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 int
  15 SIGPROCMASK (int how, const sigset_t *set, sigset_t *oset)
  16 {
  17 #ifdef POSIX_SIGNALS
  18     return sigprocmask(how, set, oset);
  19 #else
  20 # ifdef BSD_SIGNALS
  21     switch(how) {
  22     case SIG_BLOCK:
  23         *oset = sigblock(*set);
  24         break;
  25     case SIG_UNBLOCK:
  26         sigfillset(*oset);
  27         *oset = sigsetmask(*oset);
  28         sigsetmask(*oset & ~(*set));
  29         break;
  30     case SIG_SETMASK:
  31         *oset = sigsetmask(*set);
  32         break;
  33     default:
  34         adios(NULL, "unknown flag in SIGPROCMASK");
  35         break;
  36     }
  37     return 0;
  38 # endif
  39 #endif
  40 }
  41
  42
  43 /*
  44  * A version of the function `signal' that uses reliable
  45  * signals, if the machine supports them.  Also, (assuming
  46  * OS support), it restarts interrupted system calls for all
  47  * signals except SIGALRM.
  48  */
  49
  50 SIGNAL_HANDLER
  51 SIGNAL (int sig, SIGNAL_HANDLER func)
  52 {
  53 #ifdef POSIX_SIGNALS
  54     struct sigaction act, oact;
  55
  56     act.sa_handler = func;
  57     sigemptyset(&act.sa_mask);
  58     act.sa_flags = 0;
  59
  60     if (sig == SIGALRM) {
  61 # ifdef SA_INTERRUPT
  62         act.sa_flags |= SA_INTERRUPT;     /* SunOS */
  63 # endif
  64     } else {
  65 # ifdef SA_RESTART
  66         act.sa_flags |= SA_RESTART;       /* SVR4, BSD4.4 */
  67 # endif
  68     }
  69     if (sigaction(sig, &act, &oact) < 0)
  70         return (SIG_ERR);
  71     return (oact.sa_handler);
  72 #else
  73     return signal (sig, func);
  74 #endif
  75 }
  76
  77
  78 /*
  79  * A version of the function `signal' that will set
  80  * the handler of `sig' to `func' if the signal is
  81  * not currently set to SIG_IGN.  Also uses reliable
  82  * signals if available.
  83  */
  84 SIGNAL_HANDLER
  85 SIGNAL2 (int sig, SIGNAL_HANDLER func)
  86 {
  87 #ifdef POSIX_SIGNALS
  88     struct sigaction act, oact;
  89
  90     if (sigaction(sig, NULL, &oact) < 0)
  91         return (SIG_ERR);
  92     if (oact.sa_handler != SIG_IGN) {
  93         act.sa_handler = func;
  94         sigemptyset(&act.sa_mask);
  95         act.sa_flags = 0;
  96
  97         if (sig == SIGALRM) {
  98 # ifdef SA_INTERRUPT
  99             act.sa_flags |= SA_INTERRUPT;     /* SunOS */
 100 # endif
 101         } else {
 102 # ifdef SA_RESTART
 103             act.sa_flags |= SA_RESTART;       /* SVR4, BSD4.4 */
 104 # endif
 105         }
 106         if (sigaction(sig, &act, &oact) < 0)
 107             return (SIG_ERR);
 108     }
 109     return (oact.sa_handler);
 110 #else
 111     SIGNAL_HANDLER ofunc;
 112
 113     if ((ofunc = signal (sig, SIG_IGN)) != SIG_IGN)
 114         signal (sig, func);
 115     return ofunc;
 116 #endif
 117 }
 118