PHP 5.5.16 is released

The streamWrapper class

(PHP 4 >= 4.3.2, PHP 5)

Introduction

Allows you to implement your own protocol handlers and streams for use with all the other filesystem functions (such as fopen(), fread() etc.).

Note:

This is NOT a real class, only a prototype of how a class defining its own protocol should be.

Note:

Implementing the methods in other ways then described here can lead to undefined behaviour.

An instance of this class is initialized as soon as a stream function tries to access the protocol it is associated with.

Class synopsis

streamWrapper {
/* Properties */
public resource $context ;
/* Methods */
__construct ( void )
__destruct ( void )
public bool dir_closedir ( void )
public bool dir_opendir ( string $path , int $options )
public string dir_readdir ( void )
public bool dir_rewinddir ( void )
public bool mkdir ( string $path , int $mode , int $options )
public bool rename ( string $path_from , string $path_to )
public bool rmdir ( string $path , int $options )
public resource stream_cast ( int $cast_as )
public void stream_close ( void )
public bool stream_eof ( void )
public bool stream_flush ( void )
public bool stream_lock ( int $operation )
public bool stream_metadata ( string $path , int $option , mixed $value )
public bool stream_open ( string $path , string $mode , int $options , string &$opened_path )
public string stream_read ( int $count )
public bool stream_seek ( int $offset , int $whence = SEEK_SET )
public bool stream_set_option ( int $option , int $arg1 , int $arg2 )
public array stream_stat ( void )
public int stream_tell ( void )
public bool stream_truncate ( int $new_size )
public int stream_write ( string $data )
public bool unlink ( string $path )
public array url_stat ( string $path , int $flags )
}

Properties

resource context

The current context, or NULL if no context was passed to the caller function.

Use the stream_context_get_options() to parse the context.

Note:

This property must be public so PHP can populate it with the actual context resource.

Changelog

Version Description
5.0.0 Added the context property.

Table of Contents

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User Contributed Notes 3 notes

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2
yannick dot battail at gmail dot com
5 years ago
a php interface for wrapper

<?php
interface WrapperInterface
{
   
/**
     * resource context
     *
     * @var resource
     */
    //public $context;

    /**
     * constructor
     *
     */
   
public function __construct();

   
/**
     *
     *
     * @return bool
     */
   
public function dir_closedir();

   
/**
     * Enter description here...
     *
     * @param string $path
     * @param int $options
     * @return bool
     */
   
public function dir_opendir($path , $options);

   
/**
     * Enter description here...
     *
     * @return string
     */
   
public function dir_readdir();

   
/**
     * Enter description here...
     *
     * @return bool
     */
   
public function dir_rewinddir();

   
/**
     * Enter description here...
     *
     * @param string $path
     * @param int $mode
     * @param int $options
     * @return bool
     */
   
public function mkdir($path , $mode , $options);

   
/**
     * Enter description here...
     *
     * @param string $path_from
     * @param string $path_to
     * @return bool
     */
   
public function rename($path_from , $path_to);

   
/**
     * Enter description here...
     *
     * @param string $path
     * @param int $options
     * @return bool
     */
   
public function rmdir($path , $options);

   
/**
     * Enter description here...
     *
     * @param int $cast_as
     * @return resource
     */
   
public function stream_cast($cast_as);

   
/**
     * Enter description here...
     *
     */
   
public function stream_close();

   
/**
     * Enter description here...
     *
     * @return bool
     */
   
public function stream_eof();

   
/**
     * Enter description here...
     *
     * @return bool
     */
   
public function stream_flush();

   
/**
     * Enter description here...
     *
     * @param mode $operation
     * @return bool
     */
   
public function stream_lock($operation);

   
/**
     * Enter description here...
     *
     * @param string $path
     * @param string $mode
     * @param int $options
     * @param string &$opened_path
     * @return bool
     */
   
public function stream_open($path , $mode , $options , &$opened_path);

   
/**
     * Enter description here...
     *
     * @param int $count
     * @return string
     */
   
public function stream_read($count);

   
/**
     * Enter description here...
     *
     * @param int $offset
     * @param int $whence = SEEK_SET
     * @return bool
     */
   
public function stream_seek($offset , $whence = SEEK_SET);

   
/**
     * Enter description here...
     *
     * @param int $option
     * @param int $arg1
     * @param int $arg2
     * @return bool
     */
   
public function stream_set_option($option , $arg1 , $arg2);

   
/**
     * Enter description here...
     *
     * @return array
     */
   
public function stream_stat();

   
/**
     * Enter description here...
     *
     * @return int
     */
   
public function stream_tell();

   
/**
     * Enter description here...
     *
     * @param string $data
     * @return int
     */
   
public function stream_write($data);

   
/**
     * Enter description here...
     *
     * @param string $path
     * @return bool
     */
   
public function unlink($path);

   
/**
     * Enter description here...
     *
     * @param string $path
     * @param int $flags
     * @return array
     */
   
public function url_stat($path , $flags);
}

?>
up
1
isaac dot z dot no dot foster at spam dot gmail dot please dot com
3 years ago
It's worth noting that the interface defined by yannick at gmail should not always be implemented by a stream wrapper class, as several of the methods should not be implemented if the class has no use for them (as per the manual).

Specifically, mkdir, rename, rmdir, and unlink are methods that "should not be defined" if the wrapper has no use for them. The consequence is that the appropriate error message will not be returned.

If the interface is implemented, you won't have the flexibility to not implement those methods.

Not trying to be academic, but it was useful for me.
up
0
Anonymous
2 years ago
Here is a very simple stream wrapper which calls your callback function for reads:

<?php

class CallbackUrl
{
    const
WRAPPER_NAME = 'callback';

    public
$context;
    private
$_cb;
    private
$_eof = false;

    private static
$_isRegistered = false;

    public static function
getContext($cb)
    {
        if (!
self::$_isRegistered) {
           
stream_wrapper_register(self::WRAPPER_NAME, get_class());
           
self::$_isRegistered = true;
        }
        if (!
is_callable($cb)) return false;
        return
stream_context_create(array(self::WRAPPER_NAME => array('cb' => $cb)));
    }

    public function
stream_open($path, $mode, $options, &$opened_path)
    {
        if (!
preg_match('/^r[bt]?$/', $mode) || !$this->context) return false;
       
$opt = stream_context_get_options($this->context);
        if (!
is_array($opt[self::WRAPPER_NAME]) ||
            !isset(
$opt[self::WRAPPER_NAME]['cb']) ||
            !
is_callable($opt[self::WRAPPER_NAME]['cb'])) return false;
       
$this->_cb = $opt[self::WRAPPER_NAME]['cb'];
        return
true;
    }

    public function
stream_read($count)
    {
        if (
$this->_eof || !$count) return '';
        if ((
$s = call_user_func($this->_cb, $count)) == '') $this->_eof = true;
        return
$s;
    }

    public function
stream_eof()
    {
        return
$this->_eof;
    }
}

class
Test {
    private
$_s;
    public function
__construct($s)
    {
       
$this->_s = $s;
    }
    public function
read($count) {
        return
fread($this->_s, $count);
    }
}

$t = new Test(fopen('/etc/services', 'r'));
$fd = fopen('callback://', 'r', false, CallbackUrl::getContext(array($t, 'read')));
while((
$buf = fread($fd, 128)) != '') {
    print
$buf;
}
?>
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