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pqsignal.c
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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) 1996-2017, 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  */
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 /*
62  * Set up a signal handler, without SA_RESTART, for signal "signo"
63  *
64  * Returns the previous handler.
65  *
66  * On Windows, this would be identical to pqsignal(), so don't bother.
67  */
68 #ifndef WIN32
69 
72 {
73  struct sigaction act,
74  oact;
75 
76  act.sa_handler = func;
77  sigemptyset(&act.sa_mask);
78  act.sa_flags = 0;
79 #ifdef SA_NOCLDSTOP
80  if (signo == SIGCHLD)
81  act.sa_flags |= SA_NOCLDSTOP;
82 #endif
83  if (sigaction(signo, &act, &oact) < 0)
84  return SIG_ERR;
85  return oact.sa_handler;
86 }
87 
88 #endif /* !WIN32 */
89 
90 #endif /* !defined(WIN32) || defined(FRONTEND) */
pqsigfunc pqsignal(int signo, pqsigfunc func)
Definition: pqsignal.c:40
pqsigfunc pqsignal_no_restart(int signo, pqsigfunc func)
Definition: pqsignal.c:71
void(* pqsigfunc)(int signo)
Definition: port.h:473
#define SIG_ERR
Definition: win32.h:184
#define SIGCHLD
Definition: win32.h:198