Fix PTRACE_GETEVENTMSG usage and enhance test_ptrace_setoptions()

* strace.c (handle_ptrace_event): Fix PTRACE_GETEVENTMSG usage.
(test_ptrace_setoptions): Test that PTRACE_GETEVENTMSG works properly.

diff --git a/strace.c b/strace.c
index 6b0ebacf79e75b3866caf351e83af5ba92478a64..89fda4f09fa27b5cec6bfe969af5fe7127719823 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -696,7 +696,10 @@ startup_child (char **argv)
 static int
 test_ptrace_setoptions(void)
 {
-       int pid;
+       int pid, expected_grandchild = 0, found_grandchild = 0;
+       const unsigned int test_options = PTRACE_O_TRACECLONE |
+                                         PTRACE_O_TRACEFORK |
+                                         PTRACE_O_TRACEVFORK;
 
        if ((pid = fork()) < 0)
                return -1;
@@ -720,29 +723,37 @@ test_ptrace_setoptions(void)
                        return -1;
                }
                if (tracee_pid != pid) {
-                       /* the grandchild */
+                       found_grandchild = tracee_pid;
                        if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0 &&
                            errno != ESRCH)
                                kill(tracee_pid, SIGKILL);
                }
                else if (WIFSTOPPED(status)) {
-                       const unsigned int test_options = PTRACE_O_TRACECLONE |
-                                                         PTRACE_O_TRACEFORK |
-                                                         PTRACE_O_TRACEVFORK;
-                       if (status >> 16 == PTRACE_EVENT_FORK)
-                               ptrace_setoptions |= test_options;
-                       if (WSTOPSIG(status) == SIGSTOP) {
-                               if (ptrace(PTRACE_SETOPTIONS, pid, NULL,
-                                          test_options) < 0) {
+                       switch (WSTOPSIG(status)) {
+                       case SIGSTOP:
+                               if (ptrace(PTRACE_SETOPTIONS, pid,
+                                          NULL, test_options) < 0) {
                                        kill(pid, SIGKILL);
                                        return -1;
                                }
+                               break;
+                       case SIGTRAP:
+                               if (status >> 16 == PTRACE_EVENT_FORK) {
+                                       long msg = 0;
+
+                                       if (ptrace(PTRACE_GETEVENTMSG, pid,
+                                                  NULL, (long) &msg) == 0)
+                                               expected_grandchild = msg;
+                               }
+                               break;
                        }
                        if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0 &&
                            errno != ESRCH)
                                kill(pid, SIGKILL);
                }
        }
+       if (expected_grandchild && expected_grandchild == found_grandchild)
+               ptrace_setoptions |= test_options;
        return 0;
 }
 #endif
@@ -2365,7 +2376,7 @@ handle_ptrace_event(int status, struct tcb *tcp)
        if (status >> 16 == PTRACE_EVENT_VFORK ||
            status >> 16 == PTRACE_EVENT_CLONE ||
            status >> 16 == PTRACE_EVENT_FORK) {
-               int childpid;
+               long childpid;
 
                if (do_ptrace(PTRACE_GETEVENTMSG, tcp, NULL, &childpid) < 0) {
                        if (errno != ESRCH) {