# stream_wrapper_register

(PHP 4 >= 4.3.2, PHP 5)

stream_wrapper_register — Register a URL wrapper implemented as a PHP class

### Description

bool stream_wrapper_register ( string `$protocol` , string `$classname` )

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

To implement a wrapper, you need to define a class with a number of member functions, as defined below. When someone fopens your stream, PHP will create an instance of `classname` and then call methods on that instance. You must implement the methods exactly as described below - doing otherwise will lead to undefined behaviour.

> Note: As of PHP 5.0.0 the instance of `classname` will be populated with a `context` property referencing a Context Resource which may be accessed with stream_context_get_options(). If no context was passed to the stream creation function, `context` will be set to `NULL`.

stream_wrapper_register() will return `FALSE` if the `protocol` already has a handler.

bool stream_open ( string `$path` , string `$mode` , int `$options` , string `$opened_path` )

This method is called immediately after your stream object is created. `path` specifies the URL that was passed to fopen() and that this object is expected to retrieve. You can use parse_url() to break it apart.

`mode` is the mode used to open the file, as detailed for fopen(). You are responsible for checking that `mode` is valid for the `path` requested.

`options` holds additional flags set by the streams API. It can hold one or more of the following values OR'd together.

Flag | Description
--- | ---
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.

If the `path` is opened successfully, and STREAM_USE_PATH is set in `options` , you should set `opened_path` to the full path of the file/resource that was actually opened.

If the requested resource was opened successfully, you should return `TRUE`, otherwise you should return `FALSE`

void stream_close ( void )

This method is called when the stream is closed, using fclose(). You must release any resources that were locked or allocated by the stream.

string stream_read ( int `$count` )

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.

int stream_write ( string `$data` )

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.

bool stream_eof ( void )

This method is called in response to feof() calls on the stream. You should return `TRUE` if the read/write position is at the end of the stream and if no more data is available to be read, or `FALSE` otherwise.

int stream_tell ( void )

This method is called in response to ftell() calls on the stream. You should return the current read/write position of the stream.

bool stream_seek ( int `$offset` , int `$whence` )

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. Return `TRUE` if the position was updated, `FALSE` otherwise.

bool stream_flush ( void )

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 `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.

array stream_stat ( void )

This method is called in response to fstat() calls on the stream and should return an array containing the same values as appropriate for the stream.

bool unlink ( string `$path` )

This method is called in response to unlink() calls on URL paths associated with the wrapper and should attempt to delete the item specified by `path` . It should return `TRUE` on success or `FALSE` on failure. In order for the appropriate error message to be returned, do not define this method if your wrapper does not support unlinking.

> Note: Userspace wrapper unlink method is not supported prior to PHP 5.0.0.

bool rename ( string `$path_from` , string `$path_to` )

This method is called in response to rename() calls on URL paths associated with the wrapper and should attempt to rename the item specified by `path_from` to the specification given by `path_to` . It should return `TRUE` on success or `FALSE` on failure. In order for the appropriate error message to be returned, do not define this method if your wrapper does not support renaming.

> Note: Userspace wrapper rename method is not supported prior to PHP 5.0.0.

bool mkdir ( string `$path` , int `$mode` , int `$options` )

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

> Note: Userspace wrapper mkdir method is not supported prior to PHP 5.0.0.

bool rmdir ( string `$path` , int `$options` )

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

> Note: Userspace wrapper rmdir method is not supported prior to PHP 5.0.0.

bool dir_opendir ( string `$path` , int `$options` )

This method is called immediately when your stream object is created for examining directory contents with opendir(). `path` specifies the URL that was passed to opendir() and that this object is expected to explore. You can use parse_url() to break it apart.

array url_stat ( string `$path` , int `$flags` )

This method is called in response to stat() calls on the URL paths associated with the wrapper and 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`).

`flags` holds additional flags set by the streams API. It can hold one or more of the following values OR'd together.

Flag | Description
--- | ---
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.

string dir_readdir ( void )

This method is called in response to readdir() and should return a string representing the next filename in the location opened by dir_opendir().

bool dir_rewinddir ( void )

This method is called in response to rewinddir() and 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().

bool dir_closedir ( void )

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.

The example below implements a var:// protocol handler that allows read/write access to a named global variable using standard filesystem stream functions such as fread(). The var:// protocol implemented below, given the URL "var://foo" will read/write data to/from $GLOBALS["foo"].

Example#1 A Stream for reading/writing global variables

`<?php
class VariableStream {
var $position;
var $varname;
function stream_open($path, $mode, $options, &$opened_path)
{
$url = parse_url($path);
$this->varname = $url["host"];
$this->position = 0;
return true;
}
function stream_read($count)
{
$ret = substr($GLOBALS[$this->varname], $this->position, $count);
$this->position += strlen($ret);
return $ret;
}
function stream_write($data)
{
$left = substr($GLOBALS[$this->varname], 0, $this->position);
$right = substr($GLOBALS[$this->varname], $this->position + strlen($data));
$GLOBALS[$this->varname] = $left . $data . $right;
$this->position += strlen($data);
return strlen($data);
}
function stream_tell()
{
return $this->position;
}
function stream_eof()
{
return $this->position >= strlen($GLOBALS[$this->varname]);
}
function stream_seek($offset, $whence)
{
switch ($whence) {
case SEEK_SET:
if ($offset < strlen($GLOBALS[$this->varname]) && $offset >= 0) {
$this->position = $offset;
return true;
} else {
return false;
}
break;
case SEEK_CUR:
if ($offset >= 0) {
$this->position += $offset;
return true;
} else {
return false;
}
break;
case SEEK_END:
if (strlen($GLOBALS[$this->varname]) + $offset >= 0) {
$this->position = strlen($GLOBALS[$this->varname]) + $offset;
return true;
} else {
return false;
}
break;
default:
return false;
}
}
}
stream_wrapper_register("var", "VariableStream")
or die("Failed to register protocol");
$myvar = "";
$fp = fopen("var://myvar", "r+");
fwrite($fp, "line1\n");
fwrite($fp, "line2\n");
fwrite($fp, "line3\n");
rewind($fp);
while (!feof($fp)) {
echo fgets($fp);
}
fclose($fp);
var_dump($myvar);
?>`