MySQL Connector/C Release Notes  /  Changes in MySQL Connector/C 6.1  /  Changes in MySQL Connector/C 6.1.3 (2013-12-27)

Changes in MySQL Connector/C 6.1.3 (2013-12-27)

Security Notes

  • A new MYSQL_OPT_SSL_ENFORCE option is available for the mysql_options() C API function to indicate whether to require the connection to use SSL. If enabled, an encrypted connection is attempted. If an encrypted connection cannot be established, the connection attempt fails.

    For more information, see mysql_options().

Functionality Added or Changed

  • Some dependencies between client-side plugin header files were removed:

    • The MYSQL_PLUGIN_EXPORT macro required by plugin declarations is now declared directly in mysql/client_plugin.h instead of getting the definition from mysql/plugin.h. That macro was the only thing required by client-side plugins and declared in server-side header mysql/plugin.h, so including mysql/client_plugin.h in an application no longer requires the application to also include mysql/plugin.h.

    • mysql/plugin_trace.h no longer uses C_MODE_START or C_MODE_END. Consequently, including mysql/plugin_trace.h in an application no longer requires the application to also include my_global.h.

    Applications might require mysql/plugin.h or my_global.h for other reasons, of course. (Bug #17582168)

  • The mysql_version.h file defines two new macros, LIBMYSQL_VERSION and LIBMYSQL_VERSION_ID, that indicate the string and numeric forms of the client library version.

    • In the client library included with MySQL Server distributions, these macros have the same values as MYSQL_SERVER_VERSION and MYSQL_VERSION_ID. For example, in MySQL 5.7.4, MYSQL_SERVER_VERSION and LIBMYSQL_VERSION are "5.7.4-m14", and MYSQL_VERSION_ID and LIBMYSQL_VERSION_ID are 50704.

    • In the client library included with Connector/C distributions, MYSQL_SERVER_VERSION and MYSQL_VERSION_ID have the values of the MySQL version on which the Connector/C distribution is based, whereas LIBMYSQL_VERSION and LIBMYSQL_VERSION_ID indicate the Connector/C version. For example, Connector/C 6.1.3 is based on MySQL 5.7.4, so MYSQL_SERVER_VERSION and MYSQL_VERSION_ID have values of "5.7.4-m14" and 50704, whereas LIBMYSQL_VERSION and LIBMYSQL_VERSION_ID have values of "6.1.3" and 60103.

    In addition, the mysql_get_client_info() and mysql_get_client_version() C API functions in the client library now return values that reflect the type of distribution that provides the client library:

    (Bug #17171724)

  • Connector/C is now included in MySQL Installer (Windows).

  • A new mysql_get_option() C API function is available that returns the current value of applicable mysql_options() options. See mysql_get_option().

  • When a connection is returned to the thread pool plugin, the connection thread context must be cleaned up. Previously, this was done using COM_CHANGE_USER (which is like the mysql_change_user() C API function). However, that operation reauthenticates, which is unnecessary network roundtrip overhead in this context.

    Now it is possible for client connection state to be reset in a more lightweight manner without causing reauthentication. The API is exposed publicly through these changes:

    • A new COM_RESET_CONNECTION protocol command (defined in mysql_com.h)

    • A new mysql_reset_connection() C API function

    • A new resetconnection command for the mysql client

    Resetting a connection has effects similar to mysql_change_user() or an auto-reconnect except that the connection is not closed and reopened, and reauthentication is not done. See mysql_change_user()) and see Controlling Automatic Reconnection Behavior).

    For more information, see mysql_reset_connection() and mysql — The MySQL Command-Line Tool.

  • Because there are new API functions (mysql_get_option(), mysql_reset_connection()), the library ABI version is now 18.2. Shared library names now include 18.2 where appropriate.

Bugs Fixed

  • The C client library could leak memory when client plugins were used. (Bug #17933308)

  • It was not possible to build client-side plugins using Connector/C because client_plugin.h referenced a macro defined in the plugin.h file, which is not included in Connector/C distributions. (Bug #17582228)

    References: See also Bug #17582168.

  • Upgrading Connector/C using the 64-bit version of the Windows MSI package occurred in the default folder because registry search logic was hardcoded to use the 32-bit registry. (Bug #17515067)

  • After the fix for Bug #16409270, it was not possible to #include <mysql.h> following #include <windows.h>. (Bug #17514554)

  • A client crash occurred if mysql_set_server_option() or several other C API functions were called before mysql_real_connect(). (Bug #17338958)

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