net: fix TCPListener file leak to child processes
Hold ForkLock during dup of fd + cloexec in the net pkg,
per the locking policy documented in syscall/exec_unix.go.
R=golang-dev, dsymonds, adg
CC=golang-dev
https://golang.org/cl/6457080
diff --git a/src/pkg/net/fd.go b/src/pkg/net/fd.go
index 76c953b..ff4f4f8 100644
--- a/src/pkg/net/fd.go
+++ b/src/pkg/net/fd.go
@@ -645,10 +645,14 @@
}
func (fd *netFD) dup() (f *os.File, err error) {
+ syscall.ForkLock.RLock()
ns, err := syscall.Dup(fd.sysfd)
if err != nil {
+ syscall.ForkLock.RUnlock()
return nil, &OpError{"dup", fd.net, fd.laddr, err}
}
+ syscall.CloseOnExec(ns)
+ syscall.ForkLock.RUnlock()
// We want blocking mode for the new fd, hence the double negative.
if err = syscall.SetNonblock(ns, false); err != nil {
