interlock

   1 #! /bin/sh
   2 # interlock - wrap program invocation in lock to allow
   3 #             parallel builds to work.
   4 # Written by Tom Tromey <tromey@cygnus.com>, Aug 10 1996
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 2, or (at your option)
   9 # any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program; if not, write to the Free Software
  18 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19
  20 # Usage:
  21 #   interlock lock-dir-name program args-to-program...
  22
  23 dirname="$1"
  24 program="$2"
  25
  26 shift
  27 shift
  28
  29 while (mkdir $dirname > /dev/null 2>&1 && exit 1 || exit 0); do
  30    # Wait a bit.
  31    sleep 1
  32 done
  33
  34 # Race condition here: if interrupted after the loop but before this
  35 # trap, the lock can be left around.
  36 trap "rmdir $dirname > /dev/null 2>&1" 1 2 3 15
  37
  38 # We have the lock, so run the program.
  39 $program ${1+"$@"}
  40 ret=$?
  41
  42 # Release the lock.
  43 rmdir $dirname > /dev/null 2>&1
  44
  45 exit $ret