Correctly resolve relative paths when inlining @import directives in CSS files.

grit/format/html_inline.py

Index: grit/format/html_inline.py
diff --git a/grit/format/html_inline.py b/grit/format/html_inline.py
index f1e6bd4dc5f9012197e6df10969c64e1a93e3e6d..6aea5f71a1cc94c2d99a2e7c2f31a619ea0684c8 100755
--- a/grit/format/html_inline.py
+++ b/grit/format/html_inline.py
@@ -74,7 +74,7 @@ def SrcInlineAsDataURL(
     return src_match.group(0)
 
   filename = filename.replace(DIST_SUBSTR , distribution)
-  filepath = os.path.join(base_path, filename)
+  filepath = os.path.normpath(os.path.join(base_path, filename))
   inlined_files.add(filepath)
 
   if names_only:
@@ -129,7 +129,7 @@ def DoInline(
     return SrcInlineAsDataURL(
         src_match, filepath, distribution, inlined_files, names_only=names_only)
 
-  def GetFilepath(src_match):
+  def GetFilepath(src_match, base_path = input_filepath):
     filename = src_match.group('filename')
 
     if filename.find(':') != -1:
@@ -137,7 +137,7 @@ def DoInline(
       return None
 
     filename = filename.replace('%DISTRIBUTION%', distribution)
-    return os.path.join(input_filepath, filename)
+    return os.path.normpath(os.path.join(base_path, filename))
 
   def IsConditionSatisfied(src_match):
     expression = src_match.group('expression')
@@ -217,16 +217,18 @@ def DoInline(
     text = InlineCSSImages(text, filepath)
     return InlineCSSImports(text, filepath)
 
-  def InlineCSSFile(src_match, inlined_files=inlined_files):
-    """Helper function to inline external css files.
+  def InlineCSSFile(src_match, pattern, base_path=input_filepath):
+    """Helper function to inline external CSS files.
 
     Args:
       src_match: A regular expression match with a named group named "filename".
+      pattern: The pattern to replace with the contents of the CSS file.
+      base_path: The base path to use for resolving the CSS file.
 
     Returns:
       The text that should replace the reference to the CSS file.
     """
-    filepath = GetFilepath(src_match)
+    filepath = GetFilepath(src_match, base_path)
     if filepath is None:
       return src_match.group(0)
 
@@ -235,7 +237,8 @@ def DoInline(
     inlined_files.add(filepath)
     # When resolving CSS files we need to pass in the path so that relative URLs
     # can be resolved.
-    return InlineCSSText(util.ReadFile(filepath, util.BINARY), filepath)
+    return pattern % InlineCSSText(util.ReadFile(filepath, util.BINARY),
+                                   filepath)
 
   def InlineCSSImages(text, filepath=input_filepath):
     """Helper function that inlines external images in CSS backgrounds."""
@@ -261,8 +264,8 @@ def DoInline(
        directive.
     """
     return re.sub('@import\s+url\((?P<quote>"|\'|)(?P<filename>[^"\'()]*)' +
-                  '(?P=quote)\)',
-                  InlineCSSFile,
+                  '(?P=quote)\);',
+                  lambda m: InlineCSSFile(m, '%s', filepath),
                   text)
 
 
@@ -284,7 +287,7 @@ def DoInline(
 
   flat_text = re.sub(
       '<link rel="stylesheet".+?href="(?P<filename>[^"]*)".*?>',
-      lambda m: '<style>%s</style>' % InlineCSSFile(m),
+      lambda m: InlineCSSFile(m, '<style>%s</style>'),
       flat_text)
 
   flat_text = re.sub(
@@ -326,10 +329,14 @@ def InlineToString(input_filename, grd_node, allow_external_script=False,
   Returns:
     the inlined data as a string
   """
-  return DoInline(input_filename,
-                  grd_node,
-                  allow_external_script=allow_external_script,
-                  rewrite_function=rewrite_function).inlined_data
+  try:
+    return DoInline(input_filename,
+                    grd_node,
+                    allow_external_script=allow_external_script,
+                    rewrite_function=rewrite_function).inlined_data
+  except IOError, e:
+    raise Exception("Failed to open %s while trying to flatten %s. (%s)" %
+                    (e.filename, input_filename, e.strerror))
 
 
 def InlineToFile(input_filename, output_filename, grd_node):