ChainedBlockStream.php

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<?php

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

require_once 'PEAR.php';
require_once 'OLE.php';

class OLE_ChainedBlockStream extends PEAR
{
    var $ole;

    var $params;

    var $data;

    var $pos;

    function stream_open($path, $mode, $options, &$openedPath)
    {
        if ($mode != 'r') {
            if ($options & STREAM_REPORT_ERRORS) {
                trigger_error('Only reading is supported', E_USER_WARNING);
            }
            return false;
        }

        // 25 is length of "ole-chainedblockstream://"
        parse_str(substr($path, 25), $this->params);
        if (!isset($this->params['oleInstanceId'],
                   $this->params['blockId'],
                   $GLOBALS['_OLE_INSTANCES'][$this->params['oleInstanceId']])) {

            if ($options & STREAM_REPORT_ERRORS) {
                trigger_error('OLE stream not found', E_USER_WARNING);
            }
            return false;
        }
        $this->ole = $GLOBALS['_OLE_INSTANCES'][$this->params['oleInstanceId']];

        $blockId = $this->params['blockId'];
        $this->data = '';
        if (isset($this->params['size']) &&
            $this->params['size'] < $this->ole->bigBlockThreshold &&
            $blockId != $this->ole->root->_StartBlock) {

            // Block id refers to small blocks
            $rootPos = $this->ole->_getBlockOffset($this->ole->root->_StartBlock);
            while ($blockId != -2) {
                $pos = $rootPos + $blockId * $this->ole->bigBlockSize;
                $blockId = $this->ole->sbat[$blockId];
                fseek($this->ole->_file_handle, $pos);
                $this->data .= fread($this->ole->_file_handle, $this->ole->bigBlockSize);
            }
        } else {
            // Block id refers to big blocks
            while ($blockId != -2) {
                $pos = $this->ole->_getBlockOffset($blockId);
                fseek($this->ole->_file_handle, $pos);
                $this->data .= fread($this->ole->_file_handle, $this->ole->bigBlockSize);
                $blockId = $this->ole->bbat[$blockId];
            }
        }
        if (isset($this->params['size'])) {
            $this->data = substr($this->data, 0, $this->params['size']);
        }

        if ($options & STREAM_USE_PATH) {
            $openedPath = $path;
        }

        return true;
    }

    function stream_close()
    {
        $this->ole = null;
        unset($GLOBALS['_OLE_INSTANCES']);
    }

    function stream_read($count)
    {
        if ($this->stream_eof()) {
            return false;
        }
        $s = substr($this->data, $this->pos, $count);
        $this->pos += $count;
        return $s;
    }

    function stream_eof()
    {
        $eof = $this->pos >= strlen($this->data);
        // Workaround for bug in PHP 5.0.x: http://bugs.php.net/27508
        if (version_compare(PHP_VERSION, '5.0', '>=') &&
            version_compare(PHP_VERSION, '5.1', '<')) {

           $eof = !$eof;
        }
        return $eof;
    }

    function stream_tell()
    {
        return $this->pos;
    }

    function stream_seek($offset, $whence)
    {
        if ($whence == SEEK_SET && $offset >= 0) {
            $this->pos = $offset;
        } elseif ($whence == SEEK_CUR && -$offset <= $this->pos) {
            $this->pos += $offset;
        } elseif ($whence == SEEK_END && -$offset <= sizeof($this->data)) {
            $this->pos = strlen($this->data) + $offset;
        } else {
            return false;
        }
        return true;
    }

    function stream_stat()
    {
        return array(
            'size' => strlen($this->data),
            );
    }

    // Methods used by stream_wrapper_register() that are not implemented:
    // bool stream_flush ( void )
    // int stream_write ( string data )
    // bool rename ( string path_from, string path_to )
    // bool mkdir ( string path, int mode, int options )
    // bool rmdir ( string path, int options )
    // bool dir_opendir ( string path, int options )
    // array url_stat ( string path, int flags )
    // string dir_readdir ( void )
    // bool dir_rewinddir ( void )
    // bool dir_closedir ( void )
}

?>