It is important to know that stream_get_contents behaves differently with different versions of PHP. Consider the following
<?php
$handle = fopen('file', 'w+'); // truncate + attempt to create
fwrite($handle, '12345'); // file position > 0
rewind($handle); // position = 0
$content = stream_get_contents($handle); // file position = 0 in PHP 5.1.6, file position > 0 in PHP 5.2.17!
fwrite($handle, '6789');
fclose($handle);
/**
*
* 'file' content
*
* PHP 5.1.6:
* 67895
*
* PHP 5.2.17:
* 123456789
*
*/
?>
As a result, stream_get_contents() affects file position in 5.1, and do not affect file position in 5.2 or better.
stream_get_contents
(PHP 5, PHP 7, PHP 8)
stream_get_contents — 读取资源流到一个字符串
说明
与 file_get_contents() 一样，但是
stream_get_contents() 是对一个已经打开的资源流进行操作，并将其内容写入一个字符串返回。
返回的内容取决于 length 字节长度和 offset 指定的起始位置。
参数
返回值
返回一个字符串 或者在失败时返回 false.
更新日志
| 版本 | 说明 |
|---|---|
| 8.0.0 |
现在 length 可以为 null。
|
示例
示例 #1 stream_get_contents() 例子
<?php
if ($stream = fopen('http://www.example.com', 'r')) {
// 打印从开始的位置偏移 10 个字节后页面的所有内容
echo stream_get_contents($stream, -1, 10);
fclose($stream);
}
if ($stream = fopen('http://www.example.net', 'r')) {
// 打印前 5 个字节
echo stream_get_contents($stream, 5);
fclose($stream);
}
?>注释
注意: 此函数可安全用于二进制对象。
注意:
当指定一个非
null的length值时，即使实际内容要短得多，该函数也会立即分配一个内部缓冲区，其大小为指定的长度。
add a note
User Contributed Notes 4 notes
vasiliy at hotger dot com ¶
12 years ago
clarck dot smith at gmail dot com ¶
13 years ago
In that case when stream_get_contents/fread/fgets or other stream reading functions block indefinitely your script because they don't reached the limit of bytes to read use the socket_get_meta_data function to figure out the number of the bytes to read. It returns an array that contains a key named 'unread_bytes' and then pass that number to your favourite stream reading functions second parameter to read from the stream.
Maybe a good workaround to use the stream_select function, and set the socket to non-blocking mode with the use of stream_set_blocking($stream, 0). In this case the socket reading functions work properly.
Cheers, Ervin
m rahman ¶
13 years ago
When omitting the parameter $maxlength, any received bytes are stacked up until the underlying stream is not readable anymore, the the function returns that stack in one piece.
fearpro13 at gmail dot com ¶
1 year ago
It states that $length parameter which value is null is intended to read all remaining contents from $stream
However, example listed under docs uses -1 as $length parameter to achieve such behavior
Recently i had to start few commands from php7.4 and read content from them, proc_open was used to create processes.
Both output[1] and error[2] pipes were set to non-blocking mode. For some unknown reason sometimes process error[2] channel was available, sometimes not(it was empty string).
After some investigation it was found that stream_get_contents works just great with -1 as a $length value instead of null if you are trying to get all remaining buffer.
