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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
9import sys
10import os
11import subprocess
12
13from distutils.errors import DistutilsPlatformError, DistutilsExecError
14from distutils.debug import DEBUG
15from distutils import log
16
17
18if sys.platform == 'darwin':
19    _cfg_target = None
20    _cfg_target_split = None
21
22
23def spawn(cmd, search_path=1, verbose=0, dry_run=0):
24    """Run another program, specified as a command list 'cmd', in a new process.
25
26    'cmd' is just the argument list for the new process, ie.
27    cmd[0] is the program to run and cmd[1:] are the rest of its arguments.
28    There is no way to run a program with a name different from that of its
29    executable.
30
31    If 'search_path' is true (the default), the system's executable
32    search path will be used to find the program; otherwise, cmd[0]
33    must be the exact path to the executable.  If 'dry_run' is true,
34    the command will not actually be run.
35
36    Raise DistutilsExecError if running the program fails in any way; just
37    return on success.
38    """
39    # cmd is documented as a list, but just in case some code passes a tuple
40    # in, protect our %-formatting code against horrible death
41    cmd = list(cmd)
42
43    log.info(' '.join(cmd))
44    if dry_run:
45        return
46
47    if search_path:
48        executable = find_executable(cmd[0])
49        if executable is not None:
50            cmd[0] = executable
51
52    env = None
53    if sys.platform == 'darwin':
54        global _cfg_target, _cfg_target_split
55        if _cfg_target is None:
56            from distutils import sysconfig
57            _cfg_target = sysconfig.get_config_var(
58                                  'MACOSX_DEPLOYMENT_TARGET') or ''
59            if _cfg_target:
60                _cfg_target_split = [int(x) for x in _cfg_target.split('.')]
61        if _cfg_target:
62            # Ensure that the deployment target of the build process is not
63            # less than 10.3 if the interpreter was built for 10.3 or later.
64            # This ensures extension modules are built with correct
65            # compatibility values, specifically LDSHARED which can use
66            # '-undefined dynamic_lookup' which only works on >= 10.3.
67            cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target)
68            cur_target_split = [int(x) for x in cur_target.split('.')]
69            if _cfg_target_split[:2] >= [10, 3] and cur_target_split[:2] < [10, 3]:
70                my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: '
71                          'now "%s" but "%s" during configure;'
72                          'must use 10.3 or later'
73                                % (cur_target, _cfg_target))
74                raise DistutilsPlatformError(my_msg)
75            env = dict(os.environ,
76                       MACOSX_DEPLOYMENT_TARGET=cur_target)
77
78    try:
79        proc = subprocess.Popen(cmd, env=env)
80        proc.wait()
81        exitcode = proc.returncode
82    except OSError as exc:
83        if not DEBUG:
84            cmd = cmd[0]
85        raise DistutilsExecError(
86            "command %r failed: %s" % (cmd, exc.args[-1])) from exc
87
88    if exitcode:
89        if not DEBUG:
90            cmd = cmd[0]
91        raise DistutilsExecError(
92              "command %r failed with exit code %s" % (cmd, exitcode))
93
94
95def find_executable(executable, path=None):
96    """Tries to find 'executable' in the directories listed in 'path'.
97
98    A string listing directories separated by 'os.pathsep'; defaults to
99    os.environ['PATH'].  Returns the complete filename or None if not found.
100    """
101    _, ext = os.path.splitext(executable)
102    if (sys.platform == 'win32') and (ext != '.exe'):
103        executable = executable + '.exe'
104
105    if os.path.isfile(executable):
106        return executable
107
108    if path is None:
109        path = os.environ.get('PATH', None)
110        if path is None:
111            try:
112                path = os.confstr("CS_PATH")
113            except (AttributeError, ValueError):
114                # os.confstr() or CS_PATH is not available
115                path = os.defpath
116        # bpo-35755: Don't use os.defpath if the PATH environment variable is
117        # set to an empty string
118
119    # PATH='' doesn't match, whereas PATH=':' looks in the current directory
120    if not path:
121        return None
122
123    paths = path.split(os.pathsep)
124    for p in paths:
125        f = os.path.join(p, executable)
126        if os.path.isfile(f):
127            # the file exists, we have a shot at spawn working
128            return f
129    return None
130