utils.py 文件源码

def check_write_permissions(user, path):
    """
    Returns `True` if the given *user* has write permissions to *path*.  *user*
    can be a UID (int) or a username (string).
    """
    import pwd, grp, stat
    # Get the user's complete passwd record
    if isinstance(user, int):
        user = pwd.getpwuid(user)
    else:
        user = pwd.getpwnam(user)
    if user.pw_uid == 0:
        return True # Assume root can write to everything (NFS notwithstanding)
    groups = [] # A combination of user's primary GID and supplemental groups
    for group in grp.getgrall():
        if user.pw_name in group.gr_mem:
            groups.append(group.gr_gid)
        if group.gr_gid == user.pw_gid:
            groups.append(group.gr_gid)
    st = os.stat(path)
    other_write = bool(st.st_mode & stat.S_IWOTH)
    if other_write:
        return True # Read/write world!
    owner_write = bool(st.st_mode & stat.S_IWUSR)
    if st.st_uid == user.pw_uid and owner_write:
        return True # User can write to their own file
    group_write = bool(st.st_mode & stat.S_IWGRP)
    if st.st_gid in groups and group_write:
        return True # User belongs to a group that can write to the file
    return False