1"""distutils.spawn
2
3Provides the 'spawn()' function, a front-end to various platform-
4specific functions for launching another program in a sub-process.
5Also provides the 'find_executable()' to search the path for a given
6executable name.
7"""
8
9__revision__ = "$Id$"
10
11import sys
12import os
13
14from distutils.errors import DistutilsPlatformError, DistutilsExecError
15from distutils.debug import DEBUG
16from distutils import log
17
18def spawn(cmd, search_path=1, verbose=0, dry_run=0):
19    """Run another program, specified as a command list 'cmd', in a new process.
20
21    'cmd' is just the argument list for the new process, ie.
22    cmd[0] is the program to run and cmd[1:] are the rest of its arguments.
23    There is no way to run a program with a name different from that of its
24    executable.
25
26    If 'search_path' is true (the default), the system's executable
27    search path will be used to find the program; otherwise, cmd[0]
28    must be the exact path to the executable.  If 'dry_run' is true,
29    the command will not actually be run.
30
31    Raise DistutilsExecError if running the program fails in any way; just
32    return on success.
33    """
34    # cmd is documented as a list, but just in case some code passes a tuple
35    # in, protect our %-formatting code against horrible death
36    cmd = list(cmd)
37    if os.name == 'posix':
38        _spawn_posix(cmd, search_path, dry_run=dry_run)
39    elif os.name == 'nt':
40        _spawn_nt(cmd, search_path, dry_run=dry_run)
41    elif os.name == 'os2':
42        _spawn_os2(cmd, search_path, dry_run=dry_run)
43    else:
44        raise DistutilsPlatformError, \
45              "don't know how to spawn programs on platform '%s'" % os.name
46
47def _nt_quote_args(args):
48    """Quote command-line arguments for DOS/Windows conventions.
49
50    Just wraps every argument which contains blanks in double quotes, and
51    returns a new argument list.
52    """
53    # XXX this doesn't seem very robust to me -- but if the Windows guys
54    # say it'll work, I guess I'll have to accept it.  (What if an arg
55    # contains quotes?  What other magic characters, other than spaces,
56    # have to be escaped?  Is there an escaping mechanism other than
57    # quoting?)
58    for i, arg in enumerate(args):
59        if ' ' in arg:
60            args[i] = '"%s"' % arg
61    return args
62
63def _spawn_nt(cmd, search_path=1, verbose=0, dry_run=0):
64    executable = cmd[0]
65    cmd = _nt_quote_args(cmd)
66    if search_path:
67        # either we find one or it stays the same
68        executable = find_executable(executable) or executable
69    log.info(' '.join([executable] + cmd[1:]))
70    if not dry_run:
71        # spawn for NT requires a full path to the .exe
72        try:
73            rc = os.spawnv(os.P_WAIT, executable, cmd)
74        except OSError, exc:
75            # this seems to happen when the command isn't found
76            if not DEBUG:
77                cmd = executable
78            raise DistutilsExecError, \
79                  "command %r failed: %s" % (cmd, exc[-1])
80        if rc != 0:
81            # and this reflects the command running but failing
82            if not DEBUG:
83                cmd = executable
84            raise DistutilsExecError, \
85                  "command %r failed with exit status %d" % (cmd, rc)
86
87def _spawn_os2(cmd, search_path=1, verbose=0, dry_run=0):
88    executable = cmd[0]
89    if search_path:
90        # either we find one or it stays the same
91        executable = find_executable(executable) or executable
92    log.info(' '.join([executable] + cmd[1:]))
93    if not dry_run:
94        # spawnv for OS/2 EMX requires a full path to the .exe
95        try:
96            rc = os.spawnv(os.P_WAIT, executable, cmd)
97        except OSError, exc:
98            # this seems to happen when the command isn't found
99            if not DEBUG:
100                cmd = executable
101            raise DistutilsExecError, \
102                  "command %r failed: %s" % (cmd, exc[-1])
103        if rc != 0:
104            # and this reflects the command running but failing
105            if not DEBUG:
106                cmd = executable
107            log.debug("command %r failed with exit status %d" % (cmd, rc))
108            raise DistutilsExecError, \
109                  "command %r failed with exit status %d" % (cmd, rc)
110
111if sys.platform == 'darwin':
112    from distutils import sysconfig
113    _cfg_target = None
114    _cfg_target_split = None
115
116def _spawn_posix(cmd, search_path=1, verbose=0, dry_run=0):
117    log.info(' '.join(cmd))
118    if dry_run:
119        return
120    executable = cmd[0]
121    exec_fn = search_path and os.execvp or os.execv
122    env = None
123    if sys.platform == 'darwin':
124        global _cfg_target, _cfg_target_split
125        if _cfg_target is None:
126            _cfg_target = sysconfig.get_config_var(
127                                  'MACOSX_DEPLOYMENT_TARGET') or ''
128            if _cfg_target:
129                _cfg_target_split = [int(x) for x in _cfg_target.split('.')]
130        if _cfg_target:
131            # ensure that the deployment target of build process is not less
132            # than that used when the interpreter was built. This ensures
133            # extension modules are built with correct compatibility values
134            cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target)
135            if _cfg_target_split > [int(x) for x in cur_target.split('.')]:
136                my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: '
137                          'now "%s" but "%s" during configure'
138                                % (cur_target, _cfg_target))
139                raise DistutilsPlatformError(my_msg)
140            env = dict(os.environ,
141                       MACOSX_DEPLOYMENT_TARGET=cur_target)
142            exec_fn = search_path and os.execvpe or os.execve
143    pid = os.fork()
144
145    if pid == 0:  # in the child
146        try:
147            if env is None:
148                exec_fn(executable, cmd)
149            else:
150                exec_fn(executable, cmd, env)
151        except OSError, e:
152            if not DEBUG:
153                cmd = executable
154            sys.stderr.write("unable to execute %r: %s\n" %
155                             (cmd, e.strerror))
156            os._exit(1)
157
158        if not DEBUG:
159            cmd = executable
160        sys.stderr.write("unable to execute %r for unknown reasons" % cmd)
161        os._exit(1)
162    else:   # in the parent
163        # Loop until the child either exits or is terminated by a signal
164        # (ie. keep waiting if it's merely stopped)
165        while 1:
166            try:
167                pid, status = os.waitpid(pid, 0)
168            except OSError, exc:
169                import errno
170                if exc.errno == errno.EINTR:
171                    continue
172                if not DEBUG:
173                    cmd = executable
174                raise DistutilsExecError, \
175                      "command %r failed: %s" % (cmd, exc[-1])
176            if os.WIFSIGNALED(status):
177                if not DEBUG:
178                    cmd = executable
179                raise DistutilsExecError, \
180                      "command %r terminated by signal %d" % \
181                      (cmd, os.WTERMSIG(status))
182
183            elif os.WIFEXITED(status):
184                exit_status = os.WEXITSTATUS(status)
185                if exit_status == 0:
186                    return   # hey, it succeeded!
187                else:
188                    if not DEBUG:
189                        cmd = executable
190                    raise DistutilsExecError, \
191                          "command %r failed with exit status %d" % \
192                          (cmd, exit_status)
193
194            elif os.WIFSTOPPED(status):
195                continue
196
197            else:
198                if not DEBUG:
199                    cmd = executable
200                raise DistutilsExecError, \
201                      "unknown error executing %r: termination status %d" % \
202                      (cmd, status)
203
204def find_executable(executable, path=None):
205    """Tries to find 'executable' in the directories listed in 'path'.
206
207    A string listing directories separated by 'os.pathsep'; defaults to
208    os.environ['PATH'].  Returns the complete filename or None if not found.
209    """
210    if path is None:
211        path = os.environ.get('PATH', os.defpath)
212
213    paths = path.split(os.pathsep)
214    base, ext = os.path.splitext(executable)
215
216    if (sys.platform == 'win32' or os.name == 'os2') and (ext != '.exe'):
217        executable = executable + '.exe'
218
219    if not os.path.isfile(executable):
220        for p in paths:
221            f = os.path.join(p, executable)
222            if os.path.isfile(f):
223                # the file exists, we have a shot at spawn working
224                return f
225        return None
226    else:
227        return executable
228