import os, errno
import atexit
import tempfile

_tmpfiles = set()

def _cleanup():
    for f in _tmpfiles:
        silentremove(f)

def silentremove(filename): #export
    try:
        os.remove(filename)
    except OSError as e:
        if e.errno != errno.ENOENT:
            raise # re-raise exception if a different error occurred

def pad(token, total_size, right_align = False):
    add = total_size - len(token)
    if add <= 0:
        return token
    space = ' ' * add
    if right_align:
        return space + token
    return token + space

def atomic_store(contents, path): # export
    if path[0:3] == '/dev':
        with open(path, 'w') as outfile:
            outfile.write(contents)
        return
    outfile = tempfile.NamedTemporaryFile(prefix=os.path.basename(path), delete=False, dir=os.path.dirname(path))
    name = outfile.name
    _tmpfiles.add(name)
    outfile.write(contents)
    outfile.close()
    os.rename(name, path)
    _tmpfiles.remove(name)

atexit.register(_cleanup)