| 1 | //go:build windows |
| 2 | |
| 3 | package edge |
| 4 | |
| 5 | import ( |
| 6 | "errors" |
| 7 | "io" |
| 8 | "syscall" |
| 9 | "unsafe" |
| 10 | |
| 11 | "golang.org/x/sys/windows" |
| 12 | ) |
| 13 | |
| 14 | type _IStreamVtbl struct { |
| 15 | _IUnknownVtbl |
| 16 | Read ComProc |
| 17 | Write ComProc |
| 18 | } |
| 19 | |
| 20 | type IStream struct { |
| 21 | vtbl *_IStreamVtbl |
| 22 | } |
| 23 | |
| 24 | func (i *IStream) AddRef() error { |
| 25 | _, _, err := i.vtbl.AddRef.Call(uintptr(unsafe.Pointer(i))) |
| 26 | if err != nil && !errors.Is(err, windows.ERROR_SUCCESS) { |
| 27 | return err |
| 28 | } |
| 29 | |
| 30 | return nil |
| 31 | } |
| 32 | |
| 33 | func (i *IStream) Release() error { |
| 34 | _, _, err := i.vtbl.Release.Call(uintptr(unsafe.Pointer(i))) |
| 35 | if err != nil && !errors.Is(err, windows.ERROR_SUCCESS) { |
| 36 | return err |
| 37 | } |
| 38 | |
| 39 | return nil |
| 40 | } |
| 41 | |
| 42 | func (i *IStream) Read(p []byte) (int, error) { |
| 43 | bufLen := len(p) |
| 44 | if bufLen == 0 { |
| 45 | return 0, nil |
| 46 | } |
| 47 | |
| 48 | var n int |
| 49 | hr, _, _ := i.vtbl.Read.Call( |
| 50 | uintptr(unsafe.Pointer(i)), |
| 51 | uintptr(unsafe.Pointer(&p[0])), |
| 52 | uintptr(bufLen), |
| 53 | uintptr(unsafe.Pointer(&n)), |
| 54 | ) |
| 55 | |
| 56 | switch windows.Handle(hr) { |
| 57 | case windows.S_OK: |
| 58 | // The buffer has been completely filled |
| 59 | return n, nil |
| 60 | case windows.S_FALSE: |
| 61 | // The buffer has been filled with less than len data and the stream is EOF |
| 62 | return n, io.EOF |
| 63 | default: |
| 64 | return 0, syscall.Errno(hr) |
| 65 | } |
| 66 | } |
| 67 |