stream_wrapper_register

    (PHP 4 >= 4.3.2, PHP 5, PHP 7, PHP 8)

    stream_wrapper_register — Register a URL wrapper implemented as a PHP class

    Description

    stream_wrapper_register(string $protocol, string $class, int $flags = 0): bool

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

    Parameters

    protocol

    The wrapper name to be registered. Valid protocol names must contain alphanumerics, dots (.), plusses (+), or hyphens (-) only.

    class

    The classname which implements the protocol.

    flags

    Should be set to STREAM_IS_URL if protocol is a URL protocol. Default is 0, local stream.

    Return Values

    Returns true on success or false on failure.

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

    Examples

    Example #1 How to register a stream wrapper

    <?php
    $existed     = in_array("var", stream_get_wrappers());
    if (    $existed) {
    stream_wrapper_unregister("var");
    }
    stream_wrapper_register("var", "VariableStream");
    $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);

    if (    $existed) {
    stream_wrapper_restore("var");
    }

    ?>

    The above example will output:

    line1
line2
line3
string(18) "line1
line2
line3
"

    See Also

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    User Contributed Notes 13 notes

    up
    9
    cellog at php dot net
    19 years ago
    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. It would be really helpful to add this to the official manual!
    up
    4
    fordiman at gmail dot com
    17 years ago
    Updated. I figured there's no need to store the variable name if we're dereferenceing; we can just store the pointer and not have to dereference in each function for brevity.

    Also, I added the assertion that the stream is a string, since we're behaving basically like it has to be, and I changed the name to GlobalStream and global://, as that's a more descriptive moniker than VariableName/var://.
    <?php
    class GlobalStream {
    private     $pos;
    private     $stream;
    public function     stream_open($path, $mode, $options, &$opened_path) {
    $url = parse_url($path);
    $this->stream = &$GLOBALS[$url["host"]];
    $this->pos = 0;
    if (!    is_string($this->stream)) return false;
    return     true;
    }
    public function     stream_read($count) {
    $p=&$this->pos;
    $ret = substr($this->stream, $this->pos, $count);
    $this->pos += strlen($ret);
    return     $ret;
    }
    public function     stream_write($data){
    $l=strlen($data);
    $this->stream =
    substr($this->stream, 0, $this->pos) .
    $data .
    substr($this->stream, $this->pos += $l);
    return     $l;
    }
    public function     stream_tell() {
    return     $this->pos;
    }
    public function     stream_eof() {
    return     $this->pos >= strlen($this->stream);
    }
    public function     stream_seek($offset, $whence) {
    $l=strlen($this->stream);
    switch (    $whence) {
    case     SEEK_SET: $newPos = $offset; break;
    case     SEEK_CUR: $newPos = $this->pos + $offset; break;
    case     SEEK_END: $newPos = $l + $offset; break;
    default: return     false;
    }
    $ret = ($newPos >=0 && $newPos <=$l);
    if (    $ret) $this->pos=$newPos;
    return     $ret;
    }
    }
    stream_wrapper_register('global', 'GlobalStream') or die('Failed to register protocol global://');

    $myvar = "";

    $fp = fopen("global://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);
    ?>
    up
    4
    fordiman at gmail dot com
    17 years ago
    Updated for PHP 5, and optimized for readability, low line count, and minimum memory use:

    <?php
    class VariableStream {
    private     $position;
    private     $varname;
    public function     stream_open($path, $mode, $options, &$opened_path) {
    $url = parse_url($path);
    $this->varname = $url["host"];
    $this->position = 0;
    return     true;
    }
    public function     stream_read($count) {
    $p=&$this->position;
    $ret = substr($GLOBALS[$this->varname], $p, $count);
    $p += strlen($ret);
    return     $ret;
    }
    public function     stream_write($data){
    $v=&$GLOBALS[$this->varname];
    $l=strlen($data);
    $p=&$this->position;
    $v = substr($v, 0, $p) . $data . substr($v, $p += $l);
    return     $l;
    }
    public function     stream_tell() {
    return     $this->position;
    }
    public function     stream_eof() {
    return     $this->position >= strlen($GLOBALS[$this->varname]);
    }
    public function     stream_seek($offset, $whence) {
    $l=strlen(&$GLOBALS[$this->varname]);
    $p=&$this->position;
    switch (    $whence) {
    case     SEEK_SET: $newPos = $offset; break;
    case     SEEK_CUR: $newPos = $p + $offset; break;
    case     SEEK_END: $newPos = $l + $offset; break;
    default: return     false;
    }
    $ret = ($newPos >=0 && $newPos <=$l);
    if (    $ret) $p=$newPos;
    return     $ret;
    }
    }
    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);
    ?>
    up
    2
    phpnet at povaddict dot com dot ar
    17 years ago
    In response to Anonymouse at Coward dot com:

    The manual says "Reading stops when up to length bytes have been read, [...] or (after opening userspace stream) when 8192 bytes have been read whichever comes first."

    I tested it and fread($filehandle, 4096) returns 4096 bytes, so it's working as the manual says it should. You're right when you say "8192 bytes is always passed to stream_read as count", but that doesn't mean fread will return 8192 bytes. If you call fread twice with length 4096, PHP calls stream_read passing 8192 as count on the first fread, and doesn't call it on second fread. On both cases, fread returns the correct amount of bytes.

    <?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)
    {
    echo     "stream_read called asking for $count bytes\n";
    $ret = substr($GLOBALS[$this->varname], $this->position, $count);
    $this->position += strlen($ret);
    return     $ret;
    }

    function     stream_eof()
    {
    return     $this->position >= strlen($GLOBALS[$this->varname]);
    }

    }

    stream_wrapper_register("var", "VariableStream")
    or die(    "Failed to register protocol");

    $myvar = "";
    $l=range('a','z');
    for(    $i=0;$i<65536;$i++) {
    $myvar .= $l[array_rand($l)];
    }

    $fp = fopen("var://myvar", "r+");

    while (!    feof($fp)) {
    $out = fread($fp,1000);
    echo     "fread returned ",strlen($out)," bytes\n";
    }

    fclose($fp);

    ?>
    up
    1
    phrank
    16 years ago
    Actually, I don't know if there's a better way to figure out if stream_read() was called by fgets() or e.g. fread() than this one:

    public function stream_read($count)
    {
    $bt = debug_backtrace();
    if(($bt[0]['function'] == 'stream_read') &&
    ($bt[1]['function'] == 'fgets'))
    {
    $pos = strpos($GLOBALS[$this->varname], "\n", $this->position);
    $retval = substr($GLOBALS[$this->varname], $this->position, ($pos > $count) ? $count : $pos+1);

    }
    else
    {
    $retval = substr($GLOBALS[$this->varname], $this->position, $count);

    }
    $this->position += strlen($retval);
    return (string)$retval;
    }
    up
    1
    none at your dot biz
    17 years ago
    In case someone else starts scratching their head like I was, you should change the VariableStream::stream_eof() function to something like this:

    function stream_eof()
    {
    $eof = ($this->position >= strlen($GLOBALS[$this->varname]));
    if(version_compare(PHP_VERSION,'5.0','>=') && version_compare(PHP_VERSION,'5.1','<'))
    {
    $eof = !$eof;
    }
    return $eof;
    }

    PHP 5.0 introduced a bug that wasn't fixed until 5.1
    up
    1
    jhannus at php dot net
    19 years ago
    It is worth noting that if your wrapper supports stream_flush() then when you flcose() your stream this function will be called prior to closing the stream.
    up
    1
    yeiniel at gmail dot com
    16 years ago
    on using dir_opendir on PHP5 make sure you not return a resource object on success. A resource object is diferent from false but php make a cast to bool to dir_opendir return value and modify the value of your resource to 1.

    example:

    class myclass{
    private $mysqlHandler;
    public function dir_opendir(....)
    {
    $this->mysqlHandler = mysql_connect(....);
    return $this->mysqlHandler; //this is wrong, next
    //time you use
    //$this->mysqlHandler
    // the value is 1
    }
    }
    up
    0
    dmarjos at gmail dot com
    10 years ago
    Be aware that even when stream_wrapper_register won't fail, open_basedir will affect functionality of the class.
    up
    0
    simon at firepages dot org
    20 years ago
    using streams to use the ever useful fgetcsv() on a variable where explode() would not work (and would otherwise require regex(though that may be easier;)))

    $explode_this="yak, llama, 'big llama', 'wobmat, with a comma in it', bandycoot";

    <?php
    class csvstream{
    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_eof(){
    return     $this->position >= strlen($GLOBALS[$this->varname]);
    }
    function     stream_tell(){
    return     $this->position;
    }
    }

    stream_wrapper_register("csvstr", "csvstream") ;
    $str="yak, llama, 'big llama', 'wobmat, with a comma in it', bandycoot";

    $fp = fopen("csvstr://str", "r+");
    print_r(fgetcsv($fp,100,",","'"));

    ?>
    up
    -1
    Anonymous
    15 years ago
    "for use with all the other filesystem functions"

    "all" is not accurate. Unfortunately, zip_open(), and presumably others, will ignore your custom stream wrapper.
    up
    -2
    Hayley Watson
    19 years ago
    The current URL standard is RFC 3986 - available at www.ietf.org/rfc/rfc3986.txt
    up
    -2
    Anonymouse at Coward dot com
    17 years ago
    Use caution with writing code that may use stream wrappers with fread, as fread behaviour is 'inconsistent' with normal file operations because of the 8192 bytes internal buffer used by PHP ( >= 5.0.5 IIRC ).

    ie:

    fread($filehandle, filesize($filename))

    will not work correctly if the file is larger than 8KB, it will only get you the first 8192 bytes. Also, it seems that:

    fread($filehandle, 4096)

    will still give you 8KB (if the file is larger than 8KB) as 8192 bytes is always passed to stream_read as count.

    This makes it somewhat impossible to just 'drop in' a stream where normally a file would be used without taking special care.

    Yes, it IS mentioned in the documentation here if you read it really well, but I for one spent some time scratching my head over it, and looking at the bug tracker, I am not the only one. The dev's say this inconsistancy is a feature though, even if it does make stream wrappers pretty much useless 'out of the box'.

    file_get_contents and stream_get_contents seem to work ok though.
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