stream_get_meta_data()

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

从封装协议文件指针中取得报头／元数据

说明

stream_get_meta_data(int $fp): array

返回现有$stream的信息。可以是任何通过fopen()，fsockopen()和pfsockopen()建立的流。返回的数组包含以下项目：

• $timed_out(bool)-如果在上次调用fread()或者fgets()中等待数据时流超时了则为TRUE。

• $blocked(bool)-如果流处于阻塞 IO 模式时为TRUE。参见stream_set_blocking()。

• $eof(bool)-如果流到达文件末尾时为TRUE。注意对于 socket 流甚至当$unread_bytes为非零值时也可以为TRUE。要测定是否有更多数据可读，用feof()替代读取本项目的值。

• $unread_bytes(int)-当前在 PHP 自己的内部缓冲区中的字节数。

  Note:不要在脚本中使用此值。

以下项目是 PHP 4.3 新加的：

• $stream_type(string)-一个描述流底层实现的标注。

• $wrapper_type(string)-一个描述流的分层协议封装实现的标注。更多关于封装协议的信息见支持的协议和封装协议。

• $wrapper_data(mixed)-当前流附加的封装协议数据。更多封装协议及其数据的信息见支持的协议和封装协议。

• $filters(array)-包含有被叠加在当前流的任何过滤器名的数组。过滤器的文档见附录中的可用过滤器列表。

Note:

本函数是 PHP 4.3 引进的，在此版本之前，可以用socket_get_status()来取得前四个项目并且仅能用于基于 socket 的流。

在 PHP 4.3 及以后版本中，socket_get_status()是本函数的别名。

Note:本函数不能作用于通过Socket 扩展库创建的流。

以下项目为 PHP 5.0 新加：

• $mode(string)-对当前流所要求的访问类型（见fopen()中的表格 1）。

• $seekable(bool)-是否可以在当前流中定位。

• $uri(string)-与当前流关联的 URI 或文件名。

In PHP 5.4.24 and 5.4.25, this command does not correctly return the stream blocking status. It always returns ['blocked'] == 1 regardless of the actual blocking mode. A call to stream_set_blocking($stream, 0) will succeed (return TRUE) and subsequent calls to stream_get_contents($stream) will NOT block, even though a call to stream_get_meta_data($stream) will return 'blocked' == 1. Hopefully this will save some people a bunch of debugging time.
See bug report #47918 for more information (http://bugs.php.net/bug.php?id=47918).
Proof:
<?php
$d = array(
  0 => array('pipe', 'r'),
  1 => array('pipe', 'w'),
  2 => array('file', 'error.log', 'a')
);
$p = proc_open('php -S localhost:8000', $d, $pipes);
if (!is_resource($p))  die("proc_open() failed\n");
// Set child's stdout pipe to non-blocking.
if (!stream_set_blocking($pipes[1], 0)) {
  die("stream_set_blocking() failed\n");
}
else {
  echo "Non-blocking mode should be set.\n";
}
// View the status of that same pipe.
// Note that 'blocked' is 1! This appears to be wrong.
print_r(stream_get_meta_data($pipes[1]));
// Try to read something. This will block if in blocking mode.
// If it does not block, stream_set_blocking() worked but
// stream_get_meta_data() is lying about blocking mode.
$data = stream_get_contents($pipes[1]);
echo "data = '$data'\n";
?>
Output:
Non-blocking mode should be set.
Array
(
  [stream_type] => STDIO
  [mode] => r
  [unread_bytes] => 0
  [seekable] =>
  [timed_out] =>
  [blocked] => 1     // << claims to be in blocking mode
  [eof] =>
)
data = ''           // this would never appear if we blocked.

Below is a function I wrote to pull the "Last-Modified" header from a given URL. In PHP version 4.3 and above, it takes advantage of the stream_get_meta_data function, and in older version it uses a conventional GET procedure. On failure to connect to $url, it returns NULL. If the server does not return the Last-Modified header, it returns the current time. All times are returned in PHP's integer format (seconds since epoch).
Use it as so:
$last_modified = stream_last_modified('http://www.php.net/news.rss');
if (!is_null($last_modified))
  if ($last_modified < time() 3600) //Older than an hour
   echo 'URL is older than an hour.';
  else
   echo 'URL is fairly new.';
else
  echo 'Invalid URL!';
function stream_last_modified($url)
{
  if (function_exists('version_compare') && version_compare(phpversion(), '4.3.0') > 0)
  {
   if (!($fp = @fopen($url, 'r')))
     return NULL;
   $meta = stream_get_meta_data($fp);
   for ($j = 0; isset($meta['wrapper_data'][$j]); $j++)
   {
     if (strstr(strtolower($meta['wrapper_data'][$j]), 'last-modified'))
     {
      $modtime = substr($meta['wrapper_data'][$j], 15);
      break;
     }
   }
   fclose($fp);
  }
  else
  {
   $parts = parse_url($url);
   $host = $parts['host'];
   $path = $parts['path'];
   if (!($fp = @fsockopen($host, 80)))
     return NULL;
   $req = "HEAD $path HTTP/1.0\r\nUser-Agent: PHP/".phpversion()."\r\nHost: $host:80\r\nAccept: */*\r\n\r\n";
   fputs($fp, $req);
   while (!feof($fp))
   {
     $str = fgets($fp, 4096);
     if (strstr(strtolower($str), 'last-modified'))
     {
      $modtime = substr($str, 15);
      break;
     }
   }
   fclose($fp);
 }
  return isset($modtime) ? strtotime($modtime) : time();
}

here is just an example how to read out all meta data.
how ever I found out that the "seekable"-entry doesn't exist in most of the streaming media files.
   if (!($fp = @fopen($url, 'r')))
     return NULL;
   $meta = stream_get_meta_data($fp);
   
     foreach(array_keys($meta) as $h){
       $v = $meta[$h];
       echo "".$h.": ".$v."<br/>";
       if(is_array($v)){
         foreach(array_keys($v) as $hh){
           $vv = $v[$hh];
           echo "_".$hh.": ".$vv."<br/>";
         }
       }
     }
   fclose($fp);

Apparently, custom wrappers are always seekable.