Question

I have a PHP function below that is used for a command line tool for optimizing images, in the function below it is running ImageMagick on all files passed to it and getting the file extension.

I have only tested it on actual image files until tonight. I tested on a folder with images and other files mixed in.

The result is an error like this…

identify.exe: no decode delegate for this image format  
`E:\Server\img\testfiles\archive.php' @ error/constitute.c/ReadImage/532.

Now I know it is kind of hard to filter the non-image files out when this function is specifically for the purpose of determining that value….But is there a better way that I can handle this situation, if a non-image file is passed through my program to this function, can I suppress the errors or avoid them from happening?

The function…

/**
 * is_image 
 * @param mixed $file_path 
 * @static
 * @access public
 * @return void
 */
public static function is_image($file_path)
{
    if (!file_exists($file_path)) {
        throw new FileNotFoundException("File or path not found: " . $file_path);
    }
    $types = array("gif", "png", "gifgif", "jpg", "jpeg", "bmp");

    //exec("/usr/bin/identify -quiet -format \"%m\" $file_path", $return, $error);
    $imagemagick = self::$program_paths['imagemagick'] . '\identify';
    exec($imagemagick . ' -quiet -format %m ' . $file_path, $return, $error);

    $type = ($error === 0) ? mb_strtolower($return[0]) : "";
    if ($error == 1) {
        return false;
    }
    if (substr($type, 0, 6) === "gifgif") {
        $type = "gifgif";
    }
    return in_array($type, $types);
}

Answer 1

Use the fileinfo functions to determine whether or not it’s an image first.