"""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 givenexecutable name.""" # This module should be kept compatible with Python 2.1. __revision__ = "$Id: spawn.py 37828 2004-11-10 22:23:15Z loewis $" import sys, os, stringfrom distutils.errors import *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 # spawn ()  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 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:        # either we find one or it stays the same        executable = find_executable(executable) or executable    log.info(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 OSError, 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 _spawn_os2 (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(string.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, 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            print "command '%s' failed with exit status %d" % (cmd[0], rc)            raise DistutilsExecError, \                  "command '%s' failed with exit status %d" % (cmd[0], rc)  def _spawn_posix (cmd,                  search_path=1,                  verbose=0,                  dry_run=0):     log.info(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 OSError, 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 1:            try:                (pid, status) = os.waitpid(pid, 0)            except OSError, exc:                import errno                if exc.errno == errno.EINTR:                    continue                raise DistutilsExecError, \                      "command '%s' failed: %s" % (cmd[0], exc[-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)# _spawn_posix ()  def find_executable(executable, path=None):    """Try 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 = string.split(path, 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 # find_executable()