Bug 1187062 - Part 2: Implement a concrete JS::ubi::StackFrame class backed by js::SavedFrame; r=sfink

js/public/UbiNode.h

@@ -956,6 +956,9 @@ class Concrete<JSObject> : public TracerConcreteWithCompartment<JSObject> {
                                  UniquePtr<char16_t[], JS::FreePolicy>& outName) const override;
     size_t size(mozilla::MallocSizeOf mallocSizeOf) const override;
 
+    bool hasAllocationStack() const override;
+    StackFrame allocationStack() const override;
+
   protected:
     explicit Concrete(JSObject* ptr) : TracerConcreteWithCompartment(ptr) { }
 

js/src/vm/SavedFrame.h

@@ -7,6 +7,8 @@
 #ifndef vm_SavedFrame_h
 #define vm_SavedFrame_h
 
+#include "js/UbiNode.h"
+
 namespace js {
 
 class SavedFrame : public NativeObject {
@@ -109,4 +111,49 @@ inline void AssertObjectIsSavedFrameOrWrapper(JSContext* cx, HandleObject stack)
 
 } // namespace js
 
+namespace JS {
+namespace ubi {
+
+using js::SavedFrame;
+
+// A concrete JS::ubi::StackFrame that is backed by a live SavedFrame object.
+template<>
+class ConcreteStackFrame<SavedFrame> : public BaseStackFrame {
+    explicit ConcreteStackFrame(SavedFrame* ptr) : BaseStackFrame(ptr) { }
+    SavedFrame& get() const { return *static_cast<SavedFrame*>(ptr); }
+
+  public:
+    static void construct(void* storage, SavedFrame* ptr) { new (storage) ConcreteStackFrame(ptr); }
+
+    StackFrame parent() const override { return get().getParent(); }
+    uint32_t line() const override { return get().getLine(); }
+    uint32_t column() const override { return get().getColumn(); }
+
+    AtomOrTwoByteChars source() const override {
+        auto source = get().getSource();
+        return AtomOrTwoByteChars(source);
+    }
+
+    AtomOrTwoByteChars functionDisplayName() const override {
+        auto name = get().getFunctionDisplayName();
+        return AtomOrTwoByteChars(name);
+    }
+
+    void trace(JSTracer* trc) override {
+        JSObject* obj = &get();
+        js::TraceManuallyBarrieredEdge(trc, &obj, "ConcreteStackFrame<SavedFrame>::ptr");
+        ptr = obj;
+    }
+
+    bool isSelfHosted() const override { return get().isSelfHosted(); }
+
+    bool isSystem() const override;
+
+    bool constructSavedFrameStack(JSContext* cx,
+                                 MutableHandleObject outSavedFrameStack) const override;
+};
+
+} // namespace ubi
+} // namespace JS
+
 #endif // vm_SavedFrame_h

js/src/vm/SavedStacks.cpp

@@ -1375,3 +1375,29 @@ CompartmentChecker::check(SavedStacks* stacks)
 #endif /* JS_CRASH_DIAGNOSTICS */
 
 } /* namespace js */
+
+namespace JS {
+namespace ubi {
+
+bool
+ConcreteStackFrame<SavedFrame>::isSystem() const
+{
+    auto trustedPrincipals = get().runtimeFromAnyThread()->trustedPrincipals();
+    return get().getPrincipals() == trustedPrincipals;
+}
+
+bool
+ConcreteStackFrame<SavedFrame>::constructSavedFrameStack(JSContext* cx,
+                                                         MutableHandleObject outSavedFrameStack)
+    const
+{
+    outSavedFrameStack.set(&get());
+    if (!cx->compartment()->wrap(cx, outSavedFrameStack)) {
+        outSavedFrameStack.set(nullptr);
+        return false;
+    }
+    return true;
+}
+
+} // namespace ubi
+} // namespace JS

js/src/vm/UbiNode.cpp

@@ -11,6 +11,8 @@
 #include "mozilla/Range.h"
 #include "mozilla/Scoped.h"
 
+#include <algorithm>
+
 #include "jscntxt.h"
 #include "jsobj.h"
 #include "jsscript.h"
@@ -22,6 +24,7 @@
 #include "js/TypeDecls.h"
 #include "js/Utility.h"
 #include "js/Vector.h"
+#include "vm/Debugger.h"
 #include "vm/GlobalObject.h"
 #include "vm/ScopeObject.h"
 #include "vm/Shape.h"
@@ -32,24 +35,87 @@
 #include "vm/Debugger-inl.h"
 
 using mozilla::Some;
+using mozilla::RangedPtr;
 using mozilla::UniquePtr;
 using JS::DispatchTraceKindTyped;
 using JS::HandleValue;
 using JS::Value;
 using JS::ZoneSet;
+using JS::ubi::AtomOrTwoByteChars;
 using JS::ubi::Concrete;
 using JS::ubi::Edge;
 using JS::ubi::EdgeRange;
 using JS::ubi::Node;
 using JS::ubi::SimpleEdge;
 using JS::ubi::SimpleEdgeVector;
+using JS::ubi::StackFrame;
 using JS::ubi::TracerConcrete;
 using JS::ubi::TracerConcreteWithCompartment;
 
+template<typename CharT>
+static size_t
+copyToBuffer(const CharT* src, RangedPtr<char16_t> dest, size_t length)
+{
+    size_t i = 0;
+    for ( ; i < length; i++)
+        dest[i] = src[i];
+    return i;
+}
+
+struct CopyToBufferMatcher
+{
+    using ReturnType = size_t;
+
+    RangedPtr<char16_t> destination;
+    size_t              maxLength;
+
+    CopyToBufferMatcher(RangedPtr<char16_t> destination, size_t maxLength)
+      : destination(destination)
+      , maxLength(maxLength)
+    { }
+
+    size_t
+    match(JSAtom* atom)
+    {
+        if (!atom)
+            return 0;
+
+        size_t length = std::min(atom->length(), maxLength);
+        JS::AutoCheckCannotGC noGC;
+        return atom->hasTwoByteChars()
+            ? copyToBuffer(atom->twoByteChars(noGC), destination, length)
+            : copyToBuffer(atom->latin1Chars(noGC), destination, length);
+    }
+
+    size_t
+    match(const char16_t* chars)
+    {
+        if (!chars)
+            return 0;
+
+        size_t length = std::min(js_strlen(chars), maxLength);
+        return copyToBuffer(chars, destination, length);
+    }
+};
+
+size_t
+StackFrame::source(RangedPtr<char16_t> destination, size_t length) const
+{
+    CopyToBufferMatcher m(destination, length);
+    return source().match(m);
+}
+
+size_t
+StackFrame::functionDisplayName(RangedPtr<char16_t> destination, size_t length) const
+{
+    CopyToBufferMatcher m(destination, length);
+    return functionDisplayName().match(m);
+}
+
 // All operations on null ubi::Nodes crash.
-const char16_t* Concrete<void>::typeName() const          { MOZ_CRASH("null ubi::Node"); }
-JS::Zone* Concrete<void>::zone() const                    { MOZ_CRASH("null ubi::Node"); }
-JSCompartment* Concrete<void>::compartment() 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"); }
+JSCompartment* Concrete<void>::compartment() const { MOZ_CRASH("null ubi::Node"); }
 
 UniquePtr<EdgeRange>
 Concrete<void>::edges(JSContext*, bool) const {
@@ -218,6 +284,19 @@ TracerConcreteWithCompartment<Referent>::compartment() const
     return TracerBase::get().compartment();
 }
 
+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
 {