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284 lines
8.3 KiB
C
284 lines
8.3 KiB
C
// This test file is from occlum, to test whether we implement signal correctly.
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#define _GNU_SOURCE
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <ucontext.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 <spawn.h>
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#include <assert.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <pthread.h>
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#include <errno.h>
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#include <time.h>
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// ============================================================================
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// Helper functions
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// ============================================================================
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#define THROW_ERROR(fmt, ...) do { \
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printf("\t\tERROR:" fmt " in func %s at line %d of file %s with errno %d: %s\n", \
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##__VA_ARGS__, __func__, __LINE__, __FILE__, errno, strerror(errno)); \
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return -1; \
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} while (0)
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// ============================================================================
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// Test sigprocmask
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// ============================================================================
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#define sigcmpset(a, b) memcmp((a), (b), 8)
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int test_sigprocmask() {
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int ret;
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sigset_t new, old;
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sigset_t expected_old;
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// Check sigmask == []
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if ((ret = sigprocmask(0, NULL, &old)) < 0) {
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THROW_ERROR("sigprocmask failed unexpectedly");
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}
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sigemptyset(&expected_old);
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if (sigcmpset(&old, &expected_old) != 0) {
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THROW_ERROR("unexpected old sigset");
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}
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// SIG_BLOCK: [] --> [SIGSEGV]
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sigemptyset(&new);
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sigaddset(&new, SIGSEGV);
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if ((ret = sigprocmask(SIG_BLOCK, &new, &old)) < 0) {
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THROW_ERROR("sigprocmask failed unexpectedly");
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}
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sigemptyset(&expected_old);
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if (sigcmpset(&old, &expected_old) != 0) {
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THROW_ERROR("unexpected old sigset");
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}
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// SIG_SETMASK: [SIGSEGV] --> [SIGIO]
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sigemptyset(&new);
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sigaddset(&new, SIGIO);
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if ((ret = sigprocmask(SIG_SETMASK, &new, &old)) < 0) {
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THROW_ERROR("sigprocmask failed unexpectedly");
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}
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sigemptyset(&expected_old);
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sigaddset(&expected_old, SIGSEGV);
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if (sigcmpset(&old, &expected_old) != 0) {
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THROW_ERROR("unexpected old sigset");
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}
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// SIG_UNBLOCK: [SIGIO] -> []
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if ((ret = sigprocmask(SIG_UNBLOCK, &new, &old)) < 0) {
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THROW_ERROR("sigprocmask failed unexpectedly");
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}
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sigemptyset(&expected_old);
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sigaddset(&expected_old, SIGIO);
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if (sigcmpset(&old, &expected_old) != 0) {
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THROW_ERROR("unexpected old sigset");
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}
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// Check sigmask == []
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if ((ret = sigprocmask(0, NULL, &old)) < 0) {
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THROW_ERROR("sigprocmask failed unexpectedly");
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}
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sigemptyset(&expected_old);
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if (sigcmpset(&old, &expected_old) != 0) {
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THROW_ERROR("unexpected old sigset");
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}
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return 0;
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}
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// ============================================================================
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// Test raise syscall and user-registered signal handlers
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// ============================================================================
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#define MAX_RECURSION_LEVEL 3
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static void handle_sigio(int num, siginfo_t *info, void *context) {
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static volatile int recursion_level = 0;
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printf("Hello from SIGIO signal handler (recursion_level = %d)!\n", recursion_level);
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fflush(stdout);
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recursion_level++;
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if (recursion_level <= MAX_RECURSION_LEVEL) {
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raise(SIGIO);
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}
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recursion_level--;
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}
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int test_raise() {
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struct sigaction new_action, old_action;
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memset(&new_action, 0, sizeof(struct sigaction));
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memset(&old_action, 0, sizeof(struct sigaction));
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new_action.sa_sigaction = handle_sigio;
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new_action.sa_flags = SA_SIGINFO | SA_NODEFER;
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if (sigaction(SIGIO, &new_action, &old_action) < 0) {
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THROW_ERROR("registering new signal handler failed");
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}
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if (old_action.sa_handler != SIG_DFL) {
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THROW_ERROR("unexpected old sig handler");
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}
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raise(SIGIO);
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if (sigaction(SIGIO, &old_action, NULL) < 0) {
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THROW_ERROR("restoring old signal handler failed");
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}
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return 0;
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}
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// ============================================================================
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// Test catching and handling hardware exception
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// ============================================================================
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static void handle_sigfpe(int num, siginfo_t *info, void *_context) {
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printf("SIGFPE Caught\n");
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fflush(stdout);
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assert(num == SIGFPE);
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assert(info->si_signo == SIGFPE);
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ucontext_t *ucontext = _context;
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mcontext_t *mcontext = &ucontext->uc_mcontext;
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// The faulty instruction should be `idiv %esi` (f7 fe)
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mcontext->gregs[REG_RIP] += 2;
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return;
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}
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// Note: this function is fragile in the sense that compiler may not always
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// emit the instruction pattern that triggers divide-by-zero as we expect.
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// TODO: rewrite this in assembly
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int div_maybe_zero(int x, int y) {
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return x / y;
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}
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#define fxsave(addr) __asm __volatile("fxsave %0" : "=m" (*(addr)))
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int test_handle_sigfpe() {
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// Set up a signal handler that handles divide-by-zero exception
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struct sigaction new_action, old_action;
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memset(&new_action, 0, sizeof(struct sigaction));
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memset(&old_action, 0, sizeof(struct sigaction));
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new_action.sa_sigaction = handle_sigfpe;
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new_action.sa_flags = SA_SIGINFO;
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if (sigaction(SIGFPE, &new_action, &old_action) < 0) {
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THROW_ERROR("registering new signal handler failed");
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}
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if (old_action.sa_handler != SIG_DFL) {
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THROW_ERROR("unexpected old sig handler");
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}
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char x[512] __attribute__((aligned(16))) = {};
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char y[512] __attribute__((aligned(16))) = {};
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// Trigger divide-by-zero exception
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int a = 1;
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int b = 0;
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// Use volatile to prevent compiler optimization
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volatile int c;
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fxsave(x);
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c = div_maybe_zero(a, b);
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fxsave(y);
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// jinux does not save and restore fpregs now, so we emit this check.
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// if (memcmp(x, y, 512) != 0) {
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// THROW_ERROR("floating point registers are modified");
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// }
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printf("Signal handler successfully jumped over the divide-by-zero instruction\n");
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fflush(stdout);
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if (sigaction(SIGFPE, &old_action, NULL) < 0) {
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THROW_ERROR("restoring old signal handler failed");
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}
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return 0;
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}
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// TODO: rewrite this in assembly
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int read_maybe_null(int *p) {
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return *p;
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}
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static void handle_sigsegv(int num, siginfo_t *info, void *_context) {
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printf("SIGSEGV Caught\n");
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fflush(stdout);
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assert(num == SIGSEGV);
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assert(info->si_signo == SIGSEGV);
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ucontext_t *ucontext = _context;
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mcontext_t *mcontext = &ucontext->uc_mcontext;
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// TODO: how long is the instruction?
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// The faulty instruction should be `idiv %esi` (f7 fe)
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mcontext->gregs[REG_RIP] += 2;
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return;
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}
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int test_handle_sigsegv() {
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// Set up a signal handler that handles divide-by-zero exception
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struct sigaction new_action, old_action;
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memset(&new_action, 0, sizeof(struct sigaction));
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memset(&old_action, 0, sizeof(struct sigaction));
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new_action.sa_sigaction = handle_sigsegv;
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new_action.sa_flags = SA_SIGINFO;
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if (sigaction(SIGSEGV, &new_action, &old_action) < 0) {
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THROW_ERROR("registering new signal handler failed");
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}
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if (old_action.sa_handler != SIG_DFL) {
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THROW_ERROR("unexpected old sig handler");
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}
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int *addr = NULL;
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volatile int val = read_maybe_null(addr);
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(void)val; // to suppress "unused variables" warning
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printf("Signal handler successfully jumped over a null-dereferencing instruction\n");
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fflush(stdout);
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if (sigaction(SIGSEGV, &old_action, NULL) < 0) {
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THROW_ERROR("restoring old signal handler failed");
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}
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return 0;
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}
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// ============================================================================
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// Test SIGCHLD signal
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// ============================================================================
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int sigchld = 0;
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void proc_exit() {
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sigchld = 1;
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}
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int test_sigchld() {
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signal(SIGCHLD, proc_exit);
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printf("Run a parent process has pid = %d\n", getpid());
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fflush(stdout);
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int pid = fork();
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if(pid == 0) {
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// child process
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printf("create a new proces successfully (pid = %d)\n", getpid());
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fflush(stdout);
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} else {
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// parent process
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wait(NULL);
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printf("sigchld = %d\n", sigchld);
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fflush(stdout);
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}
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return 0;
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}
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int main() {
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test_sigprocmask();
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test_raise();
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test_handle_sigfpe();
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test_handle_sigsegv();
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test_sigchld();
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return 0;
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} |