lib: fix parse commnad line arguments

Adds a placeholder string at argv[0] position because Ceph will start
parsing the provided arguments at position argv[1] (skipping what would
normally be the executable name).

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>

conn.go

@@ -179,12 +179,20 @@ func (c *Conn) GetClusterStats() (stat ClusterStat, err error) {
 
 // ParseCmdLineArgs configures the connection from command line arguments.
 func (c *Conn) ParseCmdLineArgs(args []string) error {
-    argc := C.int(len(args))
+    // add an empty element 0 -- Ceph treats the array as the actual contents
+    // of argv and skips the first element (the executable name)
+    argc := C.int(len(args) + 1)
     argv := make([]*C.char, argc)
+
+    // make the first element a string just in case it is ever examined
+    argv[0] = C.CString("placeholder")
+    defer C.free(unsafe.Pointer(argv[0]))
+
     for i, arg := range args {
-        argv[i] = C.CString(arg)
-        defer C.free(unsafe.Pointer(argv[i]))
+        argv[i+1] = C.CString(arg)
+        defer C.free(unsafe.Pointer(argv[i+1]))
     }
+
     ret := C.rados_conf_parse_argv(c.cluster, argc, &argv[0])
     if ret < 0 {
         return RadosError(int(ret))

rados_test.go

@@ -56,16 +56,17 @@ func TestParseDefaultConfigEnv(t *testing.T) {
 
 func TestParseCmdLineArgs(t *testing.T) {
     conn, _ := rados.NewConn()
+    conn.ReadDefaultConfigFile()
 
-    log_file_val, _ := conn.GetConfigOption("mon_host")
-    assert.NotEqual(t, log_file_val, "127.0.0.1")
+    mon_host_val, _ := conn.GetConfigOption("mon_host")
+    assert.NotEqual(t, mon_host_val, "1.1.1.1")
 
-    args := []string{ "--mon-host 127.0.0.1" }
+    args := []string{ "--mon-host", "1.1.1.1" }
     err := conn.ParseCmdLineArgs(args)
     assert.NoError(t, err)
 
-    log_file_val, _ = conn.GetConfigOption("mon_host")
-    assert.Equal(t, log_file_val, "127.0.0.1")
+    mon_host_val, _ = conn.GetConfigOption("mon_host")
+    assert.Equal(t, mon_host_val, "1.1.1.1")
 }
 
 func TestGetClusterStats(t *testing.T) {