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) 1996-2019, 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 uses this only for SIGPIPE (and even then, only in
32 * non-ENABLE_THREAD_SAFETY builds), so the incompatibility isn't
33 * troublesome for internal references.
34 */
35 pqsigfunc
pqsignal(int signo,pqsigfunc func)36 pqsignal(int signo, pqsigfunc func)
37 {
38 #ifndef WIN32
39 struct sigaction act,
40 oact;
41
42 act.sa_handler = func;
43 sigemptyset(&act.sa_mask);
44 act.sa_flags = 0;
45 if (signo != SIGALRM)
46 act.sa_flags |= SA_RESTART;
47 #ifdef SA_NOCLDSTOP
48 if (signo == SIGCHLD)
49 act.sa_flags |= SA_NOCLDSTOP;
50 #endif
51 if (sigaction(signo, &act, &oact) < 0)
52 return SIG_ERR;
53 return oact.sa_handler;
54 #else /* WIN32 */
55 return signal(signo, func);
56 #endif
57 }
58