Fix HID enumeration on X64 (#18439)
### Link to issue number:
Fixup for #18207
### Summary of the issue:
HID enumeration does not work on the experimental X64 branch. I actually
found two issues with the current code.
### Description of user facing changes:
None
### Description of developer facing changes:
None
### Description of development approach:
1. it turned out that wrong packing was used. The correct packing is 1
on X86 and 8 on X64. This can be easily found in `SetupAPI.h`, the
header that defines `SP_DEVICE_INTERFACE_DETAIL_DATA_W`. I validated
with a small c program that `sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA_W))`
returns 8 on X64 builds and 6 on x86 builds. I also validated this with
ctypes on X86 and X64 runs of NVDA.
2. The current code allocates a buffer that is twice too big for the
data. This is also easy to explain. The struct contains a DWORD cbSize
field as well as an array of wchars. The array of wchars should be the
required size as fetched by the first call of
`SetupDiGetDeviceInterfaceDetail`, mines the cbSize field. In the old
situation however, there wasn't accounted for the fact that WCHAR is
already two bytes. Therefore we now divide through the size of WCHAR.
Old situation:
```python
dwNeeded = DWORD(200)
class SP_DEVICE_INTERFACE_DETAIL_DATA_W(ctypes.Structure):
_fields_ = (
("cbSize", DWORD),
("DevicePath", WCHAR * (dwNeeded.value - ctypes.sizeof(DWORD))),
)
>>> sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA_W)
396
```
New situation
```python
dwNeeded = DWORD(200)
class SP_DEVICE_INTERFACE_DETAIL_DATA_W(ctypes.Structure):
_fields_ = (
("cbSize", DWORD),
("DevicePath", WCHAR * ((dwNeeded.value - ctypes.sizeof(DWORD)) // ctypes.sizeof(WCHAR))),
)
>>> sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA_W)
200
```
### Testing strategy:
Ensured that hid devices could be enumerated on both x86 master based
builds as well as experimental 64 bit runs of NVDA.
### Known issues with pull request:
None
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- [x] Documentation:
- Change log entry
- User Documentation
- Developer / Technical Documentation
- Context sensitive help for GUI changes
- [x] Testing:
- Unit tests
- System (end to end) tests
- Manual testing
- [x] UX of all users considered:
- Speech
- Braille
- Low Vision
- Different web browsers
- Localization in other languages / culture than English
- [x] API is compatible with existing add-ons.
- [x] Security precautions taken.
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@coderabbitai summary
---------
Co-authored-by: Sascha Cowley <16543535+SaschaCowley@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
