1 files changed, 294 insertions, 0 deletions
diff --git a/usr/austin/ogle/event.go b/usr/austin/ogle/event.go
new file mode 100644
index 000000000..dee1ba58e
--- /dev/null
+++ b/usr/austin/ogle/event.go
@@ -0,0 +1,294 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ogle
+
+import (
+	"fmt";
+	"os";
+	"ptrace";
+)
+
+/*
+ * Hooks and events
+ */
+
+// An EventHandler is a function that takes an event and returns a
+// response to that event and possibly an error.  If an event handler
+// returns an error, the process stops and no other handlers for that
+// event are executed.
+type EventHandler func(e Event) (EventAction, os.Error)
+
+// An EventAction is an event handler's response to an event.  If all
+// of an event's handlers execute without returning errors, their
+// results are combined as follows: If any handler returned
+// EAContinue, then the process resumes (without returning from
+// WaitStop); otherwise, if any handler returned EAStop, the process
+// remains stopped; otherwise, if all handlers returned EADefault, the
+// process resumes.  A handler may return EARemoveSelf bit-wise or'd
+// with any other action to indicate that the handler should be
+// removed from the hook.
+type EventAction int
+
+const (
+	EARemoveSelf EventAction = 0x100;
+	EADefault    EventAction = iota;
+	EAStop;
+	EAContinue;
+)
+
+// A EventHook allows event handlers to be added and removed.
+type EventHook interface {
+	AddHandler(EventHandler);
+	RemoveHandler(EventHandler);
+	NumHandler() int;
+	handle(e Event) (EventAction, os.Error);
+	String() string;
+}
+
+// EventHook is almost, but not quite, suitable for user-defined
+// events.  If we want user-defined events, make EventHook a struct,
+// special-case adding and removing handlers in breakpoint hooks, and
+// provide a public interface for posting events to hooks.
+
+type Event interface {
+	Process() *Process;
+	Thread() *Thread;
+	String() string;
+}
+
+type commonHook struct {
+	// Head of handler chain
+	head *handler;
+	// Number of non-internal handlers
+	len int;
+}
+
+type handler struct {
+	eh EventHandler;
+	// True if this handler must be run before user-defined
+	// handlers in order to ensure correctness.
+	internal bool;
+	// True if this handler has been removed from the chain.
+	removed bool;
+	next *handler;
+}
+
+func (h *commonHook) AddHandler(eh EventHandler) {
+	h.addHandler(eh, false);
+}
+
+func (h *commonHook) addHandler(eh EventHandler, internal bool) {
+	// Ensure uniqueness of handlers
+	h.RemoveHandler(eh);
+
+	if !internal {
+		h.len++;
+	}
+	// Add internal handlers to the beginning
+	if internal || h.head == nil {
+		h.head = &handler{eh, internal, false, h.head};
+		return;
+	}
+	// Add handler after internal handlers
+	// TODO(austin) This should probably go on the end instead
+	prev := h.head;
+	for prev.next != nil && prev.internal {
+		prev = prev.next;
+	}
+	prev.next = &handler{eh, internal, false, prev.next};
+}
+
+func (h *commonHook) RemoveHandler(eh EventHandler) {
+	plink := &h.head;
+	for l := *plink; l != nil; plink, l = &l.next, l.next {
+		if l.eh == eh {
+			if !l.internal {
+				h.len--;
+			}
+			l.removed = true;
+			*plink = l.next;
+			break;
+		}
+	}
+}
+
+func (h *commonHook) NumHandler() int {
+	return h.len;
+}
+
+func (h *commonHook) handle(e Event) (EventAction, os.Error) {
+	action := EADefault;
+	plink := &h.head;
+	for l := *plink; l != nil; plink, l = &l.next, l.next {
+		if l.removed {
+			continue;
+		}
+		a, err := l.eh(e);
+		if a & EARemoveSelf == EARemoveSelf {
+			if !l.internal {
+				h.len--;
+			}
+			l.removed = true;
+			*plink = l.next;
+			a &^= EARemoveSelf;
+		}
+		if err != nil {
+			return EAStop, err;
+		}
+		if a > action {
+			action = a;
+		}
+	}
+	return action, nil;
+}
+
+type commonEvent struct {
+	// The process of this event
+	p *Process;
+	// The thread of this event.
+	t *Thread;
+}
+
+func (e *commonEvent) Process() *Process {
+	return e.p;
+}
+
+func (e *commonEvent) Thread() *Thread {
+	return e.t;
+}
+
+/*
+ * Standard event handlers
+ */
+
+// EventPrint is a standard event handler that prints events as they
+// occur.  It will not cause the process to stop.
+func EventPrint(ev Event) (EventAction, os.Error) {
+	// TODO(austin) Include process name here?
+	fmt.Fprintf(os.Stderr, "*** %v\n", ev.String());
+	return EADefault, nil;
+}
+
+// EventStop is a standard event handler that causes the process to stop.
+func EventStop(ev Event) (EventAction, os.Error) {
+	return EAStop, nil;
+}
+
+/*
+ * Breakpoints
+ */
+
+type breakpointHook struct {
+	commonHook;
+	p *Process;
+	pc ptrace.Word;
+}
+
+// A Breakpoint event occurs when a process reaches a particular
+// program counter.  When this event is handled, the current thread
+// will be the thread that reached the program counter.
+type Breakpoint struct {
+	commonEvent;
+	osThread ptrace.Thread;
+	pc ptrace.Word;
+}
+
+func (h *breakpointHook) AddHandler(eh EventHandler) {
+	h.addHandler(eh, false);
+}
+
+func (h *breakpointHook) addHandler(eh EventHandler, internal bool) {
+	// We register breakpoint events lazily to avoid holding
+	// references to breakpoints without handlers.  Be sure to use
+	// the "canonical" breakpoint if there is one.
+	if cur, ok := h.p.breakpointHooks[h.pc]; ok {
+		h = cur;
+	}
+	oldhead := h.head;
+	h.commonHook.addHandler(eh, internal);
+	if oldhead == nil && h.head != nil {
+		h.p.proc.AddBreakpoint(h.pc);
+		h.p.breakpointHooks[h.pc] = h;
+	}
+}
+
+func (h *breakpointHook) RemoveHandler(eh EventHandler) {
+	oldhead := h.head;
+	h.commonHook.RemoveHandler(eh);
+	if oldhead != nil && h.head == nil {
+		h.p.proc.RemoveBreakpoint(h.pc);
+		h.p.breakpointHooks[h.pc] = nil, false;
+	}
+}
+
+func (h *breakpointHook) String() string {
+	// TODO(austin) Include process name?
+	// TODO(austin) Use line:pc or at least sym+%#x
+	return fmt.Sprintf("breakpoint at %#x", h.pc);
+}
+
+func (b *Breakpoint) PC() ptrace.Word {
+	return b.pc;
+}
+
+func (b *Breakpoint) String() string {
+	// TODO(austin) Include process name and thread
+	// TODO(austin) Use line:pc or at least sym+%#x
+	return fmt.Sprintf("breakpoint at %#x", b.pc);
+}
+
+/*
+ * Thread create/exit
+ */
+
+type threadCreateHook struct {
+	commonHook;
+}
+
+func (h *threadCreateHook) String() string {
+	return "thread create";
+}
+
+// A ThreadCreate event occurs when a process creates a new Go thread.
+// When this event is handled, the current thread will be the newly
+// created thread.
+type ThreadCreate struct {
+	commonEvent;
+	parent *Thread;
+}
+
+// Parent returns the thread that created this thread.  May be nil if
+// this event is the creation of the first thread.
+func (e *ThreadCreate) Parent() *Thread {
+	return e.parent;
+}
+
+func (e *ThreadCreate) String() string {
+	// TODO(austin) Include process name
+	if e.parent == nil {
+		return fmt.Sprintf("%v created", e.t);
+	}
+	return fmt.Sprintf("%v created by %v", e.t, e.parent);
+}
+
+type threadExitHook struct {
+	commonHook;
+}
+
+func (h *threadExitHook) String() string {
+	return "thread exit";
+}
+
+// A ThreadExit event occurs when a Go thread exits.
+type ThreadExit struct {
+	commonEvent;
+}
+
+func (e *ThreadExit) String() string {
+	// TODO(austin) Include process name
+	//return fmt.Sprintf("%v exited", e.t);
+	// For debugging purposes
+	return fmt.Sprintf("thread %#x exited", e.t.g.addr().base);
+}