unix: add Poll function on Dragonfly

Tested with TestPoll extracted from syscall_linux_test.go. Once Poll is
supported on all OSes this test can be moved to syscall_unix_test.go.

Change-Id: I03f4396be2e190770abb219c1c5324ca55bcfa27
Reviewed-on: https://go-review.googlesource.com/73430
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_dragonfly.go

@@ -125,6 +125,15 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 	return
 }
 
+//sys   poll(fds *PollFd, nfds int, timeout int) (n int, err error)
+
+func Poll(fds []PollFd, timeout int) (n int, err error) {
+	if len(fds) == 0 {
+		return poll(nil, 0, timeout)
+	}
+	return poll(&fds[0], len(fds), timeout)
+}
+
 /*
  * Exposed directly
  */
@@ -257,7 +266,6 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 // Searchfs
 // Delete
 // Copyfile
-// Poll
 // Watchevent
 // Waitevent
 // Modwatch
@@ -403,7 +411,6 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 // Pread_nocancel
 // Pwrite_nocancel
 // Waitid_nocancel
-// Poll_nocancel
 // Msgsnd_nocancel
 // Msgrcv_nocancel
 // Sem_wait_nocancel

unix/types_dragonfly.go

@@ -17,6 +17,7 @@ package unix
 #define KERNEL
 #include <dirent.h>
 #include <fcntl.h>
+#include <poll.h>
 #include <signal.h>
 #include <termios.h>
 #include <stdio.h>
@@ -247,3 +248,20 @@ const (
 	AT_FDCWD            = C.AT_FDCWD
 	AT_SYMLINK_NOFOLLOW = C.AT_SYMLINK_NOFOLLOW
 )
+
+// poll
+
+type PollFd C.struct_pollfd
+
+const (
+	POLLERR    = C.POLLERR
+	POLLHUP    = C.POLLHUP
+	POLLIN     = C.POLLIN
+	POLLNVAL   = C.POLLNVAL
+	POLLOUT    = C.POLLOUT
+	POLLPRI    = C.POLLPRI
+	POLLRDBAND = C.POLLRDBAND
+	POLLRDNORM = C.POLLRDNORM
+	POLLWRBAND = C.POLLWRBAND
+	POLLWRNORM = C.POLLWRNORM
+)

unix/zsyscall_dragonfly_amd64.go

@@ -412,6 +412,17 @@ func extpwrite(fd int, p []byte, flags int, offset int64) (n int, err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func poll(fds *PollFd, nfds int, timeout int) (n int, err error) {
+	r0, _, e1 := Syscall(SYS_POLL, uintptr(unsafe.Pointer(fds)), uintptr(nfds), uintptr(timeout))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Access(path string, mode uint32) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)

unix/ztypes_dragonfly_amd64.go

@@ -446,3 +446,22 @@ const (
 	AT_FDCWD            = 0xfffafdcd
 	AT_SYMLINK_NOFOLLOW = 0x1
 )
+
+type PollFd struct {
+	Fd      int32
+	Events  int16
+	Revents int16
+}
+
+const (
+	POLLERR    = 0x8
+	POLLHUP    = 0x10
+	POLLIN     = 0x1
+	POLLNVAL   = 0x20
+	POLLOUT    = 0x4
+	POLLPRI    = 0x2
+	POLLRDBAND = 0x80
+	POLLRDNORM = 0x40
+	POLLWRBAND = 0x100
+	POLLWRNORM = 0x4
+)