Added a watchdog mechanism to break out of the wait4 call in case it
didn't return properly (can happen at thread exit).
diff --git a/server/object.h b/server/object.h
index 56a6bcd..681c807 100644
--- a/server/object.h
+++ b/server/object.h
@@ -153,6 +153,9 @@
/* signal functions */
+extern void start_watchdog(void);
+extern void stop_watchdog(void);
+extern int watchdog_triggered(void);
extern void init_signals(void);
extern void close_signals(void);
diff --git a/server/ptrace.c b/server/ptrace.c
index c1a8cb7..5667d99 100644
--- a/server/ptrace.c
+++ b/server/ptrace.c
@@ -139,23 +139,30 @@
{
int res, status;
+ start_watchdog();
for (;;)
{
if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
{
- if (errno == EINTR) continue;
- if (errno == ECHILD) /* must have died */
+ if (errno == EINTR)
+ {
+ if (!watchdog_triggered()) continue;
+ if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
+ }
+ else if (errno == ECHILD) /* must have died */
{
thread->unix_pid = -1;
thread->unix_tid = -1;
thread->attached = 0;
}
else perror( "wait4" );
+ stop_watchdog();
return 0;
}
res = handle_child_status( thread, res, status, signal );
if (!res || res == signal) break;
}
+ stop_watchdog();
return (thread->unix_pid != -1);
}
@@ -190,21 +197,6 @@
return (ret != -1);
}
-/* attach to a Unix thread */
-static int attach_thread( struct thread *thread )
-{
- /* this may fail if the client is already being debugged */
- if (!use_ptrace) return 0;
- if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
- {
- if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
- return 0;
- }
- if (debug_level) fprintf( stderr, "%04x: *attached*\n", thread->id );
- thread->attached = 1;
- return wait4_thread( thread, SIGSTOP );
-}
-
/* detach from a Unix thread and kill it */
void detach_thread( struct thread *thread, int sig )
{
@@ -264,10 +256,21 @@
if (thread->attached)
{
if (!send_thread_signal( thread, SIGSTOP )) goto error;
- if (!wait4_thread( thread, SIGSTOP )) goto error;
- return 1;
}
- if (attach_thread( thread )) return 1;
+ else
+ {
+ /* this may fail if the client is already being debugged */
+ if (!use_ptrace) goto error;
+ if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
+ {
+ if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
+ goto error;
+ }
+ if (debug_level) fprintf( stderr, "%04x: *attached*\n", thread->id );
+ thread->attached = 1;
+ }
+ if (wait4_thread( thread, SIGSTOP )) return 1;
+ resume_after_ptrace( thread );
error:
set_error( STATUS_ACCESS_DENIED );
return 0;
diff --git a/server/signal.c b/server/signal.c
index 9ce3640..2888015 100644
--- a/server/signal.c
+++ b/server/signal.c
@@ -88,6 +88,8 @@
static sigset_t blocked_sigset;
+static int watchdog;
+
/* create a signal handler */
static struct handler *create_handler( signal_callback callback )
{
@@ -199,6 +201,12 @@
do_signal( handler_sigint );
}
+/* SIGALRM handler */
+static void do_sigalrm( int signum )
+{
+ watchdog = 1;
+}
+
/* SIGCHLD handler */
static void do_sigchld( int signum )
{
@@ -214,6 +222,23 @@
}
#endif
+void start_watchdog(void)
+{
+ alarm( 3 );
+ watchdog = 0;
+}
+
+void stop_watchdog(void)
+{
+ alarm( 0 );
+ watchdog = 0;
+}
+
+int watchdog_triggered(void)
+{
+ return watchdog != 0;
+}
+
void init_signals(void)
{
struct sigaction action;
@@ -228,6 +253,7 @@
sigaddset( &blocked_sigset, SIGCHLD );
sigaddset( &blocked_sigset, SIGHUP );
sigaddset( &blocked_sigset, SIGINT );
+ sigaddset( &blocked_sigset, SIGALRM );
sigaddset( &blocked_sigset, SIGIO );
sigaddset( &blocked_sigset, SIGQUIT );
sigaddset( &blocked_sigset, SIGTERM );
@@ -246,6 +272,8 @@
sigaction( SIGHUP, &action, NULL );
action.sa_handler = do_sigint;
sigaction( SIGINT, &action, NULL );
+ action.sa_handler = do_sigalrm;
+ sigaction( SIGALRM, &action, NULL );
action.sa_handler = do_sigterm;
sigaction( SIGQUIT, &action, NULL );
sigaction( SIGTERM, &action, NULL );
