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"""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. """
# created 1999/07/24, Greg Ward
__revision__ = "$Id$"
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:
# either we find one or it stays the same
executable = find_executable(executable) or executable
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 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_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 ()
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') 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()
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