syscall: implement Sendfile for Darwin.

Update #5847
Summary: syscall: implement Sendfile for OpenBSD and NetBSD

R=golang-dev, rsc, dave
CC=golang-dev
https://golang.org/cl/10980043

doc/go1.2.txt

@@ -23,4 +23,5 @@ go/build: support including C++ code with cgo (CL 8248043).
 io: Copy prioritizes WriterTo over ReaderFrom (CL 9462044).
 net: new build tag netgo for building a pure Go net package (CL 7100050).
 sort: new Stable function provides stable sort (CL 9612044).
+syscall: implemented Sendfile for Darwin, added Syscall9 for Darwin/amd64 (CL 10980043).
 testing: AllocsPerRun is now quantized to an integer (the type is still float64) (CL 9837049).

src/pkg/syscall/syscall_darwin.go

@@ -96,11 +96,6 @@ func Pipe(p []int) (err error) {
 	return
 }
 
-// TODO
-func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
-	return -1, ENOSYS
-}
-
 /*
  * Wrapped
  */

src/pkg/syscall/syscall_darwin_386.go

@@ -4,6 +4,8 @@
 
 package syscall
 
+import "unsafe"
+
 func Getpagesize() int { return 4096 }
 
 func TimespecToNsec(ts Timespec) int64 { return int64(ts.Sec)*1e9 + int64(ts.Nsec) }
@@ -52,4 +54,17 @@ func (cmsg *Cmsghdr) SetLen(length int) {
 	cmsg.Len = uint32(length)
 }
 
+func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	var length = uint64(count)
+
+	_, _, e1 := Syscall9(SYS_SENDFILE, uintptr(infd), uintptr(outfd), uintptr(*offset), uintptr(*offset>>32), uintptr(unsafe.Pointer(&length)), 0, 0, 0, 0)
+
+	written = int(length)
+
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno) // sic

src/pkg/syscall/syscall_darwin_amd64.go

@@ -4,6 +4,8 @@
 
 package syscall
 
+import "unsafe"
+
 func Getpagesize() int { return 4096 }
 
 func TimespecToNsec(ts Timespec) int64 { return int64(ts.Sec)*1e9 + int64(ts.Nsec) }
@@ -51,3 +53,18 @@ func (msghdr *Msghdr) SetControllen(length int) {
 func (cmsg *Cmsghdr) SetLen(length int) {
 	cmsg.Len = uint32(length)
 }
+
+func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	var length = uint64(count)
+
+	_, _, e1 := Syscall6(SYS_SENDFILE, uintptr(infd), uintptr(outfd), uintptr(*offset), uintptr(unsafe.Pointer(&length)), 0, 0)
+
+	written = int(length)
+
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
+func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno) // sic