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Overview
Comment:Improved documentation for SQLITE_DBCONFIG_DEFENSIVE. Add a NEVER() macro on an unreachable branch.
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SHA3-256: 9292d3351c40339de7ad6bc26c02e7592e6cdee2592e0c790fae63ccf21ea88c
User & Date: drh 2018-11-08 17:32:50.888
References
2018-11-10
04:14
Remove a NEVER() that is reachable after all. Reverts checkin [9292d3351c40339]. (Closed-Leaf check-in: c5dc7fb873 user: drh tags: read-only-shadow)
Context
2018-11-10
03:47
Merge fixes from trunk. (check-in: bf88efcec4 user: drh tags: read-only-shadow)
2018-11-08
17:32
Improved documentation for SQLITE_DBCONFIG_DEFENSIVE. Add a NEVER() macro on an unreachable branch. (check-in: 9292d3351c user: drh tags: read-only-shadow)
2018-11-07
16:46
Performance improvement in subroutine that decides whether or not a table is read-only. (check-in: 6e4968b005 user: drh tags: read-only-shadow)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/build.c.
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  if( zTail==0 ) return 0;
  *zTail = 0;
  pTab = sqlite3FindTable(db, zName, 0);
  *zTail = '_';
  if( pTab==0 ) return 0;
  if( !IsVirtual(pTab) ) return 0;
  pMod = (Module*)sqlite3HashFind(&db->aModule, pTab->azModuleArg[0]);
  if( pMod==0 ) return 0;
  if( pMod->pModule->iVersion<3 ) return 0;
  if( pMod->pModule->xShadowName==0 ) return 0;
  return pMod->pModule->xShadowName(zTail+1);
}

/*
** This routine is called to report the final ")" that terminates








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  if( zTail==0 ) return 0;
  *zTail = 0;
  pTab = sqlite3FindTable(db, zName, 0);
  *zTail = '_';
  if( pTab==0 ) return 0;
  if( !IsVirtual(pTab) ) return 0;
  pMod = (Module*)sqlite3HashFind(&db->aModule, pTab->azModuleArg[0]);
  if( NEVER(pMod==0) ) return 0;
  if( pMod->pModule->iVersion<3 ) return 0;
  if( pMod->pModule->xShadowName==0 ) return 0;
  return pMod->pModule->xShadowName(zTail+1);
}

/*
** This routine is called to report the final ")" that terminates
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Changes to src/sqlite.h.in.
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** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
** </ol>
** Because resetting a database is destructive and irreversible, the
** process requires the use of this obscure API and multiple steps to help
** ensure that it does not happen by accident.
**
** <dt>SQLITE_DBCONFIG_DEFENSIVE</dt>
** <dd>The SQLITE_DBCONFIG_DEFENSIVE option actives or deactivates the
** "defensive" flag for a database connection.  When the defensive
** flag is enabled, some obscure features of SQLite are disabled in order
** to reduce the attack surface. Applications that run untrusted SQL
** can activate this flag to reduce the risk of zero-day exploits.
** <p>
** Features disabled by the defensive flag include:
** <ul>
** <li>The [PRAGMA writable_schema=ON] statement.
** <li>Writes to the [sqlite_dbpage] virtual table.

** </ul>
** New restrictions may be added in future releases.
** <p>
** To be clear: It should never be possible for hostile SQL to cause
** arbitrary memory reads, memory leaks, buffer overflows, assertion
** faults, arbitrary code execution, crashes, or other mischief, regardless
** of the value of the defensive flag.  Any occurrance of these problems
** is considered a serious bug and will be fixed promptly.  It is not
** necessary to enable the defensive flag in order to make SQLite secure
** against attack. The defensive flag merely provides an additional layer
** of defense against unknown vulnerabilities.
** </dd>
** </dl>
*/
#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */








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** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
** </ol>
** Because resetting a database is destructive and irreversible, the
** process requires the use of this obscure API and multiple steps to help
** ensure that it does not happen by accident.
**
** <dt>SQLITE_DBCONFIG_DEFENSIVE</dt>
** <dd>The SQLITE_DBCONFIG_DEFENSIVE option activates or deactivates the
** "defensive" flag for a database connection.  When the defensive
** flag is enabled, language features that allow ordinary SQL to 
** deliberately corrupt the database file are disabled.  The disabled


** features include but are not limited to the following:
** <ul>
** <li> The [PRAGMA writable_schema=ON] statement.
** <li> Writes to the [sqlite_dbpage] virtual table.
** <li> Direct writes to shadow tables.
** </ul>










** </dd>
** </dl>
*/
#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
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