src/port/pqsignal.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pqsignal.c
   4  *        reliable BSD-style signal(2) routine stolen from RWW who stole it
   5  *        from Stevens...
   6  *
   7  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  *
  11  * IDENTIFICATION
  12  *        src/port/pqsignal.c
  13  *
  14  *      We now assume that all Unix-oid systems have POSIX sigaction(2)
  15  *      with support for restartable signals (SA_RESTART).  We used to also
  16  *      support BSD-style signal(2), but there really shouldn't be anything
  17  *      out there anymore that doesn't have the POSIX API.
  18  *
  19  *      Windows, of course, is resolutely in a class by itself.  In the backend,
  20  *      we don't use this file at all; src/backend/port/win32/signal.c provides
  21  *      pqsignal() for the backend environment.  Frontend programs can use
  22  *      this version of pqsignal() if they wish, but beware that this does
  23  *      not provide restartable signals on Windows.
  24  *
  25  * ------------------------------------------------------------------------
  26  */
  27
  28 #include "c.h"
  29
  30 #include <signal.h>
  31
  32 #if !defined(WIN32) || defined(FRONTEND)
  33
  34 /*
  35  * Set up a signal handler, with SA_RESTART, for signal "signo"
  36  *
  37  * Returns the previous handler.
  38  */
  39 pqsigfunc
  40 pqsignal(int signo, pqsigfunc func)
  41 {
  42 #ifndef WIN32
  43         struct sigaction act,
  44                                 oact;
  45
  46         act.sa_handler = func;
  47         sigemptyset(&act.sa_mask);
  48         act.sa_flags = SA_RESTART;
  49 #ifdef SA_NOCLDSTOP
  50         if (signo == SIGCHLD)
  51                 act.sa_flags |= SA_NOCLDSTOP;
  52 #endif
  53         if (sigaction(signo, &act, &oact) < 0)
  54                 return SIG_ERR;
  55         return oact.sa_handler;
  56 #else                                                   /* WIN32 */
  57         return signal(signo, func);
  58 #endif
  59 }
  60
  61 #endif                                                  /* !defined(WIN32) || defined(FRONTEND) */