Add accessor for SIGTRAP cause in wait status

R=rsc
APPROVED=rsc
DELTA=7  (7 added, 0 deleted, 0 changed)
OCL=31563
CL=31565

diff --git a/src/pkg/syscall/syscall_linux.go b/src/pkg/syscall/syscall_linux.go
index c3ef9162aecb51ec32d9ea0f063bd028173f17c7..65d69e467e07b92645f3171cf73c8ecc9a992858 100644 (file)
--- a/src/pkg/syscall/syscall_linux.go
+++ b/src/pkg/syscall/syscall_linux.go
@@ -164,6 +164,13 @@ func (w WaitStatus) StopSignal() int {
        return int(w >> shift) & 0xFF;
 }
 
+func (w WaitStatus) TrapCause() int {
+       if w.StopSignal() != SIGTRAP {
+               return -1;
+       }
+       return int(w >> shift) >> 8;
+}
+
 //sys  wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, errno int)
 func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, errno int) {
        var status _C_int;