grit: xtb_reader: parse inputs in binary mode

When parsing opening files in text mode for XTB parsing, Python 3
will use the active system locale.  If the locale is not UTF-8, we
run into errors as Python tries to convert to ASCII.  To avoid this,
open the XTB files in binary mode before passing to the XML layers.

Normally another option would be to use io.open with an explicit
encoding='utf-8' setting, and indeed, that works fine for Python 3.
Unfortunately Python 2's XML libs don't handle unicode strings well
leading to similar ASCII encoding errors.  It seems to work fine
when opened in binary mode though, so lets go that route.

Due to Python 2's implementation of bytes, the xtb_reader.Parse API
change shouldn't be noticed.  The code didn't work well with Python
3, so there aren't any users there yet :).  Not that it seems like
a big deal as cs.chromium.org says all API users are internal.

Bug: 983071
Test: `./grit/test_suite_all.py` passes

Change-Id: Idbd282ce9b93c4fcb4bb2dc4cce1dba3a84f6c27
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2043315Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739443}

tools/grit/grit/node/node_io.py

@@ -41,7 +41,7 @@ class FileNode(base.Node):
     defs = getattr(root, 'defines', {})
     target_platform = getattr(root, 'target_platform', '')
 
-    xtb_file = open(self.ToRealPath(self.GetInputPath()))
+    xtb_file = open(self.ToRealPath(self.GetInputPath()), 'rb')
     try:
       lang = xtb_reader.Parse(xtb_file,
                               self.UberClique().GenerateXtbParserCallback(

tools/grit/grit/tool/menu_from_parts.py

@@ -49,7 +49,7 @@ to being one message for the whole menu.'''
           msg.append(part[1])
       if len(msg):
         xtb[msg_id] = ''.join(msg)
-    with open(xtb_file) as f:
+    with open(xtb_file, 'rb') as f:
       xtb_reader.Parse(f, Callback)
 
     translations = []  # list of translations as per transl2tc.WriteTranslations

tools/grit/grit/xtb_reader.py

@@ -116,7 +116,7 @@ def Parse(xtb_file, callback_function, defs=None, debug=False,
   (if is_placeholder is True).
 
   Args:
-    xtb_file:           open('fr.xtb')
+    xtb_file:           open('fr.xtb', 'rb')
     callback_function:  def Callback(msg_id, parts): pass
     defs:               None, or a dictionary of preprocessor definitions.
     debug:              Default False. Set True for verbose debug output.
@@ -131,7 +131,7 @@ def Parse(xtb_file, callback_function, defs=None, debug=False,
   # TODO(joi) Remove this ugly hack by getting the TC gang to change the
   # XTB files somehow?
   front_of_file = xtb_file.read(1024)
-  xtb_file.seek(front_of_file.find('<translationbundle'))
+  xtb_file.seek(front_of_file.find(b'<translationbundle'))
 
   handler = XtbContentHandler(callback=callback_function, defs=defs,
                               debug=debug, target_platform=target_platform)

tools/grit/grit/xtb_reader_unittest.py

@@ -7,6 +7,7 @@
 
 from __future__ import print_function
 
+import io
 import os
 import sys
 if __name__ == '__main__':
@@ -14,8 +15,6 @@ if __name__ == '__main__':
 
 import unittest
 
-from six import StringIO
-
 from grit import util
 from grit import xtb_reader
 from grit.node import empty
@@ -23,7 +22,7 @@ from grit.node import empty
 
 class XtbReaderUnittest(unittest.TestCase):
   def testParsing(self):
-    xtb_file = StringIO('''<?xml version="1.0" encoding="UTF-8"?>
+    xtb_file = io.BytesIO(b'''<?xml version="1.0" encoding="UTF-8"?>
       <!DOCTYPE translationbundle>
       <translationbundle lang="fr">
         <translation id="5282608565720904145">Bingo.</translation>
@@ -59,12 +58,14 @@ and another after a blank line.</translation>
     clique_hello_user = msgs.children[1].GetCliques()[0]
     msg_hello_user = clique_hello_user.GetMessage()
 
-    xtb_file = StringIO('''<?xml version="1.0" encoding="UTF-8"?>
+    xtb_file = io.BytesIO(b'''<?xml version="1.0" encoding="UTF-8"?>
       <!DOCTYPE translationbundle>
       <translationbundle lang="is">
         <translation id="%s">Meirihattar!</translation>
         <translation id="%s">Saelir <ph name="USERNAME"/></translation>
-      </translationbundle>''' % (msg_mega.GetId(), msg_hello_user.GetId()))
+      </translationbundle>''' % (
+        msg_mega.GetId().encode('utf-8'),
+        msg_hello_user.GetId().encode('utf-8')))
 
     xtb_reader.Parse(xtb_file,
                      msgs.UberClique().GenerateXtbParserCallback('is'))
@@ -82,7 +83,7 @@ and another after a blank line.</translation>
     clique = msgs.children[0].GetCliques()[0]
     msg = clique.GetMessage()
 
-    xtb_file = StringIO('''<?xml version="1.0" encoding="UTF-8"?>
+    xtb_file = io.BytesIO(b'''<?xml version="1.0" encoding="UTF-8"?>
       <!DOCTYPE translationbundle>
       <translationbundle lang="is">
         <if expr="is_linux">
@@ -100,7 +101,8 @@ and another after a blank line.</translation>
   def testParseLargeFile(self):
     def Callback(id, structure):
       pass
-    with open(util.PathFromRoot('grit/testdata/generated_resources_fr.xtb')) as xtb:
+    path = util.PathFromRoot('grit/testdata/generated_resources_fr.xtb')
+    with open(path, 'rb') as xtb:
       xtb_reader.Parse(xtb, Callback)