"""distutils.spawn Provides the 'spawn()' function, a front-end to various platform- specific functions for launching another program in a sub-process.""" # created 1999/07/24, Greg Ward __rcsid__ = "$Id$" import sys, os, string from distutils.errors import * 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 'verbose' is true, a one-line summary of the command will be printed before it is run. 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, verbose, dry_run) elif os.name == 'nt': _spawn_nt (cmd, search_path, verbose, dry_run) else: raise DistutilsPlatformError, \ "don't know how to spawn programs on platform '%s'" % os.name # spawn () def _nt_quote_args (args): """Obscure quoting command line arguments on NT. Simply quote every argument which contains blanks.""" # 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 in range (len (args)): if string.find (args[i], ' ') != -1: args[i] = '"%s"' % args[i] 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: paths = string.split( os.environ['PATH'], os.pathsep) base,ext = os.path.splitext(executable) if (ext != '.exe'): executable = executable + '.exe' if not os.path.isfile(executable): paths.reverse() # go over the paths and keep the last one 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 executable = f if verbose: print string.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 os.error, exc: # this seems to happen when the command isn't found raise DistutilsExecError, \ "command '%s' failed: %s" % (cmd[0], exc[-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 _examine_status (child_name, status): """Examine the termination status of a child process to determine if it failed or not, and what we should do next. If the child process failed (non-zero termination status), raises DistutilsExecError. If the child is merely stopped, rather than terminated, returns false. If the child terminated successfully, returns true. Note that detecting stopped child processes is only possible under Python 1.5.2 and later, since earlier versions do not provide the WIFSTOPPED function.""" # Python provides the WIFSIGNALED (and friends) macros: this requires # a system C library that provides those macros and Python 1.5.2 # or later. if hasattr (os, 'WIFSIGNALED'): if os.WIFSIGNALED (status): raise DistutilsExecError, \ "command '%s' terminated by signal %d" % \ (child_name, os.WTERMSIG (status)) elif os.WIFEXITED (status): exit_status = os.WEXITSTATUS (status) if exit_status == 0: return 1 # child process terminated successfully else: raise DistutilsExecError, \ "command '%s' failed with exit status %d" % \ (child_name, exit_status) elif os.WIFSTOPPED (status): # child process is stopped return 0 else: raise DistutilsExecError, \ "unknown error executing '%s': termination status %d" % \ (child_name, status) # Old Python or non-POSIX-compliant OS: do the best we can. else: if status == 0: return 1 else: exit_status = (status >> 8) & 0xFF signal = (status & 0x7F) if exit_status != 0: raise DistutilsExecError, \ "command '%s' failed with exit status %d" % \ (child_name, exit_status) elif signal != 0: raise DistutilsExecError, \ "command '%s' terminated by signal %d" % \ (child_name, signal) else: raise DistutilsExecError, \ ("command '%s' terminated for unknown reason " + "(termination status %d)") % \ (child_name, status) # _examine_status () def _spawn_posix (cmd, search_path=1, verbose=0, dry_run=0): if verbose: print string.join (cmd, ' ') if dry_run: return exec_fn = search_path and os.execvp or os.execv pid = os.fork () if pid == 0: # in the child try: #print "cmd[0] =", cmd[0] #print "cmd =", cmd exec_fn (cmd[0], cmd) except os.error, e: sys.stderr.write ("unable to execute '%s': %s\n" % (cmd[0], e[-1])) 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) done = 0 while not done: (pid, status) = os.waitpid (pid, 0) done = _examine_status (cmd[0], status) # _spawn_posix ()