syscall: fix Plan 9 build.

Move mmapper from syscall.go to syscall_unix.go.
Remove Sendfile from syscall_plan9.go.

R=rsc, alex.brainman
CC=golang-dev
https://golang.org/cl/4368060

src/pkg/syscall/syscall.go

@@ -13,11 +13,6 @@
 // errno is an operating system error number describing the failure.
 package syscall
 
-import (
-	"sync"
-	"unsafe"
-)
-
 // StringByteSlice returns a NUL-terminated slice of bytes
 // containing the text of s.
 func StringByteSlice(s string) []byte {
@@ -33,63 +28,3 @@ func StringBytePtr(s string) *byte { return &StringByteSlice(s)[0] }
 // Single-word zero for use when we need a valid pointer to 0 bytes.
 // See mksyscall.sh.
 var _zero uintptr
-
-// Mmap manager, for use by operating system-specific implementations.
-
-type mmapper struct {
-	sync.Mutex
-	active map[*byte][]byte // active mappings; key is last byte in mapping
-	mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, int)
-	munmap func(addr uintptr, length uintptr) int
-}
-
-func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, errno int) {
-	if length <= 0 {
-		return nil, EINVAL
-	}
-
-	// Map the requested memory.
-	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
-	if errno != 0 {
-		return nil, errno
-	}
-
-	// Slice memory layout
-	var sl = struct {
-		addr uintptr
-		len  int
-		cap  int
-	}{addr, length, length}
-
-	// Use unsafe to turn sl into a []byte.
-	b := *(*[]byte)(unsafe.Pointer(&sl))
-
-	// Register mapping in m and return it.
-	p := &b[cap(b)-1]
-	m.Lock()
-	defer m.Unlock()
-	m.active[p] = b
-	return b, 0
-}
-
-func (m *mmapper) Munmap(data []byte) (errno int) {
-	if len(data) == 0 || len(data) != cap(data) {
-		return EINVAL
-	}
-
-	// Find the base of the mapping.
-	p := &data[cap(data)-1]
-	m.Lock()
-	defer m.Unlock()
-	b := m.active[p]
-	if b == nil || &b[0] != &data[0] {
-		return EINVAL
-	}
-
-	// Unmap the memory and update m.
-	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != 0 {
-		return errno
-	}
-	m.active[p] = nil, false
-	return 0
-}

src/pkg/syscall/syscall_plan9.go

@@ -327,11 +327,6 @@ func Getgroups() (gids []int, err Error) {
 	return make([]int, 0), nil
 }
 
-// TODO
-func Sendfile(outfd int, infd int, offset *int64, count int) (written int, errno int) {
-	return -1, ENOSYS
-}
-
 //sys	Dup(oldfd int, newfd int) (fd int, err Error)
 //sys	Open(path string, mode int) (fd int, err Error)
 //sys	Create(path string, mode int, perm uint32) (fd int, err Error)

src/pkg/syscall/syscall_unix.go

@@ -4,6 +4,12 @@
 
 package syscall
 
+import (
+	"sync"
+	"unsafe"
+)
+
+
 var (
 	Stdin  = 0
 	Stdout = 1
@@ -21,3 +27,63 @@ func Errstr(errno int) string {
 	}
 	return errors[errno]
 }
+
+// Mmap manager, for use by operating system-specific implementations.
+
+type mmapper struct {
+	sync.Mutex
+	active map[*byte][]byte // active mappings; key is last byte in mapping
+	mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, int)
+	munmap func(addr uintptr, length uintptr) int
+}
+
+func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, errno int) {
+	if length <= 0 {
+		return nil, EINVAL
+	}
+
+	// Map the requested memory.
+	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
+	if errno != 0 {
+		return nil, errno
+	}
+
+	// Slice memory layout
+	var sl = struct {
+		addr uintptr
+		len  int
+		cap  int
+	}{addr, length, length}
+
+	// Use unsafe to turn sl into a []byte.
+	b := *(*[]byte)(unsafe.Pointer(&sl))
+
+	// Register mapping in m and return it.
+	p := &b[cap(b)-1]
+	m.Lock()
+	defer m.Unlock()
+	m.active[p] = b
+	return b, 0
+}
+
+func (m *mmapper) Munmap(data []byte) (errno int) {
+	if len(data) == 0 || len(data) != cap(data) {
+		return EINVAL
+	}
+
+	// Find the base of the mapping.
+	p := &data[cap(data)-1]
+	m.Lock()
+	defer m.Unlock()
+	b := m.active[p]
+	if b == nil || &b[0] != &data[0] {
+		return EINVAL
+	}
+
+	// Unmap the memory and update m.
+	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != 0 {
+		return errno
+	}
+	m.active[p] = nil, false
+	return 0
+}