rebase: use go-ceph version with NFS-Admin API

The NFS-Admin API has been added to go-ceph v0.15.0. As the API can not
be tested in the go-ceph CI, it requires build-tag `ceph_ci_untested`.
This additional build-tag has been added to the `Makefile` and should be
removed when the API does not require the build-tag anymore.

See-also: ceph/go-ceph#655
Signed-off-by: Niels de Vos <ndevos@redhat.com>

vendor/github.com/ceph/go-ceph/internal/cutil/buffergroup.go

@@ -0,0 +1,89 @@
+package cutil
+
+// #include <stdlib.h>
+import "C"
+
+import (
+	"unsafe"
+)
+
+// BufferGroup is a helper structure that holds Go-allocated slices of
+// C-allocated strings and their respective lengths. Useful for C functions
+// that consume byte buffers with explicit length instead of null-terminated
+// strings. When used as input arguments in C functions, caller must make sure
+// the C code will not hold any pointers to either of the struct's attributes
+// after that C function returns.
+type BufferGroup struct {
+	// C-allocated buffers.
+	Buffers []CharPtr
+	// Lengths of C buffers, where Lengths[i] = length(Buffers[i]).
+	Lengths []SizeT
+}
+
+// TODO: should BufferGroup implementation change and the slices would contain
+//       nested Go pointers, they must be pinned with PtrGuard.
+
+// NewBufferGroupStrings returns new BufferGroup constructed from strings.
+func NewBufferGroupStrings(strs []string) *BufferGroup {
+	s := &BufferGroup{
+		Buffers: make([]CharPtr, len(strs)),
+		Lengths: make([]SizeT, len(strs)),
+	}
+
+	for i, str := range strs {
+		bs := []byte(str)
+		s.Buffers[i] = CharPtr(C.CBytes(bs))
+		s.Lengths[i] = SizeT(len(bs))
+	}
+
+	return s
+}
+
+// NewBufferGroupBytes returns new BufferGroup constructed
+// from slice of byte slices.
+func NewBufferGroupBytes(bss [][]byte) *BufferGroup {
+	s := &BufferGroup{
+		Buffers: make([]CharPtr, len(bss)),
+		Lengths: make([]SizeT, len(bss)),
+	}
+
+	for i, bs := range bss {
+		s.Buffers[i] = CharPtr(C.CBytes(bs))
+		s.Lengths[i] = SizeT(len(bs))
+	}
+
+	return s
+}
+
+// Free free()s the C-allocated memory.
+func (s *BufferGroup) Free() {
+	for _, ptr := range s.Buffers {
+		C.free(unsafe.Pointer(ptr))
+	}
+
+	s.Buffers = nil
+	s.Lengths = nil
+}
+
+// BuffersPtr returns a pointer to the beginning of the Buffers slice.
+func (s *BufferGroup) BuffersPtr() CharPtrPtr {
+	if len(s.Buffers) == 0 {
+		return nil
+	}
+
+	return CharPtrPtr(&s.Buffers[0])
+}
+
+// LengthsPtr returns a pointer to the beginning of the Lengths slice.
+func (s *BufferGroup) LengthsPtr() SizeTPtr {
+	if len(s.Lengths) == 0 {
+		return nil
+	}
+
+	return SizeTPtr(&s.Lengths[0])
+}
+
+func testBufferGroupGet(s *BufferGroup, index int) (str string, length int) {
+	bs := C.GoBytes(unsafe.Pointer(s.Buffers[index]), C.int(s.Lengths[index]))
+	return string(bs), int(s.Lengths[index])
+}