How do l make a function that validates and image - php

Question

l have used the function below but its allowing even pdf to be uploaded
and its not checking if its an image
function image_allowed($file_extn) {
$allowed = array('jpg','jpeg','gif','png');
$file_name = $_FILES['image']['image_name'];
$file_extn = strtolower(end(explode('.', $file_name)));
$file_temp = $_FILES['image']['tmp_name'];
if (in_array($allowed,$file_extn )=== true){
return true;
}else {
return false;
}
and l checked using the code below and l dont know were lam getting it wrong
if (image_allowed($_POST['image'])=== true) {
$errors[] = ' images only are allowed.';
and l would love to know any checks that l might have ommited here

Answer 1

While comparing extensions might do the trick, it's not very safe as it easy to fake an extension. I would advise to check the mime types of the files.
Option 1 - using finfo
$finfo = finfo_open(FILEINFO_MIME_TYPE);
$file_type = finfo_file($finfo, "image.gif");
finfo_close($finfo);
Output for this case: image/gif
Just remember to change your $allowed array accordingly.
You can see a list of possible mime types for images at wikipedia.
Option 2 - Using exif-imagetype
exif_imagetype('image.gif')
Just notice that in that case your $allowed array should contain constants that represent possible return values. (For further information look at the manual - link above)

Answer 2

You can check your image type using pathinfo (http://php.net/manual/en/function.pathinfo.php):
$path_parts = pathinfo('/your/image/path/');
echo $path_parts['extension']; // Your extension...
In your function code:
function image_allowed($imagePath) {
$allowed = array('jpg','jpeg','gif','png');
$myExtension = pathinfo($imagePath);
if(in_array($myExtension['extension'], $allowed)
return true;
else
return false;
}

Answer 3

You need to use like this:
function image_allowed() {
$allowed = array('jpg','jpeg','gif','png');
$file_name = $_FILES['image']['name'];
$file_extn = strtolower(end(explode('.', $file_name)));
$file_temp = $_FILES['image']['tmp_name'];
if (in_array($file_extn,$allowed)=== true){
return true;
}
return false;
}
if (image_allowed()=== false) {
$errors[] = ' images only are allowed.';
}else{
//save image or something else
}