PHP streamWrapper dir_readdir() Method

The PHP streamWrapper::dir_readdir() method reads entry from directory handle. This method is called in response to readdir() function.

Syntax

public streamWrapper::dir_readdir()

Parameters

No parameter is required.

Return Value

Returns string representing the next filename, or false if there is no next file.

Exceptions

Emits E_WARNING if call to this method fails (i.e. not implemented).

Example: Listing files from tar archives

The example below shows the usage of streamWrapper::dir_readdir() method.

<?php
class streamWrapper {
  protected $fp;

  public function dir_opendir($path, $options) {
    $url = parse_url($path);

    $path = $url["host"] . $url["path"];

    if (!is_readable($path)) {
      trigger_error("$path isn't readable for me", E_USER_NOTICE);
      return false;
    }
    if (!is_file($path)) {
      trigger_error("$path isn't a file", E_USER_NOTICE);
      return false;
    }

    $this->fp = fopen($path, "rb");
    return true;
  }

  public function dir_readdir() {
    //extract the header for this entry
    $header = fread($this->fp, 512);
    $data = unpack("a100filename/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1filetype/a100link/a100linkedfile", $header);

    //trim the filename and filesize
    $filename = trim($data["filename"]);

    //no filename - reached at the end of the archive
    if (!$filename) {
      return false;
    }

    $octal_bytes = trim($data["size"]);
    // Filesize is defined in octects
    $bytes = octdec($octal_bytes);

    //tar rounds up filesizes up to multiple 
    //of 512 bytes (zero filled)
    $rest = $bytes % 512;
    if ($rest > 0) {
      $bytes += 512 - $rest;
    }

    //seek over the file
    fseek($this->fp, $bytes, SEEK_CUR);

    return $filename;
  }

  public function dir_closedir() {
    return fclose($this->fp);
  }

  public function dir_rewinddir() {
    return fseek($this->fp, 0, SEEK_SET);
  }
}

stream_wrapper_register("tar", "streamWrapper");
$handle = opendir("tar://example.tar");
while (false !== ($file = readdir($handle))) {
  var_dump($file);
}

echo "Rewinding..\n";
rewind($handle);
var_dump(readdir($handle));

closedir($handle);
?>

The output of the above code will be similar to:

string(13) "construct.xml"
string(16) "dir-closedir.xml"
string(15) "dir-opendir.xml"
string(15) "dir-readdir.xml"
string(17) "dir-rewinddir.xml"
string(9) "mkdir.xml"
string(10) "rename.xml"
string(9) "rmdir.xml"
string(15) "stream-cast.xml"
string(16) "stream-close.xml"
string(14) "stream-eof.xml"
string(16) "stream-flush.xml"
string(15) "stream-lock.xml"
string(15) "stream-open.xml"
string(15) "stream-read.xml"
string(15) "stream-seek.xml"
string(21) "stream-set-option.xml"
string(15) "stream-stat.xml"
string(15) "stream-tell.xml"
string(16) "stream-write.xml"
string(10) "unlink.xml"
string(12) "url-stat.xml"
Rewinding..
string(13) "construct.xml"

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