anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer Class Reference

Error handler that wraps parse error messages, removes details and silences warnings. More...

Inheritance diagram for anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer:

Public Member Functions
	Parse_error_anonymizer (THD *thd, Item *arg)
bool	handle_condition (THD *, uint, const char *, Sql_condition::enum_severity_level *level, const char *message) override
	Handle a sql condition. More...
	~Parse_error_anonymizer () override

Private Attributes
THD *	m_thd
Item *	m_arg
bool	is_handling = false
	This avoids infinite recursion through my_error(). More...

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

Error handler that wraps parse error messages, removes details and silences warnings.

We don't want statement_digest() to raise warnings about deprecated syntax or semantic problems. This is likely not interesting to the caller. Therefore this handler issues a blanket silencing of all warnings.

The reason we want to anonymize parse errors is to avoid leaking information in error messages that may be unintentionally visible to users of an application. For instance an application may in error insert an expression instead of a string:

SELECT statement_digest( (SELECT * FROM( SELECT user() ) t) );

The parser would normally raise an error saying:

You have an error in your SQL syntax; /.../ near 'root@localhost'

thus leaking data from the user table. Therefore, the errors are in this not disclosed.

Constructor & Destructor Documentation

Parse_error_anonymizer()

anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::Parse_error_anonymizer ( THD *  thd, Item *  arg  )

inline

~Parse_error_anonymizer()

anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::~Parse_error_anonymizer ( )

inlineoverride

Member Function Documentation

handle_condition()

bool anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::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

is_handling

bool anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::is_handling = false

private

This avoids infinite recursion through my_error().

m_arg

Item* anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::m_arg

private

m_thd

THD* anonymous_namespace{item_strfunc.cc}::Parse_error_anonymizer::m_thd

private

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

• sql/item_strfunc.cc