viewvc-4intranet/lib/popen.py

# -*-python-*-
#
# Copyright (C) 1999-2013 The ViewCVS Group. All Rights Reserved.
#
# By using this file, you agree to the terms and conditions set forth in
# the LICENSE.html file which can be found at the top level of the ViewVC
# distribution or at http://viewvc.org/license-1.html.
#
# For more information, visit http://viewvc.org/
#
# -----------------------------------------------------------------------
#
# popen.py: a replacement for os.popen()
#
# This implementation of popen() provides a cmd + args calling sequence,
# rather than a system() type of convention. The shell facilities are not
# available, but that implies we can avoid worrying about shell hacks in
# the arguments.
#
# -----------------------------------------------------------------------

import os
import sys
import sapi
import threading

if sys.platform == "win32":
  import win32popen
  import win32event
  import win32process
  import debug
  import StringIO

def popen(cmd, args, mode, capture_err=1):
  if sys.platform == "win32":
    command = win32popen.CommandLine(cmd, args)

    if mode.find('r') >= 0:
      hStdIn = None

      if debug.SHOW_CHILD_PROCESSES:
        dbgIn, dbgOut = None, StringIO.StringIO()

        handle, hStdOut = win32popen.MakeSpyPipe(0, 1, (dbgOut,))

        if capture_err:
          hStdErr = hStdOut
          dbgErr = dbgOut
        else:
          dbgErr = StringIO.StringIO()
          x, hStdErr = win32popen.MakeSpyPipe(None, 1, (dbgErr,))
      else:
        handle, hStdOut = win32popen.CreatePipe(0, 1)
        if capture_err:
          hStdErr = hStdOut
        else:
          hStdErr = win32popen.NullFile(1)

    else:
      if debug.SHOW_CHILD_PROCESSES:
        dbgIn, dbgOut, dbgErr = StringIO.StringIO(), StringIO.StringIO(), StringIO.StringIO()
        hStdIn, handle = win32popen.MakeSpyPipe(1, 0, (dbgIn,))
        x, hStdOut = win32popen.MakeSpyPipe(None, 1, (dbgOut,))
        x, hStdErr = win32popen.MakeSpyPipe(None, 1, (dbgErr,))
      else:
        hStdIn, handle = win32popen.CreatePipe(0, 1)
        hStdOut = None
        hStdErr = None

    phandle, pid, thandle, tid = win32popen.CreateProcess(command, hStdIn, hStdOut, hStdErr)

    if debug.SHOW_CHILD_PROCESSES:
      debug.Process(command, dbgIn, dbgOut, dbgErr)

    return _pipe(win32popen.File2FileObject(handle, mode), phandle)

  # flush the stdio buffers since we are about to change the FD under them
  sys.stdout.flush()
  sys.stderr.flush()

  r, w = os.pipe()
  pid = os.fork()
  if pid:
    # in the parent

    # close the descriptor that we don't need and return the other one.
    if mode.find('r') >= 0:
      os.close(w)
      return _pipe(os.fdopen(r, mode), pid)
    os.close(r)
    return _pipe(os.fdopen(w, mode), pid)

  # in the child

  # we'll need /dev/null for the discarded I/O
  null = os.open('/dev/null', os.O_RDWR)

  if mode.find('r') >= 0:
    # hook stdout/stderr to the "write" channel
    os.dup2(w, 1)
    # "close" stdin; the child shouldn't use it
    ### this isn't quite right... we may want the child to read from stdin
    os.dup2(null, 0)
    # what to do with errors?
    if capture_err:
      os.dup2(w, 2)
    else:
      os.dup2(null, 2)
  else:
    # hook stdin to the "read" channel
    os.dup2(r, 0)
    # "close" stdout/stderr; the child shouldn't use them
    ### this isn't quite right... we may want the child to write to these
    os.dup2(null, 1)
    os.dup2(null, 2)

  # don't need these FDs any more
  os.close(null)
  os.close(r)
  os.close(w)

  # the stdin/stdout/stderr are all set up. exec the target
  try:
    os.execvp(cmd, (cmd,) + tuple(args))
  except:
    # aid debugging, if the os.execvp above fails for some reason:
    print "<h2>exec failed:</h2><pre>", cmd, ' '.join(args), "</pre>"
    raise

  # crap. shouldn't be here.
  sys.exit(127)

class _pipe:
  "Wrapper for a file which can wait() on a child process at close time."

  def __init__(self, file, child_pid, done_event = None, thread = None):
    self.file = file
    self.child_pid = child_pid
    if sys.platform == "win32":
      if done_event:
        self.wait_for = (child_pid, done_event)
      else:
        self.wait_for = (child_pid,)
    else:
      self.thread = thread

  def eof(self):
    ### should be calling file.eof() here instead of file.close(), there
    ### may be data in the pipe or buffer after the process exits
    if sys.platform == "win32":
      r = win32event.WaitForMultipleObjects(self.wait_for, 1, 0)
      if r == win32event.WAIT_OBJECT_0:
        self.file.close()
        self.file = None
        return win32process.GetExitCodeProcess(self.child_pid)
      return None

    if self.thread and self.thread.isAlive():
      return None

    pid, status = os.waitpid(self.child_pid, os.WNOHANG)
    if pid:
      self.file.close()
      self.file = None
      return status
    return None

  def close(self):
    if self.file:
      self.file.close()
      self.file = None
      if sys.platform == "win32":
        win32event.WaitForMultipleObjects(self.wait_for, 1, win32event.INFINITE)
        return win32process.GetExitCodeProcess(self.child_pid)
      else:
        if self.thread:
          self.thread.join()
        if type(self.child_pid) == type([]):
          for pid in self.child_pid:
            exit = os.waitpid(pid, 0)[1]
          return exit
        else:
          return os.waitpid(self.child_pid, 0)[1]
    return None

  def __getattr__(self, name):
    return getattr(self.file, name)

  def __del__(self):
    self.close()