/*
** 2005 May 25
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
*/
#include "sqliteInt.h"

/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
static void corruptSchema(
 InitData *pData, /* Initialization context */
 char **azObj, /* Type and name of object being parsed */
 const char *zExtra /* Error information */
){
 sqlite3 *db = pData->db;
 if( db->mallocFailed ){
 pData->rc = SQLITE_NOMEM_BKPT;
 }else if( pData->pzErrMsg[0]!=0 ){
 /* A error message has already been generated. Do not overwrite it */
 }else if( pData->mInitFlags & (INITFLAG_AlterMask) ){
 static const char *azAlterType[] = {
 "rename",
 "drop column",
 "add column"
 };
 *pData->pzErrMsg = sqlite3MPrintf(db, 
 "error in %s %s after %s: %s", azObj[0], azObj[1], 
 azAlterType[(pData->mInitFlags&INITFLAG_AlterMask)-1], 
 zExtra
 );
 pData->rc = SQLITE_ERROR;
 }else if( db->flags & SQLITE_WriteSchema ){
 pData->rc = SQLITE_CORRUPT_BKPT;
 }else{
 char *z;
 const char *zObj = azObj[1] ? azObj[1] : "?";
 z = sqlite3MPrintf(db, "malformed database schema (%s)", zObj);
 if( zExtra && zExtra[0] ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);
 *pData->pzErrMsg = z;
 pData->rc = SQLITE_CORRUPT_BKPT;
 }
}

/*
** Check to see if any sibling index (another index on the same table)
** of pIndex has the same root page number, and if it does, return true.
** This would indicate a corrupt schema.
*/
int sqlite3IndexHasDuplicateRootPage(Index *pIndex){
 Index *p;
 for(p=pIndex->pTable->pIndex; p; p=p->pNext){
 if( p->tnum==pIndex->tnum && p!=pIndex ) return 1;
 }
 return 0;
}

/* forward declaration */
static int sqlite3Prepare(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 u32 prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 Vdbe *pReprepare, /* VM being reprepared */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
);


/*
** This is the callback routine for the code that initializes the
** database. See sqlite3Init() below for additional information.
** This routine is also called from the OP_ParseSchema opcode of the VDBE.
**
** Each callback contains the following information:
**
** argv[0] = type of object: "table", "index", "trigger", or "view".
** argv[1] = name of thing being created
** argv[2] = associated table if an index or trigger
** argv[3] = root page number for table or index. 0 for trigger or view.
** argv[4] = SQL text for the CREATE statement.
**
*/
int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
 InitData *pData = (InitData*)pInit;
 sqlite3 *db = pData->db;
 int iDb = pData->iDb;

 assert( argc==5 );
 UNUSED_PARAMETER2(NotUsed, argc);
 assert( sqlite3_mutex_held(db->mutex) );
 db->mDbFlags |= DBFLAG_EncodingFixed;
 if( argv==0 ) return 0; /* Might happen if EMPTY_RESULT_CALLBACKS are on */
 pData->nInitRow++;
 if( db->mallocFailed ){
 corruptSchema(pData, argv, 0);
 return 1;
 }

 assert( iDb>=0 && iDb<db->nDb );
 if( argv[3]==0 ){
 corruptSchema(pData, argv, 0);
 }else if( argv[4]
 && 'c'==sqlite3UpperToLower[(unsigned char)argv[4][0]]
 && 'r'==sqlite3UpperToLower[(unsigned char)argv[4][1]] ){
 /* Call the parser to process a CREATE TABLE, INDEX or VIEW.
 ** But because db->init.busy is set to 1, no VDBE code is generated
 ** or executed. All the parser does is build the internal data
 ** structures that describe the table, index, or view.
 **
 ** No other valid SQL statement, other than the variable CREATE statements,
 ** can begin with the letters "C" and "R". Thus, it is not possible run
 ** any other kind of statement while parsing the schema, even a corrupt
 ** schema.
 */
 int rc;
 u8 saved_iDb = db->init.iDb;
 sqlite3_stmt *pStmt;
 TESTONLY(int rcp); /* Return code from sqlite3_prepare() */

 assert( db->init.busy );
 db->init.iDb = iDb;
 if( sqlite3GetUInt32(argv[3], &db->init.newTnum)==0
 || (db->init.newTnum>pData->mxPage && pData->mxPage>0)
 ){
 if( sqlite3Config.bExtraSchemaChecks ){
 corruptSchema(pData, argv, "invalid rootpage");
 }
 }
 db->init.orphanTrigger = 0;
 db->init.azInit = (const char**)argv;
 pStmt = 0;
 TESTONLY(rcp = ) sqlite3Prepare(db, argv[4], -1, 0, 0, &pStmt, 0);
 rc = db->errCode;
 assert( (rc&0xFF)==(rcp&0xFF) );
 db->init.iDb = saved_iDb;
 /* assert( saved_iDb==0 || (db->mDbFlags & DBFLAG_Vacuum)!=0 ); */
 if( SQLITE_OK!=rc ){
 if( db->init.orphanTrigger ){
 assert( iDb==1 );
 }else{
 if( rc > pData->rc ) pData->rc = rc;
 if( rc==SQLITE_NOMEM ){
 sqlite3OomFault(db);
 }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED ){
 corruptSchema(pData, argv, sqlite3_errmsg(db));
 }
 }
 }
 db->init.azInit = sqlite3StdType; /* Any array of string ptrs will do */
 sqlite3_finalize(pStmt);
 }else if( argv[1]==0 || (argv[4]!=0 && argv[4][0]!=0) ){
 corruptSchema(pData, argv, 0);
 }else{
 /* If the SQL column is blank it means this is an index that
 ** was created to be the PRIMARY KEY or to fulfill a UNIQUE
 ** constraint for a CREATE TABLE. The index should have already
 ** been created when we processed the CREATE TABLE. All we have
 ** to do here is record the root page number for that index.
 */
 Index *pIndex;
 pIndex = sqlite3FindIndex(db, argv[1], db->aDb[iDb].zDbSName);
 if( pIndex==0 ){
 corruptSchema(pData, argv, "orphan index");
 }else
 if( sqlite3GetUInt32(argv[3],&pIndex->tnum)==0
 || pIndex->tnum<2
 || pIndex->tnum>pData->mxPage
 || sqlite3IndexHasDuplicateRootPage(pIndex)
 ){
 if( sqlite3Config.bExtraSchemaChecks ){
 corruptSchema(pData, argv, "invalid rootpage");
 }
 }
 }
 return 0;
}

/*
** Attempt to read the database schema and initialize internal
** data structures for a single database file. The index of the
** database file is given by iDb. iDb==0 is used for the main
** database. iDb==1 should never be used. iDb>=2 is used for
** auxiliary databases. Return one of the SQLITE_ error codes to
** indicate success or failure.
*/
int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
 int rc;
 int i;
#ifndef SQLITE_OMIT_DEPRECATED
 int size;
#endif
 Db *pDb;
 char const *azArg[6];
 int meta[5];
 InitData initData;
 const char *zSchemaTabName;
 int openedTransaction = 0;
 int mask = ((db->mDbFlags & DBFLAG_EncodingFixed) | ~DBFLAG_EncodingFixed);

 assert( (db->mDbFlags & DBFLAG_SchemaKnownOk)==0 );
 assert( iDb>=0 && iDb<db->nDb );
 assert( db->aDb[iDb].pSchema );
 assert( sqlite3_mutex_held(db->mutex) );
 assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

 db->init.busy = 1;

 /* Construct the in-memory representation schema tables (sqlite_schema or
 ** sqlite_temp_schema) by invoking the parser directly. The appropriate
 ** table name will be inserted automatically by the parser so we can just
 ** use the abbreviation "x" here. The parser will also automatically tag
 ** the schema table as read-only. */
 azArg[0] = "table";
 azArg[1] = zSchemaTabName = SCHEMA_TABLE(iDb);
 azArg[2] = azArg[1];
 azArg[3] = "1";
 azArg[4] = "CREATE TABLE x(type text,name text,tbl_name text,"
 "rootpage int,sql text)";
 azArg[5] = 0;
 initData.db = db;
 initData.iDb = iDb;
 initData.rc = SQLITE_OK;
 initData.pzErrMsg = pzErrMsg;
 initData.mInitFlags = mFlags;
 initData.nInitRow = 0;
 initData.mxPage = 0;
 sqlite3InitCallback(&initData, 5, (char **)azArg, 0);
 db->mDbFlags &= mask;
 if( initData.rc ){
 rc = initData.rc;
 goto error_out;
 }

 /* Create a cursor to hold the database open
 */
 pDb = &db->aDb[iDb];
 if( pDb->pBt==0 ){
 assert( iDb==1 );
 DbSetProperty(db, 1, DB_SchemaLoaded);
 rc = SQLITE_OK;
 goto error_out;
 }

 /* If there is not already a read-only (or read-write) transaction opened
 ** on the b-tree database, open one now. If a transaction is opened, it 
 ** will be closed before this function returns. */
 sqlite3BtreeEnter(pDb->pBt);
 if( sqlite3BtreeTxnState(pDb->pBt)==SQLITE_TXN_NONE ){
 rc = sqlite3BtreeBeginTrans(pDb->pBt, 0, 0);
 if( rc!=SQLITE_OK ){
 sqlite3SetString(pzErrMsg, db, sqlite3ErrStr(rc));
 goto initone_error_out;
 }
 openedTransaction = 1;
 }

 /* Get the database meta information.
 **
 ** Meta values are as follows:
 ** meta[0] Schema cookie. Changes with each schema change.
 ** meta[1] File format of schema layer.
 ** meta[2] Size of the page cache.
 ** meta[3] Largest rootpage (auto/incr_vacuum mode)
 ** meta[4] Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE
 ** meta[5] User version
 ** meta[6] Incremental vacuum mode
 ** meta[7] unused
 ** meta[8] unused
 ** meta[9] unused
 **
 ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to
 ** the possible values of meta[4].
 */
 for(i=0; i<ArraySize(meta); i++){
 sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]);
 }
 if( (db->flags & SQLITE_ResetDatabase)!=0 ){
 memset(meta, 0, sizeof(meta));
 }
 pDb->pSchema->schema_cookie = meta[BTREE_SCHEMA_VERSION-1];

 /* If opening a non-empty database, check the text encoding. For the
 ** main database, set sqlite3.enc to the encoding of the main database.
 ** For an attached db, it is an error if the encoding is not the same
 ** as sqlite3.enc.
 */
 if( meta[BTREE_TEXT_ENCODING-1] ){ /* text encoding */
 if( iDb==0 && (db->mDbFlags & DBFLAG_EncodingFixed)==0 ){
 u8 encoding;
#ifndef SQLITE_OMIT_UTF16
 /* If opening the main database, set ENC(db). */
 encoding = (u8)meta[BTREE_TEXT_ENCODING-1] & 3;
 if( encoding==0 ) encoding = SQLITE_UTF8;
#else
 encoding = SQLITE_UTF8;
#endif
 if( db->nVdbeActive>0 && encoding!=ENC(db)
 && (db->mDbFlags & DBFLAG_Vacuum)==0
 ){
 rc = SQLITE_LOCKED;
 goto initone_error_out;
 }else{
 sqlite3SetTextEncoding(db, encoding);
 }
 }else{
 /* If opening an attached database, the encoding much match ENC(db) */
 if( (meta[BTREE_TEXT_ENCODING-1] & 3)!=ENC(db) ){
 sqlite3SetString(pzErrMsg, db, "attached databases must use the same"
 " text encoding as main database");
 rc = SQLITE_ERROR;
 goto initone_error_out;
 }
 }
 }
 pDb->pSchema->enc = ENC(db);

 if( pDb->pSchema->cache_size==0 ){
#ifndef SQLITE_OMIT_DEPRECATED
 size = sqlite3AbsInt32(meta[BTREE_DEFAULT_CACHE_SIZE-1]);
 if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }
 pDb->pSchema->cache_size = size;
#else
 pDb->pSchema->cache_size = SQLITE_DEFAULT_CACHE_SIZE;
#endif
 sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
 }

 /*
 ** file_format==1 Version 3.0.0.
 ** file_format==2 Version 3.1.3. // ALTER TABLE ADD COLUMN
 ** file_format==3 Version 3.1.4. // ditto but with non-NULL defaults
 ** file_format==4 Version 3.3.0. // DESC indices. Boolean constants
 */
 pDb->pSchema->file_format = (u8)meta[BTREE_FILE_FORMAT-1];
 if( pDb->pSchema->file_format==0 ){
 pDb->pSchema->file_format = 1;
 }
 if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){
 sqlite3SetString(pzErrMsg, db, "unsupported file format");
 rc = SQLITE_ERROR;
 goto initone_error_out;
 }

 /* Ticket #2804: When we open a database in the newer file format,
 ** clear the legacy_file_format pragma flag so that a VACUUM will
 ** not downgrade the database and thus invalidate any descending
 ** indices that the user might have created.
 */
 if( iDb==0 && meta[BTREE_FILE_FORMAT-1]>=4 ){
 db->flags &= ~(u64)SQLITE_LegacyFileFmt;
 }

 /* Read the schema information out of the schema tables
 */
 assert( db->init.busy );
 initData.mxPage = sqlite3BtreeLastPage(pDb->pBt);
 {
 char *zSql;
 zSql = sqlite3MPrintf(db, 
 "SELECT*FROM\"%w\".%s ORDER BY rowid",
 db->aDb[iDb].zDbSName, zSchemaTabName);
#ifndef SQLITE_OMIT_AUTHORIZATION
 {
 sqlite3_xauth xAuth;
 xAuth = db->xAuth;
 db->xAuth = 0;
#endif
 rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);
#ifndef SQLITE_OMIT_AUTHORIZATION
 db->xAuth = xAuth;
 }
#endif
 if( rc==SQLITE_OK ) rc = initData.rc;
 sqlite3DbFree(db, zSql);
#ifndef SQLITE_OMIT_ANALYZE
 if( rc==SQLITE_OK ){
 sqlite3AnalysisLoad(db, iDb);
 }
#endif
 }
 assert( pDb == &(db->aDb[iDb]) );
 if( db->mallocFailed ){
 rc = SQLITE_NOMEM_BKPT;
 sqlite3ResetAllSchemasOfConnection(db);
 pDb = &db->aDb[iDb];
 }else
 if( rc==SQLITE_OK || ((db->flags&SQLITE_NoSchemaError) && rc!=SQLITE_NOMEM)){
 /* Hack: If the SQLITE_NoSchemaError flag is set, then consider
 ** the schema loaded, even if errors (other than OOM) occurred. In
 ** this situation the current sqlite3_prepare() operation will fail,
 ** but the following one will attempt to compile the supplied statement
 ** against whatever subset of the schema was loaded before the error
 ** occurred.
 **
 ** The primary purpose of this is to allow access to the sqlite_schema
 ** table even when its contents have been corrupted.
 */
 DbSetProperty(db, iDb, DB_SchemaLoaded);
 rc = SQLITE_OK;
 }

 /* Jump here for an error that occurs after successfully allocating
 ** curMain and calling sqlite3BtreeEnter(). For an error that occurs
 ** before that point, jump to error_out.
 */
initone_error_out:
 if( openedTransaction ){
 sqlite3BtreeCommit(pDb->pBt);
 }
 sqlite3BtreeLeave(pDb->pBt);

error_out:
 if( rc ){
 if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
 sqlite3OomFault(db);
 }
 sqlite3ResetOneSchema(db, iDb);
 }
 db->init.busy = 0;
 return rc;
}

/*
** Initialize all database files - the main database file, the file
** used to store temporary tables, and any additional database files
** created using ATTACH statements. Return a success code. If an
** error occurs, write an error message into *pzErrMsg.
**
** After a database is initialized, the DB_SchemaLoaded bit is set
** bit is set in the flags field of the Db structure. 
*/
int sqlite3Init(sqlite3 *db, char **pzErrMsg){
 int i, rc;
 int commit_internal = !(db->mDbFlags&DBFLAG_SchemaChange);
 
 assert( sqlite3_mutex_held(db->mutex) );
 assert( sqlite3BtreeHoldsMutex(db->aDb[0].pBt) );
 assert( db->init.busy==0 );
 ENC(db) = SCHEMA_ENC(db);
 assert( db->nDb>0 );
 /* Do the main schema first */
 if( !DbHasProperty(db, 0, DB_SchemaLoaded) ){
 rc = sqlite3InitOne(db, 0, pzErrMsg, 0);
 if( rc ) return rc;
 }
 /* All other schemas after the main schema. The "temp" schema must be last */
 for(i=db->nDb-1; i>0; i--){
 assert( i==1 || sqlite3BtreeHoldsMutex(db->aDb[i].pBt) );
 if( !DbHasProperty(db, i, DB_SchemaLoaded) ){
 rc = sqlite3InitOne(db, i, pzErrMsg, 0);
 if( rc ) return rc;
 }
 }
 if( commit_internal ){
 sqlite3CommitInternalChanges(db);
 }
 return SQLITE_OK;
}

/*
** This routine is a no-op if the database schema is already initialized.
** Otherwise, the schema is loaded. An error code is returned.
*/
int sqlite3ReadSchema(Parse *pParse){
 int rc = SQLITE_OK;
 sqlite3 *db = pParse->db;
 assert( sqlite3_mutex_held(db->mutex) );
 if( !db->init.busy ){
 rc = sqlite3Init(db, &pParse->zErrMsg);
 if( rc!=SQLITE_OK ){
 pParse->rc = rc;
 pParse->nErr++;
 }else if( db->noSharedCache ){
 db->mDbFlags |= DBFLAG_SchemaKnownOk;
 }
 }
 return rc;
}


/*
** Check schema cookies in all databases. If any cookie is out
** of date set pParse->rc to SQLITE_SCHEMA. If all schema cookies
** make no changes to pParse->rc.
*/
static void schemaIsValid(Parse *pParse){
 sqlite3 *db = pParse->db;
 int iDb;
 int rc;
 int cookie;

 assert( pParse->checkSchema );
 assert( sqlite3_mutex_held(db->mutex) );
 for(iDb=0; iDb<db->nDb; iDb++){
 int openedTransaction = 0; /* True if a transaction is opened */
 Btree *pBt = db->aDb[iDb].pBt; /* Btree database to read cookie from */
 if( pBt==0 ) continue;

 /* If there is not already a read-only (or read-write) transaction opened
 ** on the b-tree database, open one now. If a transaction is opened, it 
 ** will be closed immediately after reading the meta-value. */
 if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_NONE ){
 rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
 if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
 sqlite3OomFault(db);
 pParse->rc = SQLITE_NOMEM;
 }
 if( rc!=SQLITE_OK ) return;
 openedTransaction = 1;
 }

 /* Read the schema cookie from the database. If it does not match the 
 ** value stored as part of the in-memory schema representation,
 ** set Parse.rc to SQLITE_SCHEMA. */
 sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&cookie);
 assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 if( cookie!=db->aDb[iDb].pSchema->schema_cookie ){
 if( DbHasProperty(db, iDb, DB_SchemaLoaded) ) pParse->rc = SQLITE_SCHEMA;
 sqlite3ResetOneSchema(db, iDb);
 }

 /* Close the transaction, if one was opened. */
 if( openedTransaction ){
 sqlite3BtreeCommit(pBt);
 }
 }
}

/*
** Convert a schema pointer into the iDb index that indicates
** which database file in db->aDb[] the schema refers to.
**
** If the same database is attached more than once, the first
** attached database is returned.
*/
int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){
 int i = -32768;

 /* If pSchema is NULL, then return -32768. This happens when code in 
 ** expr.c is trying to resolve a reference to a transient table (i.e. one
 ** created by a sub-select). In this case the return value of this 
 ** function should never be used.
 **
 ** We return -32768 instead of the more usual -1 simply because using
 ** -32768 as the incorrect index into db->aDb[] is much 
 ** more likely to cause a segfault than -1 (of course there are assert()
 ** statements too, but it never hurts to play the odds) and
 ** -32768 will still fit into a 16-bit signed integer.
 */
 assert( sqlite3_mutex_held(db->mutex) );
 if( pSchema ){
 for(i=0; 1; i++){
 assert( i<db->nDb );
 if( db->aDb[i].pSchema==pSchema ){
 break;
 }
 }
 assert( i>=0 && i<db->nDb );
 }
 return i;
}

/*
** Free all memory allocations in the pParse object
*/
void sqlite3ParseObjectReset(Parse *pParse){
 sqlite3 *db = pParse->db;
 assert( db!=0 );
 assert( db->pParse==pParse );
 assert( pParse->nested==0 );
#ifndef SQLITE_OMIT_SHARED_CACHE
 if( pParse->aTableLock ) sqlite3DbNNFreeNN(db, pParse->aTableLock);
#endif
 while( pParse->pCleanup ){
 ParseCleanup *pCleanup = pParse->pCleanup;
 pParse->pCleanup = pCleanup->pNext;
 pCleanup->xCleanup(db, pCleanup->pPtr);
 sqlite3DbNNFreeNN(db, pCleanup);
 }
 if( pParse->aLabel ) sqlite3DbNNFreeNN(db, pParse->aLabel);
 if( pParse->pConstExpr ){
 sqlite3ExprListDelete(db, pParse->pConstExpr);
 }
 assert( db->lookaside.bDisable >= pParse->disableLookaside );
 db->lookaside.bDisable -= pParse->disableLookaside;
 db->lookaside.sz = db->lookaside.bDisable ? 0 : db->lookaside.szTrue;
 assert( pParse->db->pParse==pParse );
 db->pParse = pParse->pOuterParse;
}

/*
** Add a new cleanup operation to a Parser. The cleanup should happen when
** the parser object is destroyed. But, beware: the cleanup might happen
** immediately.
**
** Use this mechanism for uncommon cleanups. There is a higher setup
** cost for this mechanism (an extra malloc), so it should not be used
** for common cleanups that happen on most calls. But for less
** common cleanups, we save a single NULL-pointer comparison in
** sqlite3ParseObjectReset(), which reduces the total CPU cycle count.
**
** If a memory allocation error occurs, then the cleanup happens immediately.
** When either SQLITE_DEBUG or SQLITE_COVERAGE_TEST are defined, the
** pParse->earlyCleanup flag is set in that case. Calling code show verify
** that test cases exist for which this happens, to guard against possible
** use-after-free errors following an OOM. The preferred way to do this is
** to immediately follow the call to this routine with:
**
** testcase( pParse->earlyCleanup );
**
** This routine returns a copy of its pPtr input (the third parameter)
** except if an early cleanup occurs, in which case it returns NULL. So
** another way to check for early cleanup is to check the return value.
** Or, stop using the pPtr parameter with this call and use only its
** return value thereafter. Something like this:
**
** pObj = sqlite3ParserAddCleanup(pParse, destructor, pObj);
*/
void *sqlite3ParserAddCleanup(
 Parse *pParse, /* Destroy when this Parser finishes */
 void (*xCleanup)(sqlite3*,void*), /* The cleanup routine */
 void *pPtr /* Pointer to object to be cleaned up */
){
 ParseCleanup *pCleanup = sqlite3DbMallocRaw(pParse->db, sizeof(*pCleanup));
 if( pCleanup ){
 pCleanup->pNext = pParse->pCleanup;
 pParse->pCleanup = pCleanup;
 pCleanup->pPtr = pPtr;
 pCleanup->xCleanup = xCleanup;
 }else{
 xCleanup(pParse->db, pPtr);
 pPtr = 0;
#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
 pParse->earlyCleanup = 1;
#endif
 }
 return pPtr;
}

/*
** Turn bulk memory into a valid Parse object and link that Parse object
** into database connection db.
**
** Call sqlite3ParseObjectReset() to undo this operation.
**
** Caution: Do not confuse this routine with sqlite3ParseObjectInit() which
** is generated by Lemon.
*/
void sqlite3ParseObjectInit(Parse *pParse, sqlite3 *db){
 memset(PARSE_HDR(pParse), 0, PARSE_HDR_SZ);
 memset(PARSE_TAIL(pParse), 0, PARSE_TAIL_SZ);
 assert( db->pParse!=pParse );
 pParse->pOuterParse = db->pParse;
 db->pParse = pParse;
 pParse->db = db;
 if( db->mallocFailed ) sqlite3ErrorMsg(pParse, "out of memory");
}

/*
** Maximum number of times that we will try again to prepare a statement
** that returns SQLITE_ERROR_RETRY.
*/
#ifndef SQLITE_MAX_PREPARE_RETRY
# define SQLITE_MAX_PREPARE_RETRY 25
#endif

/*
** Compile the UTF-8 encoded SQL statement zSql into a statement handle.
*/
static int sqlite3Prepare(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 u32 prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 Vdbe *pReprepare, /* VM being reprepared */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
){
 int rc = SQLITE_OK; /* Result code */
 int i; /* Loop counter */
 Parse sParse; /* Parsing context */

 /* sqlite3ParseObjectInit(&sParse, db); // inlined for performance */
 memset(PARSE_HDR(&sParse), 0, PARSE_HDR_SZ);
 memset(PARSE_TAIL(&sParse), 0, PARSE_TAIL_SZ);
 sParse.pOuterParse = db->pParse;
 db->pParse = &sParse;
 sParse.db = db;
 if( pReprepare ){
 sParse.pReprepare = pReprepare;
 sParse.explain = sqlite3_stmt_isexplain((sqlite3_stmt*)pReprepare);
 }else{
 assert( sParse.pReprepare==0 );
 }
 assert( ppStmt && *ppStmt==0 );
 if( db->mallocFailed ){
 sqlite3ErrorMsg(&sParse, "out of memory");
 db->errCode = rc = SQLITE_NOMEM;
 goto end_prepare;
 }
 assert( sqlite3_mutex_held(db->mutex) );

 /* For a long-term use prepared statement avoid the use of
 ** lookaside memory.
 */
 if( prepFlags & SQLITE_PREPARE_PERSISTENT ){
 sParse.disableLookaside++;
 DisableLookaside;
 }
 sParse.prepFlags = prepFlags & 0xff;

 /* Check to verify that it is possible to get a read lock on all
 ** database schemas. The inability to get a read lock indicates that
 ** some other database connection is holding a write-lock, which in
 ** turn means that the other connection has made uncommitted changes
 ** to the schema.
 **
 ** Were we to proceed and prepare the statement against the uncommitted
 ** schema changes and if those schema changes are subsequently rolled
 ** back and different changes are made in their place, then when this
 ** prepared statement goes to run the schema cookie would fail to detect
 ** the schema change. Disaster would follow.
 **
 ** This thread is currently holding mutexes on all Btrees (because
 ** of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it
 ** is not possible for another thread to start a new schema change
 ** while this routine is running. Hence, we do not need to hold 
 ** locks on the schema, we just need to make sure nobody else is 
 ** holding them.
 **
 ** Note that setting READ_UNCOMMITTED overrides most lock detection,
 ** but it does *not* override schema lock detection, so this all still
 ** works even if READ_UNCOMMITTED is set.
 */
 if( !db->noSharedCache ){
 for(i=0; i<db->nDb; i++) {
 Btree *pBt = db->aDb[i].pBt;
 if( pBt ){
 assert( sqlite3BtreeHoldsMutex(pBt) );
 rc = sqlite3BtreeSchemaLocked(pBt);
 if( rc ){
 const char *zDb = db->aDb[i].zDbSName;
 sqlite3ErrorWithMsg(db, rc, "database schema is locked: %s", zDb);
 testcase( db->flags & SQLITE_ReadUncommit );
 goto end_prepare;
 }
 }
 }
 }

#ifndef SQLITE_OMIT_VIRTUALTABLE
 if( db->pDisconnect ) sqlite3VtabUnlockList(db);
#endif

 if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
 char *zSqlCopy;
 int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
 testcase( nBytes==mxLen );
 testcase( nBytes==mxLen+1 );
 if( nBytes>mxLen ){
 sqlite3ErrorWithMsg(db, SQLITE_TOOBIG, "statement too long");
 rc = sqlite3ApiExit(db, SQLITE_TOOBIG);
 goto end_prepare;
 }
 zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
 if( zSqlCopy ){
 sqlite3RunParser(&sParse, zSqlCopy);
 sParse.zTail = &zSql[sParse.zTail-zSqlCopy];
 sqlite3DbFree(db, zSqlCopy);
 }else{
 sParse.zTail = &zSql[nBytes];
 }
 }else{
 sqlite3RunParser(&sParse, zSql);
 }
 assert( 0==sParse.nQueryLoop );

 if( pzTail ){
 *pzTail = sParse.zTail;
 }

 if( db->init.busy==0 ){
 sqlite3VdbeSetSql(sParse.pVdbe, zSql, (int)(sParse.zTail-zSql), prepFlags);
 }
 if( db->mallocFailed ){
 sParse.rc = SQLITE_NOMEM_BKPT;
 sParse.checkSchema = 0;
 }
 if( sParse.rc!=SQLITE_OK && sParse.rc!=SQLITE_DONE ){
 if( sParse.checkSchema && db->init.busy==0 ){
 schemaIsValid(&sParse);
 }
 if( sParse.pVdbe ){
 sqlite3VdbeFinalize(sParse.pVdbe);
 }
 assert( 0==(*ppStmt) );
 rc = sParse.rc;
 if( sParse.zErrMsg ){
 sqlite3ErrorWithMsg(db, rc, "%s", sParse.zErrMsg);
 sqlite3DbFree(db, sParse.zErrMsg);
 }else{
 sqlite3Error(db, rc);
 }
 }else{
 assert( sParse.zErrMsg==0 );
 *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
 rc = SQLITE_OK;
 sqlite3ErrorClear(db);
 }


 /* Delete any TriggerPrg structures allocated while parsing this statement. */
 while( sParse.pTriggerPrg ){
 TriggerPrg *pT = sParse.pTriggerPrg;
 sParse.pTriggerPrg = pT->pNext;
 sqlite3DbFree(db, pT);
 }

end_prepare:

 sqlite3ParseObjectReset(&sParse);
 return rc;
}
static int sqlite3LockAndPrepare(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 u32 prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 Vdbe *pOld, /* VM being reprepared */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
){
 int rc;
 int cnt = 0;

#ifdef SQLITE_ENABLE_API_ARMOR
 if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
#endif
 *ppStmt = 0;
 if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
 return SQLITE_MISUSE_BKPT;
 }
 sqlite3_mutex_enter(db->mutex);
 sqlite3BtreeEnterAll(db);
 do{
 /* Make multiple attempts to compile the SQL, until it either succeeds
 ** or encounters a permanent error. A schema problem after one schema
 ** reset is considered a permanent error. */
 rc = sqlite3Prepare(db, zSql, nBytes, prepFlags, pOld, ppStmt, pzTail);
 assert( rc==SQLITE_OK || *ppStmt==0 );
 if( rc==SQLITE_OK || db->mallocFailed ) break;
 }while( (rc==SQLITE_ERROR_RETRY && (cnt++)<SQLITE_MAX_PREPARE_RETRY)
 || (rc==SQLITE_SCHEMA && (sqlite3ResetOneSchema(db,-1), cnt++)==0) );
 sqlite3BtreeLeaveAll(db);
 rc = sqlite3ApiExit(db, rc);
 assert( (rc&db->errMask)==rc );
 db->busyHandler.nBusy = 0;
 sqlite3_mutex_leave(db->mutex);
 assert( rc==SQLITE_OK || (*ppStmt)==0 );
 return rc;
}


/*
** Rerun the compilation of a statement after a schema change.
**
** If the statement is successfully recompiled, return SQLITE_OK. Otherwise,
** if the statement cannot be recompiled because another connection has
** locked the sqlite3_schema table, return SQLITE_LOCKED. If any other error
** occurs, return SQLITE_SCHEMA.
*/
int sqlite3Reprepare(Vdbe *p){
 int rc;
 sqlite3_stmt *pNew;
 const char *zSql;
 sqlite3 *db;
 u8 prepFlags;

 assert( sqlite3_mutex_held(sqlite3VdbeDb(p)->mutex) );
 zSql = sqlite3_sql((sqlite3_stmt *)p);
 assert( zSql!=0 ); /* Reprepare only called for prepare_v2() statements */
 db = sqlite3VdbeDb(p);
 assert( sqlite3_mutex_held(db->mutex) );
 prepFlags = sqlite3VdbePrepareFlags(p);
 rc = sqlite3LockAndPrepare(db, zSql, -1, prepFlags, p, &pNew, 0);
 if( rc ){
 if( rc==SQLITE_NOMEM ){
 sqlite3OomFault(db);
 }
 assert( pNew==0 );
 return rc;
 }else{
 assert( pNew!=0 );
 }
 sqlite3VdbeSwap((Vdbe*)pNew, p);
 sqlite3TransferBindings(pNew, (sqlite3_stmt*)p);
 sqlite3VdbeResetStepResult((Vdbe*)pNew);
 sqlite3VdbeFinalize((Vdbe*)pNew);
 return SQLITE_OK;
}


/*
** Two versions of the official API. Legacy and new use. In the legacy
** version, the original SQL text is not saved in the prepared statement
** and so if a schema change occurs, SQLITE_SCHEMA is returned by
** sqlite3_step(). In the new version, the original SQL text is retained
** and the statement is automatically recompiled if an schema change
** occurs.
*/
int sqlite3_prepare(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
){
 int rc;
 rc = sqlite3LockAndPrepare(db,zSql,nBytes,0,0,ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 ); /* VERIFY: F13021 */
 return rc;
}
int sqlite3_prepare_v2(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
){
 int rc;
 /* EVIDENCE-OF: R-37923-12173 The sqlite3_prepare_v2() interface works
 ** exactly the same as sqlite3_prepare_v3() with a zero prepFlags
 ** parameter.
 **
 ** Proof in that the 5th parameter to sqlite3LockAndPrepare is 0 */
 rc = sqlite3LockAndPrepare(db,zSql,nBytes,SQLITE_PREPARE_SAVESQL,0,
 ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );
 return rc;
}
int sqlite3_prepare_v3(
 sqlite3 *db, /* Database handle. */
 const char *zSql, /* UTF-8 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const char **pzTail /* OUT: End of parsed string */
){
 int rc;
 /* EVIDENCE-OF: R-56861-42673 sqlite3_prepare_v3() differs from
 ** sqlite3_prepare_v2() only in having the extra prepFlags parameter,
 ** which is a bit array consisting of zero or more of the
 ** SQLITE_PREPARE_* flags.
 **
 ** Proof by comparison to the implementation of sqlite3_prepare_v2()
 ** directly above. */
 rc = sqlite3LockAndPrepare(db,zSql,nBytes,
 SQLITE_PREPARE_SAVESQL|(prepFlags&SQLITE_PREPARE_MASK),
 0,ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );
 return rc;
}


#ifndef SQLITE_OMIT_UTF16
/*
** Compile the UTF-16 encoded SQL statement zSql into a statement handle.
*/
static int sqlite3Prepare16(
 sqlite3 *db, /* Database handle. */ 
 const void *zSql, /* UTF-16 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 u32 prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const void **pzTail /* OUT: End of parsed string */
){
 /* This function currently works by first transforming the UTF-16
 ** encoded string to UTF-8, then invoking sqlite3_prepare(). The
 ** tricky bit is figuring out the pointer to return in *pzTail.
 */
 char *zSql8;
 const char *zTail8 = 0;
 int rc = SQLITE_OK;

#ifdef SQLITE_ENABLE_API_ARMOR
 if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
#endif
 *ppStmt = 0;
 if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
 return SQLITE_MISUSE_BKPT;
 }
 if( nBytes>=0 ){
 int sz;
 const char *z = (const char*)zSql;
 for(sz=0; sz<nBytes && (z[sz]!=0 || z[sz+1]!=0); sz += 2){}
 nBytes = sz;
 }
 sqlite3_mutex_enter(db->mutex);
 zSql8 = sqlite3Utf16to8(db, zSql, nBytes, SQLITE_UTF16NATIVE);
 if( zSql8 ){
 rc = sqlite3LockAndPrepare(db, zSql8, -1, prepFlags, 0, ppStmt, &zTail8);
 }

 if( zTail8 && pzTail ){
 /* If sqlite3_prepare returns a tail pointer, we calculate the
 ** equivalent pointer into the UTF-16 string by counting the unicode
 ** characters between zSql8 and zTail8, and then returning a pointer
 ** the same number of characters into the UTF-16 string.
 */
 int chars_parsed = sqlite3Utf8CharLen(zSql8, (int)(zTail8-zSql8));
 *pzTail = (u8 *)zSql + sqlite3Utf16ByteLen(zSql, chars_parsed);
 }
 sqlite3DbFree(db, zSql8); 
 rc = sqlite3ApiExit(db, rc);
 sqlite3_mutex_leave(db->mutex);
 return rc;
}

/*
** Two versions of the official API. Legacy and new use. In the legacy
** version, the original SQL text is not saved in the prepared statement
** and so if a schema change occurs, SQLITE_SCHEMA is returned by
** sqlite3_step(). In the new version, the original SQL text is retained
** and the statement is automatically recompiled if an schema change
** occurs.
*/
int sqlite3_prepare16(
 sqlite3 *db, /* Database handle. */ 
 const void *zSql, /* UTF-16 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const void **pzTail /* OUT: End of parsed string */
){
 int rc;
 rc = sqlite3Prepare16(db,zSql,nBytes,0,ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 ); /* VERIFY: F13021 */
 return rc;
}
int sqlite3_prepare16_v2(
 sqlite3 *db, /* Database handle. */ 
 const void *zSql, /* UTF-16 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const void **pzTail /* OUT: End of parsed string */
){
 int rc;
 rc = sqlite3Prepare16(db,zSql,nBytes,SQLITE_PREPARE_SAVESQL,ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 ); /* VERIFY: F13021 */
 return rc;
}
int sqlite3_prepare16_v3(
 sqlite3 *db, /* Database handle. */ 
 const void *zSql, /* UTF-16 encoded SQL statement. */
 int nBytes, /* Length of zSql in bytes. */
 unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
 sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
 const void **pzTail /* OUT: End of parsed string */
){
 int rc;
 rc = sqlite3Prepare16(db,zSql,nBytes,
 SQLITE_PREPARE_SAVESQL|(prepFlags&SQLITE_PREPARE_MASK),
 ppStmt,pzTail);
 assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 ); /* VERIFY: F13021 */
 return rc;
}

#endif /* SQLITE_OMIT_UTF16 */