Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
Err, s/ArgumentSignature/AccessorSignature/
On Thu, Apr 20, 2017 at 1:24 PM, Kenton Varda wrote:
> Hi Toon,
>
> Now I have a new problem: When I attach an ArgumentSignature to my
> property, it fails when accessing the property on the global object (both
> with and without "this."). Signatures on methods seem to work fine, though,
> even when calling on the global object. Is there a special-case that needs
> to be copied over?
>
> -Kenton
>
> On Thu, Apr 20, 2017 at 12:57 PM, Kenton Varda
> wrote:
>
>> Oh I see, somehow I missed your CL link.
>>
>> Thanks! :)
>>
>> -Kenton
>>
>> On Thu, Apr 20, 2017 at 12:09 PM, Toon Verwaest
>> wrote:
>>
>>> That's exactly why I'm fixing the problem :-) The fix was temporarily
>>> reverted since there are tests in Blink for which the expectations change,
>>> and that takes a while to sync; but you can try with the CL I linked above.
>>>
>>> On Thu, Apr 20, 2017 at 6:40 PM 'Kenton Varda' via v8-users <
>>> v8-users@googlegroups.com> wrote:
>>>
Thanks, but what if I don't control the scripts and can't force them to
prefix global property access with "this."?
-Kenton
On Thu, Apr 20, 2017 at 1:39 AM, Toon Verwaest
wrote:
> The problem is that since you're accessing the global property via
> 'contextual access', we're passing out the global object rather than the
> global proxy (see https://developer.mozilla.org/
> en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object for
> background). If you replace
>
> v8::Local source =
> v8::String::NewFromUtf8(isolate, "func(); prop;",
> v8::NewStringType::kNormal).
>
> with
>
> v8::Local source =
> v8::String::NewFromUtf8(isolate, "func(); this.prop;",
> v8::NewStringType::kNormal).
>
> it works. Changing it so it works as expected:
>
> https://chromium-review.googlesource.com/c/483199/
>
> cheers,
> Toon
>
> On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
> v8-users@googlegroups.com> wrote:
>
>> Hi,
>>
>> I'm trying to understand what I'm doing wrong here.
>>
>> I have created an ObjectTemplate for the global object which contains
>> a method, a property, and an internal field. After creating the context,
>> I
>> use Global()->SetAlignedPointerInInternalField() to set a pointer on
>> the object, then I call the function and read the property.
>>
>> In the function callback, I'm able to read the pointer from the
>> internal field as expected.
>>
>> However, in the property callback, GetAlignedPointerInInternalField()
>> crashes!
>>
>> InternalFieldCount(), though, still returns the actual number of
>> internal fields I allocated. So it seems like it's *supposed* to be the
>> right object.
>>
>> OTOH, GetIdentityHash() returns something that doesn't match
>> context.Global()->GetIdentityHash(), whereas in the function
>> callback these do match.
>>
>> I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9
>> (April 14).
>>
>> Sample code and output below.
>>
>> Surely people have created properties on the global object before, so
>> I must be doing it wrong. What's the right way to do it?
>>
>> Thanks,
>> -Kenton
>>
>> ==
>> CODE
>> ==
>>
>> #include
>> #include
>> #include
>>
>> #include
>> #include
>>
>> void funcCallback(const v8::FunctionCallbackInfo& info) {
>> printf("in func()\n");
>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash
>> ());
>> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCoun
>> t());
>>
>> // This works fine.
>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>> (const char*)info.This()->GetAlignedP
>> ointerFromInternalField(0));
>> }
>>
>> void propCallback(v8::Local, const
>> v8::PropertyCallbackInfo& info) {
>> printf("getting prop\n");
>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash
>> ());
>> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCoun
>> t());
>>
>> // THIS CRASHES
>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>> (const char*)info.This()->GetAlignedP
>> ointerFromInternalField(0));
>> }
>>
>> int main(int argc, char* argv[]) {
>> // Initialize V8.
>> v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
>> v8::V8::InitializeICUDefaultLocation(argv[0]);
>> v8::V8::InitializeExternalStartupData(argv[0]);
>
Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
Hi Toon,
Now I have a new problem: When I attach an ArgumentSignature to my
property, it fails when accessing the property on the global object (both
with and without "this."). Signatures on methods seem to work fine, though,
even when calling on the global object. Is there a special-case that needs
to be copied over?
-Kenton
On Thu, Apr 20, 2017 at 12:57 PM, Kenton Varda
wrote:
> Oh I see, somehow I missed your CL link.
>
> Thanks! :)
>
> -Kenton
>
> On Thu, Apr 20, 2017 at 12:09 PM, Toon Verwaest
> wrote:
>
>> That's exactly why I'm fixing the problem :-) The fix was temporarily
>> reverted since there are tests in Blink for which the expectations change,
>> and that takes a while to sync; but you can try with the CL I linked above.
>>
>> On Thu, Apr 20, 2017 at 6:40 PM 'Kenton Varda' via v8-users <
>> v8-users@googlegroups.com> wrote:
>>
>>> Thanks, but what if I don't control the scripts and can't force them to
>>> prefix global property access with "this."?
>>>
>>> -Kenton
>>>
>>> On Thu, Apr 20, 2017 at 1:39 AM, Toon Verwaest
>>> wrote:
>>>
The problem is that since you're accessing the global property via
'contextual access', we're passing out the global object rather than the
global proxy (see https://developer.mozilla.org/
en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object for background).
If you replace
v8::Local source =
v8::String::NewFromUtf8(isolate, "func(); prop;",
v8::NewStringType::kNormal).
with
v8::Local source =
v8::String::NewFromUtf8(isolate, "func(); this.prop;",
v8::NewStringType::kNormal).
it works. Changing it so it works as expected:
https://chromium-review.googlesource.com/c/483199/
cheers,
Toon
On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
v8-users@googlegroups.com> wrote:
> Hi,
>
> I'm trying to understand what I'm doing wrong here.
>
> I have created an ObjectTemplate for the global object which contains
> a method, a property, and an internal field. After creating the context, I
> use Global()->SetAlignedPointerInInternalField() to set a pointer on
> the object, then I call the function and read the property.
>
> In the function callback, I'm able to read the pointer from the
> internal field as expected.
>
> However, in the property callback, GetAlignedPointerInInternalField()
> crashes!
>
> InternalFieldCount(), though, still returns the actual number of
> internal fields I allocated. So it seems like it's *supposed* to be the
> right object.
>
> OTOH, GetIdentityHash() returns something that doesn't match
> context.Global()->GetIdentityHash(), whereas in the function callback
> these do match.
>
> I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9
> (April 14).
>
> Sample code and output below.
>
> Surely people have created properties on the global object before, so
> I must be doing it wrong. What's the right way to do it?
>
> Thanks,
> -Kenton
>
> ==
> CODE
> ==
>
> #include
> #include
> #include
>
> #include
> #include
>
> void funcCallback(const v8::FunctionCallbackInfo& info) {
> printf("in func()\n");
> printf(" this identity = %x\n", info.This()->GetIdentityHash());
> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash
> ());
> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCoun
> t());
>
> // This works fine.
> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
> (const char*)info.This()->GetAlignedP
> ointerFromInternalField(0));
> }
>
> void propCallback(v8::Local, const
> v8::PropertyCallbackInfo& info) {
> printf("getting prop\n");
> printf(" this identity = %x\n", info.This()->GetIdentityHash());
> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash
> ());
> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCoun
> t());
>
> // THIS CRASHES
> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
> (const char*)info.This()->GetAlignedP
> ointerFromInternalField(0));
> }
>
> int main(int argc, char* argv[]) {
> // Initialize V8.
> v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
> v8::V8::InitializeICUDefaultLocation(argv[0]);
> v8::V8::InitializeExternalStartupData(argv[0]);
> v8::Platform* platform = v8::platform::CreateDefaultPlatform();
> v8::V8::InitializePlatform(platform);
> v8::V8::Initialize();
>
> v8::Isolate::CreateParams create_params;
> create_params.array_buffer_allocator =
>
Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
Oh I see, somehow I missed your CL link.
Thanks! :)
-Kenton
On Thu, Apr 20, 2017 at 12:09 PM, Toon Verwaest
wrote:
> That's exactly why I'm fixing the problem :-) The fix was temporarily
> reverted since there are tests in Blink for which the expectations change,
> and that takes a while to sync; but you can try with the CL I linked above.
>
> On Thu, Apr 20, 2017 at 6:40 PM 'Kenton Varda' via v8-users <
> v8-users@googlegroups.com> wrote:
>
>> Thanks, but what if I don't control the scripts and can't force them to
>> prefix global property access with "this."?
>>
>> -Kenton
>>
>> On Thu, Apr 20, 2017 at 1:39 AM, Toon Verwaest
>> wrote:
>>
>>> The problem is that since you're accessing the global property via
>>> 'contextual access', we're passing out the global object rather than the
>>> global proxy (see https://developer.mozilla.org/
>>> en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object for background).
>>> If you replace
>>>
>>> v8::Local source =
>>> v8::String::NewFromUtf8(isolate, "func(); prop;",
>>> v8::NewStringType::kNormal).
>>>
>>> with
>>>
>>> v8::Local source =
>>> v8::String::NewFromUtf8(isolate, "func(); this.prop;",
>>> v8::NewStringType::kNormal).
>>>
>>> it works. Changing it so it works as expected:
>>>
>>> https://chromium-review.googlesource.com/c/483199/
>>>
>>> cheers,
>>> Toon
>>>
>>> On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
>>> v8-users@googlegroups.com> wrote:
>>>
Hi,
I'm trying to understand what I'm doing wrong here.
I have created an ObjectTemplate for the global object which contains a
method, a property, and an internal field. After creating the context, I
use Global()->SetAlignedPointerInInternalField() to set a pointer on
the object, then I call the function and read the property.
In the function callback, I'm able to read the pointer from the
internal field as expected.
However, in the property callback, GetAlignedPointerInInternalField()
crashes!
InternalFieldCount(), though, still returns the actual number of
internal fields I allocated. So it seems like it's *supposed* to be the
right object.
OTOH, GetIdentityHash() returns something that doesn't match
context.Global()->GetIdentityHash(), whereas in the function callback
these do match.
I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9 (April
14).
Sample code and output below.
Surely people have created properties on the global object before, so I
must be doing it wrong. What's the right way to do it?
Thanks,
-Kenton
==
CODE
==
#include
#include
#include
#include
#include
void funcCallback(const v8::FunctionCallbackInfo& info) {
printf("in func()\n");
printf(" this identity = %x\n", info.This()->GetIdentityHash());
printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
printf(" InternalFieldCount = %d\n", info.This()->
InternalFieldCount());
// This works fine.
printf(" GetAlignedPointerFromInternalField(0) = %s\n",
(const char*)info.This()->GetAlignedPointerFromInternalField(0));
}
void propCallback(v8::Local, const
v8::PropertyCallbackInfo& info) {
printf("getting prop\n");
printf(" this identity = %x\n", info.This()->GetIdentityHash());
printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
printf(" InternalFieldCount = %d\n", info.This()->
InternalFieldCount());
// THIS CRASHES
printf(" GetAlignedPointerFromInternalField(0) = %s\n",
(const char*)info.This()->GetAlignedPointerFromInternalField(0));
}
int main(int argc, char* argv[]) {
// Initialize V8.
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
v8::V8::InitializeICUDefaultLocation(argv[0]);
v8::V8::InitializeExternalStartupData(argv[0]);
v8::Platform* platform = v8::platform::CreateDefaultPlatform();
v8::V8::InitializePlatform(platform);
v8::V8::Initialize();
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator =
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
v8::Isolate* isolate = v8::Isolate::New(create_params);
{
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
// Create global ObjectTemplate.
auto globalInstanceTmpl = v8::ObjectTemplate::New(isolate);
globalInstanceTmpl->SetInternalFieldCount(123);
globalInstanceTmpl->Set(isolate, "func",
v8::FunctionTemplate::New(isolate,
&funcCallback));
globalInstanceTmpl->SetAcce
Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
That's exactly why I'm fixing the problem :-) The fix was temporarily
reverted since there are tests in Blink for which the expectations change,
and that takes a while to sync; but you can try with the CL I linked above.
On Thu, Apr 20, 2017 at 6:40 PM 'Kenton Varda' via v8-users <
v8-users@googlegroups.com> wrote:
> Thanks, but what if I don't control the scripts and can't force them to
> prefix global property access with "this."?
>
> -Kenton
>
> On Thu, Apr 20, 2017 at 1:39 AM, Toon Verwaest
> wrote:
>
>> The problem is that since you're accessing the global property via
>> 'contextual access', we're passing out the global object rather than the
>> global proxy (see
>> https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object
>> for
>> background). If you replace
>>
>> v8::Local source =
>> v8::String::NewFromUtf8(isolate, "func(); prop;",
>> v8::NewStringType::kNormal).
>>
>> with
>>
>> v8::Local source =
>> v8::String::NewFromUtf8(isolate, "func(); this.prop;",
>> v8::NewStringType::kNormal).
>>
>> it works. Changing it so it works as expected:
>>
>> https://chromium-review.googlesource.com/c/483199/
>>
>> cheers,
>> Toon
>>
>> On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
>> v8-users@googlegroups.com> wrote:
>>
>>> Hi,
>>>
>>> I'm trying to understand what I'm doing wrong here.
>>>
>>> I have created an ObjectTemplate for the global object which contains a
>>> method, a property, and an internal field. After creating the context, I
>>> use Global()->SetAlignedPointerInInternalField() to set a pointer on the
>>> object, then I call the function and read the property.
>>>
>>> In the function callback, I'm able to read the pointer from the internal
>>> field as expected.
>>>
>>> However, in the property callback, GetAlignedPointerInInternalField()
>>> crashes!
>>>
>>> InternalFieldCount(), though, still returns the actual number of
>>> internal fields I allocated. So it seems like it's *supposed* to be the
>>> right object.
>>>
>>> OTOH, GetIdentityHash() returns something that doesn't match
>>> context.Global()->GetIdentityHash(), whereas in the function callback these
>>> do match.
>>>
>>> I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9 (April
>>> 14).
>>>
>>> Sample code and output below.
>>>
>>> Surely people have created properties on the global object before, so I
>>> must be doing it wrong. What's the right way to do it?
>>>
>>> Thanks,
>>> -Kenton
>>>
>>> ==
>>> CODE
>>> ==
>>>
>>> #include
>>> #include
>>> #include
>>>
>>> #include
>>> #include
>>>
>>> void funcCallback(const v8::FunctionCallbackInfo& info) {
>>> printf("in func()\n");
>>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
>>> printf(" InternalFieldCount = %d\n",
>>> info.This()->InternalFieldCount());
>>>
>>> // This works fine.
>>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>>> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
>>> }
>>>
>>> void propCallback(v8::Local, const
>>> v8::PropertyCallbackInfo& info) {
>>> printf("getting prop\n");
>>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
>>> printf(" InternalFieldCount = %d\n",
>>> info.This()->InternalFieldCount());
>>>
>>> // THIS CRASHES
>>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>>> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
>>> }
>>>
>>> int main(int argc, char* argv[]) {
>>> // Initialize V8.
>>> v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
>>> v8::V8::InitializeICUDefaultLocation(argv[0]);
>>> v8::V8::InitializeExternalStartupData(argv[0]);
>>> v8::Platform* platform = v8::platform::CreateDefaultPlatform();
>>> v8::V8::InitializePlatform(platform);
>>> v8::V8::Initialize();
>>>
>>> v8::Isolate::CreateParams create_params;
>>> create_params.array_buffer_allocator =
>>> v8::ArrayBuffer::Allocator::NewDefaultAllocator();
>>> v8::Isolate* isolate = v8::Isolate::New(create_params);
>>>
>>> {
>>> v8::Isolate::Scope isolate_scope(isolate);
>>> v8::HandleScope handle_scope(isolate);
>>>
>>> // Create global ObjectTemplate.
>>> auto globalInstanceTmpl = v8::ObjectTemplate::New(isolate);
>>> globalInstanceTmpl->SetInternalFieldCount(123);
>>> globalInstanceTmpl->Set(isolate, "func",
>>> v8::FunctionTemplate::New(isolate, &funcCallback));
>>> globalInstanceTmpl->SetAccessor(
>>> v8::String::NewFromUtf8(isolate, "prop",
>>> v8::NewStringType::kInternalized).ToLocalChecked(),
>>> &propCallback);
>>>
>>> v8::Local context = v8::Context::New(isolate, nullptr,
>>> globalInstanceTmpl);
>>>
>>> // Set internal fi
Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
Thanks, but what if I don't control the scripts and can't force them to
prefix global property access with "this."?
-Kenton
On Thu, Apr 20, 2017 at 1:39 AM, Toon Verwaest
wrote:
> The problem is that since you're accessing the global property via
> 'contextual access', we're passing out the global object rather than the
> global proxy (see https://developer.mozilla.org/
> en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object for background). If
> you replace
>
> v8::Local source =
> v8::String::NewFromUtf8(isolate, "func(); prop;",
> v8::NewStringType::kNormal).
>
> with
>
> v8::Local source =
> v8::String::NewFromUtf8(isolate, "func(); this.prop;",
> v8::NewStringType::kNormal).
>
> it works. Changing it so it works as expected:
>
> https://chromium-review.googlesource.com/c/483199/
>
> cheers,
> Toon
>
> On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
> v8-users@googlegroups.com> wrote:
>
>> Hi,
>>
>> I'm trying to understand what I'm doing wrong here.
>>
>> I have created an ObjectTemplate for the global object which contains a
>> method, a property, and an internal field. After creating the context, I
>> use Global()->SetAlignedPointerInInternalField() to set a pointer on the
>> object, then I call the function and read the property.
>>
>> In the function callback, I'm able to read the pointer from the internal
>> field as expected.
>>
>> However, in the property callback, GetAlignedPointerInInternalField()
>> crashes!
>>
>> InternalFieldCount(), though, still returns the actual number of internal
>> fields I allocated. So it seems like it's *supposed* to be the right object.
>>
>> OTOH, GetIdentityHash() returns something that doesn't match
>> context.Global()->GetIdentityHash(), whereas in the function callback
>> these do match.
>>
>> I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9 (April
>> 14).
>>
>> Sample code and output below.
>>
>> Surely people have created properties on the global object before, so I
>> must be doing it wrong. What's the right way to do it?
>>
>> Thanks,
>> -Kenton
>>
>> ==
>> CODE
>> ==
>>
>> #include
>> #include
>> #include
>>
>> #include
>> #include
>>
>> void funcCallback(const v8::FunctionCallbackInfo& info) {
>> printf("in func()\n");
>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
>> printf(" InternalFieldCount = %d\n", info.This()->
>> InternalFieldCount());
>>
>> // This works fine.
>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
>> }
>>
>> void propCallback(v8::Local, const
>> v8::PropertyCallbackInfo& info) {
>> printf("getting prop\n");
>> printf(" this identity = %x\n", info.This()->GetIdentityHash());
>> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
>> printf(" InternalFieldCount = %d\n", info.This()->
>> InternalFieldCount());
>>
>> // THIS CRASHES
>> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
>> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
>> }
>>
>> int main(int argc, char* argv[]) {
>> // Initialize V8.
>> v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
>> v8::V8::InitializeICUDefaultLocation(argv[0]);
>> v8::V8::InitializeExternalStartupData(argv[0]);
>> v8::Platform* platform = v8::platform::CreateDefaultPlatform();
>> v8::V8::InitializePlatform(platform);
>> v8::V8::Initialize();
>>
>> v8::Isolate::CreateParams create_params;
>> create_params.array_buffer_allocator =
>> v8::ArrayBuffer::Allocator::NewDefaultAllocator();
>> v8::Isolate* isolate = v8::Isolate::New(create_params);
>>
>> {
>> v8::Isolate::Scope isolate_scope(isolate);
>> v8::HandleScope handle_scope(isolate);
>>
>> // Create global ObjectTemplate.
>> auto globalInstanceTmpl = v8::ObjectTemplate::New(isolate);
>> globalInstanceTmpl->SetInternalFieldCount(123);
>> globalInstanceTmpl->Set(isolate, "func",
>> v8::FunctionTemplate::New(isolate,
>> &funcCallback));
>> globalInstanceTmpl->SetAccessor(
>> v8::String::NewFromUtf8(isolate, "prop", v8::NewStringType::
>> kInternalized).ToLocalChecked(),
>> &propCallback);
>>
>> v8::Local context = v8::Context::New(isolate, nullptr,
>> globalInstanceTmpl);
>>
>> // Set internal field pointer on global.
>> alignas(long long) const char TEXT[] = "internal-field-value";
>> context->Global()->SetAlignedPointerInInternalField(0, (void*)TEXT);
>> printf("global identity = %x\n", context->Global()->
>> GetIdentityHash());
>>
>> // Call func() then read prop.
>> v8::Context::Scope context_scope(context);
>> v8::Local source =
>> v8::String::NewFromUtf8(isolate, "func(); prop;",
>>
Re: [v8-users] info.This().GetAlignedPointerFromInternalField() crashes in property callbacks when applied to global object?
The problem is that since you're accessing the global property via
'contextual access', we're passing out the global object rather than the
global proxy (see
https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Split_object
for
background). If you replace
v8::Local source =
v8::String::NewFromUtf8(isolate, "func(); prop;",
v8::NewStringType::kNormal).
with
v8::Local source =
v8::String::NewFromUtf8(isolate, "func(); this.prop;",
v8::NewStringType::kNormal).
it works. Changing it so it works as expected:
https://chromium-review.googlesource.com/c/483199/
cheers,
Toon
On Thu, Apr 20, 2017 at 3:14 AM kenton via v8-users <
v8-users@googlegroups.com> wrote:
> Hi,
>
> I'm trying to understand what I'm doing wrong here.
>
> I have created an ObjectTemplate for the global object which contains a
> method, a property, and an internal field. After creating the context, I
> use Global()->SetAlignedPointerInInternalField() to set a pointer on the
> object, then I call the function and read the property.
>
> In the function callback, I'm able to read the pointer from the internal
> field as expected.
>
> However, in the property callback, GetAlignedPointerInInternalField()
> crashes!
>
> InternalFieldCount(), though, still returns the actual number of internal
> fields I allocated. So it seems like it's *supposed* to be the right object.
>
> OTOH, GetIdentityHash() returns something that doesn't match
> context.Global()->GetIdentityHash(), whereas in the function callback these
> do match.
>
> I'm using v8 at commit 49d32849b3e67b1fa05f5f7aeea57dd83634adb9 (April 14).
>
> Sample code and output below.
>
> Surely people have created properties on the global object before, so I
> must be doing it wrong. What's the right way to do it?
>
> Thanks,
> -Kenton
>
> ==
> CODE
> ==
>
> #include
> #include
> #include
>
> #include
> #include
>
> void funcCallback(const v8::FunctionCallbackInfo& info) {
> printf("in func()\n");
> printf(" this identity = %x\n", info.This()->GetIdentityHash());
> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCount());
>
> // This works fine.
> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
> }
>
> void propCallback(v8::Local, const
> v8::PropertyCallbackInfo& info) {
> printf("getting prop\n");
> printf(" this identity = %x\n", info.This()->GetIdentityHash());
> printf(" holder identity = %x\n", info.Holder()->GetIdentityHash());
> printf(" InternalFieldCount = %d\n", info.This()->InternalFieldCount());
>
> // THIS CRASHES
> printf(" GetAlignedPointerFromInternalField(0) = %s\n",
> (const char*)info.This()->GetAlignedPointerFromInternalField(0));
> }
>
> int main(int argc, char* argv[]) {
> // Initialize V8.
> v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
> v8::V8::InitializeICUDefaultLocation(argv[0]);
> v8::V8::InitializeExternalStartupData(argv[0]);
> v8::Platform* platform = v8::platform::CreateDefaultPlatform();
> v8::V8::InitializePlatform(platform);
> v8::V8::Initialize();
>
> v8::Isolate::CreateParams create_params;
> create_params.array_buffer_allocator =
> v8::ArrayBuffer::Allocator::NewDefaultAllocator();
> v8::Isolate* isolate = v8::Isolate::New(create_params);
>
> {
> v8::Isolate::Scope isolate_scope(isolate);
> v8::HandleScope handle_scope(isolate);
>
> // Create global ObjectTemplate.
> auto globalInstanceTmpl = v8::ObjectTemplate::New(isolate);
> globalInstanceTmpl->SetInternalFieldCount(123);
> globalInstanceTmpl->Set(isolate, "func",
> v8::FunctionTemplate::New(isolate, &funcCallback));
> globalInstanceTmpl->SetAccessor(
> v8::String::NewFromUtf8(isolate, "prop",
> v8::NewStringType::kInternalized).ToLocalChecked(),
> &propCallback);
>
> v8::Local context = v8::Context::New(isolate, nullptr,
> globalInstanceTmpl);
>
> // Set internal field pointer on global.
> alignas(long long) const char TEXT[] = "internal-field-value";
> context->Global()->SetAlignedPointerInInternalField(0, (void*)TEXT);
> printf("global identity = %x\n", context->Global()->GetIdentityHash());
>
> // Call func() then read prop.
> v8::Context::Scope context_scope(context);
> v8::Local source =
> v8::String::NewFromUtf8(isolate, "func(); prop;",
>
> v8::NewStringType::kNormal).ToLocalChecked();
> v8::Local script = v8::Script::Compile(context,
> source).ToLocalChecked();
> (void)script->Run(context);
> }
>
> isolate->Dispose();
> v8::V8::Dispose();
> v8::V8::ShutdownPlatform();
> delete platform;
> delete create_params.array_buffer_allocator;
> return 0;
> }
>
> ==
>
