MXS-2274 Reserve names starting with @@ for use by MaxScale

Names starting with '@@' can now longer be used in configuration files.
Subsequent commits will prevent such names from being used when objects
are created dynamically.

Documentation/Changelog.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## MariaDB MaxScale 2.4
+
+* Names starting with `@@` are reserved for use by MaxScale.
+
+For more details, please refer to:
+
+* [MariaDB MaxScale 2.4.0 Release Notes](Release-Notes/MaxScale-2.4.0-Release-Notes.md)
+
 ## MariaDB MaxScale 2.3
 
 * Runtime Configuration of the Cache

Documentation/Release-Notes/MaxScale-2.4.0-Release-Notes.md

@@ -0,0 +1,45 @@
+# MariaDB MaxScale 2.4.0 Release Notes
+
+Release 2.4.0 is a Beta release.
+
+This document describes the changes in release 2.4.0, when compared to
+release 2.3.
+
+For any problems you encounter, please consider submitting a bug
+report at [Jira](https://jira.mariadb.org).
+
+## Changed Features
+
+### Section and object names
+
+Section and object names starting with `@@` are now reserved for
+use by MaxScale itself. If any such names are encountered in
+configuration files, then MaxScale will not start.
+
+## Dropped Features
+
+## New Features
+
+## Bug fixes
+
+[Here is a list of bugs fixed in MaxScale 2.4.0.](https://jira.mariadb.org/issues/?jql=project%20%3D%20MXS%20AND%20issuetype%20%3D%20Bug%20AND%20status%20%3D%20Closed%20AND%20fixVersion%20%3D%202.4.0)
+
+## Known Issues and Limitations
+
+There are some limitations and known issues within this version of MaxScale.
+For more information, please refer to the [Limitations](../About/Limitations.md) document.
+
+## Packaging
+
+RPM and Debian packages are provided for the Linux distributions supported
+by MariaDB Enterprise.
+
+Packages can be downloaded [here](https://mariadb.com/resources/downloads).
+
+## Source Code
+
+The source code of MaxScale is tagged at GitHub with a tag, which is identical
+with the version of MaxScale. For instance, the tag of version X.Y.Z of MaxScale
+is X.Y.Z. Further, *master* always refers to the latest released non-beta version.
+
+The source code is available [here](https://github.com/mariadb-corporation/MaxScale).

Documentation/Upgrading/Upgrading-To-MaxScale-2.4.md

@@ -0,0 +1,24 @@
+# Upgrading MariaDB MaxScale from 2.3 to 2.4
+
+This document describes possible issues when upgrading MariaDB
+MaxScale from version 2.3 to 2.4.
+
+For more information about MariaDB MaxScale 2.4, please refer
+to the [ChangeLog](../Changelog.md).
+
+Before starting the upgrade, we recommend you back up your current
+configuration file.
+
+## Section Names
+
+Section and object names starting with `@@` are now reserved for
+internal use by MaxScale.
+
+In case such names have been used, they must manually be changed
+in all configuration files of MaxScale, before MaxScale 2.4 is started.
+
+Those files are:
+
+* The main configuration file; typically `/etc/maxscale.cnf`.
+* All nested configuration files; typically `/etc/maxscale.cnf.d/*`.
+* All dynamic configuration files; typically `/var/lib/maxscale/maxscale.cnd.d/*`.

include/maxscale/config.hh

@@ -601,6 +601,22 @@ bool config_set_writeq_low_water(uint32_t size);
 bool config_parse_disk_space_threshold(SERVER::DiskSpaceLimits* disk_space_threshold,
                                        const char* config_value);
 
+/**
+ * @brief Check whether section/object name is valid.
+ *
+ * @param name     The name to be checked.
+ * @param reason   If non-null, will in case the name is not valid contain
+ *                 the reason when the function returns.
+ *
+ * @return True, if the name is valid, false otherwise.
+ */
+bool config_is_valid_name(const char* name, std::string* reason = nullptr);
+
+inline bool config_is_valid_name(const std::string& name, std::string* reason = nullptr)
+{
+    return config_is_valid_name(name.c_str());
+}
+
 
 namespace maxscale
 {

server/core/config.cc

@@ -751,6 +751,23 @@ static int ini_handler(void* userdata, const char* section, const char* name, co
     strcpy(fixed_section, section);
     fix_section_name(fixed_section);
 
+    string reason;
+    if (!config_is_valid_name(fixed_section, &reason))
+    {
+        /* A set that holds all the section names that are invalid. As the configuration file
+         * is parsed multiple times, we need to do this to prevent the same complaint from
+         * being logged multiple times.
+         */
+        static std::set<string> warned_invalid_names;
+
+        if (warned_invalid_names.find(reason) == warned_invalid_names.end())
+        {
+            MXS_ERROR("%s", reason.c_str());
+            warned_invalid_names.insert(reason);
+        }
+        return 0;
+    }
+
     /*
      * If we already have some parameters for the object
      * add the parameters to that object. If not create
@@ -5038,3 +5055,40 @@ std::string closest_matching_parameter(const std::string& str,
 
     return rval;
 }
+
+bool config_is_valid_name(const char* zName, std::string* pReason)
+{
+    bool is_valid = true;
+
+    for (const char* z = zName; is_valid && *z; z++)
+    {
+        if (isspace(*z))
+        {
+            is_valid = false;
+
+            if (pReason)
+            {
+                *pReason = "The name '";
+                *pReason += zName;
+                *pReason += "' contains whitespace.";
+            }
+        }
+    }
+
+    if (is_valid)
+    {
+        if (strncmp(zName, "@@", 2) == 0)
+        {
+            is_valid = false;
+
+            if (pReason)
+            {
+                *pReason = "The name '";
+                *pReason += zName;
+                *pReason += "' starts with '@@', which is a prefix reserved for MaxScale.";
+            }
+        }
+    }
+
+    return is_valid;
+}