fix(wgpu): C-allocate device descriptor to allow DeviceLostCallback - #8
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dhannyell wants to merge 1 commit into
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fix(wgpu): C-allocate device descriptor to allow DeviceLostCallback#8dhannyell wants to merge 1 commit into
dhannyell wants to merge 1 commit into
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RequestDevice Go-allocated the descriptor with &C.WGPUDeviceDescriptor{} and then embedded the DeviceLostCallback handle (a Go pointer, &pointers[0] from newHandle) in desc.deviceLostCallbackInfo.userdata1. Passing desc (a Go pointer to Go memory now containing a Go pointer) to C violates the cgo pointer rule and panics with 'Go pointer to unpinned Go pointer'.
C-allocate desc with calloc instead, matching the pattern already used for requiredFeatures/requiredLimits/deviceExtras in the same function. The checker does not scan C memory, so the embedded Go pointer is allowed; &pointers[0] points to byte storage with no nested pointers. wgpuAdapterRequestDevice is synchronous, so freeing at function exit is safe. The nil-descriptor path is unchanged.
Verified: RequestDevice with a DeviceLostCallback now succeeds instead of panicking; RequestDevice(nil) still works; three devices created/released in sequence (nil, label+callback, label+RequiredLimits+callback) all succeed; go run -race clean; go build ./wgpu/ and go vet ./wgpu/ pass.
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Fixes #7
C-allocates the device descriptor in
RequestDeviceso the cgo pointer checkerdoes not scan it as Go memory, allowing the
DeviceLostCallbackhandle to beembedded without panicking. See #7 for the full root-cause analysis and the
minimal reproduction.
Diff
if descriptor != nil { - desc = &C.WGPUDeviceDescriptor{} + desc = (*C.WGPUDeviceDescriptor)(C.calloc(1, C.size_t(unsafe.Sizeof(C.WGPUDeviceDescriptor{})))) + defer C.free(unsafe.Pointer(desc))Validation
label+callback → label+RequiredLimits+callback) all succeed.
pass.