v_header['size'] = 0;
    }
    $v_header['link'] = trim($v_data['link']);
    
    /* ----- All these fields are removed form the header because
       they do not carry interesting info
       $v_header[magic] = trim($v_data[magic]);
       $v_header[version] = trim($v_data[version]);
       $v_header[uname] = trim($v_data[uname]);
       $v_header[gname] = trim($v_data[gname]);
       $v_header[devmajor] = trim($v_data[devmajor]);
       $v_header[devminor] = trim($v_data[devminor]);
       */
    return true;
}