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| 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 |
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