+
−# Copyright 2009 the Melange authors.
+
−#
+
−# Licensed under the Apache License, Version 2.0 (the "License");
+
−# you may not use this file except in compliance with the License.
+
−# You may obtain a copy of the License at
+
−#
+
−#   http://www.apache.org/licenses/LICENSE-2.0
+
−#
+
−# Unless required by applicable law or agreed to in writing, software
+
−# distributed under the License is distributed on an "AS IS" BASIS,
+
−# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
−# See the License for the specific language governing permissions and
+
−# limitations under the License.
+
−
+
−"""Various utilities.
+
−
+
−Current contents:
+
− - Text colorization using ANSI color codes
+
− - A class to construct and manage paths under a root path.
+
− - A helper to manage running subprocesses, wrapping the subprocess module.
+
−"""
+
−
+
−__authors__ = [
+
−    # alphabetical order by last name, please
+
−    '"David Anderson" <dave@natulte.net>',
+
−    ]
+
−
+
−
+
−import os.path
+
−import re
+
−try:
+
−  import cStringIO as StringIO
+
−except ImportError:
+
−  import StringIO
+
−import subprocess
+
−import threading
+
−
+
−import error
+
−import log
+
−
+
−
+
−class Error(error.Error):
+
−  pass
+
−
+
−
+
−class SubprocessFailed(Error):
+
−  """A subprocess returned a non-zero error code."""
+
−  pass
+
−
+
−
+
−# The magic escape sequence understood by modern terminal emulators to
+
−# configure fore/background colors and other basic text display
+
−# settings.
+
−_ANSI_ESCAPE = '\x1b[%dm'
+
−_ANSI_ESCAPE_RE = re.compile(r'\x1b\[\d+m')
+
−
+
−
+
−# Some internal non-color settings that we use.
+
−_RESET = 0  # Reset to terminal defaults.
+
−_BOLD = 1   # Brighter colors.
+
−
+
−
+
−# ANSI color codes.
+
−RED = 31
+
−GREEN = 32
+
−WHITE = 37
+
−
+
−
+
−def _ansi_escape(code):
+
−  return _ANSI_ESCAPE % code
+
−
+
−
+
−def colorize(text, color, bold=False):
+
−  """Colorize some text using ANSI color codes.
+
−
+
−  Note that while ANSI color codes look good in a terminal they look
+
−  like noise in log files unless viewed in an ANSI color capable
+
−  viewer (such as 'less -R').
+
−
+
−  Args:
+
−    text: The text to colorize.
+
−    color: One of the color symbols from this module.
+
−    bold: If True, make the color brighter.
+
−
+
−  Returns:
+
−    The input text string, appropriately sprinkled with color
+
−    codes. Colors are reset to terminal defaults after the input
+
−    text.
+
−  """
+
−  bold = _ansi_escape(_BOLD) if bold else ''
+
−  return '%s%s%s%s' % (bold, _ansi_escape(color),
+
−                       text, _ansi_escape(_RESET))
+
−
+
−
+
−def decolorize(text):
+
−  """Remove ANSI color codes from text."""
+
−  return _ANSI_ESCAPE_RE.sub('', text)
+
−
+
−
+
−class Paths(object):
+
−  """A helper to construct and check paths under a given root."""
+
−
+
−  def __init__(self, root):
+
−    """Initializer.
+
−
+
−    Args:
+
−      root: The root of all paths this instance will consider.
+
−    """
+
−    self._root = os.path.abspath(
+
−      os.path.expandvars(os.path.expanduser(root)))
+
−
+
−  def path(self, path=''):
+
−    """Construct and return a path under the path root.
+
−
+
−    Args:
+
−      path: The desired path string relative to the root.
+
−
+
−    Returns:
+
−      The absolute path corresponding to the relative input path.
+
−    """
+
−    assert not os.path.isabs(path)
+
−    return os.path.abspath(os.path.join(self._root, path))
+
−
+
−  def exists(self, path=''):
+
−    """Check for the existence of a path under the path root.
+
−
+
−    Does not discriminate on the path type (ie. it could be a
+
−    directory, a file, a symbolic link...), just checks for the
+
−    existence of the path.
+
−
+
−    Args:
+
−      path: The path string relative to the root.
+
−
+
−    Returns:
+
−      True if the path exists, False otherwise.
+
−    """
+
−    return os.path.exists(self.path(path))
+
−
+
−
+
−class _PipeAdapter(threading.Thread):
+
−  """A thread that connects one file-like object to another"""
+
−  def __init__(self, pipe, logfile):
+
−    threading.Thread.__init__(self)
+
−    self.pipe, self.logfile = pipe, logfile
+
−    self.setDaemon(True)
+
−    self.start()
+
−
+
−  def run(self):
+
−    try:
+
−      while True:
+
−        data = self.pipe.read(512)  # Small to retain interactivity
+
−        if not data:
+
−          return
+
−        self.logfile.write(data)
+
−    except (EOFError, OSError):
+
−      pass
+
−
+
−
+
−def run(argv, cwd=None, capture=False, split_capture=True, stdin=None):
+
−  """Run the given command and optionally return its output.
+
−
+
−  Note that if you set capture=True, the command's output is
+
−  buffered in memory. Output capture should only be used with
+
−  commands that output small amounts of data. O(kB) is fine, O(MB)
+
−  is starting to push it a little.
+
−
+
−  Args:
+
−    argv: A list containing the name of the program to run, followed
+
−      by its argument vector.
+
−    cwd: Run the program from this directory.
+
−    capture: If True, capture the program's stdout stream. If False,
+
−      stdout will output to sys.stdout.
+
−    split_capture: If True, return the captured output as a list of
+
−      lines. Else, return as a single unaltered string.
+
−    stdin: The string to feed to the program's stdin stream.
+
−
+
−  Returns:
+
−    If capture is True, a string containing the combined
+
−    stdout/stderr output of the program. If capture is False,
+
−    nothing is returned.
+
−
+
−  Raises:
+
−    SubprocessFailed: The subprocess exited with a non-zero exit code.
+
−  """
+
−  log.debug(colorize('# ' + ' '.join(argv), WHITE, bold=True))
+
−
+
−  process = subprocess.Popen(argv,
+
−                             shell=False,
+
−                             cwd=cwd,
+
−                             stdin=(subprocess.PIPE if stdin else None),
+
−                             stdout=subprocess.PIPE,
+
−                             stderr=subprocess.PIPE)
+
−
+
−  # Spin up threads to capture stdout and stderr. Depending on the
+
−  # value of the capture parameter, stdout is pushed either into the
+
−  # log or into a string for processing. stderr always goes
+
−  # into the log.
+
−  #
+
−  # Threads are necessary because all of writing to stdin, reading
+
−  # from stdout and reading from stderr must all happen
+
−  # simultaneously. Otherwise, there is a risk that one of the pipes
+
−  # will fill up, causing the subprocess and us to deadlock. So,
+
−  # threads are used to keep the pipes safely flowing.
+
−  stdout = StringIO.StringIO() if capture else log.FileLikeLogger()
+
−  out_adapter = _PipeAdapter(process.stdout, stdout)
+
−  err_adapter = _PipeAdapter(process.stderr, log.FileLikeLogger())
+
−  
+
−  if stdin:
+
−    process.stdin.write(stdin)
+
−
+
−  out_adapter.join()
+
−  err_adapter.join()
+
−  process.wait()
+
−
+
−  if process.returncode != 0:
+
−    if capture:
+
−      raise SubprocessFailed('Process %s failed with output: %s' %
+
−                             (argv[0], stdout.getvalue()))
+
−    else:
+
−      raise SubprocessFailed('Process %s failed' % argv[0])
+
−
+
−  if capture:
+
−    out = stdout.getvalue()
+
−    stdout.close()
+
−
+
−    if split_capture:
+
−      out = out.strip().split('\n')
+
−    return out