unix: add Linux CopyFileRange syscall

Introduces the CopyFileRange syscall which first appears in Linux 4.5.
Allows copying file content between file descriptors within the kernel
without transferring data to user space. This syscall also allows the
kernel to take advantage of reflinking or other fast copy methods on
supported file systems.
http://man7.org/linux/man-pages/man2/copy_file_range.2.html

Change-Id: Id365f1e5d4d5ddf7159478e3a13084c9576ebd5c
Reviewed-on: https://go-review.googlesource.com/39992
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/syscall_linux.go

@@ -1038,6 +1038,7 @@ func Mount(source string, target string, fstype string, flags uintptr, data stri
 //sys	Chroot(path string) (err error)
 //sys	ClockGettime(clockid int32, time *Timespec) (err error)
 //sys	Close(fd int) (err error)
+//sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
 //sys	Dup(oldfd int) (fd int, err error)
 //sys	Dup3(oldfd int, newfd int, flags int) (err error)
 //sysnb	EpollCreate(size int) (fd int, err error)

unix/zsyscall_linux_386.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_amd64.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_arm.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_arm64.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_mips.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_mips64.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_mips64le.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_mipsle.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_ppc64.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_ppc64le.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_s390x.go

@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)

unix/zsyscall_linux_sparc64.go

@@ -1,5 +1,5 @@
 // mksyscall.pl -tags linux,sparc64 syscall_linux.go syscall_linux_sparc64.go
-// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+// Code generated by the command above; see README.md. DO NOT EDIT.
 
 // +build linux,sparc64
 
@@ -312,6 +312,17 @@ func Close(fd int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := Syscall6(SYS_COPY_FILE_RANGE, uintptr(rfd), uintptr(unsafe.Pointer(roff)), uintptr(wfd), uintptr(unsafe.Pointer(woff)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Dup(oldfd int) (fd int, err error) {
 	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), 0, 0)
 	fd = int(r0)