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[libc] Add sigaction
Summary: This patch adds `sigaction` and the `sa_restorer` signal trampoline function `__restore_rt` Reviewers: sivachandra, MaskRay, PaulkaToast Reviewed By: sivachandra Subscribers: gchatelet, mgorny, tschuett, libc-commits Differential Revision: https://reviews.llvm.org/D75802
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11 files changed

+253
-2
lines changed

11 files changed

+253
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‎libc/config/linux/api.td‎

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@@ -180,9 +180,28 @@ def SysMManAPI : PublicAPI<"sys/mman.h"> {
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];
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}
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def StructSigactionDefn : TypeDecl<"struct sigaction"> {
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let Decl = [{
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struct __sigaction {
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union {
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void (*sa_handler)(int);
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void (*sa_action)(int, siginfo_t *, void *);
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};
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sigset_t sa_mask;
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int sa_flags;
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void (*sa_restorer)(void);
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};
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}];
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}
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def SignalAPI : PublicAPI<"signal.h"> {
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let TypeDeclarations = [
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StructSigactionDefn,
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];
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let Functions = [
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"raise",
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"sigaction",
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"sigprocmask",
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"sigemptyset",
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"sigaddset",

‎libc/config/linux/signal.h.in‎

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@@ -9,3 +9,7 @@
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%%begin()
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#include <linux/signal.h>
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#ifndef __LLVM_LIBC_INTERNAL_SIGACTION
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#define sigaction __sigaction
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#endif

‎libc/lib/CMakeLists.txt‎

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@@ -18,6 +18,7 @@ add_entrypoint_library(
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# signal.h entrypoints
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raise
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sigaction
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sigaddset
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sigemptyset
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sigprocmask

‎libc/spec/posix.td‎

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@@ -4,6 +4,12 @@ def ConstSigSetPtrType : ConstType<SigSetPtrType>;
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def RestrictSigSetType : RestrictedPtrType<SigSetType>;
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def ConstRestrictSigSetType : ConstType<RestrictSigSetType>;
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def StructSigaction : NamedType<"struct sigaction">;
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def StructSigactionPtr : PtrType<StructSigaction>;
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def ConstStructSigactionPtr : ConstType<StructSigactionPtr>;
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def RestrictStructSigactionPtr : RestrictedPtrType<StructSigaction>;
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def ConstRestrictStructSigactionPtr : ConstType<RestrictStructSigactionPtr>;
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def POSIX : StandardSpec<"POSIX"> {
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NamedType OffTType = NamedType<"off_t">;
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@@ -137,9 +143,19 @@ def POSIX : StandardSpec<"POSIX"> {
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HeaderSpec Signal = HeaderSpec<
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"signal.h",
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[], // Macros
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[], // Types
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[
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SigSetType,
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StructSigaction,
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],
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[], // Enumerations
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[
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FunctionSpec<
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"sigaction",
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RetValSpec<IntType>,
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[ArgSpec<IntType>,
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ArgSpec<ConstRestrictStructSigactionPtr>,
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ArgSpec<RestrictStructSigactionPtr>]
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>,
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FunctionSpec<
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"sigprocmask",
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RetValSpec<IntType>,

‎libc/spec/stdc.td‎

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@@ -225,7 +225,6 @@ def StdC : StandardSpec<"stdc"> {
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Macro<"SIGTERM">
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],
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[
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NamedType<"sigset_t">,
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SizeTType,
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],
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[], // Enumerations

‎libc/src/signal/linux/CMakeLists.txt‎

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@@ -12,6 +12,39 @@ add_entrypoint_object(
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signal_h
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)
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add_object(
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__restore
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SRC
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__restore.cpp
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COMPILE_OPTIONS
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-fomit-frame-pointer
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-O3
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-Wframe-larger-than=0
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-Werror
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-Wno-attributes
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# asan creates asan.module_ctor which uses stack space, causing warinngs.
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-fno-sanitize=address
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DEPENDS
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linux_syscall_h
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sys_syscall_h
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)
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add_entrypoint_object(
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sigaction
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SRCS
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sigaction.cpp
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HDRS
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signal.h
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../sigaction.h
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DEPENDS
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__restore
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sys_syscall_h
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linux_syscall_h
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signal_h
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SPECIAL_OBJECTS
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__restore
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)
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add_entrypoint_object(
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sigprocmask
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SRCS

‎libc/src/signal/linux/__restore.cpp‎

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@@ -0,0 +1,20 @@
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//===----------------- Linux implementation of __restore_rt ---------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// This file is implemented seperately from sigaction.cpp so that we can
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// strongly control the options this file is compiled with. __restore_rt cannot
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// make any stack allocations so we must ensure this.
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#include "config/linux/syscall.h"
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#include "include/sys/syscall.h"
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extern "C" void __restore_rt()
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__attribute__((no_sanitize("thread", "memory", "undefined", "fuzzer"),
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hidden));
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extern "C" void __restore_rt() { __llvm_libc::syscall(SYS_rt_sigreturn); }

‎libc/src/signal/linux/sigaction.cpp‎

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@@ -0,0 +1,56 @@
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//===----------------- Linux implementation of sigaction ------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#define __LLVM_LIBC_INTERNAL_SIGACTION
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#include "src/signal/sigaction.h"
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#include "src/errno/llvmlibc_errno.h"
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#include "src/signal/linux/signal.h"
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#include "src/__support/common.h"
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namespace __llvm_libc {
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// TOOD: Some architectures will have their signal trampoline functions in the
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// vdso, use those when available.
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extern "C" void __restore_rt();
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template <typename T, typename V>
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static void copySigaction(T &dest, const V &source) {
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dest.sa_handler = source.sa_handler;
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dest.sa_mask = source.sa_mask;
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dest.sa_flags = source.sa_flags;
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dest.sa_restorer = source.sa_restorer;
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}
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int LLVM_LIBC_ENTRYPOINT(sigaction)(
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int signal, const struct __sigaction *__restrict libc_new,
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struct __sigaction *__restrict libc_old) {
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struct sigaction kernel_new;
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if (libc_new) {
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copySigaction(kernel_new, *libc_new);
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if (!(kernel_new.sa_flags & SA_RESTORER)) {
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kernel_new.sa_flags |= SA_RESTORER;
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kernel_new.sa_restorer = __restore_rt;
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}
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}
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struct sigaction kernel_old;
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int ret = syscall(SYS_rt_sigaction, signal, libc_new ? &kernel_new : nullptr,
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libc_old ? &kernel_old : nullptr, sizeof(sigset_t));
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if (ret) {
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llvmlibc_errno = -ret;
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return -1;
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}
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if (libc_old)
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copySigaction(*libc_old, kernel_old);
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return 0;
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}
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} // namespace __llvm_libc

‎libc/src/signal/sigaction.h‎

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@@ -0,0 +1,22 @@
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//===------------ Implementation header for sigaction --------*- C++ -*--===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_SIGNAL_SIGACTION_H
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#define LLVM_LIBC_SRC_SIGNAL_SIGACTION_H
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#define __LLVM_LIBC_INTERNAL_SIGACTION
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#include "include/signal.h"
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namespace __llvm_libc {
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int sigaction(int signal, const struct __sigaction *__restrict libc_new,
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struct __sigaction *__restrict libc_old);
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} // namespace __llvm_libc
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#endif // LLVM_LIBC_SRC_SIGNAL_SIGACTION_H

‎libc/test/src/signal/CMakeLists.txt‎

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@@ -11,6 +11,21 @@ add_libc_unittest(
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signal_h
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)
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add_libc_unittest(
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sigaction_test
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SUITE
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libc_signal_unittests
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SRCS
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sigaction_test.cpp
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DEPENDS
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sigaction
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raise
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signal_h
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errno_h
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__errno_location
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__restore
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)
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add_libc_unittest(
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sigprocmask_test
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SUITE

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