(legacy, crashreporter) limit presentation and upload size of PHP_errors.log...

(legacy, crashreporter) limit presentation and upload size of PHP_errors.log to 1MB, closes https://github.com/opnsense/core/issues/768

src/www/crash_reporter.php

@@ -104,7 +104,11 @@ if (isset($_POST['Submit'])) {
             $crash_report_header .= "Description\n\n{$desc}";
         }
         file_put_contents('/var/crash/crashreport_header.txt', $crash_report_header);
-        @rename('/tmp/PHP_errors.log', '/var/crash/PHP_errors.log');
+        if (file_exists('/tmp/PHP_errors.log')) {
+            // limit PHP_errors to send to 1MB
+            exec('/usr/bin/tail -c 1048576 /tmp/PHP_errors.log > /var/crash/PHP_errors.log');
+            @unlink('/tmp/PHP_errors.log');
+        }
         @copy('/var/run/dmesg.boot', '/var/crash/dmesg.boot');
         exec('/usr/bin/gzip /var/crash/*');
         $files_to_upload = glob('/var/crash/*');
@@ -132,9 +136,25 @@ $email = isset($config['system']['contact_email']) ? $config['system']['contact_
 if ($has_crashed) {
     $crash_files = glob("/var/crash/*");
     $crash_reports['System Information'] = trim($crash_report_header);
-    $php_errors = @file_get_contents('/tmp/PHP_errors.log');
-    if (!empty($php_errors)) {
-        $crash_reports['PHP Errors'] = trim($php_errors);
+    if (file_exists('/tmp/PHP_errors.log')) {
+        $php_errors_size = @filesize('/tmp/PHP_errors.log');
+        $max_php_errors_size = 1048576; // 1MB
+        // limit reporting for PHP_errors.log to $max_php_errors_size characters
+        if ($php_errors_size > $max_php_errors_size) {
+            // if file is to large, only display last $max_php_errors_size characters
+            $php_errors .= @file_get_contents(
+                          '/tmp/PHP_errors.log',
+                          NULL,
+                          NULL,
+                          ($php_errors_size - $max_php_errors_size),
+                          $max_php_errors_size
+            );
+        } else {
+            $php_errors = @file_get_contents('/tmp/PHP_errors.log');
+        }
+        if (!empty($php_errors)) {
+            $crash_reports['PHP Errors'] = trim($php_errors);
+        }
     }
     $dmesg_boot = @file_get_contents('/var/run/dmesg.boot');
     if (!empty($dmesg_boot)) {