Fix PTRACE_SETOPTIONS tests
* strace.c [LINUX] (kill_save_errno): New function. (test_ptrace_setoptions_followfork): Change return type to void. Fix and harden error handling. Use kill_save_errno() to avoid errno clobbering. Treat EIO from ptrace() the same way as EINVAL. (test_ptrace_setoptions_for_all): Use kill_save_errno() to avoid errno clobbering. Treat EIO from ptrace() the same way as EINVAL. (main): Update use of test_ptrace_setoptions_followfork().
This commit is contained in:
Denys Vlasenko
parent
25caa318ee
commit
04f8b4860f
161
strace.c
161
strace.c
@ -723,12 +723,20 @@ startup_child(char **argv)
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}
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#ifdef LINUX
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static void kill_save_errno(pid_t pid, int sig)
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{
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int saved_errno = errno;
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(void) kill(pid, sig);
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errno = saved_errno;
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}
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/*
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* Test whether the kernel support PTRACE_O_TRACECLONE et al options.
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* First fork a new child, call ptrace with PTRACE_SETOPTIONS on it,
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* and then see which options are supported by the kernel.
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*/
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static int
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static void
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test_ptrace_setoptions_followfork(void)
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{
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int pid, expected_grandchild = 0, found_grandchild = 0;
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@ -737,59 +745,93 @@ test_ptrace_setoptions_followfork(void)
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PTRACE_O_TRACEVFORK;
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if ((pid = fork()) < 0)
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return -1;
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perror_msg_and_die("fork");
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else if (pid == 0) {
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if (ptrace(PTRACE_TRACEME, 0, (char *)1, 0) < 0)
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_exit(1);
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kill(getpid(), SIGSTOP);
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_exit(fork() < 0);
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pid = getpid();
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if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
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perror_msg_and_die("%s: PTRACE_TRACEME doesn't work",
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__func__);
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kill(pid, SIGSTOP);
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if (fork() < 0)
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perror_msg_and_die("fork");
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_exit(0);
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}
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while (1) {
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int status, tracee_pid;
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errno = 0;
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tracee_pid = wait(&status);
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if (tracee_pid == -1) {
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if (tracee_pid <= 0) {
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if (errno == EINTR)
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continue;
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else if (errno == ECHILD)
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break;
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perror("test_ptrace_setoptions_followfork");
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return -1;
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kill_save_errno(pid, SIGKILL);
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perror_msg_and_die("%s: unexpected wait result %d",
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__func__, tracee_pid);
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}
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status)) {
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if (tracee_pid != pid)
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kill_save_errno(pid, SIGKILL);
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error_msg_and_die("%s: unexpected exit status %u",
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__func__, WEXITSTATUS(status));
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}
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continue;
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}
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if (WIFSIGNALED(status)) {
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if (tracee_pid != pid)
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kill_save_errno(pid, SIGKILL);
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error_msg_and_die("%s: unexpected signal %u",
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__func__, WTERMSIG(status));
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}
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if (!WIFSTOPPED(status)) {
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if (tracee_pid != pid)
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kill_save_errno(tracee_pid, SIGKILL);
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kill(pid, SIGKILL);
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error_msg_and_die("%s: unexpected wait status %x",
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__func__, status);
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}
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if (tracee_pid != pid) {
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found_grandchild = tracee_pid;
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if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0 &&
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errno != ESRCH)
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kill(tracee_pid, SIGKILL);
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}
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else if (WIFSTOPPED(status)) {
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switch (WSTOPSIG(status)) {
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case SIGSTOP:
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if (ptrace(PTRACE_SETOPTIONS, pid,
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NULL, test_options) < 0) {
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kill(pid, SIGKILL);
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return -1;
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}
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break;
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case SIGTRAP:
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if (status >> 16 == PTRACE_EVENT_FORK) {
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long msg = 0;
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if (ptrace(PTRACE_GETEVENTMSG, pid,
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NULL, (long) &msg) == 0)
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expected_grandchild = msg;
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}
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break;
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if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) {
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kill_save_errno(tracee_pid, SIGKILL);
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kill_save_errno(pid, SIGKILL);
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perror_msg_and_die("PTRACE_CONT doesn't work");
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}
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if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0 &&
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errno != ESRCH)
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kill(pid, SIGKILL);
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continue;
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}
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switch (WSTOPSIG(status)) {
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case SIGSTOP:
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if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0
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&& errno != EINVAL && errno != EIO)
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perror_msg("PTRACE_SETOPTIONS");
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break;
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case SIGTRAP:
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if (status >> 16 == PTRACE_EVENT_FORK) {
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long msg = 0;
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if (ptrace(PTRACE_GETEVENTMSG, pid,
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NULL, (long) &msg) == 0)
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expected_grandchild = msg;
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}
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break;
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}
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if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) {
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kill_save_errno(pid, SIGKILL);
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perror_msg_and_die("PTRACE_SYSCALL doesn't work");
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}
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}
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if (expected_grandchild && expected_grandchild == found_grandchild)
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if (expected_grandchild && expected_grandchild == found_grandchild) {
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ptrace_setoptions |= test_options;
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return 0;
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if (debug)
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fprintf(stderr, "ptrace_setoptions = %#x\n",
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ptrace_setoptions);
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return;
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}
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error_msg("Test for PTRACE_O_TRACECLONE failed, "
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"giving up using this feature.");
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}
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/*
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@ -809,7 +851,8 @@ test_ptrace_setoptions_followfork(void)
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static void
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test_ptrace_setoptions_for_all(void)
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{
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const unsigned int test_options = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC;
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const unsigned int test_options = PTRACE_O_TRACESYSGOOD |
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PTRACE_O_TRACEEXEC;
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int pid;
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int it_worked = 0;
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@ -821,7 +864,8 @@ test_ptrace_setoptions_for_all(void)
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pid = getpid();
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if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0)
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/* Note: exits with exitcode 1 */
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perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", __func__);
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perror_msg_and_die("%s: PTRACE_TRACEME doesn't work",
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__func__);
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kill(pid, SIGSTOP);
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_exit(0); /* parent should see entry into this syscall */
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}
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@ -834,18 +878,24 @@ test_ptrace_setoptions_for_all(void)
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if (tracee_pid <= 0) {
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if (errno == EINTR)
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continue;
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kill(pid, SIGKILL);
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perror_msg_and_die("%s: unexpected wait result %d", __func__, tracee_pid);
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kill_save_errno(pid, SIGKILL);
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perror_msg_and_die("%s: unexpected wait result %d",
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__func__, tracee_pid);
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}
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status) == 0)
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break;
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/* PTRACE_TRACEME failed in child. This is fatal. */
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exit(1);
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error_msg_and_die("%s: unexpected exit status %u",
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__func__, WEXITSTATUS(status));
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}
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if (WIFSIGNALED(status)) {
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error_msg_and_die("%s: unexpected signal %u",
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__func__, WTERMSIG(status));
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}
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if (!WIFSTOPPED(status)) {
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kill(pid, SIGKILL);
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error_msg_and_die("%s: unexpected wait status %x", __func__, status);
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error_msg_and_die("%s: unexpected wait status %x",
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__func__, status);
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}
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if (WSTOPSIG(status) == SIGSTOP) {
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/*
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@ -854,15 +904,15 @@ test_ptrace_setoptions_for_all(void)
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* and thus will decide to not use the option.
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* IOW: the outcome of the test will be correct.
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*/
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if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0)
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if (errno != EINVAL)
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perror_msg("PTRACE_SETOPTIONS");
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if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0
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&& errno != EINVAL && errno != EIO)
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perror_msg("PTRACE_SETOPTIONS");
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}
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if (WSTOPSIG(status) == (SIGTRAP | 0x80)) {
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it_worked = 1;
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}
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if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) {
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kill(pid, SIGKILL);
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kill_save_errno(pid, SIGKILL);
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perror_msg_and_die("PTRACE_SYSCALL doesn't work");
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}
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}
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@ -876,8 +926,8 @@ test_ptrace_setoptions_for_all(void)
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return;
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}
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fprintf(stderr,
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"Test for PTRACE_O_TRACESYSGOOD failed, giving up using this feature.\n");
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error_msg("Test for PTRACE_O_TRACESYSGOOD failed, "
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"giving up using this feature.");
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}
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#endif
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@ -1067,17 +1117,8 @@ main(int argc, char *argv[])
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}
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#ifdef LINUX
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if (followfork) {
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if (test_ptrace_setoptions_followfork() < 0) {
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fprintf(stderr,
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"Test for options supported by PTRACE_SETOPTIONS "
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"failed, giving up using this feature.\n");
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ptrace_setoptions = 0;
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}
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if (debug)
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fprintf(stderr, "ptrace_setoptions = %#x\n",
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ptrace_setoptions);
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}
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if (followfork)
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test_ptrace_setoptions_followfork();
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test_ptrace_setoptions_for_all();
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#endif
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