PHP输出缓冲，由ob_gzhandler引起的内容编码错误? [英] PHP Output buffering, Content Encoding Error caused by ob_gzhandler?

问题描述

任何人都可以解释为什么我收到以下错误吗?

Can anyone explain why I am receiving the following error?

在代码中，如果echo $gz;被注释掉，我不会收到任何错误(但也不会输出！)，如果不是，我会收到(从Firefox)，

In the code, if the echo $gz; is commented out I receive no error (but also no output!), if it isn't I get (from Firefox),

内容编码错误

您的页面 试图查看无法显示 因为它使用了无效或 不支持的压缩形式.

The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression.

---

感谢您的帮助，下面是代码:

---

Thanks for your help, here's the code:

ob_start('ob_gzhandler') OR ob_start();
echo 'eh?';
$gz = ob_get_clean();
echo $gz;

推荐答案

应用程序的输出应仅包含一种输出编码.如果您有多个块的编码方式不同，那么浏览器将得到无法使用的结果.因此出现编码错误.

The output of your application should only contain one output encoding. If you have multiple chunks that are encoded differently, then the browser will get a result that it is impossible to work with. Hence the encoding error.

Kohana本身已经使用了输出缓冲区.如果要将其与ob_gzhandler输出缓冲区结合使用，则需要在kohana初始化自己的缓冲区之前启动缓冲区.那是因为输出缓冲区是可堆叠的.当kohana完成输出缓冲后，您的将应用:

Kohana itself makes already use of the output buffer. If you want to combine that with your ob_gzhandler output buffer, you need to start your buffer before kohana initialized it's own. That's because output buffer are stackable. When kohana has finished it's output buffering, yours will apply:

ob_start('ob_gzhandler'); # your buffer:
   ob_starts and ends by kohana

因此，每当kohana完成某些输出时，这些块都将传递到您的输出回调中( ob_gzhandler() )，并将进行gz编码.

So whenever kohana has done some output, these chunks will get passed on into your output callback (ob_gzhandler()) and will be gz-encoded.

然后，浏览器应该只获取gz编码的数据，因为它是最顶层的输出缓冲区.

The browser should then only get gz-encoded data as it was the output buffer at the topmost level.

如果使用ob_start('ob_gzhandler')来让PHP处理压缩，然后又使用echo ob_get_clean()，则将创建不可靠的输出.这与压缩与输出缓冲的工作方式有关:

If you make use of ob_start('ob_gzhandler') to let PHP deal with the compression and you then echo ob_get_clean(), you will create an unreliable output. That's related to how the compression togther with output buffering works:

PHP将缓冲输出的块.这意味着，PHP开始压缩输出，但保留一些字节以继续压缩.因此，ob_get_clean()返回缓冲区的当前压缩部分.通常结果是不完整的.

PHP will buffer chunks of output. That means, PHP starts to compress the output but keeps some bytes to continue compressing. So ob_get_clean() returns the so-far compressed part of the buffer. Often that result is not complete.

要解决此问题，请先刷新缓冲区:

To deal with that, flush the buffer first:

ob_start('ob_gzhandler') OR ob_start();
echo 'eh?';
ob_flush();
$gz = ob_get_clean();
echo $gz;

并确保之后没有其他输出.

And ensure you don't have any more output after that.

如果您要让PHP到达脚本的末尾，则可以解决此问题:刷新并输出.

If you would have PHP reached the end of your script, it would have taken care of that: Flushing and outputting.

现在，您需要手动调用ob_flush()，以使PHP通过回调显式推送缓冲区.

Now you need to manually call ob_flush() to explicitly make PHP push the buffer through the callbacks.

由于firefox将返回错误，因此需要另一个工具来检查导致编码错误的原因.您可以使用 curl 来跟踪正在发生的事情:

As firefox will return an error, another tool to inspect what's causing the encoding error is needed. You can use curl to track what's going on:

curl --compress -i URL

在显示所有响应标头和未编码的正文时，将请求启用了压缩的URL.这是必要的，因为PHP会根据请求标头透明地启用/禁用ob_gzhandler回调的压缩.

Will request the URL with compression enabled while displaying all response headers and the body unencoded. This is necessary as PHP transparently enables / disables compression of the ob_gzhandler callback based on request headers.

响应还显示PHP也将设置所需的响应头.因此，无需手动指定它们.这甚至是危险的，因为仅通过调用ob_start('ob_gzhandler')您就无法确定是否启用了压缩.

A response also shows that PHP will set the needed response headers as well. So no need to specify them manually. That would be even dangerously, because only by calling ob_start('ob_gzhandler') you can not say if compression is enabled or not.

如果压缩失败，则curl将给出错误描述，但不会显示主体.

In case the compression is broken, curl will give an error description but would not display the body.

以下是这样的卷曲错误消息，它是由错误的php脚本生成的输出不完整而引起的:

Following is such a curl error message provoked with an incompletely generated output by a faulty php script:

HTTP/1.1 200 OK
X-Powered-By: PHP/5.3.6
Content-Encoding: gzip
...

curl: (23) Error while processing content unencoding: invalid code lengths set

通过添加--raw开关，您甚至可以在原始响应主体中达到顶峰:

By adding the --raw switch, you can even peak into the raw response body:

curl --compress --raw -i URL

这可能会给人留下深刻的印象，例如身体中未压缩的部分.

That can give an impression what's going wrong, like uncompressed parts within the body.

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