libgo: update to Go1.16rc1

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/287493

1 files changed, 8 insertions, 0 deletions

diff --git a/libgo/go/os/file_unix.go b/libgo/go/os/file_unix.go
index 8315887..5888d48 100644
--- a/libgo/go/os/file_unix.go
+++ b/libgo/go/os/file_unix.go
@@ -66,6 +66,10 @@ type file struct {
 // making it invalid; see runtime.SetFinalizer for more information on when
 // a finalizer might be run. On Unix systems this will cause the SetDeadline
 // methods to stop working.
+// Because file descriptors can be reused, the returned file descriptor may
+// only be closed through the Close method of f, or by its finalizer during
+// garbage collection. Otherwise, during garbage collection the finalizer
+// may close an unrelated file descriptor with the same (reused) number.
 //
 // As an alternative, see the f.SyscallConn method.
 func (f *File) Fd() uintptr {
@@ -90,6 +94,10 @@ func (f *File) Fd() uintptr {
 // descriptor. On Unix systems, if the file descriptor is in
 // non-blocking mode, NewFile will attempt to return a pollable File
 // (one for which the SetDeadline methods work).
+//
+// After passing it to NewFile, fd may become invalid under the same
+// conditions described in the comments of the Fd method, and the same
+// constraints apply.
 func NewFile(fd uintptr, name string) *File {
 	kind := kindNewFile
 	if nb, err := unix.IsNonblock(int(fd)); err == nil && nb {