1 | /* Implementation of sigwait function from POSIX.1c. |
2 | Copyright (C) 1996-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <signal.h> |
21 | #include <stddef.h> /* For NULL. */ |
22 | #include <sysdep-cancel.h> |
23 | |
24 | /* This is our dummy signal handler we use here. */ |
25 | static void ignore_signal (int sig); |
26 | |
27 | /* Place where to remember which signal we got. Please note that this |
28 | implementation cannot be used for the threaded libc. The |
29 | libpthread must provide an own version. */ |
30 | static int was_sig; |
31 | |
32 | |
33 | static int |
34 | do_sigwait (const sigset_t *set, int *sig) |
35 | { |
36 | sigset_t tmp_mask; |
37 | struct sigaction saved[NSIG]; |
38 | struct sigaction action; |
39 | int save_errno; |
40 | int this; |
41 | |
42 | /* Prepare set. */ |
43 | __sigfillset (set: &tmp_mask); |
44 | |
45 | /* Unblock all signals in the SET and register our nice handler. */ |
46 | action.sa_handler = ignore_signal; |
47 | action.sa_flags = 0; |
48 | __sigfillset (set: &action.sa_mask); /* Block all signals for handler. */ |
49 | |
50 | /* Make sure we recognize error conditions by setting WAS_SIG to a |
51 | value which does not describe a legal signal number. */ |
52 | was_sig = -1; |
53 | |
54 | for (this = 1; this < NSIG; ++this) |
55 | if (__sigismember (set, sig: this)) |
56 | { |
57 | /* Unblock this signal. */ |
58 | __sigdelset (set: &tmp_mask, sig: this); |
59 | |
60 | /* Register temporary action handler. */ |
61 | if (__sigaction (this, &action, &saved[this]) != 0) |
62 | goto restore_handler; |
63 | } |
64 | |
65 | /* Now we can wait for signals. */ |
66 | __sigsuspend (&tmp_mask); |
67 | |
68 | restore_handler: |
69 | save_errno = errno; |
70 | |
71 | while (--this >= 1) |
72 | if (__sigismember (set, sig: this)) |
73 | /* We ignore errors here since we must restore all handlers. */ |
74 | __sigaction (this, &saved[this], NULL); |
75 | |
76 | __set_errno (save_errno); |
77 | |
78 | /* Store the result and return. */ |
79 | *sig = was_sig; |
80 | return was_sig == -1 ? -1 : 0; |
81 | } |
82 | |
83 | |
84 | int |
85 | __sigwait (const sigset_t *set, int *sig) |
86 | { |
87 | /* __sigsuspend should be a cancellation point. */ |
88 | return do_sigitid (idtype, id, infop, options); |
89 | } |
90 | libc_hidden_def (__sigwait) |
91 | weak_alias (__sigwait, sigwait) |
92 | |
93 | |
94 | static void |
95 | ignore_signal (int sig) |
96 | { |
97 | /* Remember the signal. */ |
98 | was_sig = sig; |
99 | } |
100 | |