cvs2svn_lib/process.py

   1 # (Be in -*- python -*- mode.)
   2 #
   3 # ====================================================================
   4 # Copyright (c) 2000-2008 CollabNet.  All rights reserved.
   5 #
   6 # This software is licensed as described in the file COPYING, which
   7 # you should have received as part of this distribution.  The terms
   8 # are also available at http://subversion.tigris.org/license-1.html.
   9 # If newer versions of this license are posted there, you may use a
  10 # newer version instead, at your option.
  11 #
  12 # This software consists of voluntary contributions made by many
  13 # individuals.  For exact contribution history, see the revision
  14 # history and logs, available at http://cvs2svn.tigris.org/.
  15 # ====================================================================
  16
  17 """This module contains generic utilities used by cvs2svn."""
  18
  19
  20 import subprocess
  21
  22 from cvs2svn_lib.common import FatalError
  23 from cvs2svn_lib.common import CommandError
  24
  25
  26 def call_command(command, **kw):
  27   """Call the specified command, checking that it exits successfully.
  28
  29   Raise a FatalError if the command cannot be executed, or if it exits
  30   with a non-zero exit code.  Pass KW as keyword arguments to
  31   subprocess.call()."""
  32
  33   try:
  34     retcode = subprocess.call(command, **kw)
  35     if retcode < 0:
  36       raise FatalError(
  37           'Command terminated by signal %d: "%s"'
  38           % (-retcode, ' '.join(command),)
  39           )
  40     elif retcode > 0:
  41       raise FatalError(
  42           'Command failed with return code %d: "%s"'
  43           % (retcode, ' '.join(command),)
  44           )
  45   except OSError, e:
  46     raise FatalError(
  47         'Command execution failed (%s): "%s"'
  48         % (e, ' '.join(command),)
  49         )
  50
  51
  52 class CommandFailedException(Exception):
  53   """Exception raised if check_command_runs() fails."""
  54
  55   pass
  56
  57
  58 def check_command_runs(cmd, cmdname):
  59   """Check whether the command CMD can be executed without errors.
  60
  61   CMD is a list or string, as accepted by subprocess.Popen().  CMDNAME
  62   is the name of the command as it should be included in exception
  63   error messages.
  64
  65   This function checks three things: (1) the command can be run
  66   without throwing an OSError; (2) it exits with status=0; (3) it
  67   doesn't output anything to stderr.  If any of these conditions is
  68   not met, raise a CommandFailedException describing the problem."""
  69
  70   try:
  71     pipe = subprocess.Popen(
  72         cmd,
  73         stdin=subprocess.PIPE,
  74         stdout=subprocess.PIPE,
  75         stderr=subprocess.PIPE,
  76         )
  77   except OSError, e:
  78     raise CommandFailedException('error executing %s: %s' % (cmdname, e,))
  79   pipe.stdin.close()
  80   pipe.stdout.read()
  81   errmsg = pipe.stderr.read()
  82   status = pipe.wait()
  83   if status or errmsg:
  84     msg = 'error executing %s: status %s' % (cmdname, status,)
  85     if errmsg:
  86       msg += ', error output:\n%s' % (errmsg,)
  87     raise CommandFailedException(msg)
  88
  89
  90 class PipeStream(object):
  91   """A file-like object from which revision contents can be read."""
  92
  93   def __init__(self, pipe_command):
  94     self._pipe_command_str = ' '.join(pipe_command)
  95     self.pipe = subprocess.Popen(
  96         pipe_command,
  97         stdin=subprocess.PIPE,
  98         stdout=subprocess.PIPE,
  99         stderr=subprocess.PIPE,
 100         )
 101     self.pipe.stdin.close()
 102
 103   def read(self, size=None):
 104     if size is None:
 105       return self.pipe.stdout.read()
 106     else:
 107       return self.pipe.stdout.read(size)
 108
 109   def close(self):
 110     self.pipe.stdout.close()
 111     error_output = self.pipe.stderr.read()
 112     exit_status = self.pipe.wait()
 113     if exit_status or error_output:
 114       raise CommandError(self._pipe_command_str, exit_status, error_output)
 115
 116