Windows shared memory. (#181)

internal/testcfg/testcfg.go

@@ -19,7 +19,8 @@ func init() {
 		path := filepath.Join(os.TempDir(), "wazero")
 		if err := os.MkdirAll(path, 0777); err == nil {
 			if cache, err := wazero.NewCompilationCacheWithDir(path); err == nil {
-				sqlite3.RuntimeConfig.WithCompilationCache(cache)
+				sqlite3.RuntimeConfig = sqlite3.RuntimeConfig.
+					WithCompilationCache(cache)
 			}
 		}
 	}

internal/util/mmap.go

@@ -55,10 +55,10 @@ type MappedRegion struct {
 	used bool
 }
 
-func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32, prot int) (*MappedRegion, error) {
+func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32, readOnly bool) (*MappedRegion, error) {
 	s := ctx.Value(moduleKey{}).(*moduleState)
 	r := s.new(ctx, mod, size)
-	err := r.mmap(f, offset, prot)
+	err := r.mmap(f, offset, readOnly)
 	if err != nil {
 		return nil, err
 	}
@@ -75,7 +75,11 @@ func (r *MappedRegion) Unmap() error {
 	return err
 }
 
-func (r *MappedRegion) mmap(f *os.File, offset int64, prot int) error {
+func (r *MappedRegion) mmap(f *os.File, offset int64, readOnly bool) error {
+	prot := unix.PROT_READ
+	if !readOnly {
+		prot |= unix.PROT_WRITE
+	}
 	_, err := unix.MmapPtr(int(f.Fd()), offset, r.addr, uintptr(r.size),
 		prot, unix.MAP_SHARED|unix.MAP_FIXED)
 	r.used = err == nil

internal/util/mmap_windows.go

@@ -0,0 +1,53 @@
+//go:build !sqlite3_nosys
+
+package util
+
+import (
+	"context"
+	"os"
+	"reflect"
+	"unsafe"
+
+	"github.com/tetratelabs/wazero/api"
+	"golang.org/x/sys/windows"
+)
+
+type MappedRegion struct {
+	windows.Handle
+	Data []byte
+	addr uintptr
+}
+
+func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32) (*MappedRegion, error) {
+	h, err := windows.CreateFileMapping(windows.Handle(f.Fd()), nil, windows.PAGE_READWRITE, 0, 0, nil)
+	if h == 0 {
+		return nil, err
+	}
+
+	a, err := windows.MapViewOfFile(h, windows.FILE_MAP_WRITE,
+		uint32(offset>>32), uint32(offset), uintptr(size))
+	if a == 0 {
+		windows.CloseHandle(h)
+		return nil, err
+	}
+
+	res := &MappedRegion{Handle: h, addr: a}
+	// SliceHeader, although deprecated, avoids a go vet warning.
+	sh := (*reflect.SliceHeader)(unsafe.Pointer(&res.Data))
+	sh.Len = int(size)
+	sh.Cap = int(size)
+	sh.Data = a
+	return res, nil
+}
+
+func (r *MappedRegion) Unmap() error {
+	if r.Data == nil {
+		return nil
+	}
+	err := windows.UnmapViewOfFile(r.addr)
+	if err != nil {
+		return err
+	}
+	r.Data = nil
+	return windows.CloseHandle(r.Handle)
+}