Archive_Tar::_openAppend PHP Method

    function _openAppend()
    {
        if (filesize($this->_tarname) == 0) {
            return $this->_openWrite();
        }
        if ($this->_compress) {
            $this->_close();
            if (!@rename($this->_tarname, $this->_tarname . ".tmp")) {
                $this->_error('Error while renaming \'' . $this->_tarname . '\' to temporary file \'' . $this->_tarname . '.tmp\'');
                return false;
            }
            if ($this->_compress_type == 'gz') {
                $v_temp_tar = @gzopen($this->_tarname . ".tmp", "rb");
            } elseif ($this->_compress_type == 'bz2') {
                $v_temp_tar = @bzopen($this->_tarname . ".tmp", "r");
            }
            if ($v_temp_tar == 0) {
                $this->_error('Unable to open file \'' . $this->_tarname . '.tmp\' in binary read mode');
                @rename($this->_tarname . ".tmp", $this->_tarname);
                return false;
            }
            if (!$this->_openWrite()) {
                @rename($this->_tarname . ".tmp", $this->_tarname);
                return false;
            }
            if ($this->_compress_type == 'gz') {
                while (!@gzeof($v_temp_tar)) {
                    $v_buffer = @gzread($v_temp_tar, 512);
                    if ($v_buffer == ARCHIVE_TAR_END_BLOCK) {
                        // do not copy end blocks, we will re-make them
                        // after appending
                        continue;
                    }
                    $v_binary_data = pack("a512", $v_buffer);
                    $this->_writeBlock($v_binary_data);
                }
                @gzclose($v_temp_tar);
            } elseif ($this->_compress_type == 'bz2') {
                while (strlen($v_buffer = @bzread($v_temp_tar, 512)) > 0) {
                    if ($v_buffer == ARCHIVE_TAR_END_BLOCK) {
                        continue;
                    }
                    $v_binary_data = pack("a512", $v_buffer);
                    $this->_writeBlock($v_binary_data);
                }
                @bzclose($v_temp_tar);
            }
            if (!@unlink($this->_tarname . ".tmp")) {
                $this->_error('Error while deleting temporary file \'' . $this->_tarname . '.tmp\'');
            }
        } else {
            // ----- For not compressed tar, just add files before the last
            //       one or two 512 bytes block
            if (!$this->_openReadWrite()) {
                return false;
            }
            clearstatcache();
            $v_size = filesize($this->_tarname);
            // We might have zero, one or two end blocks.
            // The standard is two, but we should try to handle
            // other cases.
            fseek($this->_file, $v_size - 1024);
            if (fread($this->_file, 512) == ARCHIVE_TAR_END_BLOCK) {
                fseek($this->_file, $v_size - 1024);
            } elseif (fread($this->_file, 512) == ARCHIVE_TAR_END_BLOCK) {
                fseek($this->_file, $v_size - 512);
            }
        }
        return true;
    }