Symbol import: preemptively error on non-utf8 symbols

Summary:
Put a test somewhere we can --ignore it.

Also fix path tests.

Test Plan: insert good/bad values at various positions.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8353

Author: avivey

scripts/symbols/import_project_symbols.php

@@ -106,6 +106,21 @@ function commit_symbols ($syms, $project, $no_purge) {
 
 }
 
+function check_string_value($value, $field_name, $line_no, $max_length) {
+   if (strlen($value) > $max_length) {
+      throw new Exception(
+        "{$field_name} '{$value}' defined on line #{$line_no} is too long, ".
+        "maximum {$field_name} length is {$max_length} characters.");
+    }
+
+    if (!phutil_is_utf8_with_only_bmp_characters($value)) {
+      throw new Exception(
+        "{$field_name} '{$value}' defined on line #{$line_no} is not a valid ".
+        "UTF-8 string, ".
+        "it should contain only UTF-8 characters.");
+    }
+}
+
 $no_purge = $args->getArg('no-purge');
 $symbols = array();
 foreach ($input as $key => $line) {
@@ -137,31 +152,13 @@ function commit_symbols ($syms, $project, $no_purge) {
     $line_number = $matches['line'];
     $path        = $matches['path'];
 
-    if (strlen($context) > 128) {
-      throw new Exception(
-        "Symbol context '{$context}' defined on line #{$line_no} is too long, ".
-        "maximum symbol context length is 128 characters.");
-    }
-
-    if (strlen($name) > 128) {
-      throw new Exception(
-        "Symbol name '{$name}' defined on line #{$line_no} is too long, ".
-        "maximum symbol name length is 128 characters.");
-    }
-
-    if (strlen($type) > 12) {
-      throw new Exception(
-        "Symbol type '{$type}' defined on line #{$line_no} is too long, ".
-        "maximum symbol type length is 12 characters.");
-    }
-
-    if (strlen($lang) > 32) {
-      throw new Exception(
-        "Symbol language '{$lang}' defined on line #{$line_no} is too long, ".
-        "maximum symbol language length is 32 characters.");
-    }
+    check_string_value($context, 'Symbol context', $line_no, 128);
+    check_string_value($name, 'Symbol name', $line_no, 128);
+    check_string_value($type, 'Symbol type', $line_no, 12);
+    check_string_value($lang, 'Symbol language', $line_no, 32);
+    check_string_value($path, 'Path', $line_no, 512);
 
-    if (!strlen($path) || $path[0] != 0) {
+    if (!strlen($path) || $path[0] != '/') {
       throw new Exception(
         "Path '{$path}' defined on line #{$line_no} is invalid. Paths should ".
         "begin with '/' and specify a path from the root of the project, like ".