1 files changed, 527 insertions, 0 deletions
diff --git a/js/src/vm/UbiNode.cpp b/js/src/vm/UbiNode.cpp
new file mode 100644
index 0000000000..424c5a9d78
--- /dev/null
+++ b/js/src/vm/UbiNode.cpp
@@ -0,0 +1,527 @@
+/* -*- 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/. */
+
+#include "js/UbiNode.h"
+
+#include "mozilla/Assertions.h"
+
+#include <algorithm>
+
+#include "debugger/Debugger.h"
+#include "gc/GC.h"
+#include "jit/JitCode.h"
+#include "js/Debug.h"
+#include "js/TracingAPI.h"
+#include "js/TypeDecls.h"
+#include "js/UbiNodeUtils.h"
+#include "js/Utility.h"
+#include "util/Text.h"
+#include "vm/BigIntType.h"
+#include "vm/Compartment.h"
+#include "vm/EnvironmentObject.h"
+#include "vm/GetterSetter.h"
+#include "vm/GlobalObject.h"
+#include "vm/JSContext.h"
+#include "vm/JSObject.h"
+#include "vm/JSScript.h"
+#include "vm/PropMap.h"
+#include "vm/Scope.h"
+#include "vm/Shape.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
+
+#include "debugger/Debugger-inl.h"
+#include "gc/StableCellHasher-inl.h"
+#include "vm/JSObject-inl.h"
+
+using namespace js;
+
+using JS::ApplyGCThingTyped;
+using JS::HandleValue;
+using JS::Value;
+using JS::ZoneSet;
+using JS::ubi::AtomOrTwoByteChars;
+using JS::ubi::CoarseType;
+using JS::ubi::Concrete;
+using JS::ubi::Edge;
+using JS::ubi::EdgeRange;
+using JS::ubi::EdgeVector;
+using JS::ubi::Node;
+using JS::ubi::StackFrame;
+using JS::ubi::TracerConcrete;
+using JS::ubi::TracerConcreteWithRealm;
+using mozilla::RangedPtr;
+
+struct CopyToBufferMatcher {
+  RangedPtr<char16_t> destination;
+  size_t maxLength;
+
+  CopyToBufferMatcher(RangedPtr<char16_t> destination, size_t maxLength)
+      : destination(destination), maxLength(maxLength) {}
+
+  template <typename CharT>
+  static size_t copyToBufferHelper(const CharT* src, RangedPtr<char16_t> dest,
+                                   size_t length) {
+    size_t i = 0;
+    for (; i < length; i++) {
+      dest[i] = src[i];
+    }
+    return i;
+  }
+
+  size_t operator()(JSAtom* atom) {
+    if (!atom) {
+      return 0;
+    }
+
+    size_t length = std::min(atom->length(), maxLength);
+    JS::AutoCheckCannotGC noGC;
+    return atom->hasTwoByteChars()
+               ? copyToBufferHelper(atom->twoByteChars(noGC), destination,
+                                    length)
+               : copyToBufferHelper(atom->latin1Chars(noGC), destination,
+                                    length);
+  }
+
+  size_t operator()(const char16_t* chars) {
+    if (!chars) {
+      return 0;
+    }
+
+    size_t length = std::min(js_strlen(chars), maxLength);
+    return copyToBufferHelper(chars, destination, length);
+  }
+};
+
+size_t JS::ubi::AtomOrTwoByteChars::copyToBuffer(
+    RangedPtr<char16_t> destination, size_t length) {
+  CopyToBufferMatcher m(destination, length);
+  return match(m);
+}
+
+struct LengthMatcher {
+  size_t operator()(JSAtom* atom) { return atom ? atom->length() : 0; }
+
+  size_t operator()(const char16_t* chars) {
+    return chars ? js_strlen(chars) : 0;
+  }
+};
+
+size_t JS::ubi::AtomOrTwoByteChars::length() {
+  LengthMatcher m;
+  return match(m);
+}
+
+size_t StackFrame::source(RangedPtr<char16_t> destination,
+                          size_t length) const {
+  auto s = source();
+  return s.copyToBuffer(destination, length);
+}
+
+size_t StackFrame::functionDisplayName(RangedPtr<char16_t> destination,
+                                       size_t length) const {
+  auto name = functionDisplayName();
+  return name.copyToBuffer(destination, length);
+}
+
+size_t StackFrame::sourceLength() { return source().length(); }
+
+size_t StackFrame::functionDisplayNameLength() {
+  return functionDisplayName().length();
+}
+
+// All operations on null ubi::Nodes crash.
+CoarseType Concrete<void>::coarseType() const { MOZ_CRASH("null ubi::Node"); }
+const char16_t* Concrete<void>::typeName() const {
+  MOZ_CRASH("null ubi::Node");
+}
+JS::Zone* Concrete<void>::zone() const { MOZ_CRASH("null ubi::Node"); }
+JS::Compartment* Concrete<void>::compartment() const {
+  MOZ_CRASH("null ubi::Node");
+}
+JS::Realm* Concrete<void>::realm() const { MOZ_CRASH("null ubi::Node"); }
+
+UniquePtr<EdgeRange> Concrete<void>::edges(JSContext*, bool) const {
+  MOZ_CRASH("null ubi::Node");
+}
+
+Node::Size Concrete<void>::size(mozilla::MallocSizeOf mallocSizeof) const {
+  MOZ_CRASH("null ubi::Node");
+}
+
+Node::Node(JS::GCCellPtr thing) {
+  ApplyGCThingTyped(thing, [this](auto t) { this->construct(t); });
+}
+
+Node::Node(HandleValue value) {
+  if (!ApplyGCThingTyped(value, [this](auto t) { this->construct(t); })) {
+    construct<void>(nullptr);
+  }
+}
+
+static bool IsSafeToExposeToJS(JSObject* obj) {
+  if (obj->is<js::EnvironmentObject>() || obj->is<js::ScriptSourceObject>() ||
+      obj->is<js::DebugEnvironmentProxy>()) {
+    return false;
+  }
+  if (obj->is<JSFunction>() && js::IsInternalFunctionObject(*obj)) {
+    return false;
+  }
+  return true;
+}
+
+Value Node::exposeToJS() const {
+  Value v;
+
+  if (is<JSObject>()) {
+    JSObject* obj = as<JSObject>();
+    if (IsSafeToExposeToJS(obj)) {
+      v.setObject(*obj);
+    } else {
+      v.setUndefined();
+    }
+  } else if (is<JSString>()) {
+    v.setString(as<JSString>());
+  } else if (is<JS::Symbol>()) {
+    v.setSymbol(as<JS::Symbol>());
+  } else if (is<BigInt>()) {
+    v.setBigInt(as<BigInt>());
+  } else {
+    v.setUndefined();
+  }
+
+  ExposeValueToActiveJS(v);
+
+  return v;
+}
+
+// A JS::CallbackTracer subclass that adds a Edge to a Vector for each
+// edge on which it is invoked.
+class EdgeVectorTracer final : public JS::CallbackTracer {
+  // The vector to which we add Edges.
+  EdgeVector* vec;
+
+  // True if we should populate the edge's names.
+  bool wantNames;
+
+  void onChild(JS::GCCellPtr thing, const char* name) override {
+    if (!okay) {
+      return;
+    }
+
+    // Don't trace permanent atoms and well-known symbols that are owned by
+    // a parent JSRuntime.
+    if (thing.is<JSString>() && thing.as<JSString>().isPermanentAtom()) {
+      return;
+    }
+    if (thing.is<JS::Symbol>() && thing.as<JS::Symbol>().isWellKnownSymbol()) {
+      return;
+    }
+
+    char16_t* name16 = nullptr;
+    if (wantNames) {
+      // Ask the tracer to compute an edge name for us.
+      char buffer[1024];
+      context().getEdgeName(name, buffer, sizeof(buffer));
+      name = buffer;
+
+      // Convert the name to char16_t characters.
+      name16 = js_pod_malloc<char16_t>(strlen(name) + 1);
+      if (!name16) {
+        okay = false;
+        return;
+      }
+
+      size_t i;
+      for (i = 0; name[i]; i++) {
+        name16[i] = name[i];
+      }
+      name16[i] = '\0';
+    }
+
+    // The simplest code is correct! The temporary Edge takes
+    // ownership of name; if the append succeeds, the vector element
+    // then takes ownership; if the append fails, then the temporary
+    // retains it, and its destructor will free it.
+    if (!vec->append(Edge(name16, Node(thing)))) {
+      okay = false;
+      return;
+    }
+  }
+
+ public:
+  // True if no errors (OOM, say) have yet occurred.
+  bool okay;
+
+  EdgeVectorTracer(JSRuntime* rt, EdgeVector* vec, bool wantNames)
+      : JS::CallbackTracer(rt), vec(vec), wantNames(wantNames), okay(true) {}
+};
+
+template <typename Referent>
+JS::Zone* TracerConcrete<Referent>::zone() const {
+  return get().zoneFromAnyThread();
+}
+
+template JS::Zone* TracerConcrete<js::BaseScript>::zone() const;
+template JS::Zone* TracerConcrete<js::Shape>::zone() const;
+template JS::Zone* TracerConcrete<js::BaseShape>::zone() const;
+template JS::Zone* TracerConcrete<js::GetterSetter>::zone() const;
+template JS::Zone* TracerConcrete<js::PropMap>::zone() const;
+template JS::Zone* TracerConcrete<js::RegExpShared>::zone() const;
+template JS::Zone* TracerConcrete<js::Scope>::zone() const;
+template JS::Zone* TracerConcrete<JS::Symbol>::zone() const;
+template JS::Zone* TracerConcrete<BigInt>::zone() const;
+template JS::Zone* TracerConcrete<JSString>::zone() const;
+
+template <typename Referent>
+UniquePtr<EdgeRange> TracerConcrete<Referent>::edges(JSContext* cx,
+                                                     bool wantNames) const {
+  auto range = js::MakeUnique<SimpleEdgeRange>();
+  if (!range) {
+    return nullptr;
+  }
+
+  if (!range->addTracerEdges(cx->runtime(), ptr,
+                             JS::MapTypeToTraceKind<Referent>::kind,
+                             wantNames)) {
+    return nullptr;
+  }
+
+  // Note: Clang 3.8 (or older) require an explicit construction of the
+  // target UniquePtr type. When we no longer require to support these Clang
+  // versions the return statement can be simplified to |return range;|.
+  return UniquePtr<EdgeRange>(range.release());
+}
+
+template UniquePtr<EdgeRange> TracerConcrete<js::BaseScript>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::Shape>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::BaseShape>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::GetterSetter>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::PropMap>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::RegExpShared>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<js::Scope>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<JS::Symbol>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<BigInt>::edges(
+    JSContext* cx, bool wantNames) const;
+template UniquePtr<EdgeRange> TracerConcrete<JSString>::edges(
+    JSContext* cx, bool wantNames) const;
+
+template <typename Referent>
+JS::Compartment* TracerConcreteWithRealm<Referent>::compartment() const {
+  return TracerBase::get().compartment();
+}
+
+template <typename Referent>
+Realm* TracerConcreteWithRealm<Referent>::realm() const {
+  return TracerBase::get().realm();
+}
+
+template Realm* TracerConcreteWithRealm<js::BaseScript>::realm() const;
+template JS::Compartment* TracerConcreteWithRealm<js::BaseScript>::compartment()
+    const;
+
+bool Concrete<JSObject>::hasAllocationStack() const {
+  return !!js::Debugger::getObjectAllocationSite(get());
+}
+
+StackFrame Concrete<JSObject>::allocationStack() const {
+  MOZ_ASSERT(hasAllocationStack());
+  return StackFrame(js::Debugger::getObjectAllocationSite(get()));
+}
+
+const char* Concrete<JSObject>::jsObjectClassName() const {
+  return Concrete::get().getClass()->name;
+}
+
+JS::Compartment* Concrete<JSObject>::compartment() const {
+  return Concrete::get().compartment();
+}
+
+Realm* Concrete<JSObject>::realm() const {
+  // Cross-compartment wrappers are shared by all realms in the compartment,
+  // so we return nullptr in that case.
+  return JS::GetObjectRealmOrNull(&Concrete::get());
+}
+
+const char16_t Concrete<JS::Symbol>::concreteTypeName[] = u"JS::Symbol";
+const char16_t Concrete<BigInt>::concreteTypeName[] = u"JS::BigInt";
+const char16_t Concrete<js::BaseScript>::concreteTypeName[] = u"js::BaseScript";
+const char16_t Concrete<js::jit::JitCode>::concreteTypeName[] =
+    u"js::jit::JitCode";
+const char16_t Concrete<js::Shape>::concreteTypeName[] = u"js::Shape";
+const char16_t Concrete<js::BaseShape>::concreteTypeName[] = u"js::BaseShape";
+const char16_t Concrete<js::GetterSetter>::concreteTypeName[] =
+    u"js::GetterSetter";
+const char16_t Concrete<js::PropMap>::concreteTypeName[] = u"js::PropMap";
+const char16_t Concrete<js::Scope>::concreteTypeName[] = u"js::Scope";
+const char16_t Concrete<js::RegExpShared>::concreteTypeName[] =
+    u"js::RegExpShared";
+
+namespace JS {
+namespace ubi {
+
+RootList::RootList(JSContext* cx, bool wantNames /* = false */)
+    : cx(cx), wantNames(wantNames), inited(false) {}
+
+std::pair<bool, JS::AutoCheckCannotGC> RootList::init() {
+  EdgeVectorTracer tracer(cx->runtime(), &edges, wantNames);
+  js::TraceRuntime(&tracer);
+  inited = tracer.okay;
+  return {tracer.okay, JS::AutoCheckCannotGC(cx)};
+}
+
+std::pair<bool, JS::AutoCheckCannotGC> RootList::init(
+    CompartmentSet& debuggees) {
+  EdgeVector allRootEdges;
+  EdgeVectorTracer tracer(cx->runtime(), &allRootEdges, wantNames);
+
+  ZoneSet debuggeeZones;
+  for (auto range = debuggees.all(); !range.empty(); range.popFront()) {
+    if (!debuggeeZones.put(range.front()->zone())) {
+      return {false, JS::AutoCheckCannotGC(cx)};
+    }
+  }
+
+  js::TraceRuntime(&tracer);
+  if (!tracer.okay) {
+    return {false, JS::AutoCheckCannotGC(cx)};
+  }
+  js::gc::TraceIncomingCCWs(&tracer, debuggees);
+  if (!tracer.okay) {
+    return {false, JS::AutoCheckCannotGC(cx)};
+  }
+
+  for (EdgeVector::Range r = allRootEdges.all(); !r.empty(); r.popFront()) {
+    Edge& edge = r.front();
+
+    JS::Compartment* compartment = edge.referent.compartment();
+    if (compartment && !debuggees.has(compartment)) {
+      continue;
+    }
+
+    Zone* zone = edge.referent.zone();
+    if (zone && !debuggeeZones.has(zone)) {
+      continue;
+    }
+
+    if (!edges.append(std::move(edge))) {
+      return {false, JS::AutoCheckCannotGC(cx)};
+    }
+  }
+
+  inited = true;
+  return {true, JS::AutoCheckCannotGC(cx)};
+}
+
+std::pair<bool, JS::AutoCheckCannotGC> RootList::init(HandleObject debuggees) {
+  MOZ_ASSERT(debuggees && JS::dbg::IsDebugger(*debuggees));
+  js::Debugger* dbg = js::Debugger::fromJSObject(debuggees.get());
+
+  CompartmentSet debuggeeCompartments;
+
+  for (js::WeakGlobalObjectSet::Range r = dbg->allDebuggees(); !r.empty();
+       r.popFront()) {
+    if (!debuggeeCompartments.put(r.front()->compartment())) {
+      return {false, JS::AutoCheckCannotGC(cx)};
+    }
+  }
+
+  auto [ok, nogc] = init(debuggeeCompartments);
+  if (!ok) {
+    return {false, nogc};
+  }
+
+  // Ensure that each of our debuggee globals are in the root list.
+  for (js::WeakGlobalObjectSet::Range r = dbg->allDebuggees(); !r.empty();
+       r.popFront()) {
+    if (!addRoot(JS::ubi::Node(static_cast<JSObject*>(r.front())),
+                 u"debuggee global")) {
+      return {false, nogc};
+    }
+  }
+
+  inited = true;
+  return {true, nogc};
+}
+
+bool RootList::addRoot(Node node, const char16_t* edgeName) {
+  MOZ_ASSERT_IF(wantNames, edgeName);
+
+  UniqueTwoByteChars name;
+  if (edgeName) {
+    name = js::DuplicateString(edgeName);
+    if (!name) {
+      return false;
+    }
+  }
+
+  return edges.append(Edge(name.release(), node));
+}
+
+const char16_t Concrete<RootList>::concreteTypeName[] = u"JS::ubi::RootList";
+
+UniquePtr<EdgeRange> Concrete<RootList>::edges(JSContext* cx,
+                                               bool wantNames) const {
+  MOZ_ASSERT_IF(wantNames, get().wantNames);
+  return js::MakeUnique<PreComputedEdgeRange>(get().edges);
+}
+
+bool SimpleEdgeRange::addTracerEdges(JSRuntime* rt, void* thing,
+                                     JS::TraceKind kind, bool wantNames) {
+  EdgeVectorTracer tracer(rt, &edges, wantNames);
+  JS::TraceChildren(&tracer, JS::GCCellPtr(thing, kind));
+  settle();
+  return tracer.okay;
+}
+
+void Concrete<JSObject>::construct(void* storage, JSObject* ptr) {
+  if (ptr) {
+    auto clasp = ptr->getClass();
+    auto callback = ptr->compartment()
+                        ->runtimeFromMainThread()
+                        ->constructUbiNodeForDOMObjectCallback;
+    if (clasp->isDOMClass() && callback) {
+      AutoSuppressGCAnalysis suppress;
+      callback(storage, ptr);
+      return;
+    }
+  }
+  new (storage) Concrete(ptr);
+}
+
+void SetConstructUbiNodeForDOMObjectCallback(JSContext* cx,
+                                             void (*callback)(void*,
+                                                              JSObject*)) {
+  cx->runtime()->constructUbiNodeForDOMObjectCallback = callback;
+}
+
+JS_PUBLIC_API const char* CoarseTypeToString(CoarseType type) {
+  switch (type) {
+    case CoarseType::Other:
+      return "Other";
+    case CoarseType::Object:
+      return "Object";
+    case CoarseType::Script:
+      return "Script";
+    case CoarseType::String:
+      return "String";
+    case CoarseType::DOMNode:
+      return "DOMNode";
+    default:
+      return "Unknown";
+  }
+};
+
+}  // namespace ubi
+}  // namespace JS