DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Mercurial (c68fe15a81fc)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef debugger_Frame_h
#define debugger_Frame_h

#include "mozilla/Attributes.h"  // for MOZ_MUST_USE
#include "mozilla/Maybe.h"       // for Maybe
#include "mozilla/Range.h"       // for Range
#include "mozilla/Result.h"      // for Result

#include <stddef.h>  // for size_t

#include "jsapi.h"  // for JSContext, CallArgs

#include "NamespaceImports.h"   // for Value, MutableHandleValue, HandleObject
#include "debugger/DebugAPI.h"  // for ResumeMode
#include "debugger/Debugger.h"  // for ResumeMode, Handler, Debugger
#include "gc/Barrier.h"         // for HeapPtr
#include "gc/Rooting.h"         // for HandleDebuggerFrame, HandleNativeObject
#include "vm/FrameIter.h"       // for FrameIter
#include "vm/JSObject.h"        // for JSObject
#include "vm/NativeObject.h"    // for NativeObject
#include "vm/Stack.h"           // for AbstractFramePtr

namespace js {

class AbstractGeneratorObject;
class GlobalObject;

/*
 * An OnStepHandler represents a handler function that is called when a small
 * amount of progress is made in a frame.
 */
struct OnStepHandler : Handler {
  /*
   * If we have made a small amount of progress in a frame, this method is
   * called with the frame as argument. If succesful, this method should
   * return true, with `resumeMode` and `vp` set to a resumption value
   * specifiying how execution should continue.
   */
  virtual bool onStep(JSContext* cx, HandleDebuggerFrame frame,
                      ResumeMode& resumeMode, MutableHandleValue vp) = 0;
};

class ScriptedOnStepHandler final : public OnStepHandler {
 public:
  explicit ScriptedOnStepHandler(JSObject* object);
  virtual JSObject* object() const override;
  virtual void hold(JSObject* owner) override;
  virtual void drop(JSFreeOp* fop, JSObject* owner) override;
  virtual void trace(JSTracer* tracer) override;
  virtual size_t allocSize() const override;
  virtual bool onStep(JSContext* cx, HandleDebuggerFrame frame,
                      ResumeMode& resumeMode, MutableHandleValue vp) override;

 private:
  const HeapPtr<JSObject*> object_;
};

/*
 * An OnPopHandler represents a handler function that is called just before a
 * frame is popped.
 */
struct OnPopHandler : Handler {
  /*
   * The given `frame` is about to be popped; `completion` explains why.
   *
   * When this method returns true, it must set `resumeMode` and `vp` to a
   * resumption value specifying how execution should continue.
   *
   * When this method returns false, it should set an exception on `cx`.
   */
  virtual bool onPop(JSContext* cx, HandleDebuggerFrame frame,
                     const Completion& completion, ResumeMode& resumeMode,
                     MutableHandleValue vp) = 0;
};

class ScriptedOnPopHandler final : public OnPopHandler {
 public:
  explicit ScriptedOnPopHandler(JSObject* object);
  virtual JSObject* object() const override;
  virtual void hold(JSObject* owner) override;
  virtual void drop(JSFreeOp* fop, JSObject* owner) override;
  virtual void trace(JSTracer* tracer) override;
  virtual size_t allocSize() const override;
  virtual bool onPop(JSContext* cx, HandleDebuggerFrame frame,
                     const Completion& completion, ResumeMode& resumeMode,
                     MutableHandleValue vp) override;

 private:
  const HeapPtr<JSObject*> object_;
};

enum class DebuggerFrameType { Eval, Global, Call, Module, WasmCall };

enum class DebuggerFrameImplementation { Interpreter, Baseline, Ion, Wasm };

class DebuggerArguments : public NativeObject {
 public:
  static const JSClass class_;

  static DebuggerArguments* create(JSContext* cx, HandleObject proto,
                                   HandleDebuggerFrame frame);

 private:
  enum { FRAME_SLOT };

  static const unsigned RESERVED_SLOTS = 1;
};

class DebuggerFrame : public NativeObject {
  friend class DebuggerArguments;
  friend class ScriptedOnStepHandler;
  friend class ScriptedOnPopHandler;

 public:
  static const JSClass class_;

  enum {
    OWNER_SLOT = 0,
    ARGUMENTS_SLOT,
    ONSTEP_HANDLER_SLOT,
    ONPOP_HANDLER_SLOT,

    HAS_INCREMENTED_STEPPER_SLOT,

    // If this is a frame for a generator call, and the generator object has
    // been created (which doesn't happen until after default argument
    // evaluation and destructuring), then this is a PrivateValue pointing to a
    // GeneratorInfo struct that points to the call's AbstractGeneratorObject.
    // This allows us to implement Debugger.Frame methods even while the call is
    // suspended, and we have no FrameIter::Data.
    //
    // While Debugger::generatorFrames maps an AbstractGeneratorObject to its
    // Debugger.Frame, this link represents the reverse relation, from a
    // Debugger.Frame to its generator object. This slot is set if and only if
    // there is a corresponding entry in generatorFrames.
    GENERATOR_INFO_SLOT,

    RESERVED_SLOTS,
  };

  void trace(JSTracer* trc);

  static NativeObject* initClass(JSContext* cx, Handle<GlobalObject*> global,
                                 HandleObject dbgCtor);
  static DebuggerFrame* create(JSContext* cx, HandleObject proto,
                               HandleNativeObject debugger,
                               const FrameIter* maybeIter,
                               Handle<AbstractGeneratorObject*> maybeGenerator);

  static MOZ_MUST_USE bool getArguments(JSContext* cx,
                                        HandleDebuggerFrame frame,
                                        MutableHandleDebuggerArguments result);
  static MOZ_MUST_USE bool getCallee(JSContext* cx, HandleDebuggerFrame frame,
                                     MutableHandleDebuggerObject result);
  static MOZ_MUST_USE bool getIsConstructing(JSContext* cx,
                                             HandleDebuggerFrame frame,
                                             bool& result);
  static MOZ_MUST_USE bool getEnvironment(
      JSContext* cx, HandleDebuggerFrame frame,
      MutableHandleDebuggerEnvironment result);
  static MOZ_MUST_USE bool getOffset(JSContext* cx, HandleDebuggerFrame frame,
                                     size_t& result);
  static MOZ_MUST_USE bool getOlder(JSContext* cx, HandleDebuggerFrame frame,
                                    MutableHandleDebuggerFrame result);
  static MOZ_MUST_USE bool getAsyncPromise(JSContext* cx,
                                           HandleDebuggerFrame frame,
                                           MutableHandleDebuggerObject result);
  static MOZ_MUST_USE bool getOlderSavedFrame(JSContext* cx,
                                              HandleDebuggerFrame frame,
                                              MutableHandleSavedFrame result);
  static MOZ_MUST_USE bool getThis(JSContext* cx, HandleDebuggerFrame frame,
                                   MutableHandleValue result);
  static DebuggerFrameType getType(HandleDebuggerFrame frame);
  static DebuggerFrameImplementation getImplementation(
      HandleDebuggerFrame frame);
  static MOZ_MUST_USE bool setOnStepHandler(JSContext* cx,
                                            HandleDebuggerFrame frame,
                                            OnStepHandler* handler);

  static MOZ_MUST_USE JS::Result<Completion> eval(
      JSContext* cx, HandleDebuggerFrame frame,
      mozilla::Range<const char16_t> chars, HandleObject bindings,
      const EvalOptions& options);

  static MOZ_MUST_USE DebuggerFrame* check(JSContext* cx, HandleValue thisv);

  bool isOnStack() const;

  // Like isOnStack, but works even in the midst of a relocating GC.
  bool isOnStackMaybeForwarded() const;

  OnStepHandler* onStepHandler() const;
  OnPopHandler* onPopHandler() const;
  void setOnPopHandler(JSContext* cx, OnPopHandler* handler);

  inline bool hasGenerator() const;

  // If hasGenerator(), return an direct cross-compartment reference to this
  // Debugger.Frame's generator object.
  AbstractGeneratorObject& unwrappedGenerator() const;

#ifdef DEBUG
  JSScript* generatorScript() const;
#endif

  /*
   * Associate the generator object genObj with this Debugger.Frame. This
   * association allows the Debugger.Frame to track the generator's execution
   * across suspensions and resumptions, and to implement some methods even
   * while the generator is suspended.
   *
   * The context `cx` must be in the Debugger.Frame's realm, and `genObj` must
   * be in a debuggee realm.
   *
   * Technically, the generator activation need not actually be on the stack
   * right now; it's okay to call this method on a Debugger.Frame that has no
   * ScriptFrameIter::Data at present. However, this function has no way to
   * verify that genObj really is the generator associated with the call for
   * which this Debugger.Frame was originally created, so it's best to make the
   * association while the call is on the stack, and the relationships are easy
   * to discern.
   */
  MOZ_MUST_USE bool setGenerator(JSContext* cx,
                                 Handle<AbstractGeneratorObject*> genObj);

  /*
   * Undo the effects of a prior call to setGenerator.
   *
   * If provided, owner must be the Debugger to which this Debugger.Frame
   * belongs; remove this frame's entry from its generatorFrames map, and clean
   * up its cross-compartment wrapper table entry. The owner must be passed
   * unless this method is being called from the Debugger.Frame's finalizer. (In
   * that case, the owner is not reliably available, and is not actually
   * necessary.)
   *
   * If maybeGeneratorFramesEnum is non-null, use it to remove this frame's
   * entry from the Debugger's generatorFrames weak map. In this case, this
   * function will not otherwise disturb generatorFrames. Passing the enum
   * allows this function to be used while iterating over generatorFrames.
   */
  void clearGenerator(JSFreeOp* fop);
  void clearGenerator(
      JSFreeOp* fop, Debugger* owner,
      Debugger::GeneratorWeakMap::Enum* maybeGeneratorFramesEnum = nullptr);

  /*
   * Called after a generator/async frame is resumed, before exposing this
   * Debugger.Frame object to any hooks.
   */
  bool resume(const FrameIter& iter);

  bool hasAnyHooks() const;

 private:
  static const JSClassOps classOps_;

  static const JSPropertySpec properties_[];
  static const JSFunctionSpec methods_[];

  static void finalize(JSFreeOp* fop, JSObject* obj);

  static AbstractFramePtr getReferent(HandleDebuggerFrame frame);
  static MOZ_MUST_USE bool getFrameIter(JSContext* cx,
                                        HandleDebuggerFrame frame,
                                        mozilla::Maybe<FrameIter>& result);
  static MOZ_MUST_USE bool requireScriptReferent(JSContext* cx,
                                                 HandleDebuggerFrame frame);

  static MOZ_MUST_USE bool construct(JSContext* cx, unsigned argc, Value* vp);

  struct CallData;

  Debugger* owner() const;

  bool hasIncrementedStepper() const;
  void setHasIncrementedStepper(bool incremented);

  MOZ_MUST_USE bool maybeIncrementStepperCounter(JSContext* cx,
                                                 AbstractFramePtr referent);
  MOZ_MUST_USE bool maybeIncrementStepperCounter(JSContext* cx,
                                                 JSScript* script);
  void maybeDecrementStepperCounter(JSFreeOp* fop, JSScript* script);

 public:
  FrameIter::Data* frameIterData() const;
  void setFrameIterData(FrameIter::Data*);
  void freeFrameIterData(JSFreeOp* fop);
  void maybeDecrementStepperCounter(JSFreeOp* fop, AbstractFramePtr referent);

  class GeneratorInfo;
  inline GeneratorInfo* generatorInfo() const;
};

} /* namespace js */

#endif /* debugger_Frame_h */