SQLite

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.428 2008/03/20 18:00:49 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#ifdef SQLITE_ENABLE_FTS3
# include "fts3.h"
#endif

int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
  int oldLimit;
  if( limitId<0 || limitId>SQLITE_N_LIMIT ){
    return -1;
  }
  oldLimit = db->aLimit[limitId];
  if( newLimit>=0 ){
    if( newLimit>aHardLimit[limitId] ){


      newLimit = aHardLimit[limitId];
    }
    db->aLimit[limitId] = newLimit;
  }
  return oldLimit;
}

** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.298 2008/03/20 18:00:49 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.

*/
void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks {F12500}
**
** This routine registers a 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_prepare16()] and [sqlite3_prepare16_v2()].  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 [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.  If the authorizer 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.
**
** 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 
** [SQLITE_COPY | action code] that specifies the particular action
** to be authorized. The third through sixth
** parameters to the callback are zero-terminated strings that contain 
** additional details about the action to be authorized.
**
** An authorizer is used when [sqlite3_prepare | preparing]
** SQL statements from an untrusted
** source, to ensure that the SQL statements do not try to access data
** that 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 [sqlite3_prepare | 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 authorizer.
**
** 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.
**
** Note that the authorizer callback is invoked only during 

** on a connection by connection basis.  The first parameter is the
** [database connection] whose limit is to be set or queried.  The
** second parameter is one of the [limit categories] that define a
** class of constructs to be size limited.  The third parameter is the
** new limit for that construct.  The function returns the old limit.
**
** If the new limit is a negative number, the limit is unchanged.


** For the limit category of SQLITE_LIMIT_XYZ there is a hard upper
** bound set by a compile-time C-preprocess macro named SQLITE_MAX_XYZ.
** (The "_LIMIT_" in the name is changed to "_MAX_".)
** Attempts to increase a limit above its hard upper bound are
** silently truncated to the hard upper limit.
**
** Run time limits are intended for use in applications that manage
** both their own internal database and also databases that are controlled
** by untrusted external sources.  An example application might be a
** webbrowser that has its own databases for storing history and
** separate databases controlled by javascript applications downloaded
** off the internet.  The internal databases can be given the
** large, default limits.  Databases managed by external sources can
** be given much smaller limits designed to prevent a denial of service
** attach.  Developers might also want to use the [sqlite3_set_authorizer()]
** interface to further control untrusted SQL.  The size of the database
** created by an untrusted script can be contained using the
** [max_page_count] [PRAGMA].
**
** This interface is currently considered experimental and is subject
** to change or removal without prior notice.
**
** INVARIANTS:
**
** {F12762} A successful call to [sqlite3_limit(D,C,V)] where V is
**          positive changes the
**          limit on the size of construct C in [database connection] D
**          to the lessor of V and the hard upper bound on the size
**          of C that is set at compile-time.
**
** {F12764} A successful call to [sqlite3_limit(D,C,V)] where V is zero
**          changes the limit on the size of construct C in
**          [database connection] D to be the hard upper bound on the size
**          of C that is set at compile-time.
**
** {F12766} A successful call to [sqlite3_limit(D,C,V)] where V is negative
**          leaves the state of [database connection] D unchanged.
**

#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file contains tests to verify that the limits defined in
# sqlite source file limits.h are enforced.
#
# $Id: sqllimits1.test,v 1.26 2008/03/20 18:00:49 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Verify that the default per-connection limits are the same as
# the compile-time hard limits.
#

  sqlite3_limit db SQLITE_LIMIT_LIKE_PATTERN_LENGTH -1
} $SQLITE_MAX_LIKE_PATTERN_LENGTH
do_test sqllimits1-4.10.1 {
  sqlite3_limit db SQLITE_LIMIT_VARIABLE_NUMBER 0x7fffffff
  sqlite3_limit db SQLITE_LIMIT_VARIABLE_NUMBER -1
} $SQLITE_MAX_VARIABLE_NUMBER



#--------------------------------------------------------------------
# Test cases sqllimits1-5.* test that the SQLITE_MAX_LENGTH limit
# is enforced.
#
db close
sqlite3 db test.db
set LARGESIZE 99999

  set tail " /* A comment to take up space in order to make the string\
                longer without increasing the expression depth */\
                AND   1  ==  1"
  set N [expr {(50000 / [string length $tail])+1}]
  append sql [string repeat $tail $N]
  catchsql $sql
} {1 {String or BLOB exceeded size limit}}




do_test sqllimits1-6.3 {
  sqlite3_limit db SQLITE_LIMIT_SQL_LENGTH 50000
  set sql "SELECT 1 WHERE 1==1"
  set tail " /* A comment to take up space in order to make the string\
                longer without increasing the expression depth */\
                AND   1  ==  1"
  set N [expr {(50000 / [string length $tail])+1}]