src/interfaces/libpq/legacy-pqsignal.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * legacy-pqsignal.c
   4  *        reliable BSD-style signal(2) routine stolen from RWW who stole it
   5  *        from Stevens...
   6  *
   7  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  *
  11  * IDENTIFICATION
  12  *        src/interfaces/libpq/legacy-pqsignal.c
  13  *
  14  *-------------------------------------------------------------------------
  15  */
  16 #include "postgres_fe.h"
  17
  18 #include <signal.h>
  19
  20
  21 /*
  22  * This version of pqsignal() exists only because pre-9.3 releases
  23  * of libpq exported pqsignal(), and some old client programs still
  24  * depend on that.  (Since 9.3, clients are supposed to get it from
  25  * libpgport instead.)
  26  *
  27  * Because it is only intended for backwards compatibility, we freeze it
  28  * with the semantics it had in 9.2; in particular, this has different
  29  * behavior for SIGALRM than the version in src/port/pqsignal.c.
  30  *
  31  * libpq itself does not use this.
  32  */
  33 pqsigfunc
  34 pqsignal(int signo, pqsigfunc func)
  35 {
  36 #ifndef WIN32
  37         struct sigaction act,
  38                                 oact;
  39
  40         act.sa_handler = func;
  41         sigemptyset(&act.sa_mask);
  42         act.sa_flags = 0;
  43         if (signo != SIGALRM)
  44                 act.sa_flags |= SA_RESTART;
  45 #ifdef SA_NOCLDSTOP
  46         if (signo == SIGCHLD)
  47                 act.sa_flags |= SA_NOCLDSTOP;
  48 #endif
  49         if (sigaction(signo, &act, &oact) < 0)
  50                 return SIG_ERR;
  51         return oact.sa_handler;
  52 #else                                                   /* WIN32 */
  53         return signal(signo, func);
  54 #endif
  55 }