1  """distutils.spawn
       2  
       3  Provides the 'spawn()' function, a front-end to various platform-
       4  specific functions for launching another program in a sub-process.
       5  Also provides the 'find_executable()' to search the path for a given
       6  executable name.
       7  """
       8  
       9  import sys
      10  import os
      11  import subprocess
      12  
      13  from distutils.errors import DistutilsPlatformError, DistutilsExecError
      14  from distutils.debug import DEBUG
      15  from distutils import log
      16  
      17  
      18  if sys.platform == 'darwin':
      19      _cfg_target = None
      20      _cfg_target_split = None
      21  
      22  
      23  def spawn(cmd, search_path=1, verbose=0, dry_run=0):
      24      """Run another program, specified as a command list 'cmd', in a new process.
      25  
      26      'cmd' is just the argument list for the new process, ie.
      27      cmd[0] is the program to run and cmd[1:] are the rest of its arguments.
      28      There is no way to run a program with a name different from that of its
      29      executable.
      30  
      31      If 'search_path' is true (the default), the system's executable
      32      search path will be used to find the program; otherwise, cmd[0]
      33      must be the exact path to the executable.  If 'dry_run' is true,
      34      the command will not actually be run.
      35  
      36      Raise DistutilsExecError if running the program fails in any way; just
      37      return on success.
      38      """
      39      # cmd is documented as a list, but just in case some code passes a tuple
      40      # in, protect our %-formatting code against horrible death
      41      cmd = list(cmd)
      42  
      43      log.info(' '.join(cmd))
      44      if dry_run:
      45          return
      46  
      47      if search_path:
      48          executable = find_executable(cmd[0])
      49          if executable is not None:
      50              cmd[0] = executable
      51  
      52      env = None
      53      if sys.platform == 'darwin':
      54          global _cfg_target, _cfg_target_split
      55          if _cfg_target is None:
      56              from distutils import sysconfig
      57              _cfg_target = sysconfig.get_config_var(
      58                                    'MACOSX_DEPLOYMENT_TARGET') or ''
      59              if _cfg_target:
      60                  _cfg_target_split = [int(x) for x in _cfg_target.split('.')]
      61          if _cfg_target:
      62              # Ensure that the deployment target of the build process is not
      63              # less than 10.3 if the interpreter was built for 10.3 or later.
      64              # This ensures extension modules are built with correct
      65              # compatibility values, specifically LDSHARED which can use
      66              # '-undefined dynamic_lookup' which only works on >= 10.3.
      67              cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target)
      68              cur_target_split = [int(x) for x in cur_target.split('.')]
      69              if _cfg_target_split[:2] >= [10, 3] and cur_target_split[:2] < [10, 3]:
      70                  my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: '
      71                            'now "%s" but "%s" during configure;'
      72                            'must use 10.3 or later'
      73                                  % (cur_target, _cfg_target))
      74                  raise DistutilsPlatformError(my_msg)
      75              env = dict(os.environ,
      76                         MACOSX_DEPLOYMENT_TARGET=cur_target)
      77  
      78      try:
      79          proc = subprocess.Popen(cmd, env=env)
      80          proc.wait()
      81          exitcode = proc.returncode
      82      except OSError as exc:
      83          if not DEBUG:
      84              cmd = cmd[0]
      85          raise DistutilsExecError(
      86              "command %r failed: %s" % (cmd, exc.args[-1])) from exc
      87  
      88      if exitcode:
      89          if not DEBUG:
      90              cmd = cmd[0]
      91          raise DistutilsExecError(
      92                "command %r failed with exit code %s" % (cmd, exitcode))
      93  
      94  
      95  def find_executable(executable, path=None):
      96      """Tries to find 'executable' in the directories listed in 'path'.
      97  
      98      A string listing directories separated by 'os.pathsep'; defaults to
      99      os.environ['PATH'].  Returns the complete filename or None if not found.
     100      """
     101      _, ext = os.path.splitext(executable)
     102      if (sys.platform == 'win32') and (ext != '.exe'):
     103          executable = executable + '.exe'
     104  
     105      if os.path.isfile(executable):
     106          return executable
     107  
     108      if path is None:
     109          path = os.environ.get('PATH', None)
     110          if path is None:
     111              try:
     112                  path = os.confstr("CS_PATH")
     113              except (AttributeError, ValueError):
     114                  # os.confstr() or CS_PATH is not available
     115                  path = os.defpath
     116          # bpo-35755: Don't use os.defpath if the PATH environment variable is
     117          # set to an empty string
     118  
     119      # PATH='' doesn't match, whereas PATH=':' looks in the current directory
     120      if not path:
     121          return None
     122  
     123      paths = path.split(os.pathsep)
     124      for p in paths:
     125          f = os.path.join(p, executable)
     126          if os.path.isfile(f):
     127              # the file exists, we have a shot at spawn working
     128              return f
     129      return None