I need to catch some warnings being thrown from some php native functions and then handle them.
Specifically:
array dns_get_record ( string $hostnam
Set and restore error handler
One possibility is to set your own error handler before the call and restore the previous error handler later with restore_error_handler()
.
set_error_handler(function() { /* ignore errors */ });
dns_get_record();
restore_error_handler();
You could build on this idea and write a re-usable error handler that logs the errors for you.
set_error_handler([$logger, 'onSilencedError']);
dns_get_record();
restore_error_handler();
Turning errors into exceptions
You can use set_error_handler()
and the ErrorException
class to turn all php errors into exceptions.
set_error_handler(function($errno, $errstr, $errfile, $errline, $errcontext) {
// error was suppressed with the @-operator
if (0 === error_reporting()) {
return false;
}
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
try {
dns_get_record();
} catch (ErrorException $e) {
// ...
}
The important thing to note when using your own error handler is that it will bypass the error_reporting
setting and pass all errors (notices, warnings, etc.) to your error handler. You can set a second argument on set_error_handler()
to define which error types you want to receive, or access the current setting using ... = error_reporting()
inside the error handler.
Suppressing the warning
Another possibility is to suppress the call with the @ operator and check the return value of dns_get_record()
afterwards. But I'd advise against this as errors/warnings are triggered to be handled, not to be suppressed.
Normaly you should never use @ unless this is the only solution. In that specific case the function dns_check_record should be use first to know if the record exists.
Combining these lines of code around a file_get_contents()
call to an external url helped me handle warnings like "failed to open stream: Connection timed out" much better:
set_error_handler(function ($err_severity, $err_msg, $err_file, $err_line, array $err_context)
{
throw new ErrorException( $err_msg, 0, $err_severity, $err_file, $err_line );
}, E_WARNING);
try {
$iResult = file_get_contents($sUrl);
} catch (Exception $e) {
$this->sErrorMsg = $e->getMessage();
}
restore_error_handler();
This solution works within object context, too. You could use it in a function:
public function myContentGetter($sUrl)
{
... code above ...
return $iResult;
}
The solution that really works turned out to be setting simple error handler with E_WARNING
parameter, like so:
set_error_handler("warning_handler", E_WARNING);
dns_get_record(...)
restore_error_handler();
function warning_handler($errno, $errstr) {
// do something
}
You should probably try to get rid of the warning completely, but if that's not possible, you can prepend the call with @ (i.e. @dns_get_record(...)) and then use any information you can get to figure out if the warning happened or not.