### -*-pyrex-*-
###
### File descriptor juggling
###
### (c) 2009 Straylight/Edgeware
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the Python interface to mLib.
###
### mLib/Python is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### mLib/Python is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with mLib/Python; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

def mdup(v):
  """
  mdup(LIST) -> LIST:
    LIST is a list (mutable sequence) of pairs (CUR, WANT).  Duplicate each
    CUR file descriptor as WANT (may be -1 to mean `don't care'), closing
    original CUR.  Works even if there are cycles.  LIST is updated in place
    with CUR reflecting the new file descriptors even on error.  Returns the
    same LIST on success.
  """
  cdef mdup_fd *vv
  cdef size_t n
  cdef int i
  cdef int rc

  n = len(v)
  vv = <mdup_fd *>xmalloc(n * PSIZEOF(vv))
  for 0 <= i < n:
    vv[i].cur, vv[i].want = v[i]
  rc = _mdup(vv, n)
  for 0 <= i < n:
    v[i] = vv[i].cur, vv[i].want
  if rc < 0:
    _oserror()
  return v

###----- That's all, folks --------------------------------------------------