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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.

"""

import sys

import os

from distutils.errors import DistutilsPlatformError, DistutilsExecError

from distutils.debug import DEBUG

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.

"""

# cmd is documented as a list, but just in case some code passes a tuple

# in, protect our %-formatting code against horrible death

cmd = list(cmd)

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)

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

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"command %r failed: %s" % (cmd, exc.args[-1]))

if rc != 0:

# and this reflects the command running but failing

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"command %r failed with exit status %d" % (cmd, 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

executable = cmd[0]

exec_fn = search_path and os.execvp or os.execv

env = None

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

pid = os.fork()

if pid == 0: # in the child

try:

if env is None:

exec_fn(executable, cmd)

else:

exec_fn(executable, cmd, env)

except OSError as e:

if not DEBUG:

cmd = executable

sys.stderr.write("unable to execute %r: %s\n"

% (cmd, e.strerror))

os._exit(1)

if not DEBUG:

cmd = executable

sys.stderr.write("unable to execute %r for unknown reasons" % cmd)

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:

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"command %r failed: %s" % (cmd, exc.args[-1]))

if os.WIFSIGNALED(status):

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"command %r terminated by signal %d"

% (cmd, os.WTERMSIG(status)))

elif os.WIFEXITED(status):

exit_status = os.WEXITSTATUS(status)

if exit_status == 0:

return # hey, it succeeded!

else:

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"command %r failed with exit status %d"

% (cmd, exit_status))

elif os.WIFSTOPPED(status):

continue

else:

if not DEBUG:

cmd = executable

raise DistutilsExecError(

"unknown error executing %r: termination status %d"

% (cmd, 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') 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

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