* strace.c (startup_attach): Take care to correctly attach

to stopped processes by resending SIGSTOP.
(collect_stopped_tcbs): Check for ^C here, not in trace().
(trace): Remove check for ^C.

diff --git a/ChangeLog b/ChangeLog
index ce685802b5174de770180abaf57c40e62fefb714..f5ff8a2f4159afcd2305d58af48a4bc760b86e9d 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2009-03-17  Denys Vlasenko  <dvlasenk@redhat.com>
+
+       * strace.c (startup_attach): Take care to correctly attach
+       to stopped processes by resending SIGSTOP.
+       (collect_stopped_tcbs): Check for ^C here, not in trace().
+       (trace): Remove check for ^C.
+
 2009-03-10  Denys Vlasenko  <dvlasenk@redhat.com>
 
        Decode fcntl's F_{GET,SET}LEASE, F_NOTIFY, and F_DUPFD_CLOEXEC.

diff --git a/strace.c b/strace.c
index fb056134a117cb1bbdf98f5b1ea9db304bd4010f..864e7f40009f5aa5061700201bdc5767fcb3e7fc 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -437,9 +437,15 @@ startup_attach(void)
                                        if (tid <= 0)
                                                continue;
                                        ++ntid;
-                                       if (ptrace(PTRACE_ATTACH, tid, (char *) 1, 0) < 0)
+                                       if (ptrace(PTRACE_ATTACH, tid, (char *) 1, 0) < 0) {
                                                ++nerr;
-                                       else if (tid != tcbtab[tcbi]->pid) {
+                                               continue;
+                                       }
+#if defined LINUX && defined __NR_tkill
+                                       syscall(__NR_tkill, tid, SIGSTOP);
+                                       ptrace(PTRACE_CONT, tid, 0, 0);
+#endif
+                                       if (tid != tcbtab[tcbi]->pid) {
                                                tcp = alloctcb(tid);
                                                tcp->flags |= TCB_ATTACHED|TCB_CLONE_THREAD|TCB_CLONE_DETACHED;
                                                tcbtab[tcbi]->nchildren++;
@@ -447,14 +453,14 @@ startup_attach(void)
                                                tcbtab[tcbi]->nclone_detached++;
                                                tcp->parent = tcbtab[tcbi];
                                        }
-                                       if (interactive) {
-                                               sigprocmask(SIG_SETMASK, &empty_set, NULL);
-                                               if (interrupted)
-                                                       return;
-                                               sigprocmask(SIG_BLOCK, &blocked_set, NULL);
-                                       }
                                }
                                closedir(dir);
+                               if (interactive) {
+                                       sigprocmask(SIG_SETMASK, &empty_set, NULL);
+                                       if (interrupted)
+                                               return;
+                                       sigprocmask(SIG_BLOCK, &blocked_set, NULL);
+                               }
                                ntid -= nerr;
                                if (ntid == 0) {
                                        perror("attach: ptrace(PTRACE_ATTACH, ...)");
@@ -476,6 +482,14 @@ startup_attach(void)
                        droptcb(tcp);
                        continue;
                }
+#if defined LINUX && defined __NR_tkill
+               /* If process was SIGSTOPed, and waited for,
+                  even before attach, we will never get SIGSTOP
+                  notification. This works around it.
+                  Borrowed from GDB, thanks Jan! */
+               syscall(__NR_tkill, tcp->pid, SIGSTOP);
+               ptrace(PTRACE_CONT, tcp->pid, 0, 0);
+#endif
                /* INTERRUPTED is going to be checked at the top of TRACE.  */
 
                if (daemonized_tracer) {
@@ -2286,6 +2300,10 @@ collect_stopped_tcbs(void)
 
        found_tcps = NULL;
        while (1) {
+               if (interrupted)
+                       break;
+               if (interactive)
+                       sigprocmask(SIG_SETMASK, &empty_set, NULL);
 #ifdef LINUX
 #ifdef __WALL
                pid = wait4(-1, &status, wait4_options | wnohang, ru_ptr);
@@ -2777,11 +2795,6 @@ trace()
        struct tcb *tcbs;
 
        while (nprocs != 0) {
-               if (interrupted)
-                       return 0;
-               if (interactive)
-                       sigprocmask(SIG_SETMASK, &empty_set, NULL);
-
                /* The loop of "wait for one tracee, serve it, repeat"
                 * may leave some tracees never served.
                 * Kernel provides no guarantees of fairness when you have