diplodocus.org Git - nmh/blob - sbr/signals.c

   1
   2 /*
   3  * signals.c -- general signals interface for nmh
   4  *
   5  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   6  * COPYRIGHT file in the root directory of the nmh distribution for
   7  * complete copyright information.
   8  */
   9
  10 #include <h/mh.h>
  11 #include <h/signals.h>
  12
  13
  14 /*
  15  * A version of the function `signal' that uses reliable
  16  * signals, if the machine supports them.  Also, (assuming
  17  * OS support), it restarts interrupted system calls for all
  18  * signals except SIGALRM.
  19  *
  20  * Since we are now assuming POSIX signal support everywhere, we always
  21  * use reliable signals.
  22  */
  23
  24 SIGNAL_HANDLER
  25 SIGNAL (int sig, SIGNAL_HANDLER func)
  26 {
  27     struct sigaction act, oact;
  28
  29     act.sa_handler = func;
  30     sigemptyset(&act.sa_mask);
  31     act.sa_flags = 0;
  32
  33     if (sig == SIGALRM) {
  34 # ifdef SA_INTERRUPT
  35         act.sa_flags |= SA_INTERRUPT;     /* SunOS */
  36 # endif
  37     } else {
  38 # ifdef SA_RESTART
  39         act.sa_flags |= SA_RESTART;       /* SVR4, BSD4.4 */
  40 # endif
  41     }
  42     if (sigaction(sig, &act, &oact) < 0)
  43         return (SIG_ERR);
  44     return (oact.sa_handler);
  45 }
  46
  47
  48 /*
  49  * A version of the function `signal' that will set
  50  * the handler of `sig' to `func' if the signal is
  51  * not currently set to SIG_IGN.  Also uses reliable
  52  * signals if available.
  53  */
  54 SIGNAL_HANDLER
  55 SIGNAL2 (int sig, SIGNAL_HANDLER func)
  56 {
  57     struct sigaction act, oact;
  58
  59     if (sigaction(sig, NULL, &oact) < 0)
  60         return (SIG_ERR);
  61     if (oact.sa_handler != SIG_IGN) {
  62         act.sa_handler = func;
  63         sigemptyset(&act.sa_mask);
  64         act.sa_flags = 0;
  65
  66         if (sig == SIGALRM) {
  67 # ifdef SA_INTERRUPT
  68             act.sa_flags |= SA_INTERRUPT;     /* SunOS */
  69 # endif
  70         } else {
  71 # ifdef SA_RESTART
  72             act.sa_flags |= SA_RESTART;       /* SVR4, BSD4.4 */
  73 # endif
  74         }
  75         if (sigaction(sig, &act, &oact) < 0)
  76             return (SIG_ERR);
  77     }
  78     return (oact.sa_handler);
  79 }
  80