feature-upload: add function / class existence checks where functions from php extensions are required

Changelog.md

@@ -14,6 +14,8 @@ This file holds the changelog for Pepperminty Wiki. This is the master list of t
  - Updated the [configuration guide](https://starbeamrainbowlabs.com/labs/peppermint/peppermint-config-info.php) to include count of how many settings we have
  - Also send a `x-robots-tag: noindex, nofollow` HTTP header for the login page (Semrush Bot, you better obey this one)
  - Support `page` as either a GET parameter or a POST parameter (GET takes precedence over POST)
+ - Preview generation: If php-imagick is not installed but required for a particular operation, return a proper error message
+ - File upload: If fileinfo is not installed, return a proper error message when someone attempts to upload a file
 
 
 ## Fixed

modules/feature-upload.php

@@ -5,7 +5,7 @@
 
 register_module([
 	"name" => "Uploader",
-	"version" => "0.7",
+	"version" => "0.7.1",
 	"author" => "Starbeamrainbowlabs",
 	"description" => "Adds the ability to upload files to Pepperminty Wiki. Uploaded files act as pages and have the special 'File/' prefix.",
 	"id" => "feature-upload",
@@ -140,6 +140,11 @@ register_module([
 
 					}
 					
+					if(!function_exists("finfo_file")) {
+						http_response_code(503);
+						exit(page_renderer::render("Upload failed - Server error - $settings->sitename", "<p>Your upload couldn't be processed because <code>fileinfo</code> is not installed on the server. This is required to properly check the file type of uploaded files.</p>><p>Please contact $settings->admindetails_name, $settings->sitename's administrator for help.</p>"));
+					}
+					
 					// Calculate the target name, removing any characters we
 					// are unsure about.
 					// Also trim off whitespace (from both ends), and full stops (from the end)
@@ -383,6 +388,13 @@ register_module([
 			}
 			*/
 			
+			
+			if(!class_exists("Imagick")) {
+				http_response_code(503);
+				header("content-type: text/plain");
+				exit("Error: The PHP Imagick extension is required to perform this operation but is not installed. Please contact the system administrator.");
+			}
+			
 			$preview = new Imagick();
 			switch(substr($mime_type, 0, strpos($mime_type, "/")))
 			{