Show_create_error_handler Class Reference

An Internal_error_handler that suppresses errors regarding views' underlying tables that occur during privilege checking within SHOW CREATE VIEW commands. More...

Inheritance diagram for Show_create_error_handler:

Public Member Functions
	Show_create_error_handler (THD *thd, Table_ref *top_view)
	Creates a new Show_create_error_handler for the particular security context and view. More...
bool	handle_condition (THD *thd, uint sql_errno, const char *, Sql_condition::enum_severity_level *, const char *msg) override
	Handle a sql condition. More...

Private Member Functions
const char *	get_view_access_denied_message (THD *thd)
	Lazy instantiation of 'view access denied' message. More...

Private Attributes
Table_ref *	m_top_view
bool	m_handling
Security_context *	m_sctx
char	m_view_access_denied_message [MYSQL_ERRMSG_SIZE]
const char *	m_view_access_denied_message_ptr

Additional Inherited Members
Protected Member Functions inherited from Internal_error_handler
	Internal_error_handler ()
Internal_error_handler *	prev_internal_handler () const
virtual	~Internal_error_handler ()=default

Detailed Description

An Internal_error_handler that suppresses errors regarding views' underlying tables that occur during privilege checking within SHOW CREATE VIEW commands.

This happens in the cases when

• A view's underlying table (e.g. referenced in its SELECT list) does not exist or columns of underlying table are altered. There should not be an error as no attempt was made to access it per se.
• Access is denied for some table, column, function or stored procedure such as mentioned above. This error gets raised automatically, since we can't untangle its access checking from that of the view itself.

Constructor & Destructor Documentation

Show_create_error_handler()

Show_create_error_handler::Show_create_error_handler ( THD *  thd, Table_ref *  top_view  )

inlineexplicit

Creates a new Show_create_error_handler for the particular security context and view.

Parameters

thd	Thread context, used for security context information if needed.
top_view	The view. We do not verify at this point that top_view is in fact a view since, alas, these things do not stay constant.

Member Function Documentation

get_view_access_denied_message()

const char * Show_create_error_handler::get_view_access_denied_message ( THD *  thd )

inlineprivate

Lazy instantiation of 'view access denied' message.

The purpose of the Show_create_error_handler is to hide details of underlying tables for which we have no privileges behind ER_VIEW_INVALID messages. But this obviously does not apply if we lack privileges on the view itself. Unfortunately the information about for which table privilege checking failed is not available at this point. The only way for us to check is by reconstructing the actual error message and see if it's the same.

handle_condition()

bool Show_create_error_handler::handle_condition ( THD *  thd, uint  sql_errno, const char *  sqlstate, Sql_condition::enum_severity_level *  level, const char *  msg  )

inlineoverridevirtual

Handle a sql condition.

This method can be implemented by a subclass to achieve any of the following:

• mask a warning/error internally, prevent exposing it to the user,
• mask a warning/error and throw another one instead. When this method returns true, the sql condition is considered 'handled', and will not be propagated to upper layers. It is the responsibility of the code installing an internal handler to then check for trapped conditions, and implement logic to recover from the anticipated conditions trapped during runtime.

This mechanism is similar to C++ try/throw/catch:

• 'try' correspond to THD::push_internal_handler(),
• 'throw' correspond to my_error(), which invokes my_message_sql(),
• 'catch' correspond to checking how/if an internal handler was invoked, before removing it from the exception stack with THD::pop_internal_handler().

Parameters

thd	the calling thread
sql_errno	the error number for the condition raised.
sqlstate	the SQLSTATE for the condition raised.
level	the severity level for the condition raised.
msg	the error message for the condition raised.

Returns

true if the condition is handled

Implements Internal_error_handler.

Member Data Documentation

m_handling

bool Show_create_error_handler::m_handling

private

m_sctx

Security_context* Show_create_error_handler::m_sctx

private

m_top_view

Table_ref* Show_create_error_handler::m_top_view

private

m_view_access_denied_message

char Show_create_error_handler::m_view_access_denied_message[MYSQL_ERRMSG_SIZE]

private

m_view_access_denied_message_ptr

const char* Show_create_error_handler::m_view_access_denied_message_ptr

private

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The documentation for this class was generated from the following file:

• sql/sql_show.cc