syscall: add Dup3 on Linux
With dup3, we can avoid an extra system call on some machines
while holding syscall.ForkLock. Currently we have to
syscall.Dup + syscall.CloseOnExec.
On machines with Linux and a new enough kernel, this can just
be dup3.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12170045
diff --git a/src/pkg/syscall/syscall_linux.go b/src/pkg/syscall/syscall_linux.go
index b6d728e..79c1fda 100644
--- a/src/pkg/syscall/syscall_linux.go
+++ b/src/pkg/syscall/syscall_linux.go
@@ -778,6 +778,7 @@
//sys Creat(path string, mode uint32) (fd int, err error)
//sysnb Dup(oldfd int) (fd int, err error)
//sysnb Dup2(oldfd int, newfd int) (err error)
+//sysnb Dup3(oldfd int, newfd int, flags int) (err error)
//sysnb EpollCreate(size int) (fd int, err error)
//sysnb EpollCreate1(flag int) (fd int, err error)
//sysnb EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
diff --git a/src/pkg/syscall/zsyscall_linux_386.go b/src/pkg/syscall/zsyscall_linux_386.go
index 810cba0..6eeb118 100644
--- a/src/pkg/syscall/zsyscall_linux_386.go
+++ b/src/pkg/syscall/zsyscall_linux_386.go
@@ -310,6 +310,16 @@
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+func Dup3(oldfd int, newfd int, flags int) (err error) {
+ _, _, e1 := RawSyscall(SYS_DUP3, uintptr(oldfd), uintptr(newfd), uintptr(flags))
+ if e1 != 0 {
+ err = e1
+ }
+ return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
func EpollCreate(size int) (fd int, err error) {
r0, _, e1 := RawSyscall(SYS_EPOLL_CREATE, uintptr(size), 0, 0)
fd = int(r0)
diff --git a/src/pkg/syscall/zsyscall_linux_amd64.go b/src/pkg/syscall/zsyscall_linux_amd64.go
index 9978b81..c1c3d45 100644
--- a/src/pkg/syscall/zsyscall_linux_amd64.go
+++ b/src/pkg/syscall/zsyscall_linux_amd64.go
@@ -310,6 +310,16 @@
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+func Dup3(oldfd int, newfd int, flags int) (err error) {
+ _, _, e1 := RawSyscall(SYS_DUP3, uintptr(oldfd), uintptr(newfd), uintptr(flags))
+ if e1 != 0 {
+ err = e1
+ }
+ return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
func EpollCreate(size int) (fd int, err error) {
r0, _, e1 := RawSyscall(SYS_EPOLL_CREATE, uintptr(size), 0, 0)
fd = int(r0)
diff --git a/src/pkg/syscall/zsyscall_linux_arm.go b/src/pkg/syscall/zsyscall_linux_arm.go
index 80d3f9b..3380714 100644
--- a/src/pkg/syscall/zsyscall_linux_arm.go
+++ b/src/pkg/syscall/zsyscall_linux_arm.go
@@ -310,6 +310,16 @@
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+func Dup3(oldfd int, newfd int, flags int) (err error) {
+ _, _, e1 := RawSyscall(SYS_DUP3, uintptr(oldfd), uintptr(newfd), uintptr(flags))
+ if e1 != 0 {
+ err = e1
+ }
+ return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
func EpollCreate(size int) (fd int, err error) {
r0, _, e1 := RawSyscall(SYS_EPOLL_CREATE, uintptr(size), 0, 0)
fd = int(r0)
