/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <jni.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ucontext.h>
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#include <unistd.h>
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#include "base/macros.h"
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static int signal_count;
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static const int kMaxSignal = 1;
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#if defined(__i386__) || defined(__x86_64__)
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#if defined(__APPLE__)
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#define ucontext __darwin_ucontext
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#if defined(__x86_64__)
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// 64 bit mac build.
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#define CTX_EIP uc_mcontext->__ss.__rip
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#else
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// 32 bit mac build.
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#define CTX_EIP uc_mcontext->__ss.__eip
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#endif
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#elif defined(__x86_64__)
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// 64 bit linux build.
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#define CTX_EIP uc_mcontext.gregs[REG_RIP]
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#else
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// 32 bit linux build.
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#define CTX_EIP uc_mcontext.gregs[REG_EIP]
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#endif
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#endif
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#define BLOCKED_SIGNAL SIGUSR1
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#define UNBLOCKED_SIGNAL SIGUSR2
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static void blocked_signal(int sig ATTRIBUTE_UNUSED) {
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printf("blocked signal received\n");
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}
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static void unblocked_signal(int sig ATTRIBUTE_UNUSED) {
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printf("unblocked signal received\n");
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}
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static void signalhandler(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
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void* context) {
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printf("signal caught\n");
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++signal_count;
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if (signal_count > kMaxSignal) {
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abort();
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}
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raise(UNBLOCKED_SIGNAL);
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raise(BLOCKED_SIGNAL);
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printf("unblocking blocked signal\n");
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, BLOCKED_SIGNAL);
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sigprocmask(SIG_UNBLOCK, &mask, nullptr);
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#if defined(__arm__)
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struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
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struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
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sc->arm_pc += 2; // Skip instruction causing segv.
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#elif defined(__aarch64__)
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struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
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struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
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sc->pc += 4; // Skip instruction causing segv.
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#elif defined(__i386__)
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struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
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uc->CTX_EIP += 3;
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#elif defined(__x86_64__)
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struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
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uc->CTX_EIP += 2;
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#else
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UNUSED(context);
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#endif
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printf("signal handler done\n");
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}
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static struct sigaction oldaction;
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bool compare_sigaction(const struct sigaction* lhs, const struct sigaction* rhs) {
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// bionic's definition of `struct sigaction` has internal padding bytes, so we can't just do a
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// naive memcmp of the entire struct.
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#if defined(SA_RESTORER)
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if (lhs->sa_restorer != rhs->sa_restorer) {
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return false;
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}
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#endif
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return memcmp(&lhs->sa_mask, &rhs->sa_mask, sizeof(lhs->sa_mask)) == 0 &&
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lhs->sa_sigaction == rhs->sa_sigaction &&
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lhs->sa_flags == rhs->sa_flags;
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}
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extern "C" JNIEXPORT void JNICALL Java_Main_initSignalTest(JNIEnv*, jclass) {
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struct sigaction action;
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action.sa_sigaction = signalhandler;
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sigfillset(&action.sa_mask);
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sigdelset(&action.sa_mask, UNBLOCKED_SIGNAL);
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action.sa_flags = SA_SIGINFO | SA_ONSTACK;
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#if !defined(__APPLE__) && !defined(__mips__)
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action.sa_restorer = nullptr;
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#endif
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sigaction(SIGSEGV, &action, &oldaction);
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struct sigaction check;
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sigaction(SIGSEGV, nullptr, &check);
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if (!compare_sigaction(&check, &action)) {
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printf("sigaction returned different value\n");
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printf("action.sa_mask = %p, check.sa_mask = %p\n",
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*reinterpret_cast<void**>(&action.sa_mask),
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*reinterpret_cast<void**>(&check.sa_mask));
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printf("action.sa_sigaction = %p, check.sa_sigaction = %p\n",
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action.sa_sigaction, check.sa_sigaction);
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printf("action.sa_flags = %x, check.sa_flags = %x\n",
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action.sa_flags, check.sa_flags);
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}
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signal(BLOCKED_SIGNAL, blocked_signal);
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signal(UNBLOCKED_SIGNAL, unblocked_signal);
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}
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extern "C" JNIEXPORT void JNICALL Java_Main_terminateSignalTest(JNIEnv*, jclass) {
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sigaction(SIGSEGV, &oldaction, nullptr);
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}
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// Prevent the compiler being a smart-alec and optimizing out the assignment
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// to null.
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char *go_away_compiler = nullptr;
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extern "C" JNIEXPORT jint JNICALL Java_Main_testSignal(JNIEnv*, jclass) {
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// Unblock UNBLOCKED_SIGNAL.
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sigset_t mask;
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memset(&mask, 0, sizeof(mask));
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sigaddset(&mask, UNBLOCKED_SIGNAL);
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sigprocmask(SIG_UNBLOCK, &mask, nullptr);
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#if defined(__arm__) || defined(__i386__) || defined(__aarch64__)
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// On supported architectures we cause a real SEGV.
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*go_away_compiler = 'a';
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#elif defined(__x86_64__)
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// Cause a SEGV using an instruction known to be 2 bytes long to account for hardcoded jump
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// in the signal handler
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asm volatile("movl $0, %%eax;" "movb %%ah, (%%rax);" : : : "%eax");
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#else
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// On other architectures we simulate SEGV.
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kill(getpid(), SIGSEGV);
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#endif
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return 1234;
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}
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