Trying to suppress errors for file_get_contents ONLY but neither of these methods work.. is there another way?
$data=#file_get_contents('invalid');
try { $data=#file_get_contents('invalid'); } catch($e Exception) { echo "error"; }
Fix problems, don't hide them.
Errors, Warnings, and Notices, should be fixed rather hidden ("supressed").
For your case, all you need do is a check for is_readable.
function getFile(string $filename = 'invalid')
{
if (!is_readable($filename)) {
return false;
}
return file_get_contents($filename);
}
$fileContents = getFile('maybevalid');
if (false !== $fileContents) {
// success
} else {
// couldn't read
}
Related
I would like to use the following to detect if a file exists, however there is a warning triggered when when this is the case. It works fine when file_get_contents does not return false.
$nothing = "http://www.google.com/bababababa.doc";
if (false === file_get_contents($nothing,0,null,0,1)) {
echo "File Not Found";
} else {
echo "File Found";
}
First, I'll assume that you only want to hide this error from your logs, because of course you have display_errors turned off on a production server.
You could just hide your errors away with the # error suppression operator, but that's a bad road to start down. Instead you want to define an error handler:
<?php
// define the custom handler that just returns true for everything
$handler = function ($err, $msg, $file, $line, $ctx) {return true;}
$nothing = "http://www.google.com/bababababa.doc";
// update the error handler for warnings, keep the old value for later
$old_handler = set_error_handler($handler, E_WARNING);
// run the code
$result = file_get_contents($nothing);
// go back to normal error handling
set_error_handler($old_handler);
if (false === $result) {
echo "File Not Found";
} else {
echo "File Found";
}
Code:
if(isset($_POST['update_avatar'])) {
$url = $_POST['avatar'];
$info = getimagesize($url);
if(isset($info['name'])) {
echo "Exists";
} else {
echo "Error";
}
}
How can I avoid getting PHP errors when the user types an invalid URL, random piece of text or invalid image URL etc?
Use exception handling. Place your critical code into a try..catch block. You can find more information here.
If there's an error, getimagesize returns false, so test for that. And to suppress error messages from a function, put # before it:
$info = #getimagesize($url);
if (!$info) {
echo "Error";
} else {
// Process the image
}
Disclaimer; I'm fully aware of the pitfalls and "evils" of eval, including but not limited to: performance issues, security, portability etc.
The problem
Reading the PHP manual on eval...
eval() returns NULL unless return is
called in the evaluated code, in which
case the value passed to return is
returned. If there is a parse error in
the evaluated code, eval() returns
FALSE and execution of the following
code continues normally. It is not
possible to catch a parse error in
eval() using set_error_handler().
In short, no error capture except returning false which is very helpful, but I'm sur eI could do way better!
The reason
A part of the site's functionality I'm working on relies on executing expressions. I'd like not to pass through the path of sandbox or execution modules, so I've ended using eval. Before you shout "what if the client turned bad?!" know that the client is pretty much trusted; he wouldn't want to break his own site, and anyone getting access to this functionality pretty much owns the server, regardless of eval.
The client knows about expressions like in Excel, and it isn't a problem explaining the little differences, however, having some form of warning is pretty much standard functionality.
This is what I have so far:
define('CR',chr(13));
define('LF',chr(10));
function test($cond=''){
$cond=trim($cond);
if($cond=='')return 'Success (condition was empty).'; $result=false;
$cond='$result = '.str_replace(array(CR,LF),' ',$cond).';';
try {
$success=eval($cond);
if($success===false)return 'Error: could not run expression.';
return 'Success (condition return '.($result?'true':'false').').';
}catch(Exception $e){
return 'Error: exception '.get_class($e).', '.$e->getMessage().'.';
}
}
Notes
The function returns a message string in any event
The code expression should be a single-line piece of PHP, without PHP tags and without an ending semicolon
New lines are converted to spaces
A variable is added to contain the result (expression should return either true or false, and in order not to conflict with eval's return, a temp variable is used.)
So, what would you add to further aide the user? Is there any further parsing functions which might better pinpoint possible errors/issues?
Chris.
Since PHP 7 eval() will generate a ParseError exception for syntax errors:
try {
$result = eval($code);
} catch (ParseError $e) {
// Report error somehow
}
In PHP 5 eval() will generate a parse error, which is special-cased to not abort execution (as parse errors would usually do). However, it also cannot be caught through an error handler. A possibility is to catch the printed error message, assuming that display_errors=1:
ob_start();
$result = eval($code);
if ('' !== $error = ob_get_clean()) {
// Report error somehow
}
I've found a good alternative/answer to my question.
First of, let me start by saying that nikic's suggestion works when I set error_reporting(E_ALL); notices are shown in PHP output, and thanks to OB, they can be captured.
Next, I've found this very useful code:
/**
* Check the syntax of some PHP code.
* #param string $code PHP code to check.
* #return boolean|array If false, then check was successful, otherwise an array(message,line) of errors is returned.
*/
function php_syntax_error($code){
if(!defined("CR"))
define("CR","\r");
if(!defined("LF"))
define("LF","\n") ;
if(!defined("CRLF"))
define("CRLF","\r\n") ;
$braces=0;
$inString=0;
foreach (token_get_all('<?php ' . $code) as $token) {
if (is_array($token)) {
switch ($token[0]) {
case T_CURLY_OPEN:
case T_DOLLAR_OPEN_CURLY_BRACES:
case T_START_HEREDOC: ++$inString; break;
case T_END_HEREDOC: --$inString; break;
}
} else if ($inString & 1) {
switch ($token) {
case '`': case '\'':
case '"': --$inString; break;
}
} else {
switch ($token) {
case '`': case '\'':
case '"': ++$inString; break;
case '{': ++$braces; break;
case '}':
if ($inString) {
--$inString;
} else {
--$braces;
if ($braces < 0) break 2;
}
break;
}
}
}
$inString = #ini_set('log_errors', false);
$token = #ini_set('display_errors', true);
ob_start();
$code = substr($code, strlen('<?php '));
$braces || $code = "if(0){{$code}\n}";
if (eval($code) === false) {
if ($braces) {
$braces = PHP_INT_MAX;
} else {
false !== strpos($code,CR) && $code = strtr(str_replace(CRLF,LF,$code),CR,LF);
$braces = substr_count($code,LF);
}
$code = ob_get_clean();
$code = strip_tags($code);
if (preg_match("'syntax error, (.+) in .+ on line (\d+)$'s", $code, $code)) {
$code[2] = (int) $code[2];
$code = $code[2] <= $braces
? array($code[1], $code[2])
: array('unexpected $end' . substr($code[1], 14), $braces);
} else $code = array('syntax error', 0);
} else {
ob_end_clean();
$code = false;
}
#ini_set('display_errors', $token);
#ini_set('log_errors', $inString);
return $code;
}
Seems it easily does exactly what I need (yay)!
How to test for parse errors inside eval():
$result = #eval($evalcode . "; return true;");
If $result == false, $evalcode has a parse error and does not execute the 'return true' part. Obviously $evalcode must not return itself something, but with this trick you can test for parse errors in expressions effectively...
Good news: As of PHP 7, eval() now* throws a ParseError exception if the evaluated code is invalid:
try
{
eval("Oops :-o");
}
catch (ParseError $err)
{
echo "YAY! ERROR CAPTURED: $err";
}
* Well, for quite a while then... ;)
I think that best solution is
try {
eval(/* ... */);
} catch (Throwable $t) {
//...
}
It catches every error and exception, including Call to undefined function etc
You can also try something like this:
$filePath = '/tmp/tmp_eval'.mt_rand();
file_put_contents($filePath, $evalCode);
register_shutdown_function('unlink', $filePath);
require($filePath);
So any errors in $evalCode will be handled by errors handler.
I was wondering if there was a way to prevent a while loop from prematurely erroring out or terminating. I've thrown a try/catch in there and it seems to keep terminating. (As to the cause why it's terminating, I'm still debugging).
$stomp = $this->stomp;
if(isset($queue) && strlen($queue) > 0) {
error_log('Starting Monitor for: '.$queue);
$stomp->subscribe($queue);
while(true) {
$frame = $stomp->readFrame();
if ($frame != null) {
// Callback must be an array: array('Class','Method);
if(is_array($callback) && count($callback) == 2) {
try {
$body = $frame->body;
$callFunct = call_user_func_array($callback,array($body,$arguments));
$stomp->ack($frame);
} catch(StompException $e) {
$msg = 'Stomp Monitor readFrame() Callback Fail: '.$e->getMessage();
$this->context->reportError('STOMP',array('errorDetails'=>$msg));
}
} else {
error_log('Invalid Stomp Callback');
}
}
}
} `
Thanks,
Steve
There's nothing to break out of the loop, so while(true) will carry on until it hits a timeout or some form of error condition. As a fallback, it's worth setting either a break to break out of the loop on condition, or use a while condition that you can set to false;
while (true) {
// do some things
break;
}
or
$x = true;
while ($x) {
// do some things
$x = false;
}
that way, exit from the loop is under your control
However, timeouts and other fatal errors still terminate the script as normal
If your code is breaking out of the while loop, you should be seeing some error, unless you have an error handler suppressing it
when I'm trying to getimagesize($img) and the image doesn't exist, I get an error. I don't want to first check whether the file exists, just handle the error.
I'm not sure how try catch works, but I want to do something like:
try: getimagesize($img) $works = true
catch: $works = flase
Like you said, if used on a non-existing file, getimagesize generates a warning :
This code :
if ($data = getimagesize('not-existing.png')) {
echo "OK";
} else {
echo "NOT OK";
}
will get you a
Warning: getimagesize(not-existing.png) [function.getimagesize]:
failed to open stream: No such file or directory
A solution would be to use the # operator, to mask that error :
if ($data = #getimagesize('not-existing.png')) {
echo "OK";
} else {
echo "NOT OK";
}
As the file doesn't exist, $data will still be false ; but no warning will be displayed.
Another solution would be to check if the file exists, before using getimagesize ; something like this would do :
if (file_exists('not-existing.png') &&
($data = getimagesize('not-existing.png'))
) {
echo "OK";
} else {
echo "NOT OK";
}
If the file doesn't exist, getimagesize is not called -- which means no warning
Still, this solution is not the one you should use for images that are on another server, and accessed via HTTP (if you are in this case), as it'll mean two requests to the remote server.
For local images, that would be quite OK, I suppose ; only problem I see is the notice generated when there is a read error not being masked.
Finally :
I would allow errors to be displayed on your developpement server,
And would not display those on your production server -- see display_errors, about that ;-)
Call me a dirty hacker zombie who will be going to hell, but I usually get around this problem by catching the warning output into an output buffer, and then checking the buffer. Try this:
ob_start();
$data = getimagesize('not-existing.png');
$resize_warning = ob_get_clean();
if(!empty($resize_warning)) {
print "NOT OK";
# We could even print out the warning here, just as PHP would do
print "$resize_warning";
} else {
print "OK"
}
Like I said, not the way to get a cozy place in programmer's heaven, but when it comes to dysfunctional error handling, a man has to do what a man has to do.
I'm sorry that raise such old topic. Recently encountered a similar problem and found this topic instead a solution. For religious reasons I think that '#' is bad decision. And then I found another solution, it looks something like this:
function exception_error_handler( $errno, $errstr, $errfile, $errline ) {
throw new Exception($errstr);
}
set_error_handler("exception_error_handler");
try {
$imageinfo = getimagesize($image_url);
} catch (Exception $e) {
$imageinfo = false;
}
This solution has worked for me.
try {
if (url_exists ($photoUrl) && is_array (getimagesize ($photoUrl)))
{
return $photoUrl;
}
} catch (\Exception $e) { return ''; }
Simple and working solution based on other answers:
$img_url = "not-existing.jpg";
if ( is_file($img_url) && is_array($img_size = getimagesize($img_url)) ) {
print_r($img_size);
echo "OK";
} else {
echo "NOT OK";
}