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.
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.
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);
?>
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