I figured out my problem, although I don't know enough of the V8 system
architecture to explain why. You can return the handle from the factory method
directly if you use HandleScope instead of EscapableHandleScope.
Thanks for all the help!
Full code for posterity:
RUNTIME_FUNCTION ( Runtime_AddressOfArray ) {
HandleScope hs ( isolate );
StdoutStream os ;
MaybeObject maybe_object (* args. address_of_arg_at ( 0 ));
Object object = maybe_object. GetHeapObjectOrSmi ();
void * data_pointer = JSTypedArray :: cast ( object ). DataPtr ();
std :: ostringstream stream ;
stream << data_pointer ;
std :: string data_pointer_string = stream. str ();
data_pointer_string = data_pointer_string. substr ( 2 , data_pointer_string.
size () - 2 );
long number = stol ( data_pointer_string , nullptr , 16 );
Handle < v8 :: internal :: Object > number_handle = isolate -> factory ()->
NewNumber ( number );
return * number_handle ;
}
On Thu, Feb 16, 2023 at 4:55 PM, Pradyumna Shome < pradyumna.sh...@gmail.com >
wrote:
>
> That got me to the stage of being able to compile v8. However, in runtime,
> it crashes with the following error:
>
>
> #
> # Fatal error in v8::HandleScope::CreateHandle()
> # Cannot create a handle without a HandleScope
> #
>
>
> zsh: trace trap ~/coding/v8/out/arm64.optdebug/d8 --allow-natives-syntax
>
>
>
> I read some more and realized the SealScope wasn't appropriate since the
> factory method creates a new Handle. I switched to an
> EscapableHandleScope. However, that requires an object of type Local and
> not Handle.
>
> Am I on the right path? I'm not sure how to get from a Local to Handle or
> if I picked the right scope.
>
>
> RUNTIME_FUNCTION(Runtime_AddressOfArray) {
> v8::EscapableHandleScope ehs((v8::Isolate*)isolate);
> StdoutStream os;
> MaybeObject maybe_object(*args.address_of_arg_at(0));
> Object object = maybe_object.GetHeapObjectOrSmi();
> void* data_pointer = JSTypedArray::cast(object).DataPtr();
>
> std::ostringstream stream;
> stream << data_pointer;
> std::string data_pointer_string = stream.str();
>
>
> data_pointer_string = data_pointer_string.substr(2,
> data_pointer_string.size() - 2);
>
>
> long number = stol(data_pointer_string, nullptr, 16);
>
>
> Handle<v8::internal::Object> number_handle =
> isolate->factory()->NewNumber(number);
> return ehs.Escape(number_handle);
> }
>
>
>
>
>
>
> On Wednesday, February 15, 2023 at 12:34:48 AM UTC-5 jgr...@chromium.org
> wrote:
>
>
>> Hi, something like this should work:
>>
>>
>> RUNTIME_FUNCTION(...) {
>> ...
>> return *isolate->factory()->NewNumber(number);
>> }
>>
>>
>> On Tue, Feb 14, 2023 at 8:19 PM Pradyumna Shome < pradyum... @ gmail. com >
>> wrote:
>>
>>
>>> Hi all
>>>
>>> I'm trying to add a new runtime function to return the Data Pointer of an
>>> array as a v8::NumberObject, so I can operate upon memory addresses in
>>> other JavaScript commands. I'm having trouble constructing and returning
>>> an object of type v8::internal::Object, since it seems like every
>>> operation always returns a Local/Handle.
>>>
>>>
>>> I reached out to one of the developers (Jakob) separately, and they
>>> pointed me to the definition of v8::NumberObject::New (
>>> https://source.chromium.org/chromium/chromium/src/+/main:v8/src/api/api.cc;l=7636;drc=e14364652369744ed1a8b9c4a582f11833b35aff
>>> ). However, I'm unable to figure out the plumbing required to satisfy the
>>> compiler that what I'm returning from the runtime function is indeed a
>>> v8::internal::Object. I've shared what I've tried doing to troubleshoot,
>>> the error log (bolding the actual errors) and code snippet below.
>>>
>>>
>>> Best
>>> Pradyumna
>>>
>>>
>>> *What I've Tried*
>>> * Constructing v8::StringObjects, v8::NumberObjects, and
>>> v8::internal::Numbers,by plumbing together APIs from https:/ / v8docs.
>>> nodesource.
>>> com/ node-0. 8/ da/ d56/ classv8_1_1_number_object. html (
>>> https://v8docs.nodesource.com/node-0.8/da/d56/classv8_1_1_number_object.html
>>> ) and other sites.
>>> * Reading the relevant pieces of https:/ / v8. dev/ docs/ embed (
>>> https://v8.dev/docs/embed ) to understand what Local/Handle/Persistents
>>> are.
>>> * Searched for call sites of the NumberObject/StringObject/Number APIs on
>>> the GitHub, Google, and You search engines to see if others have tried to
>>> do something similar. It turns out not a lot of people outside of the v8
>>> developers are editing v8 (at least publicly).
>>> * Read through numbers StackOverflow questions about construction
>>> v8::internal::objects, and manipulating Locals.
>>> * Searching for related keywords on this forum.
>>>
>>>
>>>
>>> *Error Log (for one of the attempts)*
>>> *
>>> *
>>> # autoninja -C out/arm64.optdebug d8
>>> ninja: Entering directory `out/arm64.optdebug'
>>> [1/11] CXX obj/v8_base_without_compiler/runtime-test.o
>>> FAILED: obj/v8_base_without_compiler/runtime-test.o
>>> ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF
>>> obj/v8_base_without_compiler/runtime-test.o.d -D__STDC_CONSTANT_MACROS
>>> -D__STDC_FORMAT_MACROS -DCR_XCODE_VERSION=1420
>>> -DCR_CLANG_REVISION=\"llvmorg-16-init-17653-g39da55e8-2\"
>>> -DCOMPONENT_BUILD
>>> -DCR_LIBCXX_REVISION=59bae40d835ae4eabaddbef781f5e3b778dd7907
>>> -D_LIBCPP_ENABLE_ASSERTIONS=1 -D_DEBUG -DDYNAMIC_ANNOTATIONS_ENABLED=1
>>> -DCPPGC_VERIFY_HEAP -DENABLE_DISASSEMBLER
>>> -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 -DOBJECT_PRINT -DVERIFY_HEAP
>>> -DV8_TRACE_MAPS -DV8_ENABLE_ALLOCATION_TIMEOUT -DV8_ENABLE_FORCE_SLOW_PATH
>>> -DV8_ENABLE_DOUBLE_CONST_STORE_CHECK -DV8_INTL_SUPPORT
>>> -DENABLE_HANDLE_ZAPPING -DV8_CODE_COMMENTS -DV8_ENABLE_DEBUG_CODE
>>> -DV8_ENABLE_HEAP_SNAPSHOT_VERIFY -DV8_SNAPSHOT_NATIVE_CODE_COUNTERS
>>> -DV8_USE_EXTERNAL_STARTUP_DATA -DV8_ATOMIC_OBJECT_FIELD_WRITES
>>> -DV8_ENABLE_LAZY_SOURCE_POSITIONS -DV8_SHARED_RO_HEAP
>>> -DV8_WIN64_UNWINDING_INFO -DV8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH
>>> -DV8_SHORT_BUILTIN_CALLS -DV8_EXTERNAL_CODE_SPACE -DV8_ENABLE_MAGLEV
>>> -DV8_ENABLE_TURBOFAN -DV8_ENABLE_SYSTEM_INSTRUMENTATION
>>> -DV8_ENABLE_WEBASSEMBLY -DV8_ALLOCATION_FOLDING
>>> -DV8_ALLOCATION_SITE_TRACKING -DV8_ADVANCED_BIGINT_ALGORITHMS
>>> -DV8_STATIC_ROOTS -DV8_USE_ZLIB -DV8_USE_LIBM_TRIG_FUNCTIONS
>>> -DV8_ENABLE_CHECKS -DV8_COMPRESS_POINTERS
>>> -DV8_COMPRESS_POINTERS_IN_SHARED_CAGE -DV8_31BIT_SMIS_ON_64BIT_ARCH
>>> -DV8_ENABLE_SANDBOX -DV8_DEPRECATION_WARNINGS
>>> -DV8_IMMINENT_DEPRECATION_WARNINGS -DCPPGC_CAGED_HEAP
>>> -DCPPGC_YOUNG_GENERATION -DCPPGC_POINTER_COMPRESSION
>>> -DCPPGC_SLIM_WRITE_BARRIER -DV8_TARGET_ARCH_ARM64 -DV8_HAVE_TARGET_OS
>>> -DV8_TARGET_OS_MACOS -DDEBUG -DV8_RUNTIME_CALL_STATS -DBUILDING_V8_SHARED
>>> -DUSING_V8_BASE_SHARED -DUSING_V8_PLATFORM_SHARED
>>> -DU_USING_ICU_NAMESPACE=0 -DU_ENABLE_DYLOAD=0 -DUSE_CHROMIUM_ICU=1
>>> -DU_ENABLE_TRACING=1 -DU_ENABLE_RESOURCE_TRACING=0
>>> -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -I../.. -Igen
>>> -I../../buildtools/third_party/libc++ -I../../include -Igen/include
>>> -I../../third_party/icu/source/common -I../../third_party/icu/source/i18n
>>> -I../../third_party/zlib -Wall -Werror -Wextra -Wimplicit-fallthrough
>>> -Wextra-semi -Wunreachable-code-aggressive -Wthread-safety
>>> -Wunguarded-availability -Wno-missing-field-initializers
>>> -Wno-unused-parameter -Wno-psabi -Wloop-analysis
>>> -Wno-unneeded-internal-declaration -Wenum-compare-conditional
>>> -Wno-ignored-pragma-optimize -Wno-deprecated-builtins
>>> -Wno-bitfield-constant-conversion -Wshadow -fno-delete-null-pointer-checks
>>> -fno-ident -fno-strict-aliasing -fstack-protector-strong
>>> -fcolor-diagnostics -fmerge-all-constants
>>> -fcrash-diagnostics-dir=../../tools/clang/crashreports -mllvm
>>> -instcombine-lower-dbg-declare=0 -ffp-contract=off
>>> -fcomplete-member-pointers -arch arm64 -fno-global-isel -mno-outline
>>> -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__=
>>> -ffile-compilation-dir=. -no-canonical-prefixes
>>> -ftrivial-auto-var-init=pattern -fno-omit-frame-pointer -g2
>>> -gdwarf-aranges -Xclang -debug-info-kind=limited -isysroot
>>> ../../../../../../ Applications/ Xcode. app/ Contents/ Developer/ Platforms/
>>> MacOSX. platform/ Developer/ SDKs/ MacOSX13. 1. sdk (
>>> http://applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.1.sdk
>>> ) -mmacos-version-min=10.13 -Wheader-hygiene -Wstring-conversion
>>> -Wtautological-overlap-compare -Wmissing-field-initializers
>>> -Wunreachable-code -Wctad-maybe-unsupported -Wno-shadow -Wshorten-64-to-32
>>> -O0 -fvisibility=default -Wexit-time-destructors
>>> -Wno-undefined-bool-conversion -Wno-tautological-undefined-compare
>>> -std=c++20 -Wno-trigraphs -fno-exceptions -fno-rtti -nostdinc++
>>> -isystem../../buildtools/third_party/libc++/trunk/include
>>> -isystem../../buildtools/third_party/libc++abi/trunk/include -c ../../ src/
>>> runtime/ runtime-test. cc ( http://src/runtime/runtime-test.cc ) -o
>>> obj/v8_base_without_compiler/runtime-test.o
>>> *../../ src/ runtime/ runtime-test. cc:1160:57 (
>>> http://src/runtime/runtime-test.cc:1160:57 ) : error: cannot initialize a
>>> parameter of type 'Value *' with an rvalue of type 'Local<NumberObject> *'
>>> * return
>>> *(v8::internal::Object*)v8::NumberObject::Cast(&numberObjectLocal);
>>> ^~~~~~~~~~~~~~~~~~
>>> *../../include/v8-primitive-object.h:25:46: note: passing argument to
>>> parameter 'value' here
>>> * V8_INLINE static NumberObject* Cast(Value* value) {
>>> ^
>>> In file included from ../../ src/ runtime/ runtime-test. cc:10 (
>>> http://src/runtime/runtime-test.cc:10 ) :
>>> In file included from ../../include/v8-function.h:11:
>>> In file included from ../../include/v8-function-callback.h:8:
>>> *../../include/v8-local-handle.h:166:5: error: static assertion failed due
>>> to requirement 'std::is_base_of<v8::NumberObject, v8::Value>::value': type
>>> check
>>> * static_assert(std::is_base_of<T, S>::value, "type check");
>>> ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> *../../ src/ runtime/ runtime-test. cc:1159:43 (
>>> http://src/runtime/runtime-test.cc:1159:43 ) : note: in instantiation of
>>> function template specialization
>>> 'v8::Local<v8::NumberObject>::Local<v8::Value>' requested here
>>> * Local<NumberObject> numberObjectLocal =
>>> v8::NumberObject::New((v8::Isolate*)isolate, number);
>>> ^
>>> 2 errors generated.
>>> ninja: build stopped: subcommand failed.
>>> Error! - V8 compilation finished with errors.
>>>
>>>
>>>
>>> *Code Snippet*
>>> RUNTIME_FUNCTION(Runtime_AddressOfArray) {
>>> SealHandleScope shs(isolate);
>>> StdoutStream os;
>>>
>>> MaybeObject maybe_object(*args.address_of_arg_at(0));
>>> Object object = maybe_object.GetHeapObjectOrSmi();
>>>
>>> void* data_pointer = JSTypedArray::cast(object).DataPtr();
>>> os << "Data Pointer: " << data_pointer << std::endl;
>>>
>>>
>>> std::string data_pointer_string;
>>> std::ostringstream stream;
>>> stream << data_pointer_string;
>>> data_pointer_string = stream.str();
>>> int number = stoi(data_pointer_string);
>>> *Local<NumberObject> numberObjectLocal =
>>> v8::NumberObject::New((v8::Isolate*)isolate, number);
>>> return
>>> *(v8::internal::Object*)v8::NumberObject::Cast(&numberObjectLocal);*
>>> }
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>> --
>>> --
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>>>
>>
>>
>>
>
>
>
>
>
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