1 | /* Copyright (C) 1998-2017 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 | |
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 | #ifdef SIG_HOLD |
35 | /* Handle SIG_HOLD first. */ |
36 | if (disp == SIG_HOLD) |
37 | { |
38 | /* Create an empty signal set. */ |
39 | if (__sigemptyset (&set) < 0) |
40 | return SIG_ERR; |
41 | |
42 | /* Add the specified signal. */ |
43 | if (__sigaddset (&set, sig) < 0) |
44 | return SIG_ERR; |
45 | |
46 | /* Add the signal set 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 | #endif /* SIG_HOLD */ |
61 | |
62 | /* Check signal extents to protect __sigismember. */ |
63 | if (disp == SIG_ERR || sig < 1 || sig >= NSIG) |
64 | { |
65 | __set_errno (EINVAL); |
66 | return SIG_ERR; |
67 | } |
68 | |
69 | act.sa_handler = disp; |
70 | if (__sigemptyset (&act.sa_mask) < 0) |
71 | return SIG_ERR; |
72 | act.sa_flags = 0; |
73 | if (__sigaction (sig, &act, &oact) < 0) |
74 | return SIG_ERR; |
75 | |
76 | /* Create an empty signal set. */ |
77 | if (__sigemptyset (&set) < 0) |
78 | return SIG_ERR; |
79 | |
80 | /* Add the specified signal. */ |
81 | if (__sigaddset (&set, sig) < 0) |
82 | return SIG_ERR; |
83 | |
84 | /* Remove the signal set from the current signal mask. */ |
85 | if (__sigprocmask (SIG_UNBLOCK, &set, &oset) < 0) |
86 | return SIG_ERR; |
87 | |
88 | /* If the signal was already blocked return SIG_HOLD. */ |
89 | return __sigismember (&oset, sig) ? SIG_HOLD : oact.sa_handler; |
90 | } |
91 | |