1  """
       2  Basic subprocess implementation for POSIX which only uses os functions. Only
       3  implement features required by setup.py to build C extension modules when
       4  subprocess is unavailable. setup.py is not used on Windows.
       5  """
       6  import os
       7  
       8  
       9  # distutils.spawn used by distutils.command.build_ext
      10  # calls subprocess.Popen().wait()
      11  class ESC[4;38;5;81mPopen:
      12      def __init__(self, cmd, env=None):
      13          self._cmd = cmd
      14          self._env = env
      15          self.returncode = None
      16  
      17      def wait(self):
      18          pid = os.fork()
      19          if pid == 0:
      20              # Child process
      21              try:
      22                  if self._env is not None:
      23                      os.execve(self._cmd[0], self._cmd, self._env)
      24                  else:
      25                      os.execv(self._cmd[0], self._cmd)
      26              finally:
      27                  os._exit(1)
      28          else:
      29              # Parent process
      30              _, status = os.waitpid(pid, 0)
      31              self.returncode = os.waitstatus_to_exitcode(status)
      32  
      33          return self.returncode
      34  
      35  
      36  def _check_cmd(cmd):
      37      # Use regex [a-zA-Z0-9./-]+: reject empty string, space, etc.
      38      safe_chars = []
      39      for first, last in (("a", "z"), ("A", "Z"), ("0", "9")):
      40          for ch in range(ord(first), ord(last) + 1):
      41              safe_chars.append(chr(ch))
      42      safe_chars.append("./-")
      43      safe_chars = ''.join(safe_chars)
      44  
      45      if isinstance(cmd, (tuple, list)):
      46          check_strs = cmd
      47      elif isinstance(cmd, str):
      48          check_strs = [cmd]
      49      else:
      50          return False
      51  
      52      for arg in check_strs:
      53          if not isinstance(arg, str):
      54              return False
      55          if not arg:
      56              # reject empty string
      57              return False
      58          for ch in arg:
      59              if ch not in safe_chars:
      60                  return False
      61  
      62      return True
      63  
      64  
      65  # _aix_support used by distutil.util calls subprocess.check_output()
      66  def check_output(cmd, **kwargs):
      67      if kwargs:
      68          raise NotImplementedError(repr(kwargs))
      69  
      70      if not _check_cmd(cmd):
      71          raise ValueError(f"unsupported command: {cmd!r}")
      72  
      73      tmp_filename = "check_output.tmp"
      74      if not isinstance(cmd, str):
      75          cmd = " ".join(cmd)
      76      cmd = f"{cmd} >{tmp_filename}"
      77  
      78      try:
      79          # system() spawns a shell
      80          status = os.system(cmd)
      81          exitcode = os.waitstatus_to_exitcode(status)
      82          if exitcode:
      83              raise ValueError(f"Command {cmd!r} returned non-zero "
      84                               f"exit status {exitcode!r}")
      85  
      86          try:
      87              with open(tmp_filename, "rb") as fp:
      88                  stdout = fp.read()
      89          except FileNotFoundError:
      90              stdout = b''
      91      finally:
      92          try:
      93              os.unlink(tmp_filename)
      94          except OSError:
      95              pass
      96  
      97      return stdout