# Portions Copyright (c) 2008-2009 Nokia Corporation
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

_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'
    from posix import *
    try:
        from posix import _exit
    except ImportError:
        pass
    if sys.platform == 'symbian_s60':
        linesep = '\r\n'
        import ntpath as path
    else:
        linesep = '\n'
        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.

    """
    from errno import EEXIST
    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 != 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