Add MXS_MODULE_PARAM_QUOTEDSTRING configuration value type

A quoted string is a string enclosed in '"':s. This makes it clear
where the string begins and ends, avoiding ambiguity with whitespace.
After the config file has been loaded, the '"':s at the beginning
and at the end of the string are erased. Querying the config value
with config_get_string() will return this de-quoted value.

For example, if the config file reads 'my_string="test""', the actual
string will be 'test"'.

include/maxscale/modinfo.h

@@ -79,6 +79,7 @@ enum mxs_module_param_type
     MXS_MODULE_PARAM_SIZE, /**< Size in bytes */
     MXS_MODULE_PARAM_BOOL, /**< Boolean value */
     MXS_MODULE_PARAM_STRING, /**< String value */
+    MXS_MODULE_PARAM_QUOTEDSTRING, /**< String enclosed in '"':s */
     MXS_MODULE_PARAM_ENUM, /**< Enumeration of string values */
     MXS_MODULE_PARAM_PATH, /**< Path to a file or a directory */
     MXS_MODULE_PARAM_SERVICE, /**< Service name */
@@ -233,6 +234,8 @@ static inline const char* mxs_module_param_type_to_string(enum mxs_module_param_
         return "bool";
     case MXS_MODULE_PARAM_STRING:
         return "string";
+    case MXS_MODULE_PARAM_QUOTEDSTRING:
+        return "quoted string";
     case MXS_MODULE_PARAM_ENUM:
         return "enum";
     case MXS_MODULE_PARAM_PATH:

server/core/config.cc

@@ -3601,6 +3601,15 @@ void config_fix_param(const MXS_MODULE_PARAM *params, MXS_CONFIG_PARAMETER *p)
                 fix_serverlist(p->value);
                 break;
 
+            case MXS_MODULE_PARAM_QUOTEDSTRING:
+                {   // Remove the '"':s from the ends of the string
+                    char* value = p->value;
+                    size_t len = strlen(value);
+                    value[len - 1] = '\0';
+                    memmove(value, value + 1, len - 1);
+                }
+                break;
+
             default:
                 break;
             }
@@ -3697,6 +3706,17 @@ bool config_param_is_valid(const MXS_MODULE_PARAM *params, const char *key,
                 }
                 break;
 
+            case MXS_MODULE_PARAM_QUOTEDSTRING:
+                valid = false;
+                {
+                    size_t len = strlen(value);
+                    if ((len >= 2) && (value[0] == '"') && (value[len - 1] == '"'))
+                    {
+                        valid = true;
+                    }
+                }
+                break;
+
             case MXS_MODULE_PARAM_ENUM:
                 if (params[i].accepted_values)
                 {