MDL-73520 general: replace deprecated php_errormsg with error_get_last()

For a better PHP8 compatibility this commit replaces the deprecated $php_errormsg
with error_get_last().

The PHP 8.0 migration guide (https://www.php.net/manual/de/migration80.incompatible.php) says:
    The track_errors ini directive has been removed.
    This means that php_errormsg is no longer available.
    The error_get_last() function may be used instead.
Also the documentation on $php_errormsg (https://www.php.net/manual/en/reserved.variables.phperrormsg.php) says:
    This feature has been DEPRECATED as of PHP 7.2.0.
    Relying on this feature is highly discouraged.
    Use error_get_last() instead.

Signed-off-by: Daniel Ziegenberg <[email protected]>

enrol/lti/ims-blti/OAuthBody.php

@@ -134,11 +134,19 @@ function sendOAuthParamsPOST($method, $endpoint, $oauth_consumer_key, $oauth_con
     $ctx = stream_context_create($params);
     $fp = @fopen($endpoint, 'rb', false, $ctx);
     if (!$fp) {
-        throw new \Exception("Problem with $endpoint, $php_errormsg");
+        $message = "(No error message provided.)";
+        if ($error = error_get_last()) {
+            $message = $error["message"];
+        }
+        throw new \Exception("Problem with $endpoint, $message");
     }
     $response = @stream_get_contents($fp);
     if ($response === false) {
-        throw new \Exception("Problem reading data from $endpoint, $php_errormsg");
+        $message = "(No error message provided.)";
+        if ($error = error_get_last()) {
+            $message = $error["message"];
+        }
+        throw new \Exception("Problem reading data from $endpoint, $message");
     }
     return $response;
 }

enrol/lti/ims-blti/blti_util.php

@@ -208,11 +208,19 @@ function do_post_request($url, $data, $optional_headers = null)
   $fp = @fopen($url, 'rb', false, $ctx);
   if (!$fp) {
     echo @stream_get_contents($fp);
-    throw new Exception("Problem with $url, $php_errormsg");
+    $message = "(No error message provided.)";
+    if ($error = error_get_last()) {
+      $message = $error["message"];
+    }
+    throw new Exception("Problem with $url, $message");
   }
   $response = @stream_get_contents($fp);
   if ($response === false) {
-    throw new Exception("Problem reading data from $url, $php_errormsg");
+    $message = "(No error message provided.)";
+    if ($error = error_get_last()) {
+        $message = $error["message"];
+    }
+    throw new Exception("Problem reading data from $url, $message");
   }
   return $response;
 }

enrol/lti/ims-blti/readme_moodle.txt

@@ -5,3 +5,4 @@ In future releases we should look into using a supported library.
 
 2022-01-05 - MDL-73502 - Removed get_magic_quotes_gpc() use, was returning false since ages ago.
 2022-01-20 - MDL-73523 - Conditional openssl_free_key() use, deprecated by PHP 8.0
+2022-03-05 - MDL-73520 - replace deprecated php_errormsg with error_get_last(), deprecated by PHP 8.0