1 //===-- Linux implementation of sigaction ---------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #define __LLVM_LIBC_INTERNAL_SIGACTION
10 #include "src/signal/sigaction.h"
11 #include "src/errno/llvmlibc_errno.h"
12 #include "src/signal/linux/signal.h"
13 
14 #include "src/__support/common.h"
15 
16 namespace __llvm_libc {
17 
18 // TOOD: Some architectures will have their signal trampoline functions in the
19 // vdso, use those when available.
20 
21 extern "C" void __restore_rt();
22 
23 template <typename T, typename V>
24 static void copy_sigaction(T &dest, const V &source) {
25   dest.sa_handler = source.sa_handler;
26   dest.sa_mask = source.sa_mask;
27   dest.sa_flags = source.sa_flags;
28   dest.sa_restorer = source.sa_restorer;
29 }
30 
31 LLVM_LIBC_FUNCTION(int, sigaction,
32                    (int signal, const struct __sigaction *__restrict libc_new,
33                     struct __sigaction *__restrict libc_old)) {
34   struct sigaction kernel_new;
35   if (libc_new) {
36     copy_sigaction(kernel_new, *libc_new);
37     if (!(kernel_new.sa_flags & SA_RESTORER)) {
38       kernel_new.sa_flags |= SA_RESTORER;
39       kernel_new.sa_restorer = __restore_rt;
40     }
41   }
42 
43   struct sigaction kernel_old;
44   int ret = syscall(SYS_rt_sigaction, signal, libc_new ? &kernel_new : nullptr,
45                     libc_old ? &kernel_old : nullptr, sizeof(sigset_t));
46   if (ret) {
47     llvmlibc_errno = -ret;
48     return -1;
49   }
50 
51   if (libc_old)
52     copy_sigaction(*libc_old, kernel_old);
53   return 0;
54 }
55 
56 } // namespace __llvm_libc
57