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Fix error handling in Stream::getContents() #252

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merged 1 commit into from
Nov 13, 2023
Merged

Fix error handling in Stream::getContents() #252

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16 changes: 12 additions & 4 deletions src/Stream.php
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Original file line number Diff line number Diff line change
Expand Up @@ -260,11 +260,19 @@ public function getContents(): string
throw new \RuntimeException('Stream is detached');
}

if (false === $contents = @\stream_get_contents($this->stream)) {
throw new \RuntimeException('Unable to read stream contents: ' . (\error_get_last()['message'] ?? ''));
$exception = null;

\set_error_handler(static function ($type, $message) use (&$exception) {
throw $exception = new \RuntimeException('Unable to read stream contents: ' . $message);
});

try {
return \stream_get_contents($this->stream);
} catch (\Throwable $e) {
throw $e === $exception ? $e : new \RuntimeException('Unable to read stream contents: ' . $e->getMessage(), 0, $e);
} finally {
\restore_error_handler();
Comment on lines +265 to +274
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I don't understand how setting an error handler fixes this issue when other tools and even Guzzle check for a false return. Nothing about this code seems like it will actually solve the issue, because the return value of stream_get_contents is not being checked.

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@nicolas-grekas nicolas-grekas Nov 13, 2023 •
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When stream_get_contents returns false, it first always triggers a PHP warning. Since we catch those in the error handler, the function will never really return false.

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Considering that such behavior is not documented, why take that approach over checking the return value is false? Every other fix I've looked at around this issue is doing a $ret === false check...

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That would be dead code. Many things are not documented, especially regarding error handling. Returning false always means an error, and PHP has to trigger a warning to tell about the error so this is still solid IMHO. Of course, feel free to add the check on your side if you're not comfortable with the logic.

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That would be dead code.

Are you saying that checking === false does not work, or are you saying that this monkey patching with the error handler identifies the impending return false more quickly?

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@odan odan Nov 13, 2023 •
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I have a question to understand this patch a little better.
Why do you declare an "$exception" variable for the Exception although the catch block gets the same Exception instance? Is there some PHP specific logic / behavior behind this (that is not documented)?

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If we remove this check, we would always wrap the exception thrown in the error handler in another exception. This check allows removing this needless wrapping exception.

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@odan odan Nov 13, 2023 •
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Ok, thanks. Then my next question is, why not move the set_error_handler into the try-block to handle that (scope) in the same place?

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if set_error_handler fails for any reasons, we don't want restore_error_handler to be called

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And in PHP, try/catch does not create a scope anyway.

}

return $contents;
}

/**
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