lib/pthread_sigmask.c

   1 /* POSIX compatible signal blocking for threads.
   2    Copyright (C) 2011 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <signal.h>
  21
  22 #include <errno.h>
  23 #include <stddef.h>
  24
  25 #if PTHREAD_SIGMASK_UNBLOCK_BUG
  26 # include <unistd.h>
  27 #endif
  28
  29 int
  30 pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
  31 #undef pthread_sigmask
  32 {
  33 #if HAVE_PTHREAD_SIGMASK
  34   int ret = pthread_sigmask (how, new_mask, old_mask);
  35 # if PTHREAD_SIGMASK_INEFFECTIVE
  36   if (ret == 0)
  37     {
  38       /* Detect whether pthread_sigmask is currently ineffective.
  39          Don't cache the information: libpthread.so could be dynamically
  40          loaded after the program started and after pthread_sigmask was
  41          called for the first time.  */
  42       if (pthread_sigmask (1729, NULL, NULL) == 0)
  43         {
  44           /* pthread_sigmask is currently ineffective.  The program is not
  45              linked to -lpthread.  So use sigprocmask instead.  */
  46           return (sigprocmask (how, new_mask, old_mask) < 0 ? errno : 0);
  47         }
  48     }
  49 # endif
  50 # if PTHREAD_SIGMASK_FAILS_WITH_ERRNO
  51   if (ret == -1)
  52     return errno;
  53 # endif
  54 # if PTHREAD_SIGMASK_UNBLOCK_BUG
  55   if (ret == 0
  56       && new_mask != NULL
  57       && (how == SIG_UNBLOCK || how == SIG_SETMASK))
  58     {
  59       /* Give the OS the opportunity to raise signals that were pending before
  60          the pthread_sigmask call and have now been unblocked.  */
  61       usleep (1);
  62     }
  63 # endif
  64   return ret;
  65 #else
  66   int ret = sigprocmask (how, new_mask, old_mask);
  67   return (ret < 0 ? errno : 0);
  68 #endif
  69 }