Make stop causes pointers so users outside the package can

type switch on them despite their private fields.  Add some
tracing stuff.

R=rsc
APPROVED=rsc
DELTA=18  (7 added, 0 deleted, 11 changed)
OCL=33678
CL=33683

usr/austin/ptrace/process.go

@@ -179,11 +179,11 @@ type ThreadCreate struct {
 	thread Thread;
 }
 
-func (c ThreadCreate) NewThread() Thread {
+func (c *ThreadCreate) NewThread() Thread {
 	return c.thread;
 }
 
-func (c ThreadCreate) String() string {
+func (c *ThreadCreate) String() string {
 	return "thread create";
 }
 
@@ -197,28 +197,28 @@ type ThreadExit struct {
 }
 
 // Exited returns true if the thread exited normally.
-func (c ThreadExit) Exited() bool {
+func (c *ThreadExit) Exited() bool {
 	return c.exitStatus != -1;
 }
 
 // ExitStatus returns the exit status of the thread if it exited
 // normally or -1 otherwise.
-func (c ThreadExit) ExitStatus() int {
+func (c *ThreadExit) ExitStatus() int {
 	return c.exitStatus;
 }
 
 // Signaled returns true if the thread was terminated by a signal.
-func (c ThreadExit) Signaled() bool {
+func (c *ThreadExit) Signaled() bool {
 	return c.exitStatus == -1;
 }
 
 // StopSignal returns the signal that terminated the thread, or "" if
 // it was not terminated by a signal.
-func (c ThreadExit) StopSignal() string {
+func (c *ThreadExit) StopSignal() string {
 	return c.signal;
 }
 
-func (c ThreadExit) String() string {
+func (c *ThreadExit) String() string {
 	res := "thread exited ";
 	switch {
 	case c.Exited():

usr/austin/ptrace/ptrace_linux.go

@@ -33,8 +33,9 @@ import (
 // as well as experimentation and examination of gdb's behavior.
 
 const (
-	trace = true;
+	trace = false;
 	traceIP = false;
+	traceMem = false;
 )
 
 /*
@@ -215,11 +216,17 @@ func (e *newThreadError) String() string {
 
 func (t *thread) ptracePeekText(addr uintptr, out []byte) (int, os.Error) {
 	c, err := syscall.PtracePeekText(t.tid, addr, out);
+	if traceMem {
+		fmt.Printf("peek(%#x) => %v, %v\n", addr, out, err);
+	}
 	return c, os.NewSyscallError("ptrace(PEEKTEXT)", err);
 }
 
 func (t *thread) ptracePokeText(addr uintptr, out []byte) (int, os.Error) {
 	c, err := syscall.PtracePokeText(t.tid, addr, out);
+	if traceMem {
+		fmt.Printf("poke(%#x, %v) => %v\n", addr, out, err);
+	}
 	return c, os.NewSyscallError("ptrace(POKETEXT)", err);
 }
 
@@ -889,13 +896,13 @@ func (t *thread) Stopped() (Cause, os.Error) {
 			c = Signal(sigName(t.signal));
 
 		case stoppedThreadCreate:
-			c = ThreadCreate{t.newThread};
+			c = &ThreadCreate{t.newThread};
 
 		case stoppedExiting, exiting, exited:
 			if t.signal == -1 {
-				c = ThreadExit{t.exitStatus, ""};
+				c = &ThreadExit{t.exitStatus, ""};
 			} else {
-				c = ThreadExit{t.exitStatus, sigName(t.signal)};
+				c = &ThreadExit{t.exitStatus, sigName(t.signal)};
 			}
 
 		default: