add librados and test calling it

cmd/castled/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/quantum/castle/pkg/castled"
@@ -9,6 +10,13 @@ import (
 
 func main() {
 
+	if len(os.Args) > 1 && os.Args[1] == "version" {
+		fmt.Printf("cephd: %v\n", cephd.Version())
+		rmajor, rminor, rpatch := cephd.RadosVersion()
+		fmt.Printf("rados: %v.%v.%v\n", rmajor, rminor, rpatch)
+		return
+	}
+
 	if len(os.Args) > 2 && os.Args[1] == "daemon" {
 		cephd.RunDaemon(os.Args[2], os.Args[3:]...)
 		return

pkg/cephd/cephd.go

@@ -10,6 +10,7 @@ package cephd
 // #include <stdlib.h>
 // #include <string.h>
 // #include "cephd/libcephd.h"
+// #include "rados/librados.h"
 import "C"
 
 import (
@@ -18,6 +19,14 @@ import (
 	"unsafe"
 )
 
+// Version returns the major, minor, and patch components of the version of
+// the RADOS library linked against.
+func RadosVersion() (int, int, int) {
+	var c_major, c_minor, c_patch C.int
+	C.rados_version(&c_major, &c_minor, &c_patch)
+	return int(c_major), int(c_minor), int(c_patch)
+}
+
 // cephdError represents an error
 type cephdError int