"""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 == 'windows':          # ???
        # XXX should 'args' be cmd[1:] or cmd?
        # XXX how do we detect failure?
        # XXX how to do this in pre-1.5.2?
        # XXX is P_WAIT the correct mode?
        # XXX how to make Windows search the path?
        if verbose:
            print string.join (cmd, ' ')
        if not dry_run:
            os.spawnv (os.P_WAIT, cmd[0], cmd[1:])
    else:
        raise DistutilsPlatformError, \
              "don't know how to spawn programs on platform '%s'" % os.name

# spawn ()


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 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:
            (pid, status) = os.waitpid (pid, 0)
            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 ()

@@ -1239,18 +1239,26 @@
 os.name 
-==
+in ( 'nt',
  'window
@@ -1259,16 +1259,18 @@
 windows'
+ )
 :       
@@ -1290,227 +1290,892 @@
     
-# XXX should 'args' be cmd%5B1:%5D or
+_spawn_nt (cmd, search_path, verbose, dry_run)%0A    else:%0A        raise DistutilsPlatformError, %5C%0A              %22don't know how to spawn programs on platform '%25s'%22 %25 os.name%0A%0A# spawn ()%0A%0Adef _spawn_nt ( cmd,%0A                search_path=1,%0A                verbose=0,%0A                dry_run=0):%0A    import string%0A    executable =
  cmd
-?
+%5B0%5D
 %0A    
-    # XXX how do we detect failure?%0A        # XXX how to do 
+if search_path:%0A        paths = string.split( os.environ%5B'PATH'%5D, os.pathsep)%0A        base,ext = os.path.splitext(executable)%0A        if (ext != '.exe'):%0A            executable = executable + '.exe'%0A        if not os.pa
 th
+.
 is
- in pre-1.5.2?%0A        # XXX is P_WAIT the correct mode?%0A        # XXX how to make Windows search the path?%0A    
+file(executable):%0A            paths.reverse()         # go over the paths and keep the last one%0A            for p in paths:%0A                f = os.path.join( p, executable )%0A                if os.path.isfile ( f ):%0A                    # the file exists, we have a shot at spawn working%0A                    executable = f%0A
     
@@ -2182,28 +2182,24 @@
 if verbose:%0A
-    
         prin
@@ -2213,30 +2213,46 @@
 g.join (
-cmd
+ %5Bexecutable%5D + cmd%5B1:%5D
 , ' ')%0A
-    
     if n
@@ -2267,27 +2267,84 @@
 un:%0A        
-   
+# spawn for NT requires a full path to the .exe%0A        rc =
  os.spawnv (
@@ -2358,35 +2358,49 @@
 IT, 
-cmd%5B0%5D
+executable
 , cmd
-%5B1:%5D
 )%0A    
-else:%0A
+    if rc != 0:%0A    
     
@@ -2422,114 +2422,68 @@
 tils
-PlatformError, %5C%0A    
+ExecError(%22command failed: %25d%22 %25 rc) %0A%0A
     
+%0A
       
-%22don't know how to spawn programs on platform '%25s'%22 %25 os.name%0A%0A# spawn ()%0A%0A
+          
 %0Adef

Patch from Perry Stoll: support for Windows.