fix init on windows failed

The failure is due to /dev/null is not existed on windows.

splice/splice.go

@@ -8,9 +8,6 @@ package splice
 
 import (
 	"fmt"
-	"io/ioutil"
-	"log"
-	"os"
 	"syscall"
 )
 
@@ -33,33 +30,6 @@ const DefaultPipeSize = 16 * 4096
 // We empty pipes by splicing to /dev/null.
 var devNullFD uintptr
 
-func init() {
-	content, err := ioutil.ReadFile("/proc/sys/fs/pipe-max-size")
-	if err != nil {
-		maxPipeSize = DefaultPipeSize
-	} else {
-		fmt.Sscan(string(content), &maxPipeSize)
-	}
-
-	r, w, err := os.Pipe()
-	if err != nil {
-		log.Panicf("cannot create pipe: %v", err)
-	}
-	sz, errNo := fcntl(r.Fd(), F_GETPIPE_SZ, 0)
-	resizable = (errNo == 0)
-	_, errNo = fcntl(r.Fd(), F_SETPIPE_SZ, 2*sz)
-	resizable = resizable && (errNo == 0)
-	r.Close()
-	w.Close()
-
-	fd, err := syscall.Open("/dev/null", os.O_WRONLY, 0)
-	if err != nil {
-		log.Panicf("splice: %v", err)
-	}
-
-	devNullFD = uintptr(fd)
-}
-
 const F_SETPIPE_SZ = 1031
 const F_GETPIPE_SZ = 1032
 

splice/splice_darwin.go

@@ -2,9 +2,39 @@ package splice
 
 import (
 	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
 	"syscall"
 )
 
+func init() {
+	content, err := ioutil.ReadFile("/proc/sys/fs/pipe-max-size")
+	if err != nil {
+		maxPipeSize = DefaultPipeSize
+	} else {
+		fmt.Sscan(string(content), &maxPipeSize)
+	}
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		log.Panicf("cannot create pipe: %v", err)
+	}
+	sz, errNo := fcntl(r.Fd(), F_GETPIPE_SZ, 0)
+	resizable = (errNo == 0)
+	_, errNo = fcntl(r.Fd(), F_SETPIPE_SZ, 2*sz)
+	resizable = resizable && (errNo == 0)
+	r.Close()
+	w.Close()
+
+	fd, err := syscall.Open("/dev/null", os.O_WRONLY, 0)
+	if err != nil {
+		log.Panicf("splice: %v", err)
+	}
+
+	devNullFD = uintptr(fd)
+}
+
 // copy & paste from syscall.
 func fcntl(fd uintptr, cmd int, arg int) (val int, errno syscall.Errno) {
 	r0, _, e1 := syscall.Syscall(syscall.SYS_FCNTL, fd, uintptr(cmd), uintptr(arg))

splice/splice_linux.go

@@ -1,6 +1,39 @@
 package splice
 
-import "syscall"
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"syscall"
+)
+
+func init() {
+	content, err := ioutil.ReadFile("/proc/sys/fs/pipe-max-size")
+	if err != nil {
+		maxPipeSize = DefaultPipeSize
+	} else {
+		fmt.Sscan(string(content), &maxPipeSize)
+	}
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		log.Panicf("cannot create pipe: %v", err)
+	}
+	sz, errNo := fcntl(r.Fd(), F_GETPIPE_SZ, 0)
+	resizable = (errNo == 0)
+	_, errNo = fcntl(r.Fd(), F_SETPIPE_SZ, 2*sz)
+	resizable = resizable && (errNo == 0)
+	r.Close()
+	w.Close()
+
+	fd, err := syscall.Open("/dev/null", os.O_WRONLY, 0)
+	if err != nil {
+		log.Panicf("splice: %v", err)
+	}
+
+	devNullFD = uintptr(fd)
+}
 
 // copy & paste from syscall.
 func fcntl(fd uintptr, cmd int, arg int) (val int, errno syscall.Errno) {

splice/splice_windows.go

@@ -5,6 +5,9 @@ import (
 	"syscall"
 )
 
+func init() {
+}
+
 func osPipe() (int, int, error) {
 	return 0, 0, fmt.Errorf("not implemented")
 }