net: use F_DUPFD_CLOEXEC when duping fds
This means that in the common case (modern kernel), we only
make 1 system call to dup instead of two, and we also avoid
grabbing the syscall.ForkLock.
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/12476043
diff --git a/src/pkg/net/file_unix.go b/src/pkg/net/file_unix.go
index 4c8403e..1e7420c 100644
--- a/src/pkg/net/file_unix.go
+++ b/src/pkg/net/file_unix.go
@@ -12,14 +12,11 @@
)
func newFileFD(f *os.File) (*netFD, error) {
- syscall.ForkLock.RLock()
- fd, err := syscall.Dup(int(f.Fd()))
+ fd, err := dupCloseOnExec(int(f.Fd()))
if err != nil {
- syscall.ForkLock.RUnlock()
return nil, os.NewSyscallError("dup", err)
}
- syscall.CloseOnExec(fd)
- syscall.ForkLock.RUnlock()
+
if err = syscall.SetNonblock(fd, true); err != nil {
closesocket(fd)
return nil, err
