1 | /* Copyright (C) 1998-2018 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <errno.h> |
19 | #define __need_NULL |
20 | #include <stddef.h> |
21 | #include <signal.h> |
22 | #include <string.h> /* For the real memset prototype. */ |
23 | #include <sigsetops.h> |
24 | |
25 | /* Set the disposition for SIG. */ |
26 | __sighandler_t |
27 | sigset (int sig, __sighandler_t disp) |
28 | { |
29 | struct sigaction act; |
30 | struct sigaction oact; |
31 | sigset_t set; |
32 | sigset_t oset; |
33 | |
34 | /* Check signal extents to protect __sigismember. */ |
35 | if (disp == SIG_ERR || sig < 1 || sig >= NSIG) |
36 | { |
37 | __set_errno (EINVAL); |
38 | return SIG_ERR; |
39 | } |
40 | |
41 | __sigemptyset (&set); |
42 | __sigaddset (&set, sig); |
43 | |
44 | if (disp == SIG_HOLD) |
45 | { |
46 | /* Add the signal to the current signal mask. */ |
47 | if (__sigprocmask (SIG_BLOCK, &set, &oset) < 0) |
48 | return SIG_ERR; |
49 | |
50 | /* If the signal was already blocked signal this to the caller. */ |
51 | if (__sigismember (&oset, sig)) |
52 | return SIG_HOLD; |
53 | |
54 | /* We need to determine whether a specific handler is installed. */ |
55 | if (__sigaction (sig, NULL, &oact) < 0) |
56 | return SIG_ERR; |
57 | |
58 | return oact.sa_handler; |
59 | } |
60 | else |
61 | { |
62 | act.sa_handler = disp; |
63 | __sigemptyset (&act.sa_mask); |
64 | act.sa_flags = 0; |
65 | if (__sigaction (sig, &act, &oact) < 0) |
66 | return SIG_ERR; |
67 | |
68 | /* Remove the signal from the current signal mask. */ |
69 | if (__sigprocmask (SIG_UNBLOCK, &set, &oset) < 0) |
70 | return SIG_ERR; |
71 | |
72 | /* If the signal was already blocked return SIG_HOLD. */ |
73 | return __sigismember (&oset, sig) ? SIG_HOLD : oact.sa_handler; |
74 | } |
75 | } |
76 | |