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     sqlite3_set_authorizer - Compile-Time Authorization Callbacks

         int (*xAuth)(void*,int,const char*,const
         char*,const char*,const char*), void *pUserData );

     This routine registers an authorizer callback with a particular database
     connection, supplied in the first argument.  The authorizer callback is
     invoked as SQL statements are being compiled by sqlite3_prepare() or its
     variants sqlite3_prepare_v2(), sqlite3_prepare_v3(), sqlite3_prepare16(),
     sqlite3_prepare16_v2(), and sqlite3_prepare16_v3().  At various points
     during the compilation process, as logic is being created to perform
     various actions, the authorizer callback is invoked to see if those
     actions are allowed.  The authorizer callback should return SQLITE_OK to
     allow the action, SQLITE_IGNORE to disallow the specific action but allow
     the SQL statement to continue to be compiled, or SQLITE_DENY to cause the
     entire SQL statement to be rejected with an error.  If the authorizer
     callback returns any value other than SQLITE_IGNORE, SQLITE_OK, or
     SQLITE_DENY then the sqlite3_prepare_v2() or equivalent call that
     triggered the authorizer will fail with an error message.

     When the callback returns SQLITE_OK, that means the operation requested
     is ok.  When the callback returns SQLITE_DENY, the sqlite3_prepare_v2()
     or equivalent call that triggered the authorizer will fail with an error
     message explaining that access is denied.

     The first parameter to the authorizer callback is a copy of the third
     parameter to the sqlite3_set_authorizer() interface.  The second
     parameter to the callback is an integer  action code that specifies the
     particular action to be authorized.  The third through sixth parameters
     to the callback are either NULL pointers or zero-terminated strings that
     contain additional details about the action to be authorized.
     Applications must always be prepared to encounter a NULL pointer in any
     of the third through the sixth parameters of the authorization callback.

     If the action code is SQLITE_READ and the callback returns SQLITE_IGNORE
     then the prepared statement statement is constructed to substitute a NULL
     value in place of the table column that would have been read if SQLITE_OK
     had been returned.  The SQLITE_IGNORE return can be used to deny an
     untrusted user access to individual columns of a table.  When a table is
     referenced by a SELECT but no column values are extracted from that table
     (for example in a query like "SELECT count(*) FROM tab") then the
     SQLITE_READ authorizer callback is invoked once for that table with a
     column name that is an empty string.  If the action code is SQLITE_DELETE
     and the callback returns SQLITE_IGNORE then the DELETE operation proceeds
     but the truncate optimization is disabled and all rows are deleted

     An authorizer is used when  preparing SQL statements from an untrusted
     source, to ensure that the SQL statements do not try to access data they
     are not allowed to see, or that they do not try to execute malicious
     statements that damage the database.  For example, an application may
     allow a user to enter arbitrary SQL queries for evaluation by a database.
     But the application does not want the user to be able to make arbitrary
     changes to the database.  An authorizer could then be put in place while
     the user-entered SQL is being  prepared that disallows everything except
     SELECT statements.

     Applications that need to process SQL from untrusted sources might also
     consider lowering resource limits using sqlite3_limit() and limiting
     database size using the max_page_count PRAGMA in addition to using an

     Only a single authorizer can be in place on a database connection at a
     time.  Each call to sqlite3_set_authorizer overrides the previous call.
     Disable the authorizer by installing a NULL callback.  The authorizer is
     disabled by default.

     The authorizer callback must not do anything that will modify the
     database connection that invoked the authorizer callback.  Note that
     sqlite3_prepare_v2() and sqlite3_step() both modify their database
     connections for the meaning of "modify" in this paragraph.

     When sqlite3_prepare_v2() is used to prepare a statement, the statement
     might be re-prepared during sqlite3_step() due to a schema change.
     Hence, the application should ensure that the correct authorizer callback
     remains in place during the sqlite3_step().

     Note that the authorizer callback is invoked only during
     sqlite3_prepare() or its variants.  Authorization is not performed during
     statement evaluation in sqlite3_step(), unless as stated in the previous
     paragraph, sqlite3_step() invokes sqlite3_prepare_v2() to reprepare a
     statement after a schema change.

     sqlite3(3), sqlite3_stmt(3), sqlite3_limit(3), sqlite3_prepare(3),
     sqlite3_step(3), SQLITE_CREATE_INDEX(3), SQLITE_DENY(3), SQLITE_OK(3),

NetBSD 9.99                    December 19, 2018                   NetBSD 9.99