File type functions not supported on a live server in PHP

I have application on a live server where I want to check upload file is image or not. In my localhost and other live server following functions are working except one current server.

1. mime_content_type($file);
2. $file_type = exec("file $file");
3. $finfo = new finfo(FILEINFO_MIME);
   $file_type = $finfo->file($_FILES['image']['tmp_name']);

Some are deprecated, some are disabled due to security reasons. Can I have other methods/techniques to get file type which is used to check whether upload file is image or not?

Solution

You can use getimagesize() to determine if the uploaded file is image or not.

Use it like this,

$image_info = getimagesize($_FILES['file']['tmp_name']);
if ($image_info === FALSE) {
   die("Uploaded file is not an image.");
}

getimagesize() function will determine the size of any given image file and return the dimensions along with the file type and a height/width text string to be used inside a normal HTML IMG tag and the correspondent HTTP content type.

It will return FALSE in case of uploaded file is not an image.