1 //===-- Internal header for Linux signals -----------------------*- C++ -*-===// 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 #ifndef LLVM_LIBC_SRC_SIGNAL_LINUX_SIGNAL_UTILS_H 10 #define LLVM_LIBC_SRC_SIGNAL_LINUX_SIGNAL_UTILS_H 11 12 #include "hdr/types/sigset_t.h" 13 #include "src/__support/OSUtil/syscall.h" // For internal syscall function. 14 #include "src/__support/common.h" 15 #include "src/__support/macros/config.h" 16 17 #include <signal.h> // sigaction 18 #include <stddef.h> 19 #include <sys/syscall.h> // For syscall numbers. 20 21 namespace LIBC_NAMESPACE_DECL { 22 23 // The POSIX definition of struct sigaction and the sigaction data structure 24 // expected by the rt_sigaction syscall differ in their definition. So, we 25 // define the equivalent of the what the kernel expects to help with making 26 // the rt_sigaction syscall. 27 // 28 // NOTE: Though the kernel definition does not have a union to include the 29 // handler taking siginfo_t * argument, one can set sa_handler to sa_sigaction 30 // if SA_SIGINFO is set in sa_flags. 31 struct KernelSigaction { 32 LIBC_INLINE KernelSigaction &operator=(const struct sigaction &sa) { 33 sa_flags = sa.sa_flags; 34 sa_restorer = sa.sa_restorer; 35 sa_mask = sa.sa_mask; 36 if (sa_flags & SA_SIGINFO) { 37 sa_sigaction = sa.sa_sigaction; 38 } else { 39 sa_handler = sa.sa_handler; 40 } 41 return *this; 42 } 43 44 LIBC_INLINE operator struct sigaction() const { 45 struct sigaction sa; 46 sa.sa_flags = static_cast<int>(sa_flags); 47 sa.sa_mask = sa_mask; 48 sa.sa_restorer = sa_restorer; 49 if (sa_flags & SA_SIGINFO) 50 sa.sa_sigaction = sa_sigaction; 51 else 52 sa.sa_handler = sa_handler; 53 return sa; 54 } 55 56 union { 57 void (*sa_handler)(int); 58 void (*sa_sigaction)(int, siginfo_t *, void *); 59 }; 60 unsigned long sa_flags; 61 void (*sa_restorer)(void); 62 // Our public definition of sigset_t matches that of the kernel's definition. 63 // So, we can use the public sigset_t type here. 64 sigset_t sa_mask; 65 }; 66 67 static constexpr size_t BITS_PER_SIGWORD = sizeof(unsigned long) * 8; 68 69 LIBC_INLINE constexpr sigset_t full_set() { return sigset_t{{-1UL}}; } 70 71 LIBC_INLINE constexpr sigset_t empty_set() { return sigset_t{{0}}; } 72 73 // Set the bit corresponding to |signal| in |set|. Return true on success 74 // and false on failure. The function will fail if |signal| is greater than 75 // NSIG or negative. 76 LIBC_INLINE constexpr bool add_signal(sigset_t &set, int signal) { 77 if (signal > NSIG || signal <= 0) 78 return false; 79 size_t n = size_t(signal) - 1; 80 size_t word = n / BITS_PER_SIGWORD; 81 size_t bit = n % BITS_PER_SIGWORD; 82 set.__signals[word] |= (1UL << bit); 83 return true; 84 } 85 86 // Reset the bit corresponding to |signal| in |set|. Return true on success 87 // and false on failure. The function will fail if |signal| is greater than 88 // NSIG or negative. 89 LIBC_INLINE constexpr bool delete_signal(sigset_t &set, int signal) { 90 if (signal > NSIG || signal <= 0) 91 return false; 92 size_t n = size_t(signal) - 1; 93 size_t word = n / BITS_PER_SIGWORD; 94 size_t bit = n % BITS_PER_SIGWORD; 95 set.__signals[word] &= ~(1UL << bit); 96 return true; 97 } 98 99 LIBC_INLINE int block_all_signals(sigset_t &set) { 100 sigset_t full = full_set(); 101 return LIBC_NAMESPACE::syscall_impl<int>(SYS_rt_sigprocmask, SIG_BLOCK, &full, 102 &set, sizeof(sigset_t)); 103 } 104 105 LIBC_INLINE int restore_signals(const sigset_t &set) { 106 return LIBC_NAMESPACE::syscall_impl<int>(SYS_rt_sigprocmask, SIG_SETMASK, 107 &set, nullptr, sizeof(sigset_t)); 108 } 109 110 } // namespace LIBC_NAMESPACE_DECL 111 112 #endif // LLVM_LIBC_SRC_SIGNAL_LINUX_SIGNAL_UTILS_H 113