rebase: update vendored go-ceph to v0.6

Closes: #1547
Signed-off-by: Niels de Vos <ndevos@redhat.com>

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

@@ -0,0 +1,14 @@
+package cutil
+
+import "unsafe"
+
+// VoidPtr casts a uintptr value to an unsafe.Pointer value in order to use it
+// directly as a void* argument in a C function call.
+// CAUTION: NEVER store the result in a variable, or the Go GC could panic.
+func VoidPtr(i uintptr) unsafe.Pointer {
+	var nullPtr unsafe.Pointer
+	// It's not possible to cast uintptr directly to unsafe.Pointer. Therefore we
+	// cast a null pointer to uintptr and apply pointer arithmetic on it, which
+	// allows us to cast it back to unsafe.Pointer.
+	return unsafe.Pointer(uintptr(nullPtr) + i)
+}

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

@@ -0,0 +1,78 @@
+package cutil
+
+/*
+#include <stdlib.h>
+#include <sys/uio.h>
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+var iovecSize uintptr
+
+// StructIovecPtr is an unsafe pointer wrapping C's `*struct iovec`.
+type StructIovecPtr unsafe.Pointer
+
+// Iovec helps manage struct iovec arrays needed by some C functions.
+type Iovec struct {
+	// cvec represents an array of struct iovec C memory
+	cvec unsafe.Pointer
+	// length of the array (in elements)
+	length int
+}
+
+// NewIovec creates an Iovec, and underlying C memory, of the specified size.
+func NewIovec(l int) *Iovec {
+	r := &Iovec{
+		cvec:   C.malloc(C.size_t(l) * C.size_t(iovecSize)),
+		length: l,
+	}
+	return r
+}
+
+// ByteSlicesToIovec takes a slice of byte slices and returns a new iovec that
+// maps the slice data to struct iovec entries.
+func ByteSlicesToIovec(data [][]byte) *Iovec {
+	iov := NewIovec(len(data))
+	for i := range data {
+		iov.Set(i, data[i])
+	}
+	return iov
+}
+
+// Pointer returns a StructIovecPtr that represents the C memory of the
+// underlying array.
+func (v *Iovec) Pointer() StructIovecPtr {
+	return StructIovecPtr(unsafe.Pointer(v.cvec))
+}
+
+// Len returns the number of entries in the Iovec.
+func (v *Iovec) Len() int {
+	return v.length
+}
+
+// Free the C memory in the Iovec.
+func (v *Iovec) Free() {
+	if v.cvec != nil {
+		C.free(v.cvec)
+		v.cvec = nil
+		v.length = 0
+	}
+}
+
+// Set will map the memory of the given byte slice to the iovec at the
+// specified position.
+func (v *Iovec) Set(i int, buf []byte) {
+	offset := uintptr(i) * iovecSize
+	iov := (*C.struct_iovec)(unsafe.Pointer(
+		uintptr(unsafe.Pointer(v.cvec)) + offset))
+	iov.iov_base = unsafe.Pointer(&buf[0])
+	iov.iov_len = C.size_t(len(buf))
+}
+
+func init() {
+	var iovec C.struct_iovec
+	iovecSize = unsafe.Sizeof(iovec)
+}