zx/fdio/vmo: implement ReadAt
Change-Id: I5bd6a200ef96bbda8934755f58a9f35e43a4715c
diff --git a/src/syscall/zx/fdio/vmo.go b/src/syscall/zx/fdio/vmo.go
index c069d14..19018de 100644
--- a/src/syscall/zx/fdio/vmo.go
+++ b/src/syscall/zx/fdio/vmo.go
@@ -45,8 +45,27 @@
return n, err
}
-func (f *VMOFile) ReadAt(data []byte, off int64) (int, error) {
- panic("TODO")
+func (f *VMOFile) ReadAt(data []byte, off int64) (n int, err error) {
+ if off < 0 {
+ return 0, zx.Error{Status: zx.ErrInvalidArgs, Text: "fdio.VMOFile.ReadAt"}
+ }
+ if off >= f.end {
+ return 0, zx.EOF
+ }
+ if len(data) == 0 {
+ return 0, zx.EOF
+ }
+ n = len(data)
+ max := int(f.end - off)
+ if max < n {
+ n = max
+ err = zx.EOF
+ }
+ data = data[:n]
+ if n2, err2 := f.h.Read(data, uint64(off)); err2 != nil {
+ return n2, err2
+ }
+ return
}
func (f *VMOFile) Write(data []byte) (int, error) {
