TLA  Line data    Source code

       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) 1996-2023, 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                 : #ifndef FRONTEND
      33                 : #include "libpq/pqsignal.h"
      34                 : #endif
      35                 : 
      36                 : /*
      37                 :  * Set up a signal handler, with SA_RESTART, for signal "signo"
      38                 :  *
      39                 :  * Returns the previous handler.
      40                 :  */
      41                 : pqsigfunc
      42 GIC      206587 : pqsignal(int signo, pqsigfunc func)
      43                 : {
      44                 : #if !(defined(WIN32) && defined(FRONTEND))
      45                 :     struct sigaction act,
      46                 :                 oact;
      47                 : 
      48          206587 :     act.sa_handler = func;
      49          206587 :     sigemptyset(&act.sa_mask);
      50 CBC      206587 :     act.sa_flags = SA_RESTART;
      51 ECB             : #ifdef SA_NOCLDSTOP
      52 CBC      206587 :     if (signo == SIGCHLD)
      53 GIC       20003 :         act.sa_flags |= SA_NOCLDSTOP;
      54 ECB             : #endif
      55 CBC      206587 :     if (sigaction(signo, &act, &oact) < 0)
      56 UIC           0 :         return SIG_ERR;
      57 CBC      206587 :     return oact.sa_handler;
      58                 : #else
      59                 :     /* Forward to Windows native signal system. */
      60 ECB             :     return signal(signo, func);
      61                 : #endif
      62                 : }