net: add missing File method document
R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/8698049
diff --git a/src/pkg/net/tcpsock_plan9.go b/src/pkg/net/tcpsock_plan9.go
index 96cbcc2..48334fe 100644
--- a/src/pkg/net/tcpsock_plan9.go
+++ b/src/pkg/net/tcpsock_plan9.go
@@ -159,6 +159,10 @@
// File returns a copy of the underlying os.File, set to blocking
// mode. It is the caller's responsibility to close f when finished.
// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
func (l *TCPListener) File() (f *os.File, err error) { return l.dup() }
// ListenTCP announces on the TCP address laddr and returns a TCP
diff --git a/src/pkg/net/tcpsock_posix.go b/src/pkg/net/tcpsock_posix.go
index 2224e6a..876edb1 100644
--- a/src/pkg/net/tcpsock_posix.go
+++ b/src/pkg/net/tcpsock_posix.go
@@ -267,6 +267,10 @@
// File returns a copy of the underlying os.File, set to blocking
// mode. It is the caller's responsibility to close f when finished.
// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
func (l *TCPListener) File() (f *os.File, err error) { return l.fd.dup() }
// ListenTCP announces on the TCP address laddr and returns a TCP
diff --git a/src/pkg/net/unixsock_plan9.go b/src/pkg/net/unixsock_plan9.go
index 0390207..8a1281f 100644
--- a/src/pkg/net/unixsock_plan9.go
+++ b/src/pkg/net/unixsock_plan9.go
@@ -126,6 +126,10 @@
// File returns a copy of the underlying os.File, set to blocking
// mode. It is the caller's responsibility to close f when finished.
// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
func (l *UnixListener) File() (*os.File, error) {
return nil, syscall.EPLAN9
}
diff --git a/src/pkg/net/unixsock_posix.go b/src/pkg/net/unixsock_posix.go
index 6490cae..5db30df 100644
--- a/src/pkg/net/unixsock_posix.go
+++ b/src/pkg/net/unixsock_posix.go
@@ -339,6 +339,10 @@
// File returns a copy of the underlying os.File, set to blocking
// mode. It is the caller's responsibility to close f when finished.
// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
func (l *UnixListener) File() (f *os.File, err error) { return l.fd.dup() }
// ListenUnixgram listens for incoming Unix datagram packets addressed
