r"""OS routines for Mac, NT, or Posix depending on what system we're on.

This exports:

  - all functions from posix, nt, os2, mac, or ce, e.g. unlink, stat, etc.

  - os.path is one of the modules posixpath, ntpath, or macpath

  - os.name is 'posix', 'nt', 'os2', 'mac', 'ce' or 'riscos'

  - os.curdir is a string representing the current directory ('.' or ':')

  - os.pardir is a string representing the parent directory ('..' or '::')

  - os.sep is the (or a most common) pathname separator ('/' or ':' or '\\')

  - os.extsep is the extension separator ('.' or '/')

  - os.altsep is the alternate pathname separator (None or '/')

  - os.pathsep is the component separator used in $PATH etc

  - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')

  - os.defpath is the default search path for executables

  - os.devnull is the file path of the null device ('/dev/null', etc.)

Programs that import and use 'os' stand a better chance of being

portable between different platforms.  Of course, they must then

only use functions that are defined by all platforms (e.g., unlink

and opendir), and leave all pathname manipulation to os.path

(e.g., split and join).

"""

#'

import sys, errno

_names = sys.builtin_module_names

# Note:  more names are added to __all__ later.

__all__ = ["altsep", "curdir", "pardir", "sep", "pathsep", "linesep",

           "defpath", "name", "path", "devnull",

           "SEEK_SET", "SEEK_CUR", "SEEK_END"]

def _get_exports_list(module):

    try:

        return list(module.__all__)

    except AttributeError:

        return [n for n in dir(module) if n[0] != '_']

if 'posix' in _names:

    name = 'posix'

    linesep = '\n'

    from posix import *

    try:

        from posix import _exit

    except ImportError:

        pass

    import posixpath as path

    import posix

    __all__.extend(_get_exports_list(posix))

    del posix

elif 'nt' in _names:

    name = 'nt'

    linesep = '\r\n'

    from nt import *

    try:

        from nt import _exit

    except ImportError:

        pass

    import ntpath as path

    import nt

    __all__.extend(_get_exports_list(nt))

    del nt

elif 'os2' in _names:

    name = 'os2'

    linesep = '\r\n'

    from os2 import *

    try:

        from os2 import _exit

    except ImportError:

        pass

    if sys.version.find('EMX GCC') == -1:

        import ntpath as path

    else:

        import os2emxpath as path

        from _emx_link import link

    import os2

    __all__.extend(_get_exports_list(os2))

    del os2

elif 'mac' in _names:

    name = 'mac'

    linesep = '\r'

    from mac import *

    try:

        from mac import _exit

    except ImportError:

        pass

    import macpath as path

    import mac

    __all__.extend(_get_exports_list(mac))

    del mac

elif 'ce' in _names:

    name = 'ce'

    linesep = '\r\n'

    from ce import *

    try:

        from ce import _exit

    except ImportError:

        pass

    # We can use the standard Windows path.

    import ntpath as path

    import ce

    __all__.extend(_get_exports_list(ce))

    del ce

elif 'riscos' in _names:

    name = 'riscos'

    linesep = '\n'

    from riscos import *

    try:

        from riscos import _exit

    except ImportError:

        pass

    import riscospath as path

    import riscos

    __all__.extend(_get_exports_list(riscos))

    del riscos

else:

    raise ImportError, 'no os specific module found'

sys.modules['os.path'] = path

from os.path import (curdir, pardir, sep, pathsep, defpath, extsep, altsep,

    devnull)

del _names

# Python uses fixed values for the SEEK_ constants; they are mapped

# to native constants if necessary in posixmodule.c

SEEK_SET = 0

SEEK_CUR = 1

SEEK_END = 2

#'

# Super directory utilities.

# (Inspired by Eric Raymond; the doc strings are mostly his)

def makedirs(name, mode=0777):

    """makedirs(path [, mode=0777])

    Super-mkdir; create a leaf directory and all intermediate ones.

    Works like mkdir, except that any intermediate path segment (not

    just the rightmost) will be created if it does not exist.  This is

    recursive.

    """

    head, tail = path.split(name)

    if not tail:

        head, tail = path.split(head)

    if head and tail and not path.exists(head):

        try:

            makedirs(head, mode)

        except OSError, e:

            # be happy if someone already created the path

            if e.errno != errno.EEXIST:

                raise

        if tail == curdir:           # xxx/newdir/. exists if xxx/newdir exists

            return

    mkdir(name, mode)

def removedirs(name):

    """removedirs(path)

    Super-rmdir; remove a leaf directory and all empty intermediate

    ones.  Works like rmdir except that, if the leaf directory is

    successfully removed, directories corresponding to rightmost path

    segments will be pruned away until either the whole path is

    consumed or an error occurs.  Errors during this latter phase are

    ignored -- they generally mean that a directory was not empty.

    """

    rmdir(name)

    head, tail = path.split(name)

    if not tail:

        head, tail = path.split(head)

    while head and tail:

        try:

            rmdir(head)

        except error:

            break

        head, tail = path.split(head)

def renames(old, new):

    """renames(old, new)

    Super-rename; create directories as necessary and delete any left

    empty.  Works like rename, except creation of any intermediate

    directories needed to make the new pathname good is attempted

    first.  After the rename, directories corresponding to rightmost

    path segments of the old name will be pruned way until either the

    whole path is consumed or a nonempty directory is found.

    Note: this function can fail with the new directory structure made

    if you lack permissions needed to unlink the leaf directory or

    file.

    """

    head, tail = path.split(new)

    if head and tail and not path.exists(head):

        makedirs(head)

    rename(old, new)

    head, tail = path.split(old)

    if head and tail:

        try:

            removedirs(head)

        except error:

            pass

__all__.extend(["makedirs", "removedirs", "renames"])

def walk(top, topdown=True, onerror=None):

    """Directory tree generator.

    For each directory in the directory tree rooted at top (including top

    itself, but excluding '.' and '..'), yields a 3-tuple

        dirpath, dirnames, filenames

    dirpath is a string, the path to the directory.  dirnames is a list of

    the names of the subdirectories in dirpath (excluding '.' and '..').

    filenames is a list of the names of the non-directory files in dirpath.

    Note that the names in the lists are just names, with no path components.

    To get a full path (which begins with top) to a file or directory in

    dirpath, do os.path.join(dirpath, name).

    If optional arg 'topdown' is true or not specified, the triple for a

    directory is generated before the triples for any of its subdirectories

    (directories are generated top down).  If topdown is false, the triple

    for a directory is generated after the triples for all of its

    subdirectories (directories are generated bottom up).

    When topdown is true, the caller can modify the dirnames list in-place

    (e.g., via del or slice assignment), and walk will only recurse into the

    subdirectories whose names remain in dirnames; this can be used to prune

    the search, or to impose a specific order of visiting.  Modifying

    dirnames when topdown is false is ineffective, since the directories in

    dirnames have already been generated by the time dirnames itself is

    generated.

    By default errors from the os.listdir() call are ignored.  If

    optional arg 'onerror' is specified, it should be a function; it

    will be called with one argument, an os.error instance.  It can

    report the error to continue with the walk, or raise the exception

    to abort the walk.  Note that the filename is available as the

    filename attribute of the exception object.

    Caution:  if you pass a relative pathname for top, don't change the

    current working directory between resumptions of walk.  walk never

    changes the current directory, and assumes that the client doesn't

    either.

    Example:

    from os.path import join, getsize

    for root, dirs, files in walk('python/Lib/email'):

        print root, "consumes",

        print sum([getsize(join(root, name)) for name in files]),

        print "bytes in", len(files), "non-directory files"

        if 'CVS' in dirs:

            dirs.remove('CVS')  # don't visit CVS directories

    """

    from os.path import join, isdir, islink

    # We may not have read permission for top, in which case we can't

    # get a list of the files the directory contains.  os.path.walk

    # always suppressed the exception then, rather than blow up for a

    # minor reason when (say) a thousand readable directories are still

    # left to visit.  That logic is copied here.

    try:

        # Note that listdir and error are globals in this module due

        # to earlier import-*.

        names = listdir(top)

    except error, err:

        if onerror is not None:

            onerror(err)

        return

    dirs, nondirs = [], []

    for name in names:

        if isdir(join(top, name)):

            dirs.append(name)

        else:

            nondirs.append(name)

    if topdown:

        yield top, dirs, nondirs

    for name in dirs:

        path = join(top, name)

        if not islink(path):

            for x in walk(path, topdown, onerror):

                yield x

    if not topdown:

        yield top, dirs, nondirs

__all__.append("walk")

# Make sure os.environ exists, at least

try:

    environ

except NameError:

    environ = {}

def execl(file, *args):

    """execl(file, *args)

    Execute the executable file with argument list args, replacing the

    current process. """

    execv(file, args)

def execle(file, *args):

    """execle(file, *args, env)

    Execute the executable file with argument list args and

    environment env, replacing the current process. """

    env = args[-1]

    execve(file, args[:-1], env)

def execlp(file, *args):

    """execlp(file, *args)

    Execute the executable file (which is searched for along $PATH)

    with argument list args, replacing the current process. """

    execvp(file, args)

def execlpe(file, *args):

    """execlpe(file, *args, env)

    Execute the executable file (which is searched for along $PATH)

    with argument list args and environment env, replacing the current

    process. """

    env = args[-1]

    execvpe(file, args[:-1], env)

def execvp(file, args):

    """execp(file, args)

    Execute the executable file (which is searched for along $PATH)

    with argument list args, replacing the current process.

    args may be a list or tuple of strings. """

    _execvpe(file, args)

def execvpe(file, args, env):

    """execvpe(file, args, env)

    Execute the executable file (which is searched for along $PATH)

    with argument list args and environment env , replacing the

    current process.

    args may be a list or tuple of strings. """

    _execvpe(file, args, env)

__all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"])

def _execvpe(file, args, env=None):

    if env is not None:

        func = execve

        argrest = (args, env)

    else:

        func = execv

        argrest = (args,)

        env = environ

    head, tail = path.split(file)

    if head:

        func(file, *argrest)

        return

    if 'PATH' in env:

        envpath = env['PATH']

    else:

        envpath = defpath

    PATH = envpath.split(pathsep)

    saved_exc = None

    saved_tb = None

    for dir in PATH:

        fullname = path.join(dir, file)

        try:

            func(fullname, *argrest)

        except error, e:

            tb = sys.exc_info()[2]

            if (e.errno != errno.ENOENT and e.errno != errno.ENOTDIR

                and saved_exc is None):

                saved_exc = e

                saved_tb = tb

    if saved_exc:

        raise error, saved_exc, saved_tb

    raise error, e, tb

# Change environ to automatically call putenv() if it exists

try:

    # This will fail if there's no putenv

    putenv

except NameError:

    pass

else:

    import UserDict

    # Fake unsetenv() for Windows

    # not sure about os2 here but

    # I'm guessing they are the same.

    if name in ('os2', 'nt'):

        def unsetenv(key):

            putenv(key, "")

    if name == "riscos":

        # On RISC OS, all env access goes through getenv and putenv

        from riscosenviron import _Environ

    elif name in ('os2', 'nt'):  # Where Env Var Names Must Be UPPERCASE

        # But we store them as upper case

        class _Environ(UserDict.IterableUserDict):

            def __init__(self, environ):

                UserDict.UserDict.__init__(self)

                data = self.data

                for k, v in environ.items():

                    data[k.upper()] = v

            def __setitem__(self, key, item):

                putenv(key, item)

                self.data[key.upper()] = item

            def __getitem__(self, key):

                return self.data[key.upper()]

            try:

                unsetenv

            except NameError:

                def __delitem__(self, key):

                    del self.data[key.upper()]

            else:

                def __delitem__(self, key):

                    unsetenv(key)

                    del self.data[key.upper()]

            def has_key(self, key):

                return key.upper() in self.data

            def __contains__(self, key):

                return key.upper() in self.data

            def get(self, key, failobj=None):

                return self.data.get(key.upper(), failobj)

            def update(self, dict=None, **kwargs):

                if dict:

                    try:

                        keys = dict.keys()

                    except AttributeError:

                        # List of (key, value)

                        for k, v in dict:

                            self[k] = v

                    else:

                        # got keys

                        # cannot use items(), since mappings

                        # may not have them.

                        for k in keys:

                            self[k] = dict[k]

                if kwargs:

                    self.update(kwargs)

            def copy(self):

                return dict(self)

    else:  # Where Env Var Names Can Be Mixed Case

        class _Environ(UserDict.IterableUserDict):

            def __init__(self, environ):

                UserDict.UserDict.__init__(self)

                self.data = environ

            def __setitem__(self, key, item):

                putenv(key, item)

                self.data[key] = item

            def update(self,  dict=None, **kwargs):

                if dict:

                    try:

                        keys = dict.keys()

                    except AttributeError:

                        # List of (key, value)

                        for k, v in dict:

                            self[k] = v

                    else:

                        # got keys

                        # cannot use items(), since mappings

                        # may not have them.

                        for k in keys:

                            self[k] = dict[k]

                if kwargs:

                    self.update(kwargs)

            try:

                unsetenv

            except NameError:

                pass

            else:

                def __delitem__(self, key):

                    unsetenv(key)

                    del self.data[key]

            def copy(self):

                return dict(self)

    environ = _Environ(environ)

def getenv(key, default=None):

    """Get an environment variable, return None if it doesn't exist.

    The optional second argument can specify an alternate default."""

    return environ.get(key, default)

__all__.append("getenv")

def _exists(name):

    try:

        eval(name)

        return True

    except NameError:

        return False

# Supply spawn*() (probably only for Unix)

if _exists("fork") and not _exists("spawnv") and _exists("execv"):

    P_WAIT = 0

    P_NOWAIT = P_NOWAITO = 1

    # XXX Should we support P_DETACH?  I suppose it could fork()**2

    # and close the std I/O streams.  Also, P_OVERLAY is the same

    # as execv*()?

    def _spawnvef(mode, file, args, env, func):