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1#!/usr/bin/env python
2# Copyright 2013 Google Inc. All Rights Reserved.
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15
16"""Inject javascript into html page source code."""
17
18import logging
19import os
20import re
21import util
22import third_party.jsmin as jsmin
23
24DOCTYPE_RE = re.compile(r'^.{,256}?(<!--.*-->)?.{,256}?<!doctype html>',
25                        re.IGNORECASE | re.DOTALL)
26HTML_RE = re.compile(r'^.{,256}?(<!--.*-->)?.{,256}?<html.*?>',
27                     re.IGNORECASE | re.DOTALL)
28HEAD_RE = re.compile(r'^.{,256}?(<!--.*-->)?.{,256}?<head.*?>',
29                     re.IGNORECASE | re.DOTALL)
30
31
32def GetInjectScript(scripts):
33  """Loads |scripts| from disk and returns a string of their content."""
34  lines = []
35  if scripts:
36    if not isinstance(scripts, list):
37      scripts = scripts.split(',')
38    for script in scripts:
39      if os.path.exists(script):
40        with open(script) as f:
41          lines.extend(f.read())
42      elif util.resource_exists(script):
43        lines.extend(util.resource_string(script))
44      else:
45        raise Exception('Script does not exist: %s', script)
46
47  return jsmin.jsmin(''.join(lines), quote_chars="'\"`")
48
49
50def _IsHtmlContent(content):
51  content = content.strip()
52  return content.startswith('<') and content.endswith('>')
53
54
55def InjectScript(text_chunks, content_type, script_to_inject):
56  """Inject |script_to_inject| into |content| if |content_type| is 'text/html'.
57
58  Inject |script_to_inject| into |text_chunks| immediately after <head>,
59  <html> or <!doctype html>, if one of them is found. Otherwise, inject at
60  the beginning.
61
62  Returns:
63    text_chunks, already_injected
64    |text_chunks| is the new content if script is injected, otherwise
65      the original.  If the script was injected, exactly one chunk in
66      |text_chunks| will have changed.
67    |just_injected| indicates if |script_to_inject| was just injected in
68      the content.
69  """
70  if not content_type or content_type != 'text/html':
71    return text_chunks, False
72  content = "".join(text_chunks)
73  if not content or not _IsHtmlContent(content) or script_to_inject in content:
74    return text_chunks, False
75  for regexp in (HEAD_RE, HTML_RE, DOCTYPE_RE):
76    matchobj = regexp.search(content)
77    if matchobj:
78      pos = matchobj.end(0)
79      for i, chunk in enumerate(text_chunks):
80        if pos <= len(chunk):
81          result = text_chunks[:]
82          result[i] = '%s<script>%s</script>%s' % (chunk[0:pos],
83                                                   script_to_inject,
84                                                   chunk[pos:])
85          return result, True
86        pos -= len(chunk)
87  result = text_chunks[:]
88  result[0] = '<script>%s</script>%s' % (script_to_inject,
89                                         text_chunks[0])
90  logging.warning('Inject at the very beginning, because no tag of '
91                  '<head>, <html> or <!doctype html> is found.')
92  return result, True
93