1# Copyright 2013 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5"""Generic utilities for all python scripts."""
6
7import atexit
8import httplib
9import os
10import signal
11import stat
12import subprocess
13import sys
14import tempfile
15import urlparse
16
17
18def GetPlatformName():
19  """Return a string to be used in paths for the platform."""
20  if IsWindows():
21    return 'win'
22  if IsMac():
23    return 'mac'
24  if IsLinux():
25    return 'linux'
26  raise NotImplementedError('Unknown platform "%s".' % sys.platform)
27
28
29def IsWindows():
30  return sys.platform == 'cygwin' or sys.platform.startswith('win')
31
32
33def IsLinux():
34  return sys.platform.startswith('linux')
35
36
37def IsMac():
38  return sys.platform.startswith('darwin')
39
40
41def _DeleteDir(path):
42  """Deletes a directory recursively, which must exist."""
43  # Don't use shutil.rmtree because it can't delete read-only files on Win.
44  for root, dirs, files in os.walk(path, topdown=False):
45    for name in files:
46      filename = os.path.join(root, name)
47      os.chmod(filename, stat.S_IWRITE)
48      os.remove(filename)
49    for name in dirs:
50      os.rmdir(os.path.join(root, name))
51  os.rmdir(path)
52
53
54def Delete(path):
55  """Deletes the given file or directory (recursively), which must exist."""
56  if os.path.isdir(path):
57    _DeleteDir(path)
58  else:
59    os.remove(path)
60
61
62def MaybeDelete(path):
63  """Deletes the given file or directory (recurisvely), if it exists."""
64  if os.path.exists(path):
65    Delete(path)
66
67
68def MakeTempDir(parent_dir=None):
69  """Creates a temporary directory and returns an absolute path to it.
70
71  The temporary directory is automatically deleted when the python interpreter
72  exits normally.
73
74  Args:
75    parent_dir: the directory to create the temp dir in. If None, the system
76                temp dir is used.
77
78  Returns:
79    The absolute path to the temporary directory.
80  """
81  path = tempfile.mkdtemp(dir=parent_dir)
82  atexit.register(MaybeDelete, path)
83  return path
84
85
86def Unzip(zip_path, output_dir):
87  """Unzips the given zip file using a system installed unzip tool.
88
89  Args:
90    zip_path: zip file to unzip.
91    output_dir: directory to unzip the contents of the zip file. The directory
92                must exist.
93
94  Raises:
95    RuntimeError if the unzip operation fails.
96  """
97  if IsWindows():
98    unzip_cmd = ['C:\\Program Files\\7-Zip\\7z.exe', 'x', '-y']
99  else:
100    unzip_cmd = ['unzip', '-o']
101  unzip_cmd += [zip_path]
102  if RunCommand(unzip_cmd, output_dir) != 0:
103    raise RuntimeError('Unable to unzip %s to %s' % (zip_path, output_dir))
104
105
106def Kill(pid):
107  """Terminate the given pid."""
108  if IsWindows():
109    subprocess.call(['taskkill.exe', '/T', '/F', '/PID', str(pid)])
110  else:
111    os.kill(pid, signal.SIGTERM)
112
113
114def RunCommand(cmd, cwd=None):
115  """Runs the given command and returns the exit code.
116
117  Args:
118    cmd: list of command arguments.
119    cwd: working directory to execute the command, or None if the current
120         working directory should be used.
121
122  Returns:
123    The exit code of the command.
124  """
125  process = subprocess.Popen(cmd, cwd=cwd)
126  process.wait()
127  return process.returncode
128
129
130def DoesUrlExist(url):
131  """Determines whether a resource exists at the given URL.
132
133  Args:
134    url: URL to be verified.
135
136  Returns:
137    True if url exists, otherwise False.
138  """
139  parsed = urlparse.urlparse(url)
140  try:
141    conn = httplib.HTTPConnection(parsed.netloc)
142    conn.request('HEAD', parsed.path)
143    response = conn.getresponse()
144  except (socket.gaierror, socket.error):
145    return False
146  finally:
147    conn.close()
148  # Follow both permanent (301) and temporary (302) redirects.
149  if response.status == 302 or response.status == 301:
150    return DoesUrlExist(response.getheader('location'))
151  return response.status == 200
152