cvs2svn_lib/process.py

   1 # (Be in -*- python -*- mode.)
   2 #
   3 # ====================================================================
   4 # Copyright (c) 2000-2006 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 sys
  21 import os
  22
  23 from boolean import *
  24 from common import FatalError
  25
  26
  27 # ============================================================================
  28 # This code is copied with a few modifications from:
  29 #   subversion/subversion/bindings/swig/python/svn/core.py
  30
  31 if sys.platform == "win32":
  32   import re
  33   _escape_shell_arg_re = re.compile(r'(\\+)(\"|$)')
  34
  35   def escape_shell_arg(arg):
  36     # The (very strange) parsing rules used by the C runtime library are
  37     # described at:
  38     # http://msdn.microsoft.com/library/en-us/vclang/html/_pluslang_Parsing_C.2b2b_.Command.2d.Line_Arguments.asp
  39
  40     # double up slashes, but only if they are followed by a quote character
  41     arg = re.sub(_escape_shell_arg_re, r'\1\1\2', arg)
  42
  43     # surround by quotes and escape quotes inside
  44     arg = '"' + arg.replace('"', '"^""') + '"'
  45     return arg
  46
  47
  48   def argv_to_command_string(argv):
  49     """Flatten a list of command line arguments into a command string.
  50
  51     The resulting command string is expected to be passed to the system
  52     shell which os functions like popen() and system() invoke internally.
  53     """
  54
  55     # According cmd's usage notes (cmd /?), it parses the command line by
  56     # "seeing if the first character is a quote character and if so, stripping
  57     # the leading character and removing the last quote character."
  58     # So to prevent the argument string from being changed we add an extra set
  59     # of quotes around it here.
  60     return '"' + ' '.join(map(escape_shell_arg, argv)) + '"'
  61
  62 else:
  63   def escape_shell_arg(arg):
  64     return "'" + arg.replace("'", "'\\''") + "'"
  65
  66   def argv_to_command_string(argv):
  67     """Flatten a list of command line arguments into a command string.
  68
  69     The resulting command string is expected to be passed to the system
  70     shell which os functions like popen() and system() invoke internally.
  71     """
  72
  73     return ' '.join(map(escape_shell_arg, argv))
  74
  75
  76 # ============================================================================
  77
  78
  79 # Opening pipes was a mess before Python 2.4, because some methods did
  80 # not exist on some platforms, and some behaved differenly on other.
  81 # Python 2.4 solved this by adding the subprocess module, but since we
  82 # cannot require such a new version, we cannot use it directly, but
  83 # must implement a simplified Popen using the best means neccessary.
  84 #
  85 # The SimplePopen class only has the following members and methods, all
  86 # behaving as documented in the subprocess.Popen class:
  87 #     - stdin
  88 #     - stdout
  89 #     - stderr
  90 #     - wait
  91 try:
  92   # First try subprocess.Popen...
  93   import subprocess
  94   class SimplePopen:
  95     def __init__(self, cmd, capture_stderr):
  96       if capture_stderr:
  97         stderr = subprocess.PIPE
  98       else:
  99         stderr = None
 100       self._popen = subprocess.Popen(cmd, stdin=subprocess.PIPE,
 101                                     stdout=subprocess.PIPE, stderr=stderr)
 102       self.stdin = self._popen.stdin
 103       self.stdout = self._popen.stdout
 104       if capture_stderr:
 105         self.stderr = self._popen.stderr
 106       self.wait = self._popen.wait
 107 except ImportError:
 108   import popen2
 109   if hasattr(popen2, 'Popen3'):
 110     # ...then try popen2.Popen3...
 111     class SimplePopen:
 112       def __init__(self, cmd, capture_stderr):
 113         self._popen3 = popen2.Popen3(cmd, capture_stderr)
 114         self.stdin = self._popen3.tochild
 115         self.stdout = self._popen3.fromchild
 116         if capture_stderr:
 117           self.stderr = self._popen3.childerr
 118         self.wait = self._popen3.wait
 119   else:
 120     # ...and if all fails, use popen2.popen3...
 121     class SimplePopen:
 122       def __init__(self, cmd, capture_stderr):
 123         if type(cmd) != types.StringType:
 124           cmd = argv_to_command_string(cmd)
 125         self.stdout, self.stdin, self.stderr = popen2.popen3(cmd, mode='b')
 126       def wait(self):
 127         return self.stdout.close() or self.stdin.close() or \
 128                self.stderr.close()
 129
 130
 131 def run_command(command):
 132   if os.system(command):
 133     raise FatalError('Command failed: "%s"' % (command,))
 134
 135
 136 class CommandFailedException(Exception):
 137   """Exception raised if check_command_runs() fails."""
 138
 139   pass
 140
 141
 142 def check_command_runs(cmd, cmdname):
 143   """Check whether the command CMD can be executed without errors.
 144
 145   CMD is a list or string, as accepted by SimplePopen.  CMDNAME is the
 146   name of the command as it should be included in exception error
 147   messages.
 148
 149   This function checks three things: (1) the command can be run
 150   without throwing an OSError; (2) it exits with status=0; (3) it
 151   doesn't output anything to stderr.  If any of these conditions is
 152   not met, raise a CommandFailedException describing the problem."""
 153
 154   try:
 155     pipe = SimplePopen(cmd, True)
 156   except OSError, e:
 157     raise CommandFailedException('error executing %s: %s' % (cmdname, e,))
 158   pipe.stdin.close()
 159   pipe.stdout.read()
 160   errmsg = pipe.stderr.read()
 161   status = pipe.wait()
 162   if status or errmsg:
 163     msg = 'error executing %s: status %s' % (cmdname, status,)
 164     if errmsg:
 165       msg += ', error output:\n%s' % (errmsg,)
 166     raise CommandFailedException(msg)
 167
 168