Question

I have a script to resize an uploaded image, but when I use it, it just returns a black square. All error messages are pointing at this function:

function resizeImage($image,$width,$height,$scale) {
    $newImageWidth = ceil($width * $scale);
    $newImageHeight = ceil($height * $scale);
    $newImage = imagecreatetruecolor($newImageWidth,$newImageHeight);
    $source = imagecreatefromjpeg($image);
    imagecopyresampled($newImage,$source,0,0,0,0,$newImageWidth,$newImageHeight,$width,$height);
    imagejpeg($newImage,$image,90);
    chmod($image, 0777);
    return $image;
}

My error logs:

PHP Warning:  imagecreatefromjpeg() [<a href='function.imagecreatefromjpeg'>function.imagecreatefromjpeg</a>]: gd-jpeg: JPEG library reports unrecoverable error
PHP Warning:  imagecreatefromjpeg() [<a href='function.imagecreatefromjpeg'>function.imagecreatefromjpeg</a>]: 'img/[hidden].jpg' is not a valid JPEG file
PHP Warning:  imagecopyresampled(): supplied argument is not a valid Image resource

Answer 1

According to Marc B’s answer you could probably make a check if the file is a JPG file. (JPEG, JPG, jpg, jpeg extensions).

it could be something like:

$file = explode(".", $_POST['file']);
$file_ext = $file[count($file)]; // Get the last thing in the array - in this way the filename can containg dots (.)
$allowed_ext = array('jpg', 'JPG', 'jpeg', 'jpg');

if( in_array($file_ext, $allowed_ext )
{
    // The code for creating the image here.
}