runtime: use pipe2 for nonblockingPipe on dragonfly

The pipe2 syscall is available since DragonflyBSD 4.2, see
https://www.dragonflybsd.org/release42/

Change-Id: Ifc67c4935cc59bae29be459167e2fa765843ac03
Reviewed-on: https://go-review.googlesource.com/c/go/+/295471
Trust: Tobias Klauser <[email protected]>
Run-TryBot: Tobias Klauser <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: tklauser

src/runtime/defs_dragonfly.go

@@ -32,6 +32,10 @@ const (
 	EFAULT = C.EFAULT
 	EBUSY  = C.EBUSY
 	EAGAIN = C.EAGAIN
+	ENOSYS = C.ENOSYS
+
+	O_NONBLOCK = C.O_NONBLOCK
+	O_CLOEXEC  = C.O_CLOEXEC
 
 	PROT_NONE  = C.PROT_NONE
 	PROT_READ  = C.PROT_READ

src/runtime/defs_dragonfly_amd64.go

@@ -10,6 +10,10 @@ const (
 	_EFAULT = 0xe
 	_EBUSY  = 0x10
 	_EAGAIN = 0x23
+	_ENOSYS = 0x4e
+
+	_O_NONBLOCK = 0x4
+	_O_CLOEXEC  = 0x20000
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1

src/runtime/export_pipe2_test.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build freebsd || linux || netbsd || openbsd || solaris
-// +build freebsd linux netbsd openbsd solaris
+//go:build dragonfly || freebsd || linux || netbsd || openbsd || solaris
+// +build dragonfly freebsd linux netbsd openbsd solaris
 
 package runtime
 

src/runtime/export_pipe_test.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly
-// +build aix darwin dragonfly
+//go:build aix || darwin
+// +build aix darwin
 
 package runtime
 

src/runtime/nbpipe_pipe.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly
-// +build aix darwin dragonfly
+//go:build aix || darwin
+// +build aix darwin
 
 package runtime
 

src/runtime/nbpipe_pipe2.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build freebsd || linux || netbsd || openbsd || solaris
-// +build freebsd linux netbsd openbsd solaris
+//go:build dragonfly || freebsd || linux || netbsd || openbsd || solaris
+// +build dragonfly freebsd linux netbsd openbsd solaris
 
 package runtime
 

src/runtime/os_dragonfly.go

@@ -60,10 +60,11 @@ func kqueue() int32
 
 //go:noescape
 func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32
-func closeonexec(fd int32)
-func setNonblock(fd int32)
 
 func pipe() (r, w int32, errno int32)
+func pipe2(flags int32) (r, w int32, errno int32)
+func closeonexec(fd int32)
+func setNonblock(fd int32)
 
 // From DragonFly's <sys/sysctl.h>
 const (

src/runtime/sys_dragonfly_amd64.s

@@ -123,6 +123,24 @@ pipeok:
 	MOVL	$0, errno+8(FP)
 	RET
 
+// func pipe2(flags int32) (r, w int32, errno int32)
+TEXT runtime·pipe2(SB),NOSPLIT,$0-20
+	MOVL	$0, DI
+	// dragonfly expects flags as the 2nd argument
+	MOVL	flags+0(FP), SI
+	MOVL	$538, AX
+	SYSCALL
+	JCC	pipe2ok
+	MOVL	$-1,r+8(FP)
+	MOVL	$-1,w+12(FP)
+	MOVL	AX, errno+16(FP)
+	RET
+pipe2ok:
+	MOVL	AX, r+8(FP)
+	MOVL	DX, w+12(FP)
+	MOVL	$0, errno+16(FP)
+	RET
+
 TEXT runtime·write1(SB),NOSPLIT,$-8
 	MOVQ	fd+0(FP), DI		// arg 1 fd
 	MOVQ	p+8(FP), SI		// arg 2 buf