Log database errors instead of showing them.

display_errors is off unless DISPLAY_ERRORS is set in .env.

.env.example

@@ -17,3 +17,7 @@ GOOGLE_ANALYTICS_ID=
 # Directory for uploaded images waiting to be saved. Keep it outside the
 # web root. The default is xxx-uploads in the system temporary directory.
 UPLOAD_DIR=
+
+# Show PHP errors in the page (1) or on stderr (stderr). Leave it empty in
+# production: errors always go to the PHP error log.
+DISPLAY_ERRORS=

config.lib.php

@@ -39,4 +39,8 @@ function config($key, $default = NULL) {
 
   return array_key_exists($key, $values) ? $values[$key] : $default;
 }
+
+// Always log PHP errors; show them only if DISPLAY_ERRORS is set (for development)
+ini_set('log_errors', '1');
+ini_set('display_errors', (string)config('DISPLAY_ERRORS', '0'));
 ?>

display.php

@@ -60,7 +60,7 @@ function display_img($id) {
   }
 
   $query = "SELECT img, mime FROM $table WHERE 1 AND ID = ?".$hidden." LIMIT 0, 1";
-  $result = $db->execute_query($query, array((int)$id)) or die("Query failed : ".$db->error);
+  $result = $db->execute_query($query, array((int)$id)) or db_fail();
 
   $row = $result->fetch_assoc();
   if ($row) {

feed.php

@@ -13,7 +13,7 @@ header("Content-Type: application/rss+xml");
 
 // Set up a RSS "header"
 $query = "SELECT MAX(`date`) FROM $table;";
-$result = $db->query($query) or die("Query failed : ".$db->error);
+$result = $db->query($query) or db_fail();
 $most_recent = $result->fetch_row();
 $now = date("D, d M Y H:i:s O");
 

get_data.lib.php

@@ -127,13 +127,12 @@ function get_count() {
 
   //echo $count_query." <br />";
   $row_count = NULL;
-  echo $db->info;
   if ($count_query) {
     if ($result = $db->execute_query($count_query, $params)) {
       $row_count = $result->fetch_row();
       $result->close();
     } else {
-      die("Error in query: $db->error");
+      db_fail();
     }
   }
   return $row_count[0];
@@ -186,7 +185,7 @@ function get_query($id = NULL) {
     }
     $result->close();
   } else {
-    die("Error in query: $db->error");
+    db_fail();
   }
   return $results;
 }

open_db.lib.php

@@ -13,8 +13,9 @@ function open_db($state) {
       mysqli_report(MYSQLI_REPORT_OFF);
       $db = new mysqli($hostname, $view_user, $view_pass, $db_name);
       if ($db->connect_error) {
-        die ("Unable to connect to database");
-        die ('Connect Error (' . $db->connect_errno . ') ' . $db->connect_error);
+        $detail = 'connect error (' . $db->connect_errno . ') ' . $db->connect_error;
+        $db = NULL;
+        db_fail($detail);
       }
       return TRUE;
     } else
@@ -29,4 +30,20 @@ function open_db($state) {
       return FALSE;
   }
 }
+
+/*
+ * Stop the page after a database error. The details, with the file and
+ * line of the failed call, go to the PHP error log; the visitor only
+ * sees a short apology.
+ */
+function db_fail($detail = NULL) {
+  global $db;
+  if ($detail === NULL)
+    $detail = $db ? $db->error : 'no database connection';
+  $caller = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 1)[0];
+  error_log('xxx: database error at ' . basename($caller['file']) . ':' . $caller['line'] . ': ' . $detail);
+  if (!headers_sent())
+    header('HTTP/1.1 500 Internal Server Error');
+  die('<p>Sorry, something went wrong. Please try again later.</p>');
+}
 ?>

publish/login.php

@@ -27,7 +27,7 @@ if (isset($_SESSION['editor'])) {
 
   $username = (string)($_POST['username'] ?? '');
   $query = "SELECT * FROM $table WHERE username = ? LIMIT 1";
-  $getid = $db->execute_query($query, array($username)) or die("Query failed: ".$db->error);
+  $getid = $db->execute_query($query, array($username)) or db_fail();
   $row = $getid->fetch_assoc();
 
   $stored_password = '';

publish/post.lib.php

@@ -46,7 +46,7 @@ function save_data($id = NULL) {
       $mime  = $row['mime'];
       $getimg->close();
     } else {
-      die("Error in query: $db->error");
+      db_fail();
     }
   } else {
     $image_file = save_uploaded_file();
@@ -91,7 +91,7 @@ function save_data($id = NULL) {
   }
 
   //echo $query;
-  $result = $db->execute_query($query, $params) or die("Query failed: ".$db->error);
+  $result = $db->execute_query($query, $params) or db_fail();
 
   if (is_numeric($id) && $move) {
     $queue_id = $id;
@@ -100,7 +100,7 @@ function save_data($id = NULL) {
   // Get the (new) ID if we don't already have it.
   if (!is_numeric($id) || $move) {
     $query = "SELECT LAST_INSERT_ID();";
-    $getid = $db->query($query) or die("Query failed: ".$db->error);
+    $getid = $db->query($query) or db_fail();
     $row = $getid->fetch_row();
     $id = $row[0];
   }
@@ -140,7 +140,7 @@ function delete_story($id, $move = FALSE) {
 
   $query = "DELETE FROM $table WHERE `id` = ? LIMIT 1";
   //echo $query;
-  $result = $db->execute_query($query, array((int)$id)) or die("Query failed : ".$db->error);
+  $result = $db->execute_query($query, array((int)$id)) or db_fail();
 
   $message = '';
   if (!$move)

session.lib.php

@@ -55,7 +55,7 @@ function check_persistent_login() {
 
   open_db('open');
   $query = "SELECT * FROM $table WHERE username = ? AND session = ? LIMIT 1";
-  $getid = $db->execute_query($query, array($username, $key_hash)) or die("Query failed: ".$db->error);
+  $getid = $db->execute_query($query, array($username, $key_hash)) or db_fail();
   $row = $getid->fetch_assoc();
   open_db('close');
 
@@ -79,7 +79,7 @@ function create_persistent_login($username) {
 
   // Add the hash of the session key to the database
   $query = "INSERT INTO $table (username, session) VALUES (?, ?)";
-  $db->execute_query($query, array($username, persistent_key_hash($key))) or die("Query failed: ".$db->error);
+  $db->execute_query($query, array($username, persistent_key_hash($key))) or db_fail();
   open_db('close');
 
   // Create cookie with key
@@ -98,14 +98,14 @@ function delete_persistent_login() {
   // Remove this session key from the database
   if ($username !== '' && $key !== '') {
     $query = "DELETE FROM $table WHERE username = ? AND session = ?";
-    $db->execute_query($query, array($username, persistent_key_hash($key))) or die("Query failed: ".$db->error);
+    $db->execute_query($query, array($username, persistent_key_hash($key))) or db_fail();
   }
 
   // Reap old sessions, and keys stored before they were hashed
   $query = "DELETE FROM $table " . 
            " WHERE created < DATE_SUB(now(), INTERVAL 1 YEAR)" .
            " OR CHAR_LENGTH(session) <> 64;";
-  $db->query($query) or die("Query failed: ".$db->error);
+  $db->query($query) or db_fail();
 
   open_db('close');