如何输出PHP文件打开失败的原因

发布于 2024-07-29 21:37:02 字数 339 浏览 4 评论 0原文

我正在尝试调试一个巨大的、过时的（大约 2001 年）PHP Web 服务，但遇到文件打开失败的情况。 fopen 调用位于包含的模块中，调用者正在记录文件无法打开，但没有记录任何原因。

实际执行打开操作的代码是：

  // Read the file
  if (!($fp = @fopen($fileName, 'rb'))) {
    $errStr = "Failed to open '{$fileName}' for read.";
    break; // try-block
  }

How can I find why fopen failed?

原文

I'm trying to debug a huge, antiquated (circa 2001) PHP web service and I'm encountering file open failures. The fopen call is in an included module, the caller is logging that the file could not be opened but no reason is being logged.

The code that actually does the open is:

  // Read the file
  if (!($fp = @fopen($fileName, 'rb'))) {
    $errStr = "Failed to open '{$fileName}' for read.";
    break; // try-block
  }

How can I find out why fopen failed?

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捶死心动 2024-08-05 21:37:04

删除错误抑制器。

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始于初秋 2024-08-05 21:37:04

关于 @ 运算符，已经给出了很好的答案，但这里是更多信息可能对您或其他人有用：

如果出于调试目的，您需要禁用 @ 运算符，您可以安装 scream 扩展 -- 另请参阅手册 -- 当您维护某种设计/编码不佳的旧应用程序时，这非常有用 ^^
取决于您的 PHP 配置（如果 track_errors 选项已激活），您也许可以使用 $ php_errormsg 获取最后一条错误消息。

考虑这段代码：

// This file doesn't exist
if (!@fopen('/tmp/non-existant-file.txt', 'r')) {
    var_dump($php_errormsg);
}

// My Apache server doesn't have the right to read this file
if (!@fopen('/tmp/vboxdrv-Module.symvers', 'w')) {
    var_dump($php_errormsg);
}

你会得到这样的：

string 'fopen(/tmp/non-existant-file.txt) [<a href='function.fopen'>function.fopen</a>]: failed to open stream: No such file or directory' (length=129)

string 'fopen(/tmp/vboxdrv-Module.symvers) [<a href='function.fopen'>function.fopen</a>]: failed to open stream: Permission denied' (length=122)

所以，真实的，有用的，有意义的错误消息;-)

Great answers have already been given, about the @ operator, but here's a couple of more informations that could be useful, either to you or someone else :

If, for debugging purposes, you need the disable the @ operator, you can install the scream extension -- see also the manual -- which is really useful when you're maintaining some kind of old application not well designed / coded ^^
Depending on your PHP configuation (if the track_errors option is activated), you might be able to use $php_errormsg to get the last error message.

Considering this piece of code :

// This file doesn't exist
if (!@fopen('/tmp/non-existant-file.txt', 'r')) {
    var_dump($php_errormsg);
}

// My Apache server doesn't have the right to read this file
if (!@fopen('/tmp/vboxdrv-Module.symvers', 'w')) {
    var_dump($php_errormsg);
}

You would get this :

string 'fopen(/tmp/non-existant-file.txt) [<a href='function.fopen'>function.fopen</a>]: failed to open stream: No such file or directory' (length=129)

string 'fopen(/tmp/vboxdrv-Module.symvers) [<a href='function.fopen'>function.fopen</a>]: failed to open stream: Permission denied' (length=122)

So, real, useful, meaningful, error messages ;-)

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