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