1 /*
2 * Copyright (c) 2023 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 #include <signal.h>
17 #include <errno.h>
18 #include <string.h>
19 #include <stdbool.h>
20 #include "syscall.h"
21 #include "pthread_impl.h"
22 #include "libc.h"
23 #include "lock.h"
24 #include "ksigaction.h"
25
26 extern bool intercept_sigaction(int signo, const struct sigaction *restrict sa, struct sigaction *restrict old);
27
28 static volatile int dummy_lock[1] = { 0 };
29
30 extern hidden volatile int __abort_lock[1];
31
32 weak_alias(dummy_lock, __abort_lock);
33
34 static int unmask_done;
35 static unsigned long handler_set[_NSIG / (8 * sizeof(long))];
36
__get_handler_set(sigset_t * set)37 void __get_handler_set(sigset_t *set)
38 {
39 memcpy(set, handler_set, sizeof handler_set);
40 }
41
42 volatile int __eintr_valid_flag;
43
__libc_sigaction(int sig,const struct sigaction * restrict sa,struct sigaction * restrict old)44 int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
45 {
46 struct k_sigaction ksa, ksa_old;
47 unsigned long set[_NSIG / (8 * sizeof(long))];
48 if (sa) {
49 if ((uintptr_t)sa->sa_handler > 1UL) {
50 a_or_l(handler_set + (sig - 1) / (8 * sizeof(long)),
51 1UL<<(sig - 1) % (8 * sizeof(long)));
52
53 /* If pthread_create has not yet been called,
54 * implementation-internal signals might not
55 * yet have been unblocked. They must be
56 * unblocked before any signal handler is
57 * installed, so that an application cannot
58 * receive an illegal sigset_t (with them
59 * blocked) as part of the ucontext_t passed
60 * to the signal handler. */
61 if (!libc.threaded && !unmask_done) {
62 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
63 SIGPT_SET, 0, _NSIG/8);
64 unmask_done = 1;
65 }
66
67 if (!(sa->sa_flags & SA_RESTART)) {
68 a_store(&__eintr_valid_flag, 1);
69 }
70 }
71 /* Changing the disposition of SIGABRT to anything but
72 * SIG_DFL requires a lock, so that it cannot be changed
73 * while abort is terminating the process after simply
74 * calling raise(SIGABRT) failed to do so. */
75 if (sa->sa_handler != SIG_DFL && sig == SIGABRT) {
76 __block_all_sigs(&set);
77 LOCK(__abort_lock);
78 }
79 ksa.handler = sa->sa_handler;
80 ksa.flags = sa->sa_flags;
81 #ifdef SA_RESTORER
82 ksa.flags |= SA_RESTORER;
83 ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
84 #endif
85 memcpy(&ksa.mask, &sa->sa_mask, _NSIG/8);
86 }
87 int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, _NSIG/8);
88 if (sig == SIGABRT && sa && sa->sa_handler != SIG_DFL) {
89 UNLOCK(__abort_lock);
90 __restore_sigs(&set);
91 }
92 if (old && !r) {
93 old->sa_handler = ksa_old.handler;
94 old->sa_flags = ksa_old.flags;
95 memcpy(&old->sa_mask, &ksa_old.mask, _NSIG/8);
96 }
97 return __syscall_ret(r);
98 }
99
__sigaction(int sig,const struct sigaction * restrict sa,struct sigaction * restrict old)100 int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
101 {
102 if (sig - 32U < 3 || sig - 1U >= _NSIG-1) {
103 errno = EINVAL;
104 return -1;
105 }
106 /* sigchain intercepts sigaction */
107 if (intercept_sigaction(sig, sa, old)) {
108 return 0;
109 }
110
111 return __libc_sigaction(sig, sa, old);
112 }
113
114 weak_alias(__sigaction, sigaction);
115