xref: /sqlite-3.40.0/src/vdbeapi.c (revision 50f79f56)
1 /*
2 ** 2004 May 26
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 **
13 ** This file contains code use to implement APIs that are part of the
14 ** VDBE.
15 */
16 #include "sqliteInt.h"
17 #include "vdbeInt.h"
18 
19 #ifndef SQLITE_OMIT_DEPRECATED
20 /*
21 ** Return TRUE (non-zero) of the statement supplied as an argument needs
22 ** to be recompiled.  A statement needs to be recompiled whenever the
23 ** execution environment changes in a way that would alter the program
24 ** that sqlite3_prepare() generates.  For example, if new functions or
25 ** collating sequences are registered or if an authorizer function is
26 ** added or changed.
27 */
28 int sqlite3_expired(sqlite3_stmt *pStmt){
29   Vdbe *p = (Vdbe*)pStmt;
30   return p==0 || p->expired;
31 }
32 #endif
33 
34 /*
35 ** Check on a Vdbe to make sure it has not been finalized.  Log
36 ** an error and return true if it has been finalized (or is otherwise
37 ** invalid).  Return false if it is ok.
38 */
39 static int vdbeSafety(Vdbe *p){
40   if( p->db==0 ){
41     sqlite3_log(SQLITE_MISUSE, "API called with finalized prepared statement");
42     return 1;
43   }else{
44     return 0;
45   }
46 }
47 static int vdbeSafetyNotNull(Vdbe *p){
48   if( p==0 ){
49     sqlite3_log(SQLITE_MISUSE, "API called with NULL prepared statement");
50     return 1;
51   }else{
52     return vdbeSafety(p);
53   }
54 }
55 
56 /*
57 ** The following routine destroys a virtual machine that is created by
58 ** the sqlite3_compile() routine. The integer returned is an SQLITE_
59 ** success/failure code that describes the result of executing the virtual
60 ** machine.
61 **
62 ** This routine sets the error code and string returned by
63 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
64 */
65 int sqlite3_finalize(sqlite3_stmt *pStmt){
66   int rc;
67   if( pStmt==0 ){
68     /* IMPLEMENTATION-OF: R-57228-12904 Invoking sqlite3_finalize() on a NULL
69     ** pointer is a harmless no-op. */
70     rc = SQLITE_OK;
71   }else{
72     Vdbe *v = (Vdbe*)pStmt;
73     sqlite3 *db = v->db;
74 #if SQLITE_THREADSAFE
75     sqlite3_mutex *mutex;
76 #endif
77     if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
78 #if SQLITE_THREADSAFE
79     mutex = v->db->mutex;
80 #endif
81     sqlite3_mutex_enter(mutex);
82     rc = sqlite3VdbeFinalize(v);
83     rc = sqlite3ApiExit(db, rc);
84     sqlite3_mutex_leave(mutex);
85   }
86   return rc;
87 }
88 
89 /*
90 ** Terminate the current execution of an SQL statement and reset it
91 ** back to its starting state so that it can be reused. A success code from
92 ** the prior execution is returned.
93 **
94 ** This routine sets the error code and string returned by
95 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
96 */
97 int sqlite3_reset(sqlite3_stmt *pStmt){
98   int rc;
99   if( pStmt==0 ){
100     rc = SQLITE_OK;
101   }else{
102     Vdbe *v = (Vdbe*)pStmt;
103     sqlite3_mutex_enter(v->db->mutex);
104     rc = sqlite3VdbeReset(v);
105     sqlite3VdbeRewind(v);
106     assert( (rc & (v->db->errMask))==rc );
107     rc = sqlite3ApiExit(v->db, rc);
108     sqlite3_mutex_leave(v->db->mutex);
109   }
110   return rc;
111 }
112 
113 /*
114 ** Set all the parameters in the compiled SQL statement to NULL.
115 */
116 int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
117   int i;
118   int rc = SQLITE_OK;
119   Vdbe *p = (Vdbe*)pStmt;
120 #if SQLITE_THREADSAFE
121   sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
122 #endif
123   sqlite3_mutex_enter(mutex);
124   for(i=0; i<p->nVar; i++){
125     sqlite3VdbeMemRelease(&p->aVar[i]);
126     p->aVar[i].flags = MEM_Null;
127   }
128   if( p->isPrepareV2 && p->expmask ){
129     p->expired = 1;
130   }
131   sqlite3_mutex_leave(mutex);
132   return rc;
133 }
134 
135 
136 /**************************** sqlite3_value_  *******************************
137 ** The following routines extract information from a Mem or sqlite3_value
138 ** structure.
139 */
140 const void *sqlite3_value_blob(sqlite3_value *pVal){
141   Mem *p = (Mem*)pVal;
142   if( p->flags & (MEM_Blob|MEM_Str) ){
143     sqlite3VdbeMemExpandBlob(p);
144     p->flags &= ~MEM_Str;
145     p->flags |= MEM_Blob;
146     return p->n ? p->z : 0;
147   }else{
148     return sqlite3_value_text(pVal);
149   }
150 }
151 int sqlite3_value_bytes(sqlite3_value *pVal){
152   return sqlite3ValueBytes(pVal, SQLITE_UTF8);
153 }
154 int sqlite3_value_bytes16(sqlite3_value *pVal){
155   return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
156 }
157 double sqlite3_value_double(sqlite3_value *pVal){
158   return sqlite3VdbeRealValue((Mem*)pVal);
159 }
160 int sqlite3_value_int(sqlite3_value *pVal){
161   return (int)sqlite3VdbeIntValue((Mem*)pVal);
162 }
163 sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
164   return sqlite3VdbeIntValue((Mem*)pVal);
165 }
166 const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
167   return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
168 }
169 #ifndef SQLITE_OMIT_UTF16
170 const void *sqlite3_value_text16(sqlite3_value* pVal){
171   return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
172 }
173 const void *sqlite3_value_text16be(sqlite3_value *pVal){
174   return sqlite3ValueText(pVal, SQLITE_UTF16BE);
175 }
176 const void *sqlite3_value_text16le(sqlite3_value *pVal){
177   return sqlite3ValueText(pVal, SQLITE_UTF16LE);
178 }
179 #endif /* SQLITE_OMIT_UTF16 */
180 int sqlite3_value_type(sqlite3_value* pVal){
181   return pVal->type;
182 }
183 
184 /**************************** sqlite3_result_  *******************************
185 ** The following routines are used by user-defined functions to specify
186 ** the function result.
187 **
188 ** The setStrOrError() funtion calls sqlite3VdbeMemSetStr() to store the
189 ** result as a string or blob but if the string or blob is too large, it
190 ** then sets the error code to SQLITE_TOOBIG
191 */
192 static void setResultStrOrError(
193   sqlite3_context *pCtx,  /* Function context */
194   const char *z,          /* String pointer */
195   int n,                  /* Bytes in string, or negative */
196   u8 enc,                 /* Encoding of z.  0 for BLOBs */
197   void (*xDel)(void*)     /* Destructor function */
198 ){
199   if( sqlite3VdbeMemSetStr(&pCtx->s, z, n, enc, xDel)==SQLITE_TOOBIG ){
200     sqlite3_result_error_toobig(pCtx);
201   }
202 }
203 void sqlite3_result_blob(
204   sqlite3_context *pCtx,
205   const void *z,
206   int n,
207   void (*xDel)(void *)
208 ){
209   assert( n>=0 );
210   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
211   setResultStrOrError(pCtx, z, n, 0, xDel);
212 }
213 void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
214   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
215   sqlite3VdbeMemSetDouble(&pCtx->s, rVal);
216 }
217 void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
218   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
219   pCtx->isError = SQLITE_ERROR;
220   sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
221 }
222 #ifndef SQLITE_OMIT_UTF16
223 void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
224   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
225   pCtx->isError = SQLITE_ERROR;
226   sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
227 }
228 #endif
229 void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
230   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
231   sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal);
232 }
233 void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
234   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
235   sqlite3VdbeMemSetInt64(&pCtx->s, iVal);
236 }
237 void sqlite3_result_null(sqlite3_context *pCtx){
238   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
239   sqlite3VdbeMemSetNull(&pCtx->s);
240 }
241 void sqlite3_result_text(
242   sqlite3_context *pCtx,
243   const char *z,
244   int n,
245   void (*xDel)(void *)
246 ){
247   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
248   setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel);
249 }
250 #ifndef SQLITE_OMIT_UTF16
251 void sqlite3_result_text16(
252   sqlite3_context *pCtx,
253   const void *z,
254   int n,
255   void (*xDel)(void *)
256 ){
257   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
258   setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel);
259 }
260 void sqlite3_result_text16be(
261   sqlite3_context *pCtx,
262   const void *z,
263   int n,
264   void (*xDel)(void *)
265 ){
266   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
267   setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel);
268 }
269 void sqlite3_result_text16le(
270   sqlite3_context *pCtx,
271   const void *z,
272   int n,
273   void (*xDel)(void *)
274 ){
275   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
276   setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel);
277 }
278 #endif /* SQLITE_OMIT_UTF16 */
279 void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
280   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
281   sqlite3VdbeMemCopy(&pCtx->s, pValue);
282 }
283 void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
284   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
285   sqlite3VdbeMemSetZeroBlob(&pCtx->s, n);
286 }
287 void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
288   pCtx->isError = errCode;
289   if( pCtx->s.flags & MEM_Null ){
290     sqlite3VdbeMemSetStr(&pCtx->s, sqlite3ErrStr(errCode), -1,
291                          SQLITE_UTF8, SQLITE_STATIC);
292   }
293 }
294 
295 /* Force an SQLITE_TOOBIG error. */
296 void sqlite3_result_error_toobig(sqlite3_context *pCtx){
297   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
298   pCtx->isError = SQLITE_TOOBIG;
299   sqlite3VdbeMemSetStr(&pCtx->s, "string or blob too big", -1,
300                        SQLITE_UTF8, SQLITE_STATIC);
301 }
302 
303 /* An SQLITE_NOMEM error. */
304 void sqlite3_result_error_nomem(sqlite3_context *pCtx){
305   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
306   sqlite3VdbeMemSetNull(&pCtx->s);
307   pCtx->isError = SQLITE_NOMEM;
308   pCtx->s.db->mallocFailed = 1;
309 }
310 
311 /*
312 ** This function is called after a transaction has been committed. It
313 ** invokes callbacks registered with sqlite3_wal_hook() as required.
314 */
315 static int doWalCallbacks(sqlite3 *db){
316   int rc = SQLITE_OK;
317 #ifndef SQLITE_OMIT_WAL
318   int i;
319   for(i=0; i<db->nDb; i++){
320     Btree *pBt = db->aDb[i].pBt;
321     if( pBt ){
322       int nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
323       if( db->xWalCallback && nEntry>0 && rc==SQLITE_OK ){
324         rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zName, nEntry);
325       }
326     }
327   }
328 #endif
329   return rc;
330 }
331 
332 /*
333 ** Execute the statement pStmt, either until a row of data is ready, the
334 ** statement is completely executed or an error occurs.
335 **
336 ** This routine implements the bulk of the logic behind the sqlite_step()
337 ** API.  The only thing omitted is the automatic recompile if a
338 ** schema change has occurred.  That detail is handled by the
339 ** outer sqlite3_step() wrapper procedure.
340 */
341 static int sqlite3Step(Vdbe *p){
342   sqlite3 *db;
343   int rc;
344 
345   assert(p);
346   if( p->magic!=VDBE_MAGIC_RUN ){
347     /* We used to require that sqlite3_reset() be called before retrying
348     ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
349     ** with version 3.7.0, we changed this so that sqlite3_reset() would
350     ** be called automatically instead of throwing the SQLITE_MISUSE error.
351     ** This "automatic-reset" change is not technically an incompatibility,
352     ** since any application that receives an SQLITE_MISUSE is broken by
353     ** definition.
354     **
355     ** Nevertheless, some published applications that were originally written
356     ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE
357     ** returns, and those were broken by the automatic-reset change.  As a
358     ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
359     ** legacy behavior of returning SQLITE_MISUSE for cases where the
360     ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
361     ** or SQLITE_BUSY error.
362     */
363 #ifdef SQLITE_OMIT_AUTORESET
364     if( p->rc==SQLITE_BUSY || p->rc==SQLITE_LOCKED ){
365       sqlite3_reset((sqlite3_stmt*)p);
366     }else{
367       return SQLITE_MISUSE_BKPT;
368     }
369 #else
370     sqlite3_reset((sqlite3_stmt*)p);
371 #endif
372   }
373 
374   /* Check that malloc() has not failed. If it has, return early. */
375   db = p->db;
376   if( db->mallocFailed ){
377     p->rc = SQLITE_NOMEM;
378     return SQLITE_NOMEM;
379   }
380 
381   if( p->pc<=0 && p->expired ){
382     p->rc = SQLITE_SCHEMA;
383     rc = SQLITE_ERROR;
384     goto end_of_step;
385   }
386   if( p->pc<0 ){
387     /* If there are no other statements currently running, then
388     ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
389     ** from interrupting a statement that has not yet started.
390     */
391     if( db->activeVdbeCnt==0 ){
392       db->u1.isInterrupted = 0;
393     }
394 
395     assert( db->writeVdbeCnt>0 || db->autoCommit==0 || db->nDeferredCons==0 );
396 
397 #ifndef SQLITE_OMIT_TRACE
398     if( db->xProfile && !db->init.busy ){
399       sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
400     }
401 #endif
402 
403     db->activeVdbeCnt++;
404     if( p->readOnly==0 ) db->writeVdbeCnt++;
405     p->pc = 0;
406   }
407 #ifndef SQLITE_OMIT_EXPLAIN
408   if( p->explain ){
409     rc = sqlite3VdbeList(p);
410   }else
411 #endif /* SQLITE_OMIT_EXPLAIN */
412   {
413     db->vdbeExecCnt++;
414     rc = sqlite3VdbeExec(p);
415     db->vdbeExecCnt--;
416   }
417 
418 #ifndef SQLITE_OMIT_TRACE
419   /* Invoke the profile callback if there is one
420   */
421   if( rc!=SQLITE_ROW && db->xProfile && !db->init.busy && p->zSql ){
422     sqlite3_int64 iNow;
423     sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
424     db->xProfile(db->pProfileArg, p->zSql, (iNow - p->startTime)*1000000);
425   }
426 #endif
427 
428   if( rc==SQLITE_DONE ){
429     assert( p->rc==SQLITE_OK );
430     p->rc = doWalCallbacks(db);
431     if( p->rc!=SQLITE_OK ){
432       rc = SQLITE_ERROR;
433     }
434   }
435 
436   db->errCode = rc;
437   if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
438     p->rc = SQLITE_NOMEM;
439   }
440 end_of_step:
441   /* At this point local variable rc holds the value that should be
442   ** returned if this statement was compiled using the legacy
443   ** sqlite3_prepare() interface. According to the docs, this can only
444   ** be one of the values in the first assert() below. Variable p->rc
445   ** contains the value that would be returned if sqlite3_finalize()
446   ** were called on statement p.
447   */
448   assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR
449        || rc==SQLITE_BUSY || rc==SQLITE_MISUSE
450   );
451   assert( p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE );
452   if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
453     /* If this statement was prepared using sqlite3_prepare_v2(), and an
454     ** error has occured, then return the error code in p->rc to the
455     ** caller. Set the error code in the database handle to the same value.
456     */
457     rc = sqlite3VdbeTransferError(p);
458   }
459   return (rc&db->errMask);
460 }
461 
462 /*
463 ** The maximum number of times that a statement will try to reparse
464 ** itself before giving up and returning SQLITE_SCHEMA.
465 */
466 #ifndef SQLITE_MAX_SCHEMA_RETRY
467 # define SQLITE_MAX_SCHEMA_RETRY 5
468 #endif
469 
470 /*
471 ** This is the top-level implementation of sqlite3_step().  Call
472 ** sqlite3Step() to do most of the work.  If a schema error occurs,
473 ** call sqlite3Reprepare() and try again.
474 */
475 int sqlite3_step(sqlite3_stmt *pStmt){
476   int rc = SQLITE_OK;      /* Result from sqlite3Step() */
477   int rc2 = SQLITE_OK;     /* Result from sqlite3Reprepare() */
478   Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
479   int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
480   sqlite3 *db;             /* The database connection */
481 
482   if( vdbeSafetyNotNull(v) ){
483     return SQLITE_MISUSE_BKPT;
484   }
485   db = v->db;
486   sqlite3_mutex_enter(db->mutex);
487   while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
488          && cnt++ < SQLITE_MAX_SCHEMA_RETRY
489          && (rc2 = rc = sqlite3Reprepare(v))==SQLITE_OK ){
490     sqlite3_reset(pStmt);
491     assert( v->expired==0 );
492   }
493   if( rc2!=SQLITE_OK && ALWAYS(v->isPrepareV2) && ALWAYS(db->pErr) ){
494     /* This case occurs after failing to recompile an sql statement.
495     ** The error message from the SQL compiler has already been loaded
496     ** into the database handle. This block copies the error message
497     ** from the database handle into the statement and sets the statement
498     ** program counter to 0 to ensure that when the statement is
499     ** finalized or reset the parser error message is available via
500     ** sqlite3_errmsg() and sqlite3_errcode().
501     */
502     const char *zErr = (const char *)sqlite3_value_text(db->pErr);
503     sqlite3DbFree(db, v->zErrMsg);
504     if( !db->mallocFailed ){
505       v->zErrMsg = sqlite3DbStrDup(db, zErr);
506       v->rc = rc2;
507     } else {
508       v->zErrMsg = 0;
509       v->rc = rc = SQLITE_NOMEM;
510     }
511   }
512   rc = sqlite3ApiExit(db, rc);
513   sqlite3_mutex_leave(db->mutex);
514   return rc;
515 }
516 
517 /*
518 ** Extract the user data from a sqlite3_context structure and return a
519 ** pointer to it.
520 */
521 void *sqlite3_user_data(sqlite3_context *p){
522   assert( p && p->pFunc );
523   return p->pFunc->pUserData;
524 }
525 
526 /*
527 ** Extract the user data from a sqlite3_context structure and return a
528 ** pointer to it.
529 **
530 ** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
531 ** returns a copy of the pointer to the database connection (the 1st
532 ** parameter) of the sqlite3_create_function() and
533 ** sqlite3_create_function16() routines that originally registered the
534 ** application defined function.
535 */
536 sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
537   assert( p && p->pFunc );
538   return p->s.db;
539 }
540 
541 /*
542 ** The following is the implementation of an SQL function that always
543 ** fails with an error message stating that the function is used in the
544 ** wrong context.  The sqlite3_overload_function() API might construct
545 ** SQL function that use this routine so that the functions will exist
546 ** for name resolution but are actually overloaded by the xFindFunction
547 ** method of virtual tables.
548 */
549 void sqlite3InvalidFunction(
550   sqlite3_context *context,  /* The function calling context */
551   int NotUsed,               /* Number of arguments to the function */
552   sqlite3_value **NotUsed2   /* Value of each argument */
553 ){
554   const char *zName = context->pFunc->zName;
555   char *zErr;
556   UNUSED_PARAMETER2(NotUsed, NotUsed2);
557   zErr = sqlite3_mprintf(
558       "unable to use function %s in the requested context", zName);
559   sqlite3_result_error(context, zErr, -1);
560   sqlite3_free(zErr);
561 }
562 
563 /*
564 ** Allocate or return the aggregate context for a user function.  A new
565 ** context is allocated on the first call.  Subsequent calls return the
566 ** same context that was returned on prior calls.
567 */
568 void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
569   Mem *pMem;
570   assert( p && p->pFunc && p->pFunc->xStep );
571   assert( sqlite3_mutex_held(p->s.db->mutex) );
572   pMem = p->pMem;
573   testcase( nByte<0 );
574   if( (pMem->flags & MEM_Agg)==0 ){
575     if( nByte<=0 ){
576       sqlite3VdbeMemReleaseExternal(pMem);
577       pMem->flags = MEM_Null;
578       pMem->z = 0;
579     }else{
580       sqlite3VdbeMemGrow(pMem, nByte, 0);
581       pMem->flags = MEM_Agg;
582       pMem->u.pDef = p->pFunc;
583       if( pMem->z ){
584         memset(pMem->z, 0, nByte);
585       }
586     }
587   }
588   return (void*)pMem->z;
589 }
590 
591 /*
592 ** Return the auxilary data pointer, if any, for the iArg'th argument to
593 ** the user-function defined by pCtx.
594 */
595 void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
596   VdbeFunc *pVdbeFunc;
597 
598   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
599   pVdbeFunc = pCtx->pVdbeFunc;
600   if( !pVdbeFunc || iArg>=pVdbeFunc->nAux || iArg<0 ){
601     return 0;
602   }
603   return pVdbeFunc->apAux[iArg].pAux;
604 }
605 
606 /*
607 ** Set the auxilary data pointer and delete function, for the iArg'th
608 ** argument to the user-function defined by pCtx. Any previous value is
609 ** deleted by calling the delete function specified when it was set.
610 */
611 void sqlite3_set_auxdata(
612   sqlite3_context *pCtx,
613   int iArg,
614   void *pAux,
615   void (*xDelete)(void*)
616 ){
617   struct AuxData *pAuxData;
618   VdbeFunc *pVdbeFunc;
619   if( iArg<0 ) goto failed;
620 
621   assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
622   pVdbeFunc = pCtx->pVdbeFunc;
623   if( !pVdbeFunc || pVdbeFunc->nAux<=iArg ){
624     int nAux = (pVdbeFunc ? pVdbeFunc->nAux : 0);
625     int nMalloc = sizeof(VdbeFunc) + sizeof(struct AuxData)*iArg;
626     pVdbeFunc = sqlite3DbRealloc(pCtx->s.db, pVdbeFunc, nMalloc);
627     if( !pVdbeFunc ){
628       goto failed;
629     }
630     pCtx->pVdbeFunc = pVdbeFunc;
631     memset(&pVdbeFunc->apAux[nAux], 0, sizeof(struct AuxData)*(iArg+1-nAux));
632     pVdbeFunc->nAux = iArg+1;
633     pVdbeFunc->pFunc = pCtx->pFunc;
634   }
635 
636   pAuxData = &pVdbeFunc->apAux[iArg];
637   if( pAuxData->pAux && pAuxData->xDelete ){
638     pAuxData->xDelete(pAuxData->pAux);
639   }
640   pAuxData->pAux = pAux;
641   pAuxData->xDelete = xDelete;
642   return;
643 
644 failed:
645   if( xDelete ){
646     xDelete(pAux);
647   }
648 }
649 
650 #ifndef SQLITE_OMIT_DEPRECATED
651 /*
652 ** Return the number of times the Step function of a aggregate has been
653 ** called.
654 **
655 ** This function is deprecated.  Do not use it for new code.  It is
656 ** provide only to avoid breaking legacy code.  New aggregate function
657 ** implementations should keep their own counts within their aggregate
658 ** context.
659 */
660 int sqlite3_aggregate_count(sqlite3_context *p){
661   assert( p && p->pMem && p->pFunc && p->pFunc->xStep );
662   return p->pMem->n;
663 }
664 #endif
665 
666 /*
667 ** Return the number of columns in the result set for the statement pStmt.
668 */
669 int sqlite3_column_count(sqlite3_stmt *pStmt){
670   Vdbe *pVm = (Vdbe *)pStmt;
671   return pVm ? pVm->nResColumn : 0;
672 }
673 
674 /*
675 ** Return the number of values available from the current row of the
676 ** currently executing statement pStmt.
677 */
678 int sqlite3_data_count(sqlite3_stmt *pStmt){
679   Vdbe *pVm = (Vdbe *)pStmt;
680   if( pVm==0 || pVm->pResultSet==0 ) return 0;
681   return pVm->nResColumn;
682 }
683 
684 
685 /*
686 ** Check to see if column iCol of the given statement is valid.  If
687 ** it is, return a pointer to the Mem for the value of that column.
688 ** If iCol is not valid, return a pointer to a Mem which has a value
689 ** of NULL.
690 */
691 static Mem *columnMem(sqlite3_stmt *pStmt, int i){
692   Vdbe *pVm;
693   Mem *pOut;
694 
695   pVm = (Vdbe *)pStmt;
696   if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
697     sqlite3_mutex_enter(pVm->db->mutex);
698     pOut = &pVm->pResultSet[i];
699   }else{
700     /* If the value passed as the second argument is out of range, return
701     ** a pointer to the following static Mem object which contains the
702     ** value SQL NULL. Even though the Mem structure contains an element
703     ** of type i64, on certain architectures (x86) with certain compiler
704     ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
705     ** instead of an 8-byte one. This all works fine, except that when
706     ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
707     ** that a Mem structure is located on an 8-byte boundary. To prevent
708     ** these assert()s from failing, when building with SQLITE_DEBUG defined
709     ** using gcc, we force nullMem to be 8-byte aligned using the magical
710     ** __attribute__((aligned(8))) macro.  */
711     static const Mem nullMem
712 #if defined(SQLITE_DEBUG) && defined(__GNUC__)
713       __attribute__((aligned(8)))
714 #endif
715       = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0,
716 #ifdef SQLITE_DEBUG
717          0, 0,  /* pScopyFrom, pFiller */
718 #endif
719          0, 0 };
720 
721     if( pVm && ALWAYS(pVm->db) ){
722       sqlite3_mutex_enter(pVm->db->mutex);
723       sqlite3Error(pVm->db, SQLITE_RANGE, 0);
724     }
725     pOut = (Mem*)&nullMem;
726   }
727   return pOut;
728 }
729 
730 /*
731 ** This function is called after invoking an sqlite3_value_XXX function on a
732 ** column value (i.e. a value returned by evaluating an SQL expression in the
733 ** select list of a SELECT statement) that may cause a malloc() failure. If
734 ** malloc() has failed, the threads mallocFailed flag is cleared and the result
735 ** code of statement pStmt set to SQLITE_NOMEM.
736 **
737 ** Specifically, this is called from within:
738 **
739 **     sqlite3_column_int()
740 **     sqlite3_column_int64()
741 **     sqlite3_column_text()
742 **     sqlite3_column_text16()
743 **     sqlite3_column_real()
744 **     sqlite3_column_bytes()
745 **     sqlite3_column_bytes16()
746 **     sqiite3_column_blob()
747 */
748 static void columnMallocFailure(sqlite3_stmt *pStmt)
749 {
750   /* If malloc() failed during an encoding conversion within an
751   ** sqlite3_column_XXX API, then set the return code of the statement to
752   ** SQLITE_NOMEM. The next call to _step() (if any) will return SQLITE_ERROR
753   ** and _finalize() will return NOMEM.
754   */
755   Vdbe *p = (Vdbe *)pStmt;
756   if( p ){
757     p->rc = sqlite3ApiExit(p->db, p->rc);
758     sqlite3_mutex_leave(p->db->mutex);
759   }
760 }
761 
762 /**************************** sqlite3_column_  *******************************
763 ** The following routines are used to access elements of the current row
764 ** in the result set.
765 */
766 const void *sqlite3_column_blob(sqlite3_stmt *pStmt, int i){
767   const void *val;
768   val = sqlite3_value_blob( columnMem(pStmt,i) );
769   /* Even though there is no encoding conversion, value_blob() might
770   ** need to call malloc() to expand the result of a zeroblob()
771   ** expression.
772   */
773   columnMallocFailure(pStmt);
774   return val;
775 }
776 int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
777   int val = sqlite3_value_bytes( columnMem(pStmt,i) );
778   columnMallocFailure(pStmt);
779   return val;
780 }
781 int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
782   int val = sqlite3_value_bytes16( columnMem(pStmt,i) );
783   columnMallocFailure(pStmt);
784   return val;
785 }
786 double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
787   double val = sqlite3_value_double( columnMem(pStmt,i) );
788   columnMallocFailure(pStmt);
789   return val;
790 }
791 int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
792   int val = sqlite3_value_int( columnMem(pStmt,i) );
793   columnMallocFailure(pStmt);
794   return val;
795 }
796 sqlite_int64 sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
797   sqlite_int64 val = sqlite3_value_int64( columnMem(pStmt,i) );
798   columnMallocFailure(pStmt);
799   return val;
800 }
801 const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
802   const unsigned char *val = sqlite3_value_text( columnMem(pStmt,i) );
803   columnMallocFailure(pStmt);
804   return val;
805 }
806 sqlite3_value *sqlite3_column_value(sqlite3_stmt *pStmt, int i){
807   Mem *pOut = columnMem(pStmt, i);
808   if( pOut->flags&MEM_Static ){
809     pOut->flags &= ~MEM_Static;
810     pOut->flags |= MEM_Ephem;
811   }
812   columnMallocFailure(pStmt);
813   return (sqlite3_value *)pOut;
814 }
815 #ifndef SQLITE_OMIT_UTF16
816 const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
817   const void *val = sqlite3_value_text16( columnMem(pStmt,i) );
818   columnMallocFailure(pStmt);
819   return val;
820 }
821 #endif /* SQLITE_OMIT_UTF16 */
822 int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
823   int iType = sqlite3_value_type( columnMem(pStmt,i) );
824   columnMallocFailure(pStmt);
825   return iType;
826 }
827 
828 /* The following function is experimental and subject to change or
829 ** removal */
830 /*int sqlite3_column_numeric_type(sqlite3_stmt *pStmt, int i){
831 **  return sqlite3_value_numeric_type( columnMem(pStmt,i) );
832 **}
833 */
834 
835 /*
836 ** Convert the N-th element of pStmt->pColName[] into a string using
837 ** xFunc() then return that string.  If N is out of range, return 0.
838 **
839 ** There are up to 5 names for each column.  useType determines which
840 ** name is returned.  Here are the names:
841 **
842 **    0      The column name as it should be displayed for output
843 **    1      The datatype name for the column
844 **    2      The name of the database that the column derives from
845 **    3      The name of the table that the column derives from
846 **    4      The name of the table column that the result column derives from
847 **
848 ** If the result is not a simple column reference (if it is an expression
849 ** or a constant) then useTypes 2, 3, and 4 return NULL.
850 */
851 static const void *columnName(
852   sqlite3_stmt *pStmt,
853   int N,
854   const void *(*xFunc)(Mem*),
855   int useType
856 ){
857   const void *ret = 0;
858   Vdbe *p = (Vdbe *)pStmt;
859   int n;
860   sqlite3 *db = p->db;
861 
862   assert( db!=0 );
863   n = sqlite3_column_count(pStmt);
864   if( N<n && N>=0 ){
865     N += useType*n;
866     sqlite3_mutex_enter(db->mutex);
867     assert( db->mallocFailed==0 );
868     ret = xFunc(&p->aColName[N]);
869      /* A malloc may have failed inside of the xFunc() call. If this
870     ** is the case, clear the mallocFailed flag and return NULL.
871     */
872     if( db->mallocFailed ){
873       db->mallocFailed = 0;
874       ret = 0;
875     }
876     sqlite3_mutex_leave(db->mutex);
877   }
878   return ret;
879 }
880 
881 /*
882 ** Return the name of the Nth column of the result set returned by SQL
883 ** statement pStmt.
884 */
885 const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
886   return columnName(
887       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_NAME);
888 }
889 #ifndef SQLITE_OMIT_UTF16
890 const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
891   return columnName(
892       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_NAME);
893 }
894 #endif
895 
896 /*
897 ** Constraint:  If you have ENABLE_COLUMN_METADATA then you must
898 ** not define OMIT_DECLTYPE.
899 */
900 #if defined(SQLITE_OMIT_DECLTYPE) && defined(SQLITE_ENABLE_COLUMN_METADATA)
901 # error "Must not define both SQLITE_OMIT_DECLTYPE \
902          and SQLITE_ENABLE_COLUMN_METADATA"
903 #endif
904 
905 #ifndef SQLITE_OMIT_DECLTYPE
906 /*
907 ** Return the column declaration type (if applicable) of the 'i'th column
908 ** of the result set of SQL statement pStmt.
909 */
910 const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int N){
911   return columnName(
912       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DECLTYPE);
913 }
914 #ifndef SQLITE_OMIT_UTF16
915 const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int N){
916   return columnName(
917       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DECLTYPE);
918 }
919 #endif /* SQLITE_OMIT_UTF16 */
920 #endif /* SQLITE_OMIT_DECLTYPE */
921 
922 #ifdef SQLITE_ENABLE_COLUMN_METADATA
923 /*
924 ** Return the name of the database from which a result column derives.
925 ** NULL is returned if the result column is an expression or constant or
926 ** anything else which is not an unabiguous reference to a database column.
927 */
928 const char *sqlite3_column_database_name(sqlite3_stmt *pStmt, int N){
929   return columnName(
930       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DATABASE);
931 }
932 #ifndef SQLITE_OMIT_UTF16
933 const void *sqlite3_column_database_name16(sqlite3_stmt *pStmt, int N){
934   return columnName(
935       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DATABASE);
936 }
937 #endif /* SQLITE_OMIT_UTF16 */
938 
939 /*
940 ** Return the name of the table from which a result column derives.
941 ** NULL is returned if the result column is an expression or constant or
942 ** anything else which is not an unabiguous reference to a database column.
943 */
944 const char *sqlite3_column_table_name(sqlite3_stmt *pStmt, int N){
945   return columnName(
946       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_TABLE);
947 }
948 #ifndef SQLITE_OMIT_UTF16
949 const void *sqlite3_column_table_name16(sqlite3_stmt *pStmt, int N){
950   return columnName(
951       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_TABLE);
952 }
953 #endif /* SQLITE_OMIT_UTF16 */
954 
955 /*
956 ** Return the name of the table column from which a result column derives.
957 ** NULL is returned if the result column is an expression or constant or
958 ** anything else which is not an unabiguous reference to a database column.
959 */
960 const char *sqlite3_column_origin_name(sqlite3_stmt *pStmt, int N){
961   return columnName(
962       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_COLUMN);
963 }
964 #ifndef SQLITE_OMIT_UTF16
965 const void *sqlite3_column_origin_name16(sqlite3_stmt *pStmt, int N){
966   return columnName(
967       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_COLUMN);
968 }
969 #endif /* SQLITE_OMIT_UTF16 */
970 #endif /* SQLITE_ENABLE_COLUMN_METADATA */
971 
972 
973 /******************************* sqlite3_bind_  ***************************
974 **
975 ** Routines used to attach values to wildcards in a compiled SQL statement.
976 */
977 /*
978 ** Unbind the value bound to variable i in virtual machine p. This is the
979 ** the same as binding a NULL value to the column. If the "i" parameter is
980 ** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
981 **
982 ** A successful evaluation of this routine acquires the mutex on p.
983 ** the mutex is released if any kind of error occurs.
984 **
985 ** The error code stored in database p->db is overwritten with the return
986 ** value in any case.
987 */
988 static int vdbeUnbind(Vdbe *p, int i){
989   Mem *pVar;
990   if( vdbeSafetyNotNull(p) ){
991     return SQLITE_MISUSE_BKPT;
992   }
993   sqlite3_mutex_enter(p->db->mutex);
994   if( p->magic!=VDBE_MAGIC_RUN || p->pc>=0 ){
995     sqlite3Error(p->db, SQLITE_MISUSE, 0);
996     sqlite3_mutex_leave(p->db->mutex);
997     sqlite3_log(SQLITE_MISUSE,
998         "bind on a busy prepared statement: [%s]", p->zSql);
999     return SQLITE_MISUSE_BKPT;
1000   }
1001   if( i<1 || i>p->nVar ){
1002     sqlite3Error(p->db, SQLITE_RANGE, 0);
1003     sqlite3_mutex_leave(p->db->mutex);
1004     return SQLITE_RANGE;
1005   }
1006   i--;
1007   pVar = &p->aVar[i];
1008   sqlite3VdbeMemRelease(pVar);
1009   pVar->flags = MEM_Null;
1010   sqlite3Error(p->db, SQLITE_OK, 0);
1011 
1012   /* If the bit corresponding to this variable in Vdbe.expmask is set, then
1013   ** binding a new value to this variable invalidates the current query plan.
1014   **
1015   ** IMPLEMENTATION-OF: R-48440-37595 If the specific value bound to host
1016   ** parameter in the WHERE clause might influence the choice of query plan
1017   ** for a statement, then the statement will be automatically recompiled,
1018   ** as if there had been a schema change, on the first sqlite3_step() call
1019   ** following any change to the bindings of that parameter.
1020   */
1021   if( p->isPrepareV2 &&
1022      ((i<32 && p->expmask & ((u32)1 << i)) || p->expmask==0xffffffff)
1023   ){
1024     p->expired = 1;
1025   }
1026   return SQLITE_OK;
1027 }
1028 
1029 /*
1030 ** Bind a text or BLOB value.
1031 */
1032 static int bindText(
1033   sqlite3_stmt *pStmt,   /* The statement to bind against */
1034   int i,                 /* Index of the parameter to bind */
1035   const void *zData,     /* Pointer to the data to be bound */
1036   int nData,             /* Number of bytes of data to be bound */
1037   void (*xDel)(void*),   /* Destructor for the data */
1038   u8 encoding            /* Encoding for the data */
1039 ){
1040   Vdbe *p = (Vdbe *)pStmt;
1041   Mem *pVar;
1042   int rc;
1043 
1044   rc = vdbeUnbind(p, i);
1045   if( rc==SQLITE_OK ){
1046     if( zData!=0 ){
1047       pVar = &p->aVar[i-1];
1048       rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
1049       if( rc==SQLITE_OK && encoding!=0 ){
1050         rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
1051       }
1052       sqlite3Error(p->db, rc, 0);
1053       rc = sqlite3ApiExit(p->db, rc);
1054     }
1055     sqlite3_mutex_leave(p->db->mutex);
1056   }else if( xDel!=SQLITE_STATIC && xDel!=SQLITE_TRANSIENT ){
1057     xDel((void*)zData);
1058   }
1059   return rc;
1060 }
1061 
1062 
1063 /*
1064 ** Bind a blob value to an SQL statement variable.
1065 */
1066 int sqlite3_bind_blob(
1067   sqlite3_stmt *pStmt,
1068   int i,
1069   const void *zData,
1070   int nData,
1071   void (*xDel)(void*)
1072 ){
1073   return bindText(pStmt, i, zData, nData, xDel, 0);
1074 }
1075 int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
1076   int rc;
1077   Vdbe *p = (Vdbe *)pStmt;
1078   rc = vdbeUnbind(p, i);
1079   if( rc==SQLITE_OK ){
1080     sqlite3VdbeMemSetDouble(&p->aVar[i-1], rValue);
1081     sqlite3_mutex_leave(p->db->mutex);
1082   }
1083   return rc;
1084 }
1085 int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
1086   return sqlite3_bind_int64(p, i, (i64)iValue);
1087 }
1088 int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, sqlite_int64 iValue){
1089   int rc;
1090   Vdbe *p = (Vdbe *)pStmt;
1091   rc = vdbeUnbind(p, i);
1092   if( rc==SQLITE_OK ){
1093     sqlite3VdbeMemSetInt64(&p->aVar[i-1], iValue);
1094     sqlite3_mutex_leave(p->db->mutex);
1095   }
1096   return rc;
1097 }
1098 int sqlite3_bind_null(sqlite3_stmt *pStmt, int i){
1099   int rc;
1100   Vdbe *p = (Vdbe*)pStmt;
1101   rc = vdbeUnbind(p, i);
1102   if( rc==SQLITE_OK ){
1103     sqlite3_mutex_leave(p->db->mutex);
1104   }
1105   return rc;
1106 }
1107 int sqlite3_bind_text(
1108   sqlite3_stmt *pStmt,
1109   int i,
1110   const char *zData,
1111   int nData,
1112   void (*xDel)(void*)
1113 ){
1114   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF8);
1115 }
1116 #ifndef SQLITE_OMIT_UTF16
1117 int sqlite3_bind_text16(
1118   sqlite3_stmt *pStmt,
1119   int i,
1120   const void *zData,
1121   int nData,
1122   void (*xDel)(void*)
1123 ){
1124   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF16NATIVE);
1125 }
1126 #endif /* SQLITE_OMIT_UTF16 */
1127 int sqlite3_bind_value(sqlite3_stmt *pStmt, int i, const sqlite3_value *pValue){
1128   int rc;
1129   switch( pValue->type ){
1130     case SQLITE_INTEGER: {
1131       rc = sqlite3_bind_int64(pStmt, i, pValue->u.i);
1132       break;
1133     }
1134     case SQLITE_FLOAT: {
1135       rc = sqlite3_bind_double(pStmt, i, pValue->r);
1136       break;
1137     }
1138     case SQLITE_BLOB: {
1139       if( pValue->flags & MEM_Zero ){
1140         rc = sqlite3_bind_zeroblob(pStmt, i, pValue->u.nZero);
1141       }else{
1142         rc = sqlite3_bind_blob(pStmt, i, pValue->z, pValue->n,SQLITE_TRANSIENT);
1143       }
1144       break;
1145     }
1146     case SQLITE_TEXT: {
1147       rc = bindText(pStmt,i,  pValue->z, pValue->n, SQLITE_TRANSIENT,
1148                               pValue->enc);
1149       break;
1150     }
1151     default: {
1152       rc = sqlite3_bind_null(pStmt, i);
1153       break;
1154     }
1155   }
1156   return rc;
1157 }
1158 int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
1159   int rc;
1160   Vdbe *p = (Vdbe *)pStmt;
1161   rc = vdbeUnbind(p, i);
1162   if( rc==SQLITE_OK ){
1163     sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
1164     sqlite3_mutex_leave(p->db->mutex);
1165   }
1166   return rc;
1167 }
1168 
1169 /*
1170 ** Return the number of wildcards that can be potentially bound to.
1171 ** This routine is added to support DBD::SQLite.
1172 */
1173 int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
1174   Vdbe *p = (Vdbe*)pStmt;
1175   return p ? p->nVar : 0;
1176 }
1177 
1178 /*
1179 ** Return the name of a wildcard parameter.  Return NULL if the index
1180 ** is out of range or if the wildcard is unnamed.
1181 **
1182 ** The result is always UTF-8.
1183 */
1184 const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
1185   Vdbe *p = (Vdbe*)pStmt;
1186   if( p==0 || i<1 || i>p->nzVar ){
1187     return 0;
1188   }
1189   return p->azVar[i-1];
1190 }
1191 
1192 /*
1193 ** Given a wildcard parameter name, return the index of the variable
1194 ** with that name.  If there is no variable with the given name,
1195 ** return 0.
1196 */
1197 int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
1198   int i;
1199   if( p==0 ){
1200     return 0;
1201   }
1202   if( zName ){
1203     for(i=0; i<p->nzVar; i++){
1204       const char *z = p->azVar[i];
1205       if( z && memcmp(z,zName,nName)==0 && z[nName]==0 ){
1206         return i+1;
1207       }
1208     }
1209   }
1210   return 0;
1211 }
1212 int sqlite3_bind_parameter_index(sqlite3_stmt *pStmt, const char *zName){
1213   return sqlite3VdbeParameterIndex((Vdbe*)pStmt, zName, sqlite3Strlen30(zName));
1214 }
1215 
1216 /*
1217 ** Transfer all bindings from the first statement over to the second.
1218 */
1219 int sqlite3TransferBindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1220   Vdbe *pFrom = (Vdbe*)pFromStmt;
1221   Vdbe *pTo = (Vdbe*)pToStmt;
1222   int i;
1223   assert( pTo->db==pFrom->db );
1224   assert( pTo->nVar==pFrom->nVar );
1225   sqlite3_mutex_enter(pTo->db->mutex);
1226   for(i=0; i<pFrom->nVar; i++){
1227     sqlite3VdbeMemMove(&pTo->aVar[i], &pFrom->aVar[i]);
1228   }
1229   sqlite3_mutex_leave(pTo->db->mutex);
1230   return SQLITE_OK;
1231 }
1232 
1233 #ifndef SQLITE_OMIT_DEPRECATED
1234 /*
1235 ** Deprecated external interface.  Internal/core SQLite code
1236 ** should call sqlite3TransferBindings.
1237 **
1238 ** Is is misuse to call this routine with statements from different
1239 ** database connections.  But as this is a deprecated interface, we
1240 ** will not bother to check for that condition.
1241 **
1242 ** If the two statements contain a different number of bindings, then
1243 ** an SQLITE_ERROR is returned.  Nothing else can go wrong, so otherwise
1244 ** SQLITE_OK is returned.
1245 */
1246 int sqlite3_transfer_bindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1247   Vdbe *pFrom = (Vdbe*)pFromStmt;
1248   Vdbe *pTo = (Vdbe*)pToStmt;
1249   if( pFrom->nVar!=pTo->nVar ){
1250     return SQLITE_ERROR;
1251   }
1252   if( pTo->isPrepareV2 && pTo->expmask ){
1253     pTo->expired = 1;
1254   }
1255   if( pFrom->isPrepareV2 && pFrom->expmask ){
1256     pFrom->expired = 1;
1257   }
1258   return sqlite3TransferBindings(pFromStmt, pToStmt);
1259 }
1260 #endif
1261 
1262 /*
1263 ** Return the sqlite3* database handle to which the prepared statement given
1264 ** in the argument belongs.  This is the same database handle that was
1265 ** the first argument to the sqlite3_prepare() that was used to create
1266 ** the statement in the first place.
1267 */
1268 sqlite3 *sqlite3_db_handle(sqlite3_stmt *pStmt){
1269   return pStmt ? ((Vdbe*)pStmt)->db : 0;
1270 }
1271 
1272 /*
1273 ** Return true if the prepared statement is guaranteed to not modify the
1274 ** database.
1275 */
1276 int sqlite3_stmt_readonly(sqlite3_stmt *pStmt){
1277   return pStmt ? ((Vdbe*)pStmt)->readOnly : 1;
1278 }
1279 
1280 /*
1281 ** Return true if the prepared statement is in need of being reset.
1282 */
1283 int sqlite3_stmt_busy(sqlite3_stmt *pStmt){
1284   Vdbe *v = (Vdbe*)pStmt;
1285   return v!=0 && v->pc>0 && v->magic==VDBE_MAGIC_RUN;
1286 }
1287 
1288 /*
1289 ** Return a pointer to the next prepared statement after pStmt associated
1290 ** with database connection pDb.  If pStmt is NULL, return the first
1291 ** prepared statement for the database connection.  Return NULL if there
1292 ** are no more.
1293 */
1294 sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt){
1295   sqlite3_stmt *pNext;
1296   sqlite3_mutex_enter(pDb->mutex);
1297   if( pStmt==0 ){
1298     pNext = (sqlite3_stmt*)pDb->pVdbe;
1299   }else{
1300     pNext = (sqlite3_stmt*)((Vdbe*)pStmt)->pNext;
1301   }
1302   sqlite3_mutex_leave(pDb->mutex);
1303   return pNext;
1304 }
1305 
1306 /*
1307 ** Return the value of a status counter for a prepared statement
1308 */
1309 int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
1310   Vdbe *pVdbe = (Vdbe*)pStmt;
1311   int v = pVdbe->aCounter[op-1];
1312   if( resetFlag ) pVdbe->aCounter[op-1] = 0;
1313   return v;
1314 }
1315