<?php
/**
 * eGroupWare API: VFS - stream wrapper interface
 *
 * @link http://www.egroupware.org
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 * @package api
 * @subpackage vfs
 * @version $Id: class.iface_stream_wrapper.inc.php 24917 2008-01-30 06:47:53Z ralfbecker $
 */

/**
 * eGroupWare API: VFS - stream wrapper interface
 *
 * The interface is according to the docu on php.net
 *  
 * @link http://www.php.net/manual/en/function.stream-wrapper-register.php
 */
interface iface_stream_wrapper
{
	/**
	 * optional context param when opening the stream, null if no context passed
	 *
	 * @var mixed
	 */
	//var $context;

	/**
	 * This method is called immediately after your stream object is created.
	 * 
	 * @param string $path URL that was passed to fopen() and that this object is expected to retrieve
	 * @param string $mode mode used to open the file, as detailed for fopen()
	 * @param int $options additional flags set by the streams API (or'ed together): 
	 * - STREAM_USE_PATH      If path is relative, search for the resource using the include_path.
	 * - STREAM_REPORT_ERRORS If this flag is set, you are responsible for raising errors using trigger_error() during opening of the stream. 
	 *                        If this flag is not set, you should not raise any errors.
	 * @param string $opened_path full path of the file/resource, if the open was successfull and STREAM_USE_PATH was set
	 * @return boolean true if the ressource was opened successful, otherwise false
	 */
	function stream_open ( $path, $mode, $options, &$opened_path );
	
	/**
	 * This method is called when the stream is closed, using fclose(). 
	 * 
	 * You must release any resources that were locked or allocated by the stream.
	 */
	function stream_close ( );
	
	/**
	 * This method is called in response to fread() and fgets() calls on the stream.
	 * 
	 * You must return up-to count bytes of data from the current read/write position as a string. 
	 * If there are less than count bytes available, return as many as are available. 
	 * If no more data is available, return either FALSE or an empty string. 
	 * You must also update the read/write position of the stream by the number of bytes that were successfully read.
	 *
	 * @param int $count
	 * @return string/false up to count bytes read or false on EOF
	 */
	function stream_read ( $count );

	/**
	 * This method is called in response to fwrite() calls on the stream.
	 * 
	 * You should store data into the underlying storage used by your stream. 
	 * If there is not enough room, try to store as many bytes as possible. 
	 * You should return the number of bytes that were successfully stored in the stream, or 0 if none could be stored. 
	 * You must also update the read/write position of the stream by the number of bytes that were successfully written.
	 *
	 * @param string $data
	 * @return integer
	 */
	function stream_write ( $data );

 	/**
 	 * This method is called in response to feof() calls on the stream.
 	 * 
 	 * Important: PHP 5.0 introduced a bug that wasn't fixed until 5.1: the return value has to be the oposite!
 	 * 
 	 * if(version_compare(PHP_VERSION,'5.0','>=') && version_compare(PHP_VERSION,'5.1','<'))
  	 * {
 	 * 		$eof = !$eof;
 	 * }
  	 * 
 	 * @return boolean true if the read/write position is at the end of the stream and no more data availible, false otherwise
 	 */
	function stream_eof ( );

	/**
	 * This method is called in response to ftell() calls on the stream.
	 * 
	 * @return integer current read/write position of the stream
	 */
 	function stream_tell ( );

 	/**
 	 * This method is called in response to fseek() calls on the stream.
 	 *
 	 * You should update the read/write position of the stream according to offset and whence. 
 	 * See fseek() for more information about these parameters. 
 	 * 
 	 * @param integer $offset
 	 * @param integer $whence	SEEK_SET - Set position equal to offset bytes
 	 * 							SEEK_CUR - Set position to current location plus offset.
 	 * 							SEEK_END - Set position to end-of-file plus offset. (To move to a position before the end-of-file, you need to pass a negative value in offset.)
 	 * @return boolean TRUE if the position was updated, FALSE otherwise.
 	 */
	function stream_seek ( $offset, $whence );

	/**
	 * This method is called in response to fflush() calls on the stream.
	 * 
	 * If you have cached data in your stream but not yet stored it into the underlying storage, you should do so now.
	 * 
	 * @return booelan TRUE if the cached data was successfully stored (or if there was no data to store), or FALSE if the data could not be stored.
	 */
	function stream_flush ( );

	/**
	 * This method is called in response to fstat() calls on the stream.
	 * 
	 * If you plan to use your wrapper in a require_once you need to define stream_stat().  
	 * If you plan to allow any other tests like is_file()/is_dir(), you have to define url_stat().
	 * stream_stat() must define the size of the file, or it will never be included.  
	 * url_stat() must define mode, or is_file()/is_dir()/is_executable(), and any of those functions affected by clearstatcache() simply won't work.
	 * It's not documented, but directories must be a mode like 040777 (octal), and files a mode like 0100666.  
	 * If you wish the file to be executable, use 7s instead of 6s.  
	 * The last 3 digits are exactly the same thing as what you pass to chmod.  
	 * 040000 defines a directory, and 0100000 defines a file.  
	 *
	 * @return array containing the same values as appropriate for the stream.
	 */
	function stream_stat ( );

	/**
	 * This method is called in response to unlink() calls on URL paths associated with the wrapper.
	 * 
	 * It should attempt to delete the item specified by path.
	 * In order for the appropriate error message to be returned, do not define this method if your wrapper does not support unlinking!
	 *
	 * @param string $path
	 * @return boolean TRUE on success or FALSE on failure
	 */
	static function unlink ( $path );

	/**
	 * This method is called in response to rename() calls on URL paths associated with the wrapper.
	 * 
	 * It should attempt to rename the item specified by path_from to the specification given by path_to. 
	 * In order for the appropriate error message to be returned, do not define this method if your wrapper does not support renaming.
	 *
	 * The regular filesystem stream-wrapper returns an error, if $url_from and $url_to are not either both files or both dirs!
	 *
	 * @param string $path_from
	 * @param string $path_to
	 * @return boolean TRUE on success or FALSE on failure
	 */
	static function rename ( $path_from, $path_to );

	/**
	 * This method is called in response to mkdir() calls on URL paths associated with the wrapper.
	 * 
	 * It should attempt to create the directory specified by path. 
	 * In order for the appropriate error message to be returned, do not define this method if your wrapper does not support creating directories. 
	 *
	 * @param string $path
	 * @param int $mode
	 * @param int $options Posible values include STREAM_REPORT_ERRORS and STREAM_MKDIR_RECURSIVE
	 * @return boolean TRUE on success or FALSE on failure
	 */
	static function mkdir ( $path, $mode, $options );

	/**
	 * This method is called in response to rmdir() calls on URL paths associated with the wrapper.
	 * 
	 * It should attempt to remove the directory specified by path. 
	 * In order for the appropriate error message to be returned, do not define this method if your wrapper does not support removing directories.
	 *
	 * @param string $path
	 * @param int $options Possible values include STREAM_REPORT_ERRORS.
	 * @return boolean TRUE on success or FALSE on failure.
	 */
	static function rmdir ( $path, $options );

	/**
	 * This method is called immediately when your stream object is created for examining directory contents with opendir(). 
	 * 
	 * @param string $path URL that was passed to opendir() and that this object is expected to explore.
	 * @return booelan 
	 */
	function dir_opendir ( $path, $options );

	/**
	 * This method is called in response to stat() calls on the URL paths associated with the wrapper.
	 * 
	 * It should return as many elements in common with the system function as possible. 
	 * Unknown or unavailable values should be set to a rational value (usually 0).
	 * 
	 * If you plan to use your wrapper in a require_once you need to define stream_stat().  
	 * If you plan to allow any other tests like is_file()/is_dir(), you have to define url_stat().
	 * stream_stat() must define the size of the file, or it will never be included.  
	 * url_stat() must define mode, or is_file()/is_dir()/is_executable(), and any of those functions affected by clearstatcache() simply won't work.
	 * It's not documented, but directories must be a mode like 040777 (octal), and files a mode like 0100666.  
	 * If you wish the file to be executable, use 7s instead of 6s.  
	 * The last 3 digits are exactly the same thing as what you pass to chmod.  
	 * 040000 defines a directory, and 0100000 defines a file.  
	 *
	 * @param string $path
	 * @param int $flags holds additional flags set by the streams API. It can hold one or more of the following values OR'd together:
	 * - STREAM_URL_STAT_LINK	For resources with the ability to link to other resource (such as an HTTP Location: forward, 
	 *                          or a filesystem symlink). This flag specified that only information about the link itself should be returned, 
	 *                          not the resource pointed to by the link. 
	 *                          This flag is set in response to calls to lstat(), is_link(), or filetype().
	 * - STREAM_URL_STAT_QUIET	If this flag is set, your wrapper should not raise any errors. If this flag is not set, 
	 *                          you are responsible for reporting errors using the trigger_error() function during stating of the path.
	 *                          stat triggers it's own warning anyway, so it makes no sense to trigger one by our stream-wrapper!
	 * @return array 
	 */
	static function url_stat ( $path, $flags );
	
	/**
	 * This method is called in response to readdir().
	 * 
	 * It should return a string representing the next filename in the location opened by dir_opendir().
	 * 
	 * @return string
	 */
	function dir_readdir ( );

	/**
	 * This method is called in response to rewinddir().
	 * 
	 * It should reset the output generated by dir_readdir(). i.e.: 
	 * The next call to dir_readdir() should return the first entry in the location returned by dir_opendir().
	 * 
	 * @return boolean
	 */
	function dir_rewinddir ( );
	
	/**
	 * This method is called in response to closedir().
	 * 
	 * You should release any resources which were locked or allocated during the opening and use of the directory stream. 
	 * 
	 * @return boolean
	 */
	function dir_closedir ( );
}
