| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* Implementation of sigwait function from POSIX.1c. |
| 2 | Copyright (C) 1996-2015 Free Software Foundation, Inc. |
| 3 | This file is part of the GNU C Library. |
| 4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. |
| 5 | |
| 6 | The GNU C Library is free software; you can redistribute it and/or |
| 7 | modify it under the terms of the GNU Lesser General Public |
| 8 | License as published by the Free Software Foundation; either |
| 9 | version 2.1 of the License, or (at your option) any later version. |
| 10 | |
| 11 | The GNU C Library is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | Lesser General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU Lesser General Public |
| 17 | License along with the GNU C Library; if not, see |
| 18 | <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include <errno.h> |
| 21 | #include <signal.h> |
| 22 | #include <stddef.h> /* For NULL. */ |
| 23 | #include <sysdep-cancel.h> |
| 24 | |
| 25 | /* This is our dummy signal handler we use here. */ |
| 26 | static void ignore_signal (int sig); |
| 27 | |
| 28 | /* Place where to remember which signal we got. Please note that this |
| 29 | implementation cannot be used for the threaded libc. The |
| 30 | libpthread must provide an own version. */ |
| 31 | static int was_sig; |
| 32 | |
| 33 | |
| 34 | static int |
| 35 | do_sigwait (const sigset_t *set, int *sig) |
| 36 | { |
| 37 | sigset_t tmp_mask; |
| 38 | struct sigaction saved[NSIG]; |
| 39 | struct sigaction action; |
| 40 | int save_errno; |
| 41 | int this; |
| 42 | |
| 43 | /* Prepare set. */ |
| 44 | __sigfillset (&tmp_mask); |
| 45 | |
| 46 | /* Unblock all signals in the SET and register our nice handler. */ |
| 47 | action.sa_handler = ignore_signal; |
| 48 | action.sa_flags = 0; |
| 49 | __sigfillset (&action.sa_mask); /* Block all signals for handler. */ |
| 50 | |
| 51 | /* Make sure we recognize error conditions by setting WAS_SIG to a |
| 52 | value which does not describe a legal signal number. */ |
| 53 | was_sig = -1; |
| 54 | |
| 55 | for (this = 1; this < NSIG; ++this) |
| 56 | if (__sigismember (set, this)) |
| 57 | { |
| 58 | /* Unblock this signal. */ |
| 59 | __sigdelset (&tmp_mask, this); |
| 60 | |
| 61 | /* Register temporary action handler. */ |
| 62 | if (__sigaction (this, &action, &saved[this]) != 0) |
| 63 | goto restore_handler; |
| 64 | } |
| 65 | |
| 66 | /* Now we can wait for signals. */ |
| 67 | __sigsuspend (&tmp_mask); |
| 68 | |
| 69 | restore_handler: |
| 70 | save_errno = errno; |
| 71 | |
| 72 | while (--this >= 1) |
| 73 | if (__sigismember (set, this)) |
| 74 | /* We ignore errors here since we must restore all handlers. */ |
| 75 | __sigaction (this, &saved[this], NULL); |
| 76 | |
| 77 | __set_errno (save_errno); |
| 78 | |
| 79 | /* Store the result and return. */ |
| 80 | *sig = was_sig; |
| 81 | return was_sig == -1 ? -1 : 0; |
| 82 | } |
| 83 | |
| 84 | |
| 85 | int |
| 86 | __sigwait (const sigset_t *set, int *sig) |
| 87 | { |
| 88 | if (SINGLE_THREAD_P) |
| 89 | return do_sigwait (set, sig); |
| 90 | |
| 91 | int oldtype = LIBC_CANCEL_ASYNC (); |
| 92 | |
| 93 | int result = do_sigwait (set, sig); |
| 94 | |
| 95 | LIBC_CANCEL_RESET (oldtype); |
| 96 | |
| 97 | return result; |
| 98 | } |
| 99 | libc_hidden_def (__sigwait) |
| 100 | weak_alias (__sigwait, sigwait) |
| 101 | |
| 102 | |
| 103 | static void |
| 104 | ignore_signal (int sig) |
| 105 | { |
| 106 | /* Remember the signal. */ |
| 107 | was_sig = sig; |
| 108 | } |