os, syscall: use pipe2 instead of pipe syscall on OpenBSD

The pipe2 syscall is part of OpenBSD since version 5.7 and thus exists in
all officially supported versions.

Follows CL 38426 and CL 94035

Change-Id: I8f93ecbc89664241f1b6b0d069e948776941b1d0
Reviewed-on: https://go-review.googlesource.com/97356
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/os/pipe2_bsd.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build freebsd netbsd
+// +build freebsd netbsd openbsd
 
 package os
 

src/os/pipe_bsd.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly nacl openbsd solaris
+// +build darwin dragonfly nacl solaris
 
 package os
 

src/syscall/forkpipe.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly openbsd solaris
+// +build darwin dragonfly solaris
 
 package syscall
 

src/syscall/forkpipe2.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build freebsd netbsd
+// +build freebsd netbsd openbsd
 
 package syscall
 

src/syscall/syscall_openbsd.go

@@ -62,16 +62,20 @@ func direntNamlen(buf []byte) (uint64, bool) {
 	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
 }
 
-//sysnb pipe(p *[2]_C_int) (err error)
-func Pipe(p []int) (err error) {
+func Pipe(p []int) error {
+	return Pipe2(p, 0)
+}
+
+//sysnb pipe2(p *[2]_C_int, flags int) (err error)
+func Pipe2(p []int, flags int) error {
 	if len(p) != 2 {
 		return EINVAL
 	}
 	var pp [2]_C_int
-	err = pipe(&pp)
+	err := pipe2(&pp, flags)
 	p[0] = int(pp[0])
 	p[1] = int(pp[1])
-	return
+	return err
 }
 
 //sys	accept4(fd int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (nfd int, err error)

src/syscall/zsyscall_openbsd_386.go

@@ -261,8 +261,8 @@ func fcntl(fd int, cmd int, arg int) (val int, err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func pipe(p *[2]_C_int) (err error) {
-	_, _, e1 := RawSyscall(SYS_PIPE, uintptr(unsafe.Pointer(p)), 0, 0)
+func pipe2(p *[2]_C_int, flags int) (err error) {
+	_, _, e1 := RawSyscall(SYS_PIPE2, uintptr(unsafe.Pointer(p)), uintptr(flags), 0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

src/syscall/zsyscall_openbsd_amd64.go

@@ -261,8 +261,8 @@ func fcntl(fd int, cmd int, arg int) (val int, err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func pipe(p *[2]_C_int) (err error) {
-	_, _, e1 := RawSyscall(SYS_PIPE, uintptr(unsafe.Pointer(p)), 0, 0)
+func pipe2(p *[2]_C_int, flags int) (err error) {
+	_, _, e1 := RawSyscall(SYS_PIPE2, uintptr(unsafe.Pointer(p)), uintptr(flags), 0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

src/syscall/zsyscall_openbsd_arm.go

@@ -261,8 +261,8 @@ func fcntl(fd int, cmd int, arg int) (val int, err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func pipe(p *[2]_C_int) (err error) {
-	_, _, e1 := RawSyscall(SYS_PIPE, uintptr(unsafe.Pointer(p)), 0, 0)
+func pipe2(p *[2]_C_int, flags int) (err error) {
+	_, _, e1 := RawSyscall(SYS_PIPE2, uintptr(unsafe.Pointer(p)), uintptr(flags), 0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

src/syscall/zsysnum_openbsd_386.go

@@ -102,6 +102,7 @@ const (
 	SYS_CONNECT        = 98  // { int sys_connect(int s, const struct sockaddr *name, \
 	SYS_GETDENTS       = 99  // { int sys_getdents(int fd, void *buf, size_t buflen); }
 	SYS_GETPRIORITY    = 100 // { int sys_getpriority(int which, id_t who); }
+	SYS_PIPE2          = 101 // { int sys_pipe2(int *fdp, int flags); }
 	SYS_SIGRETURN      = 103 // { int sys_sigreturn(struct sigcontext *sigcntxp); }
 	SYS_BIND           = 104 // { int sys_bind(int s, const struct sockaddr *name, \
 	SYS_SETSOCKOPT     = 105 // { int sys_setsockopt(int s, int level, int name, \

src/syscall/zsysnum_openbsd_amd64.go

@@ -102,6 +102,7 @@ const (
 	SYS_CONNECT        = 98  // { int sys_connect(int s, const struct sockaddr *name, \
 	SYS_GETDENTS       = 99  // { int sys_getdents(int fd, void *buf, size_t buflen); }
 	SYS_GETPRIORITY    = 100 // { int sys_getpriority(int which, id_t who); }
+	SYS_PIPE2          = 101 // { int sys_pipe2(int *fdp, int flags); }
 	SYS_SIGRETURN      = 103 // { int sys_sigreturn(struct sigcontext *sigcntxp); }
 	SYS_BIND           = 104 // { int sys_bind(int s, const struct sockaddr *name, \
 	SYS_SETSOCKOPT     = 105 // { int sys_setsockopt(int s, int level, int name, \