1package util
 2
 3import (
 4	"context"
 5	"os"
 6	"reflect"
 7	"unsafe"
 8
 9	"github.com/tetratelabs/wazero/api"
10	"golang.org/x/sys/windows"
11)
12
13type MappedRegion struct {
14	windows.Handle
15	Data []byte
16	addr uintptr
17}
18
19func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32) (*MappedRegion, error) {
20	h, err := windows.CreateFileMapping(windows.Handle(f.Fd()), nil, windows.PAGE_READWRITE, 0, 0, nil)
21	if h == 0 {
22		return nil, err
23	}
24
25	a, err := windows.MapViewOfFile(h, windows.FILE_MAP_WRITE,
26		uint32(offset>>32), uint32(offset), uintptr(size))
27	if a == 0 {
28		windows.CloseHandle(h)
29		return nil, err
30	}
31
32	ret := &MappedRegion{Handle: h, addr: a}
33	// SliceHeader, although deprecated, avoids a go vet warning.
34	sh := (*reflect.SliceHeader)(unsafe.Pointer(&ret.Data))
35	sh.Len = int(size)
36	sh.Cap = int(size)
37	sh.Data = a
38	return ret, nil
39}
40
41func (r *MappedRegion) Unmap() error {
42	if r.Data == nil {
43		return nil
44	}
45	err := windows.UnmapViewOfFile(r.addr)
46	if err != nil {
47		return err
48	}
49	r.Data = nil
50	return windows.CloseHandle(r.Handle)
51}