unix: implement Vmsplice, add SPLICE_F_* constants

Fixes golang/go#19125

Change-Id: I822b6f260f980178da29a552c6170cb261c8e254
Reviewed-on: https://go-review.googlesource.com/37152
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/mkerrors.sh

@@ -345,6 +345,7 @@ ccflags="$@"
 		$2 ~ /^CLOCK_/ ||
 		$2 ~ /^CAN_/ ||
 		$2 ~ /^ALG_/ ||
+		$2 ~ /^SPLICE_/ ||
 		$2 !~ "WMESGLEN" &&
 		$2 ~ /^W[A-Z0-9]+$/ {printf("\t%s = C.%s\n", $2, $2)}
 		$2 ~ /^__WCOREFLAG$/ {next}
@@ -460,7 +461,7 @@ main(void)
 		printf("\t%d: \"%s\",\n", e, buf);
 	}
 	printf("}\n\n");
-	
+
 	printf("\n\n// Signal table\n");
 	printf("var signals = [...]string {\n");
 	qsort(signals, nelem(signals), sizeof signals[0], intcmp);

unix/syscall_linux.go

@@ -1118,6 +1118,25 @@ func Munmap(b []byte) (err error) {
 //sys	Mlockall(flags int) (err error)
 //sys	Munlockall() (err error)
 
+// Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
+// using the specified flags.
+func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
+	n, _, errno := Syscall6(
+		SYS_VMSPLICE,
+		uintptr(fd),
+		uintptr(unsafe.Pointer(&iovs[0])),
+		uintptr(len(iovs)),
+		uintptr(flags),
+		0,
+		0,
+	)
+	if errno != 0 {
+		return 0, syscall.Errno(errno)
+	}
+
+	return int(n), nil
+}
+
 /*
  * Unimplemented
  */
@@ -1245,7 +1264,6 @@ func Munmap(b []byte) (err error) {
 // Utimensat
 // Vfork
 // Vhangup
-// Vmsplice
 // Vserver
 // Waitid
 // _Sysctl

unix/zerrors_linux_386.go

@@ -1305,6 +1305,10 @@ const (
 	SO_TIMESTAMPING                  = 0x25
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_amd64.go

@@ -1306,6 +1306,10 @@ const (
 	SO_TIMESTAMPING                  = 0x25
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_arm.go

@@ -1229,6 +1229,10 @@ const (
 	SO_TIMESTAMPING                  = 0x25
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_arm64.go

@@ -1361,6 +1361,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_mips.go

@@ -1280,6 +1280,10 @@ const (
 	SO_TIMESTAMPING                  = 0x25
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x1008
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_mips64.go

@@ -1376,6 +1376,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x1008
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_mips64le.go

@@ -1376,6 +1376,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x1008
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_mipsle.go

@@ -1451,6 +1451,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x1008
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_ppc64.go

@@ -1429,6 +1429,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_ppc64le.go

@@ -1428,6 +1428,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_s390x.go

@@ -1483,6 +1483,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x23
 	SO_TYPE                          = 0x3
 	SO_WIFI_STATUS                   = 0x29
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000

unix/zerrors_linux_sparc64.go

@@ -1524,6 +1524,10 @@ const (
 	SO_TIMESTAMPNS                   = 0x21
 	SO_TYPE                          = 0x1008
 	SO_WIFI_STATUS                   = 0x25
+	SPLICE_F_GIFT                    = 0x8
+	SPLICE_F_MORE                    = 0x4
+	SPLICE_F_MOVE                    = 0x1
+	SPLICE_F_NONBLOCK                = 0x2
 	S_BLKSIZE                        = 0x200
 	S_IEXEC                          = 0x40
 	S_IFBLK                          = 0x6000