JezK
Edit File: spawn.py
"""distutils.spawn Provides the 'spawn()' function, a front-end to various platform- specific functions for launching another program in a sub-process. Also provides the 'find_executable()' to search the path for a given executable name. """ import sys import os from distutils.errors import DistutilsPlatformError, DistutilsExecError from distutils import log def spawn(cmd, search_path=1, verbose=0, dry_run=0): """Run another program, specified as a command list 'cmd', in a new process. 'cmd' is just the argument list for the new process, ie. cmd[0] is the program to run and cmd[1:] are the rest of its arguments. There is no way to run a program with a name different from that of its executable. If 'search_path' is true (the default), the system's executable search path will be used to find the program; otherwise, cmd[0] must be the exact path to the executable. If 'dry_run' is true, the command will not actually be run. Raise DistutilsExecError if running the program fails in any way; just return on success. """ if os.name == 'posix': _spawn_posix(cmd, search_path, dry_run=dry_run) elif os.name == 'nt': _spawn_nt(cmd, search_path, dry_run=dry_run) elif os.name == 'os2': _spawn_os2(cmd, search_path, dry_run=dry_run) else: raise DistutilsPlatformError( "don't know how to spawn programs on platform '%s'" % os.name) def _nt_quote_args(args): """Quote command-line arguments for DOS/Windows conventions. Just wraps every argument which contains blanks in double quotes, and returns a new argument list. """ # XXX this doesn't seem very robust to me -- but if the Windows guys # say it'll work, I guess I'll have to accept it. (What if an arg # contains quotes? What other magic characters, other than spaces, # have to be escaped? Is there an escaping mechanism other than # quoting?) for i, arg in enumerate(args): if ' ' in arg: args[i] = '"%s"' % arg return args def _spawn_nt(cmd, search_path=1, verbose=0, dry_run=0): executable = cmd[0] cmd = _nt_quote_args(cmd) if search_path: # either we find one or it stays the same executable = find_executable(executable) or executable log.info(' '.join([executable] + cmd[1:])) if not dry_run: # spawn for NT requires a full path to the .exe try: rc = os.spawnv(os.P_WAIT, executable, cmd) except OSError as exc: # this seems to happen when the command isn't found raise DistutilsExecError( "command '%s' failed: %s" % (cmd[0], exc.args[-1])) if rc != 0: # and this reflects the command running but failing raise DistutilsExecError( "command '%s' failed with exit status %d" % (cmd[0], rc)) def _spawn_os2(cmd, search_path=1, verbose=0, dry_run=0): executable = cmd[0] if search_path: # either we find one or it stays the same executable = find_executable(executable) or executable log.info(' '.join([executable] + cmd[1:])) if not dry_run: # spawnv for OS/2 EMX requires a full path to the .exe try: rc = os.spawnv(os.P_WAIT, executable, cmd) except OSError as exc: # this seems to happen when the command isn't found raise DistutilsExecError( "command '%s' failed: %s" % (cmd[0], exc.args[-1])) if rc != 0: # and this reflects the command running but failing log.debug("command '%s' failed with exit status %d" % (cmd[0], rc)) raise DistutilsExecError( "command '%s' failed with exit status %d" % (cmd[0], rc)) if sys.platform == 'darwin': from distutils import sysconfig _cfg_target = None _cfg_target_split = None def _spawn_posix(cmd, search_path=1, verbose=0, dry_run=0): log.info(' '.join(cmd)) if dry_run: return exec_fn = search_path and os.execvp or os.execv exec_args = [cmd[0], cmd] if sys.platform == 'darwin': global _cfg_target, _cfg_target_split if _cfg_target is None: _cfg_target = sysconfig.get_config_var( 'MACOSX_DEPLOYMENT_TARGET') or '' if _cfg_target: _cfg_target_split = [int(x) for x in _cfg_target.split('.')] if _cfg_target: # ensure that the deployment target of build process is not less # than that used when the interpreter was built. This ensures # extension modules are built with correct compatibility values cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target) if _cfg_target_split > [int(x) for x in cur_target.split('.')]: my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: ' 'now "%s" but "%s" during configure' % (cur_target, _cfg_target)) raise DistutilsPlatformError(my_msg) env = dict(os.environ, MACOSX_DEPLOYMENT_TARGET=cur_target) exec_fn = search_path and os.execvpe or os.execve exec_args.append(env) pid = os.fork() if pid == 0: # in the child try: exec_fn(*exec_args) except OSError as e: sys.stderr.write("unable to execute %s: %s\n" % (cmd[0], e.strerror)) os._exit(1) sys.stderr.write("unable to execute %s for unknown reasons" % cmd[0]) os._exit(1) else: # in the parent # Loop until the child either exits or is terminated by a signal # (ie. keep waiting if it's merely stopped) while True: try: pid, status = os.waitpid(pid, 0) except OSError as exc: import errno if exc.errno == errno.EINTR: continue raise DistutilsExecError( "command '%s' failed: %s" % (cmd[0], exc.args[-1])) if os.WIFSIGNALED(status): raise DistutilsExecError( "command '%s' terminated by signal %d" % (cmd[0], os.WTERMSIG(status))) elif os.WIFEXITED(status): exit_status = os.WEXITSTATUS(status) if exit_status == 0: return # hey, it succeeded! else: raise DistutilsExecError( "command '%s' failed with exit status %d" % (cmd[0], exit_status)) elif os.WIFSTOPPED(status): continue else: raise DistutilsExecError( "unknown error executing '%s': termination status %d" % (cmd[0], status)) def find_executable(executable, path=None): """Tries to find 'executable' in the directories listed in 'path'. A string listing directories separated by 'os.pathsep'; defaults to os.environ['PATH']. Returns the complete filename or None if not found. """ if path is None: path = os.environ['PATH'] paths = path.split(os.pathsep) base, ext = os.path.splitext(executable) if (sys.platform == 'win32' or os.name == 'os2') and (ext != '.exe'): executable = executable + '.exe' if not os.path.isfile(executable): for p in paths: f = os.path.join(p, executable) if os.path.isfile(f): # the file exists, we have a shot at spawn working return f return None else: return executable