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Last updated: Fri, 10 Oct 2008

php_check_syntax

(PHP 5 <= 5.0.4)

php_check_syntax — Check the PHP syntax of (and execute) the specified file

Description

bool php_check_syntax ( string $filename [, string &$error_message ] )

Performs a syntax (lint) check on the specified filename testing for scripting errors.

This is similar to using php -l from the commandline except that this function will execute (but not output) the checked filename .

For example, if a function is defined in filename , this defined function will be available to the file that executed php_check_syntax(), but output from filename will be suppressed.

Note: For technical reasons, this function is deprecated and removed from PHP. Instead, use php -l somefile.php from the commandline.

Parameters

filename: The name of the file being checked.
error_message: If the error_message parameter is used, it will contain the error message generated by the syntax check. error_message is passed by reference.

Return Values

Returns TRUE if the lint check passed, and FALSE if the link check failed or if filename cannot be opened.

ChangeLog

Version	Description
5.0.5	This function was removed from PHP.
5.0.3	Calling exit() after php_check_syntax() resulted in a Segfault.
5.0.1	`error_message` is passed by reference.

Examples

php -l somefile.php

The above example will output something similar to:

PHP Parse error: unexpected T_STRING in /tmp/somefile.php on line 81


Sorry, I'm retarded. I did a little more testing and found big issues. I've fixed them in the following code. This example is now dependant on http://us3.php.net/manual/en/function.token-get-all.php#80335 for a bugfix workaround with token_get_all(); So be sure to include that function in your script when you run this function.



<?php

/**

*    Check Eval

*    Performs a Syntax check without killing the parser (hopefully)

*

*    @params        string        PHP to be evaluated

*    @return        array        Parse error info or true for success

**/

function checkEval( $php )

{

    $evalStr = 'return;';



    # Get the string tokens

    $crack = token_get_all( "<?php\n".$php );

    

    # Drop our manually entered opening tag

    array_shift( $crack );

    token_fix( $crack );

    

    # Check to see how we need to proceed

    # prepare the string for parsing

    if( isset( $crack[0][0] ) &&

        (

            $crack[0][0] === T_CONSTANT_ENCAPSED_STRING ||

            $crack[0][0] === T_STRING ||

            $crack[0][0] === T_OPEN_TAG

        )

    ){

        $evalStr .= '?>';

    }



    # Make sure syntax reporting is on...probably only need E_PARSE...but I'm anal

    $oldErr = error_reporting( E_ALL | E_STRICT );



    # Prevent output

    ob_start();

    eval( $evalStr.$php );

    $evaluput = ob_get_clean();



    # Reset error reporting

    error_reporting( $oldErr );



    # Only do this if there was output

    if( $evaluput !== '' )

    {

        # Strip annoying html tags, in case html reporting is enabled in php.ini

        $evaluput = strip_tags( $evaluput );



        # Fancy Regex to pull the error that killed us

        $pattern    = '/Parse error:\s*syntax error,(.+?)\s+in\s+.+?\s*line\s+(\d+)/';

        $parse_fail    = (bool)preg_match( $pattern, $evaluput, $match );



        # Parse error to report?

        if( $parse_fail === true )

        {

            return array(

                'line'    =>    (int)$match[2],

                'msg'    =>    $match[1]

            );

        }

    }

    return true;

}

?>

alx at inbox dot lv
25-Apr-2008 07:20

2: kevin at metalaxe dot com
Hm.. i think your function didnt work...

try this:
$php = 'asfvsd <? echo \'\'aaa\'; ?> asvsdgb';
checkEval( $php );
it returns actual error... from eval(); and not expected array..

but i liked the idea about return after function.. and pattern of error, thanx :) I will complete my function

kevin at metalaxe dot com
22-Apr-2008 03:43


alx at inbox dot lv says: "Nope guys.. to check the valid php you must do the followed..."

Actually that will fail when anything fatal occurs because the code will actually be executed! :)



nicolas dot grekas+php at gmail dot com says: "I can't find a way to break the dead code sandbox. Who can ?"

Why all the complications just to protect braces? Further, unbalanced braces is something we want to syntaxually check isn't it? Let's make this useful :)



Here's what I've discovered to use without any issues over the years. From nicolas and alx's examples I remodeled it a little bit to hopefully catch any case now. By all means tell me if it is broken in some way :) Remember though that it is ONLY a syntax check!



P.S. I couldn't seem to get this to work properly in CLI interactive even with the function below as separate file include. It appears that the CLI always outputs and that OB doesn't get buffred. Makes no sense...



<?php

/**

*    Check Eval

*    Performs a Syntax check without killing the parser (hopefully)

*

*    @params        string        PHP to be evaluated

*    @return        array        Parse error info or true for success

**/

function checkEval( $php )

{

    $evalStr = 'return;';



    # Get the string tokens

    $crack = token_get_all( $php );



    # Parser tokens to check for

    # we are only checking the first token because anything else

    # would result in an expected syntax error

    $tokens = array( T_OPEN_TAG, T_OPEN_TAG_WITH_ECHO );



    # Check to see how we need to proceed

    # prepare the string for parsing

    if( isset( $crack[0] ) && in_array( $crack[0][0], $tokens, true ) )

        $evalStr .= '?>';



    # Make sure syntax reporting is on...probably only need E_PARSE...but I'm anal

    $oldErr = error_reporting( E_ALL | E_STRICT );



    # Prevent output

    ob_start();

    $test = eval( $evalStr.$php );

    $evaluput = ob_get_clean();



    # Reset error reporting

    error_reporting( $oldErr );



    # Only do this if there was output

    if( $evaluput !== '' )

    {

        # Strip annoying html tags, in case html reporting is enabled in php.ini

        $evaluput = strip_tags( $evaluput );



        # Fancy Regex to pull the error that killed us

        $pattern    = '/Parse error:\s*syntax error,(.+?)\s+in\s+.+?\s*line\s+(\d+)/';

        $parse_fail    = (bool)preg_match( $pattern, $evaluput, $match );



        # Parse error to report?

        if( $parse_fail === true )

        {

            return array(

                'line'    =>    (int)$match[2],

                'msg'    =>    $match[1]

            );

        }

    }

    return true;

}

?>

alx at inbox dot lv
11-Apr-2008 04:38


Nope guys.. to check the valid php you must do the followed:



<?

function checkPHP($source) {

ob_start();

$sowhat = @eval('?>'.$source);

$GLOBALS['sowhat'] = ob_get_contents();

ob_end_clean();

return $sowhat === NULL ? true : false;

}



$source = '

bla bla <?=$foo?> some stuff <?

foreach ($somethins as $somethig) {

 // whatever

}';



if (checkPHP($source)) {

echo 'PHP code is correct';

} else {

echo 'there are errors in your php: '.$GLOBALS['sowhat'];

}

matt dot nospam at pryor dot org dot uk
05-Feb-2008 08:35


While developing an app where I have to include PHP files written by a user, I came across the following problem:



I used "php -l somefile.php" to check the syntax of the file I was about to include and if it passed, I would include it - so far so good. But in some test cases, the file I was including would have other includes/requires inside it. If one of these was invalid, then I would still get the parse error that I was trying to avoid.



I got round it using this:



<?php

    function CheckSyntax($fileName, $checkIncludes = true)

    {

        // If it is not a file or we can't read it throw an exception

        if(!is_file($fileName) || !is_readable($fileName))

            throw new Exception("Cannot read file ".$fileName);

        

        // Sort out the formatting of the filename

        $fileName = realpath($fileName);

        

        // Get the shell output from the syntax check command

        $output = shell_exec('php -l "'.$fileName.'"');

        

        // Try to find the parse error text and chop it off

        $syntaxError = preg_replace("/Errors parsing.*$/", "", $output, -1, $count);

        

        // If the error text above was matched, throw an exception containing the syntax error

        if($count > 0)

            throw new Exception(trim($syntaxError));

        

        // If we are going to check the files includes

        if($checkIncludes)

        {

            foreach(GetIncludes($fileName) as $include)

            {

                // Check the syntax for each include

                CheckSyntax($include);

            }

        }

    }

    

    function GetIncludes($fileName)

    {

        // NOTE that any file coming into this function has already passed the syntax check, so

        // we can assume things like proper line terminations

            

        $includes = array();

        // Get the directory name of the file so we can prepend it to relative paths

        $dir = dirname($fileName);

        

        // Split the contents of $fileName about requires and includes

        // We need to slice off the first element since that is the text up to the first include/require

        $requireSplit = array_slice(preg_split('/require|include/i', file_get_contents($fileName)), 1);

        

        // For each match

        foreach($requireSplit as $string)

        {

            // Substring up to the end of the first line, i.e. the line that the require is on

            $string = substr($string, 0, strpos($string, ";"));

            

            // If the line contains a reference to a variable, then we cannot analyse it

            // so skip this iteration

            if(strpos($string, "$") !== false)

                continue;

            

            // Split the string about single and double quotes

            $quoteSplit = preg_split('/[\'"]/', $string);

            

            // The value of the include is the second element of the array

            // Putting this in an if statement enforces the presence of '' or "" somewhere in the include

            // includes with any kind of run-time variable in have been excluded earlier

            // this just leaves includes with constants in, which we can't do much about

            if($include = $quoteSplit[1])

            {

                // If the path is not absolute, add the dir and separator

                // Then call realpath to chop out extra separators

                if(strpos($include, ':') === FALSE)

                    $include = realpath($dir.DIRECTORY_SEPARATOR.$include);

            

                array_push($includes, $include);

            }

        }

        

        return $includes;

    }

?>



This checks as many of the includes inside the file as it possibly can without executing anything.

nicolas dot grekas+php at gmail dot com
25-Jan-2008 01:16


My previous code was buggy sorry, here is an update (thanks phprockstheworld). I can't find a way to break the dead code sandbox. Who can ?



<?php



function eval_syntax($code)

{

    $braces = 0;

    $inString = 0;



    // We need to know if braces are correctly balanced.

    // This is not trivial due to variable interpolation

    // which occurs in heredoc, backticked and double quoted strings

    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 '"': --$inString; break;

            }

        }

        else

        {

            switch ($token)

            {

            case '`':

            case '"': ++$inString; break;



            case '{': ++$braces; break;

            case '}':

                if ($inString) --$inString;

                else

                {

                    --$braces;

                    if ($braces < 0) return false;

                }



                break;

            }

        }

    }



    if ($braces) return false; // Unbalanced braces would break the eval below

    else

    {

        ob_start(); // Catch potential parse error messages

        $code = eval('if(0){' . $code . '}'); // Put $code in a dead code sandbox to prevent its execution

        ob_end_clean();



        return false !== $code;

    }

}

oyejorge at googlesemail dot com
12-Jan-2008 02:51


Nicolas' code is great! Just another check to make sure a } doesn't come before { and it's much more secure. Still wouldn't trust just anyones code with it though.



<?php

    function eval_syntax($code){

        $b = 0;

        

        foreach (token_get_all($code) as $token){

            if('{' == $token){

                ++$b;

            }elseif('}' == $token){

                --$b;

                if( $b < 0 ){

                    return false; // } came before {

                }

            }

        }

        

        // Unbalanced braces would break the eval below

        if( $b !== 0){

            return false;

        }

        // Catch potential parse error messages

        ob_start();

        $code = eval('if(0){' . $code . '}'); // Put $code in a dead code sandbox to prevent its execution

        ob_end_clean();

        

        return false !== $code;

    }

phprockstheworld at gmail dot com
20-Dec-2007 08:57


The code posted by nicolas dot grekas is very clever but don't use it on anything other than code you know is safe because if the code was "} delete_everything(); {" it could do anything it likes.



Just wanted to warn anyone incase they were going to put it on their website to check PHP.

nicolas dot grekas+php at gmail dot com
24-Aug-2007 07:23


This detects parse errors without executing the code:



<?php



function eval_syntax($code)

{

    $b = 0;



    foreach (token_get_all($code) as $token)

    {

             if ('{' == $token) ++$b;

        else if ('}' == $token) --$b;

    }



    if ($b) return false; // Unbalanced braces would break the eval below

    else

    {

        ob_start(); // Catch potential parse error messages

        $code = eval('if(0){' . $code . '}'); // Put $code in a dead code sandbox to prevent its execution

        ob_end_clean();



        return false !== $code;

    }

}



?>

Quis at IVEGOTspamENOUGHomicidio dot nl
24-Mar-2007 07:42


<?PHP

// Think about shell-command escaping if you`re using user-input

function php_check_syntax($file,&$error) {

  exec("php -l $file",$error,$code);

  if($code==0)

    return true;

  return false;

}

?>



Note: This is UNIX

Note: If your environment-variable PATH is not set correctly, you will need to insert the path to php (like /usr/local/bin/php)

phpdoc at michaeldouma dot com
15-Feb-2005 11:38


PROBLEM: Your page is blank, or you can not define any functions in an include. 



As mentioned below, the php_check_syntax function will include your file. So you may not be able to include it again. If you have an include later in your code, and you define any functions, you will get an error, or in some cases a blank page.

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