jsdbgapi.c

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * JS debugging API.
 */
#include "jsstddef.h"
#include <string.h>
#include "jstypes.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jsclist.h"
#include "jsapi.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsdbgapi.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsstr.h"

typedef struct JSTrap {
    JSCList         links;
    JSScript        *script;
    jsbytecode      *pc;
    JSOp            op;
    JSTrapHandler   handler;
    void            *closure;
} JSTrap;

static JSTrap *
FindTrap(JSRuntime *rt, JSScript *script, jsbytecode *pc)
{
    JSTrap *trap;

    for (trap = (JSTrap *)rt->trapList.next;
         trap != (JSTrap *)&rt->trapList;
         trap = (JSTrap *)trap->links.next) {
        if (trap->script == script && trap->pc == pc)
            return trap;
    }
    return NULL;
}

void
js_PatchOpcode(JSContext *cx, JSScript *script, jsbytecode *pc, JSOp op)
{
    JSTrap *trap;

    trap = FindTrap(cx->runtime, script, pc);
    if (trap)
        trap->op = op;
    else
        *pc = (jsbytecode)op;
}

JS_PUBLIC_API(JSBool)
JS_SetTrap(JSContext *cx, JSScript *script, jsbytecode *pc,
           JSTrapHandler handler, void *closure)
{
    JSRuntime *rt;
    JSTrap *trap;

    rt = cx->runtime;
    trap = FindTrap(rt, script, pc);
    if (trap) {
        JS_ASSERT(trap->script == script && trap->pc == pc);
        JS_ASSERT(*pc == JSOP_TRAP);
    } else {
        trap = (JSTrap *) JS_malloc(cx, sizeof *trap);
        if (!trap || !js_AddRoot(cx, &trap->closure, "trap->closure")) {
            if (trap)
                JS_free(cx, trap);
            return JS_FALSE;
        }
        JS_APPEND_LINK(&trap->links, &rt->trapList);
        trap->script = script;
        trap->pc = pc;
        trap->op = (JSOp)*pc;
        *pc = JSOP_TRAP;
    }
    trap->handler = handler;
    trap->closure = closure;
    return JS_TRUE;
}

JS_PUBLIC_API(JSOp)
JS_GetTrapOpcode(JSContext *cx, JSScript *script, jsbytecode *pc)
{
    JSTrap *trap;

    trap = FindTrap(cx->runtime, script, pc);
    if (!trap) {
        JS_ASSERT(0);   /* XXX can't happen */
        return JSOP_LIMIT;
    }
    return trap->op;
}

static void
DestroyTrap(JSContext *cx, JSTrap *trap)
{
    JS_REMOVE_LINK(&trap->links);
    *trap->pc = (jsbytecode)trap->op;
    js_RemoveRoot(cx->runtime, &trap->closure);
    JS_free(cx, trap);
}

JS_PUBLIC_API(void)
JS_ClearTrap(JSContext *cx, JSScript *script, jsbytecode *pc,
             JSTrapHandler *handlerp, void **closurep)
{
    JSTrap *trap;

    trap = FindTrap(cx->runtime, script, pc);
    if (handlerp)
        *handlerp = trap ? trap->handler : NULL;
    if (closurep)
        *closurep = trap ? trap->closure : NULL;
    if (trap)
        DestroyTrap(cx, trap);
}

JS_PUBLIC_API(void)
JS_ClearScriptTraps(JSContext *cx, JSScript *script)
{
    JSRuntime *rt;
    JSTrap *trap, *next;

    rt = cx->runtime;
    for (trap = (JSTrap *)rt->trapList.next;
         trap != (JSTrap *)&rt->trapList;
         trap = next) {
        next = (JSTrap *)trap->links.next;
        if (trap->script == script)
            DestroyTrap(cx, trap);
    }
}

JS_PUBLIC_API(void)
JS_ClearAllTraps(JSContext *cx)
{
    JSRuntime *rt;
    JSTrap *trap, *next;

    rt = cx->runtime;
    for (trap = (JSTrap *)rt->trapList.next;
         trap != (JSTrap *)&rt->trapList;
         trap = next) {
        next = (JSTrap *)trap->links.next;
        DestroyTrap(cx, trap);
    }
}

JS_PUBLIC_API(JSTrapStatus)
JS_HandleTrap(JSContext *cx, JSScript *script, jsbytecode *pc, jsval *rval)
{
    JSTrap *trap;
    JSTrapStatus status;
    jsint op;

    trap = FindTrap(cx->runtime, script, pc);
    if (!trap) {
        JS_ASSERT(0);   /* XXX can't happen */
        return JSTRAP_ERROR;
    }
    /*
     * It's important that we not use 'trap->' after calling the callback --
     * the callback might remove the trap!
     */
    op = (jsint)trap->op;
    status = trap->handler(cx, script, pc, rval, trap->closure);
    if (status == JSTRAP_CONTINUE) {
        /* By convention, return the true op to the interpreter in rval. */
        *rval = INT_TO_JSVAL(op);
    }
    return status;
}

JS_PUBLIC_API(JSBool)
JS_SetInterrupt(JSRuntime *rt, JSTrapHandler handler, void *closure)
{
    rt->interruptHandler = handler;
    rt->interruptHandlerData = closure;
    return JS_TRUE;
}

JS_PUBLIC_API(JSBool)
JS_ClearInterrupt(JSRuntime *rt, JSTrapHandler *handlerp, void **closurep)
{
    if (handlerp)
        *handlerp = (JSTrapHandler)rt->interruptHandler;
    if (closurep)
        *closurep = rt->interruptHandlerData;
    rt->interruptHandler = 0;
    rt->interruptHandlerData = 0;
    return JS_TRUE;
}

/************************************************************************/

typedef struct JSWatchPoint {
    JSCList             links;
    JSObject            *object;        /* weak link, see js_FinalizeObject */
    JSScopeProperty     *sprop;
    JSPropertyOp        setter;
    JSWatchPointHandler handler;
    void                *closure;
    jsrefcount          nrefs;
} JSWatchPoint;

#define HoldWatchPoint(wp) ((wp)->nrefs++)

static JSBool
DropWatchPoint(JSContext *cx, JSWatchPoint *wp)
{
    JSScopeProperty *sprop;

    if (--wp->nrefs != 0)
        return JS_TRUE;

    /*
     * Remove wp from the list, then if there are no other watchpoints for
     * wp->sprop in any scope, restore wp->sprop->setter from wp.
     */
    JS_REMOVE_LINK(&wp->links);
    sprop = wp->sprop;
    if (!js_GetWatchedSetter(cx->runtime, NULL, sprop)) {
        sprop = js_ChangeNativePropertyAttrs(cx, wp->object, sprop,
                                             0, sprop->attrs,
                                             sprop->getter, wp->setter);
        if (!sprop)
            return JS_FALSE;
    }
    js_RemoveRoot(cx->runtime, &wp->closure);
    JS_free(cx, wp);
    return JS_TRUE;
}

void
js_MarkWatchPoints(JSRuntime *rt)
{
    JSWatchPoint *wp;

    for (wp = (JSWatchPoint *)rt->watchPointList.next;
         wp != (JSWatchPoint *)&rt->watchPointList;
         wp = (JSWatchPoint *)wp->links.next) {
        MARK_SCOPE_PROPERTY(wp->sprop);
    }
}

static JSWatchPoint *
FindWatchPoint(JSRuntime *rt, JSScope *scope, jsid id)
{
    JSWatchPoint *wp;

    for (wp = (JSWatchPoint *)rt->watchPointList.next;
         wp != (JSWatchPoint *)&rt->watchPointList;
         wp = (JSWatchPoint *)wp->links.next) {
        if (wp->object == scope->object && wp->sprop->id == id)
            return wp;
    }
    return NULL;
}

JSScopeProperty *
js_FindWatchPoint(JSRuntime *rt, JSScope *scope, jsid id)
{
    JSWatchPoint *wp;

    wp = FindWatchPoint(rt, scope, id);
    if (!wp)
        return NULL;
    return wp->sprop;
}

JSPropertyOp
js_GetWatchedSetter(JSRuntime *rt, JSScope *scope,
                    const JSScopeProperty *sprop)
{
    JSWatchPoint *wp;

    for (wp = (JSWatchPoint *)rt->watchPointList.next;
         wp != (JSWatchPoint *)&rt->watchPointList;
         wp = (JSWatchPoint *)wp->links.next) {
        if ((!scope || wp->object == scope->object) && wp->sprop == sprop)
            return wp->setter;
    }
    return NULL;
}

JSBool JS_DLL_CALLBACK
js_watch_set(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    JSRuntime *rt;
    JSWatchPoint *wp;
    JSScopeProperty *sprop;
    jsval userid;
    JSScope *scope;
    JSBool ok;

    rt = cx->runtime;
    for (wp = (JSWatchPoint *)rt->watchPointList.next;
         wp != (JSWatchPoint *)&rt->watchPointList;
         wp = (JSWatchPoint *)wp->links.next) {
        sprop = wp->sprop;
        if (wp->object == obj && SPROP_USERID(sprop) == id) {
            JS_LOCK_OBJ(cx, obj);
            userid = SPROP_USERID(sprop);
            scope = OBJ_SCOPE(obj);
            JS_UNLOCK_OBJ(cx, obj);
            HoldWatchPoint(wp);
            ok = wp->handler(cx, obj, userid,
                             SPROP_HAS_VALID_SLOT(sprop, scope)
                             ? OBJ_GET_SLOT(cx, obj, wp->sprop->slot)
                             : JSVAL_VOID,
                             vp, wp->closure);
            if (ok) {
                /*
                 * Create pseudo-frame for call to setter so that any
                 * stack-walking security code in the setter will correctly
                 * identify the guilty party.
                 */
                JSObject *funobj = (JSObject *) wp->closure;
                JSFunction *fun = (JSFunction *) JS_GetPrivate(cx, funobj);
                JSStackFrame frame;

                memset(&frame, 0, sizeof(frame));
                frame.script = fun->script;
                frame.fun = fun;
                frame.down = cx->fp;
                cx->fp = &frame;
                ok = !wp->setter ||
                     ((sprop->attrs & JSPROP_SETTER)
                      ? js_InternalCall(cx, obj, OBJECT_TO_JSVAL(wp->setter),
                                        1, vp, vp)
                      : wp->setter(cx, OBJ_THIS_OBJECT(cx, obj), userid, vp));
                cx->fp = frame.down;
            }
            return DropWatchPoint(cx, wp);
        }
    }
    JS_ASSERT(0);       /* XXX can't happen */
    return JS_FALSE;
}

JSBool JS_DLL_CALLBACK
js_watch_set_wrapper(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
                     jsval *rval)
{
    JSObject *funobj;
    JSFunction *wrapper;
    jsval userid;

    funobj = JSVAL_TO_OBJECT(argv[-2]);
    wrapper = (JSFunction *) JS_GetPrivate(cx, funobj);
    userid = ATOM_KEY(wrapper->atom);
    *rval = argv[0];
    return js_watch_set(cx, obj, userid, rval);
}

JSPropertyOp
js_WrapWatchedSetter(JSContext *cx, jsid id, uintN attrs, JSPropertyOp setter)
{
    JSAtom *atom;
    JSFunction *wrapper;

    if (!(attrs & JSPROP_SETTER))
        return &js_watch_set;   /* & to silence schoolmarmish MSVC */

    if (!JSVAL_IS_INT(id)) {
        atom = (JSAtom *)id;
    } else {
        atom = js_AtomizeInt(cx, JSVAL_TO_INT(id), 0);