def copy_file(src, dst, preserve_mode=1, preserve_times=1, update=0,
              link=None, verbose=1, dry_run=0):
    """Copy a file 'src' to 'dst'.

    If 'dst' is a directory, then 'src' is copied there with the same name;
    otherwise, it must be a filename.  (If the file exists, it will be
    ruthlessly clobbered.)  If 'preserve_mode' is true (the default),
    the file's mode (type and permission bits, or whatever is analogous on
    the current platform) is copied.  If 'preserve_times' is true (the
    default), the last-modified and last-access times are copied as well.
    If 'update' is true, 'src' will only be copied if 'dst' does not exist,
    or if 'dst' does exist but is older than 'src'.

    'link' allows you to make hard links (os.link) or symbolic links
    (os.symlink) instead of copying: set it to "hard" or "sym"; if it is
    None (the default), files are copied.  Don't set 'link' on systems that
    don't support it: 'copy_file()' doesn't check if hard or symbolic
    linking is available.

    Under Mac OS, uses the native file copy function in macostools; on
    other systems, uses '_copy_file_contents()' to copy file contents.

    Return a tuple (dest_name, copied): 'dest_name' is the actual name of
    the output file, and 'copied' is true if the file was copied (or would
    have been copied, if 'dry_run' true).
    """
    # XXX if the destination file already exists, we clobber it if
    # copying, but blow up if linking.  Hmmm.  And I don't know what
    # macostools.copyfile() does.  Should definitely be consistent, and
    # should probably blow up if destination exists and we would be
    # changing it (ie. it's not already a hard/soft link to src OR
    # (not update) and (src newer than dst).

    from distutils.dep_util import newer
    from stat import ST_ATIME, ST_MTIME, ST_MODE, S_IMODE

    if not os.path.isfile(src):
        raise DistutilsFileError(
              "can't copy '%s': doesn't exist or not a regular file" % src)

    if os.path.isdir(dst):
        dir = dst
        dst = os.path.join(dst, os.path.basename(src))
    else:
        dir = os.path.dirname(dst)

    if update and not newer(src, dst):
        if verbose >= 1:
            log.debug("not copying %s (output up-to-date)", src)
        return dst, 0

    try:
        action = _copy_action[link]
    except __HOLE__:
        raise ValueError("invalid value '%s' for 'link' argument" % link)

    if verbose >= 1:
        if os.path.basename(dst) == os.path.basename(src):
            log.info("%s %s -> %s", action, src, dir)
        else:
            log.info("%s %s -> %s", action, src, dst)

    if dry_run:
        return (dst, 1)

    # If linking (hard or symbolic), use the appropriate system call
    # (Unix only, of course, but that's the caller's responsibility)
    if link == 'hard':
        if not (os.path.exists(dst) and os.path.samefile(src, dst)):
            os.link(src, dst)
    elif link == 'sym':
        if not (os.path.exists(dst) and os.path.samefile(src, dst)):
            os.symlink(src, dst)

    # Otherwise (non-Mac, not linking), copy the file contents and
    # (optionally) copy the times and mode.
    else:
        _copy_file_contents(src, dst)
        if preserve_mode or preserve_times:
            st = os.stat(src)

            # According to David Ascher <da@ski.org>, utime() should be done
            # before chmod() (at least under NT).
            if preserve_times:
                os.utime(dst, (st[ST_ATIME], st[ST_MTIME]))
            if preserve_mode:
                os.chmod(dst, S_IMODE(st[ST_MODE]))

    return (dst, 1)

# XXX I suspect this is Unix-specific -- need porting help!
dataset/ETHPy150Open ctxis/canape/CANAPE.Scripting/Lib/distutils/file_util.py/copy_file