xref: /sqlite-3.40.0/src/vdbeapi.c (revision c56fac74)
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 #ifndef SQLITE_OMIT_TRACE
57 /*
58 ** Invoke the profile callback.  This routine is only called if we already
59 ** know that the profile callback is defined and needs to be invoked.
60 */
61 static SQLITE_NOINLINE void invokeProfileCallback(sqlite3 *db, Vdbe *p){
62   sqlite3_int64 iNow;
63   assert( p->startTime>0 );
64   assert( db->xProfile!=0 );
65   assert( db->init.busy==0 );
66   assert( p->zSql!=0 );
67   sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
68   db->xProfile(db->pProfileArg, p->zSql, (iNow - p->startTime)*1000000);
69   p->startTime = 0;
70 }
71 /*
72 ** The checkProfileCallback(DB,P) macro checks to see if a profile callback
73 ** is needed, and it invokes the callback if it is needed.
74 */
75 # define checkProfileCallback(DB,P) \
76    if( ((P)->startTime)>0 ){ invokeProfileCallback(DB,P); }
77 #else
78 # define checkProfileCallback(DB,P)  /*no-op*/
79 #endif
80 
81 /*
82 ** The following routine destroys a virtual machine that is created by
83 ** the sqlite3_compile() routine. The integer returned is an SQLITE_
84 ** success/failure code that describes the result of executing the virtual
85 ** machine.
86 **
87 ** This routine sets the error code and string returned by
88 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
89 */
90 int sqlite3_finalize(sqlite3_stmt *pStmt){
91   int rc;
92   if( pStmt==0 ){
93     /* IMPLEMENTATION-OF: R-57228-12904 Invoking sqlite3_finalize() on a NULL
94     ** pointer is a harmless no-op. */
95     rc = SQLITE_OK;
96   }else{
97     Vdbe *v = (Vdbe*)pStmt;
98     sqlite3 *db = v->db;
99     if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
100     sqlite3_mutex_enter(db->mutex);
101     checkProfileCallback(db, v);
102     rc = sqlite3VdbeFinalize(v);
103     rc = sqlite3ApiExit(db, rc);
104     sqlite3LeaveMutexAndCloseZombie(db);
105   }
106   return rc;
107 }
108 
109 /*
110 ** Terminate the current execution of an SQL statement and reset it
111 ** back to its starting state so that it can be reused. A success code from
112 ** the prior execution is returned.
113 **
114 ** This routine sets the error code and string returned by
115 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
116 */
117 int sqlite3_reset(sqlite3_stmt *pStmt){
118   int rc;
119   if( pStmt==0 ){
120     rc = SQLITE_OK;
121   }else{
122     Vdbe *v = (Vdbe*)pStmt;
123     sqlite3 *db = v->db;
124     sqlite3_mutex_enter(db->mutex);
125     checkProfileCallback(db, v);
126     rc = sqlite3VdbeReset(v);
127     sqlite3VdbeRewind(v);
128     assert( (rc & (db->errMask))==rc );
129     rc = sqlite3ApiExit(db, rc);
130     sqlite3_mutex_leave(db->mutex);
131   }
132   return rc;
133 }
134 
135 /*
136 ** Set all the parameters in the compiled SQL statement to NULL.
137 */
138 int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
139   int i;
140   int rc = SQLITE_OK;
141   Vdbe *p = (Vdbe*)pStmt;
142 #if SQLITE_THREADSAFE
143   sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
144 #endif
145   sqlite3_mutex_enter(mutex);
146   for(i=0; i<p->nVar; i++){
147     sqlite3VdbeMemRelease(&p->aVar[i]);
148     p->aVar[i].flags = MEM_Null;
149   }
150   if( p->isPrepareV2 && p->expmask ){
151     p->expired = 1;
152   }
153   sqlite3_mutex_leave(mutex);
154   return rc;
155 }
156 
157 
158 /**************************** sqlite3_value_  *******************************
159 ** The following routines extract information from a Mem or sqlite3_value
160 ** structure.
161 */
162 const void *sqlite3_value_blob(sqlite3_value *pVal){
163   Mem *p = (Mem*)pVal;
164   if( p->flags & (MEM_Blob|MEM_Str) ){
165     if( sqlite3VdbeMemExpandBlob(p)!=SQLITE_OK ){
166       assert( p->flags==MEM_Null && p->z==0 );
167       return 0;
168     }
169     p->flags |= MEM_Blob;
170     return p->n ? p->z : 0;
171   }else{
172     return sqlite3_value_text(pVal);
173   }
174 }
175 int sqlite3_value_bytes(sqlite3_value *pVal){
176   return sqlite3ValueBytes(pVal, SQLITE_UTF8);
177 }
178 int sqlite3_value_bytes16(sqlite3_value *pVal){
179   return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
180 }
181 double sqlite3_value_double(sqlite3_value *pVal){
182   return sqlite3VdbeRealValue((Mem*)pVal);
183 }
184 int sqlite3_value_int(sqlite3_value *pVal){
185   return (int)sqlite3VdbeIntValue((Mem*)pVal);
186 }
187 sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
188   return sqlite3VdbeIntValue((Mem*)pVal);
189 }
190 unsigned int sqlite3_value_subtype(sqlite3_value *pVal){
191   return ((Mem*)pVal)->eSubtype;
192 }
193 const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
194   return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
195 }
196 #ifndef SQLITE_OMIT_UTF16
197 const void *sqlite3_value_text16(sqlite3_value* pVal){
198   return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
199 }
200 const void *sqlite3_value_text16be(sqlite3_value *pVal){
201   return sqlite3ValueText(pVal, SQLITE_UTF16BE);
202 }
203 const void *sqlite3_value_text16le(sqlite3_value *pVal){
204   return sqlite3ValueText(pVal, SQLITE_UTF16LE);
205 }
206 #endif /* SQLITE_OMIT_UTF16 */
207 /* EVIDENCE-OF: R-12793-43283 Every value in SQLite has one of five
208 ** fundamental datatypes: 64-bit signed integer 64-bit IEEE floating
209 ** point number string BLOB NULL
210 */
211 int sqlite3_value_type(sqlite3_value* pVal){
212   static const u8 aType[] = {
213      SQLITE_BLOB,     /* 0x00 */
214      SQLITE_NULL,     /* 0x01 */
215      SQLITE_TEXT,     /* 0x02 */
216      SQLITE_NULL,     /* 0x03 */
217      SQLITE_INTEGER,  /* 0x04 */
218      SQLITE_NULL,     /* 0x05 */
219      SQLITE_INTEGER,  /* 0x06 */
220      SQLITE_NULL,     /* 0x07 */
221      SQLITE_FLOAT,    /* 0x08 */
222      SQLITE_NULL,     /* 0x09 */
223      SQLITE_FLOAT,    /* 0x0a */
224      SQLITE_NULL,     /* 0x0b */
225      SQLITE_INTEGER,  /* 0x0c */
226      SQLITE_NULL,     /* 0x0d */
227      SQLITE_INTEGER,  /* 0x0e */
228      SQLITE_NULL,     /* 0x0f */
229      SQLITE_BLOB,     /* 0x10 */
230      SQLITE_NULL,     /* 0x11 */
231      SQLITE_TEXT,     /* 0x12 */
232      SQLITE_NULL,     /* 0x13 */
233      SQLITE_INTEGER,  /* 0x14 */
234      SQLITE_NULL,     /* 0x15 */
235      SQLITE_INTEGER,  /* 0x16 */
236      SQLITE_NULL,     /* 0x17 */
237      SQLITE_FLOAT,    /* 0x18 */
238      SQLITE_NULL,     /* 0x19 */
239      SQLITE_FLOAT,    /* 0x1a */
240      SQLITE_NULL,     /* 0x1b */
241      SQLITE_INTEGER,  /* 0x1c */
242      SQLITE_NULL,     /* 0x1d */
243      SQLITE_INTEGER,  /* 0x1e */
244      SQLITE_NULL,     /* 0x1f */
245   };
246   return aType[pVal->flags&MEM_AffMask];
247 }
248 
249 /* Make a copy of an sqlite3_value object
250 */
251 sqlite3_value *sqlite3_value_dup(const sqlite3_value *pOrig){
252   sqlite3_value *pNew;
253   if( pOrig==0 ) return 0;
254   pNew = sqlite3_malloc( sizeof(*pNew) );
255   if( pNew==0 ) return 0;
256   memset(pNew, 0, sizeof(*pNew));
257   memcpy(pNew, pOrig, MEMCELLSIZE);
258   pNew->flags &= ~MEM_Dyn;
259   pNew->db = 0;
260   if( pNew->flags&(MEM_Str|MEM_Blob) ){
261     pNew->flags &= ~(MEM_Static|MEM_Dyn);
262     pNew->flags |= MEM_Ephem;
263     if( sqlite3VdbeMemMakeWriteable(pNew)!=SQLITE_OK ){
264       sqlite3ValueFree(pNew);
265       pNew = 0;
266     }
267   }
268   return pNew;
269 }
270 
271 /* Destroy an sqlite3_value object previously obtained from
272 ** sqlite3_value_dup().
273 */
274 void sqlite3_value_free(sqlite3_value *pOld){
275   sqlite3ValueFree(pOld);
276 }
277 
278 
279 /**************************** sqlite3_result_  *******************************
280 ** The following routines are used by user-defined functions to specify
281 ** the function result.
282 **
283 ** The setStrOrError() function calls sqlite3VdbeMemSetStr() to store the
284 ** result as a string or blob but if the string or blob is too large, it
285 ** then sets the error code to SQLITE_TOOBIG
286 **
287 ** The invokeValueDestructor(P,X) routine invokes destructor function X()
288 ** on value P is not going to be used and need to be destroyed.
289 */
290 static void setResultStrOrError(
291   sqlite3_context *pCtx,  /* Function context */
292   const char *z,          /* String pointer */
293   int n,                  /* Bytes in string, or negative */
294   u8 enc,                 /* Encoding of z.  0 for BLOBs */
295   void (*xDel)(void*)     /* Destructor function */
296 ){
297   if( sqlite3VdbeMemSetStr(pCtx->pOut, z, n, enc, xDel)==SQLITE_TOOBIG ){
298     sqlite3_result_error_toobig(pCtx);
299   }
300 }
301 static int invokeValueDestructor(
302   const void *p,             /* Value to destroy */
303   void (*xDel)(void*),       /* The destructor */
304   sqlite3_context *pCtx      /* Set a SQLITE_TOOBIG error if no NULL */
305 ){
306   assert( xDel!=SQLITE_DYNAMIC );
307   if( xDel==0 ){
308     /* noop */
309   }else if( xDel==SQLITE_TRANSIENT ){
310     /* noop */
311   }else{
312     xDel((void*)p);
313   }
314   if( pCtx ) sqlite3_result_error_toobig(pCtx);
315   return SQLITE_TOOBIG;
316 }
317 void sqlite3_result_blob(
318   sqlite3_context *pCtx,
319   const void *z,
320   int n,
321   void (*xDel)(void *)
322 ){
323   assert( n>=0 );
324   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
325   setResultStrOrError(pCtx, z, n, 0, xDel);
326 }
327 void sqlite3_result_blob64(
328   sqlite3_context *pCtx,
329   const void *z,
330   sqlite3_uint64 n,
331   void (*xDel)(void *)
332 ){
333   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
334   assert( xDel!=SQLITE_DYNAMIC );
335   if( n>0x7fffffff ){
336     (void)invokeValueDestructor(z, xDel, pCtx);
337   }else{
338     setResultStrOrError(pCtx, z, (int)n, 0, xDel);
339   }
340 }
341 void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
342   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
343   sqlite3VdbeMemSetDouble(pCtx->pOut, rVal);
344 }
345 void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
346   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
347   pCtx->isError = SQLITE_ERROR;
348   pCtx->fErrorOrAux = 1;
349   sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
350 }
351 #ifndef SQLITE_OMIT_UTF16
352 void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
353   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
354   pCtx->isError = SQLITE_ERROR;
355   pCtx->fErrorOrAux = 1;
356   sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
357 }
358 #endif
359 void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
360   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
361   sqlite3VdbeMemSetInt64(pCtx->pOut, (i64)iVal);
362 }
363 void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
364   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
365   sqlite3VdbeMemSetInt64(pCtx->pOut, iVal);
366 }
367 void sqlite3_result_null(sqlite3_context *pCtx){
368   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
369   sqlite3VdbeMemSetNull(pCtx->pOut);
370 }
371 void sqlite3_result_subtype(sqlite3_context *pCtx, unsigned int eSubtype){
372   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
373   pCtx->pOut->eSubtype = eSubtype & 0xff;
374 }
375 void sqlite3_result_text(
376   sqlite3_context *pCtx,
377   const char *z,
378   int n,
379   void (*xDel)(void *)
380 ){
381   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
382   setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel);
383 }
384 void sqlite3_result_text64(
385   sqlite3_context *pCtx,
386   const char *z,
387   sqlite3_uint64 n,
388   void (*xDel)(void *),
389   unsigned char enc
390 ){
391   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
392   assert( xDel!=SQLITE_DYNAMIC );
393   if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
394   if( n>0x7fffffff ){
395     (void)invokeValueDestructor(z, xDel, pCtx);
396   }else{
397     setResultStrOrError(pCtx, z, (int)n, enc, xDel);
398   }
399 }
400 #ifndef SQLITE_OMIT_UTF16
401 void sqlite3_result_text16(
402   sqlite3_context *pCtx,
403   const void *z,
404   int n,
405   void (*xDel)(void *)
406 ){
407   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
408   setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel);
409 }
410 void sqlite3_result_text16be(
411   sqlite3_context *pCtx,
412   const void *z,
413   int n,
414   void (*xDel)(void *)
415 ){
416   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
417   setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel);
418 }
419 void sqlite3_result_text16le(
420   sqlite3_context *pCtx,
421   const void *z,
422   int n,
423   void (*xDel)(void *)
424 ){
425   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
426   setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel);
427 }
428 #endif /* SQLITE_OMIT_UTF16 */
429 void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
430   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
431   sqlite3VdbeMemCopy(pCtx->pOut, pValue);
432 }
433 void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
434   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
435   sqlite3VdbeMemSetZeroBlob(pCtx->pOut, n);
436 }
437 int sqlite3_result_zeroblob64(sqlite3_context *pCtx, u64 n){
438   Mem *pOut = pCtx->pOut;
439   assert( sqlite3_mutex_held(pOut->db->mutex) );
440   if( n>(u64)pOut->db->aLimit[SQLITE_LIMIT_LENGTH] ){
441     return SQLITE_TOOBIG;
442   }
443   sqlite3VdbeMemSetZeroBlob(pCtx->pOut, (int)n);
444   return SQLITE_OK;
445 }
446 void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
447   pCtx->isError = errCode;
448   pCtx->fErrorOrAux = 1;
449 #ifdef SQLITE_DEBUG
450   if( pCtx->pVdbe ) pCtx->pVdbe->rcApp = errCode;
451 #endif
452   if( pCtx->pOut->flags & MEM_Null ){
453     sqlite3VdbeMemSetStr(pCtx->pOut, sqlite3ErrStr(errCode), -1,
454                          SQLITE_UTF8, SQLITE_STATIC);
455   }
456 }
457 
458 /* Force an SQLITE_TOOBIG error. */
459 void sqlite3_result_error_toobig(sqlite3_context *pCtx){
460   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
461   pCtx->isError = SQLITE_TOOBIG;
462   pCtx->fErrorOrAux = 1;
463   sqlite3VdbeMemSetStr(pCtx->pOut, "string or blob too big", -1,
464                        SQLITE_UTF8, SQLITE_STATIC);
465 }
466 
467 /* An SQLITE_NOMEM error. */
468 void sqlite3_result_error_nomem(sqlite3_context *pCtx){
469   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
470   sqlite3VdbeMemSetNull(pCtx->pOut);
471   pCtx->isError = SQLITE_NOMEM;
472   pCtx->fErrorOrAux = 1;
473   pCtx->pOut->db->mallocFailed = 1;
474 }
475 
476 /*
477 ** This function is called after a transaction has been committed. It
478 ** invokes callbacks registered with sqlite3_wal_hook() as required.
479 */
480 static int doWalCallbacks(sqlite3 *db){
481   int rc = SQLITE_OK;
482 #ifndef SQLITE_OMIT_WAL
483   int i;
484   for(i=0; i<db->nDb; i++){
485     Btree *pBt = db->aDb[i].pBt;
486     if( pBt ){
487       int nEntry;
488       sqlite3BtreeEnter(pBt);
489       nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
490       sqlite3BtreeLeave(pBt);
491       if( db->xWalCallback && nEntry>0 && rc==SQLITE_OK ){
492         rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zName, nEntry);
493       }
494     }
495   }
496 #endif
497   return rc;
498 }
499 
500 
501 /*
502 ** Execute the statement pStmt, either until a row of data is ready, the
503 ** statement is completely executed or an error occurs.
504 **
505 ** This routine implements the bulk of the logic behind the sqlite_step()
506 ** API.  The only thing omitted is the automatic recompile if a
507 ** schema change has occurred.  That detail is handled by the
508 ** outer sqlite3_step() wrapper procedure.
509 */
510 static int sqlite3Step(Vdbe *p){
511   sqlite3 *db;
512   int rc;
513 
514   assert(p);
515   if( p->magic!=VDBE_MAGIC_RUN ){
516     /* We used to require that sqlite3_reset() be called before retrying
517     ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
518     ** with version 3.7.0, we changed this so that sqlite3_reset() would
519     ** be called automatically instead of throwing the SQLITE_MISUSE error.
520     ** This "automatic-reset" change is not technically an incompatibility,
521     ** since any application that receives an SQLITE_MISUSE is broken by
522     ** definition.
523     **
524     ** Nevertheless, some published applications that were originally written
525     ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE
526     ** returns, and those were broken by the automatic-reset change.  As a
527     ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
528     ** legacy behavior of returning SQLITE_MISUSE for cases where the
529     ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
530     ** or SQLITE_BUSY error.
531     */
532 #ifdef SQLITE_OMIT_AUTORESET
533     if( (rc = p->rc&0xff)==SQLITE_BUSY || rc==SQLITE_LOCKED ){
534       sqlite3_reset((sqlite3_stmt*)p);
535     }else{
536       return SQLITE_MISUSE_BKPT;
537     }
538 #else
539     sqlite3_reset((sqlite3_stmt*)p);
540 #endif
541   }
542 
543   /* Check that malloc() has not failed. If it has, return early. */
544   db = p->db;
545   if( db->mallocFailed ){
546     p->rc = SQLITE_NOMEM;
547     return SQLITE_NOMEM;
548   }
549 
550   if( p->pc<=0 && p->expired ){
551     p->rc = SQLITE_SCHEMA;
552     rc = SQLITE_ERROR;
553     goto end_of_step;
554   }
555   if( p->pc<0 ){
556     /* If there are no other statements currently running, then
557     ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
558     ** from interrupting a statement that has not yet started.
559     */
560     if( db->nVdbeActive==0 ){
561       db->u1.isInterrupted = 0;
562     }
563 
564     assert( db->nVdbeWrite>0 || db->autoCommit==0
565         || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
566     );
567 
568 #ifndef SQLITE_OMIT_TRACE
569     if( db->xProfile && !db->init.busy && p->zSql ){
570       sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
571     }else{
572       assert( p->startTime==0 );
573     }
574 #endif
575 
576     db->nVdbeActive++;
577     if( p->readOnly==0 ) db->nVdbeWrite++;
578     if( p->bIsReader ) db->nVdbeRead++;
579     p->pc = 0;
580   }
581 #ifdef SQLITE_DEBUG
582   p->rcApp = SQLITE_OK;
583 #endif
584 #ifndef SQLITE_OMIT_EXPLAIN
585   if( p->explain ){
586     rc = sqlite3VdbeList(p);
587   }else
588 #endif /* SQLITE_OMIT_EXPLAIN */
589   {
590     db->nVdbeExec++;
591     rc = sqlite3VdbeExec(p);
592     db->nVdbeExec--;
593   }
594 
595 #ifndef SQLITE_OMIT_TRACE
596   /* If the statement completed successfully, invoke the profile callback */
597   if( rc!=SQLITE_ROW ) checkProfileCallback(db, p);
598 #endif
599 
600   if( rc==SQLITE_DONE ){
601     assert( p->rc==SQLITE_OK );
602     p->rc = doWalCallbacks(db);
603     if( p->rc!=SQLITE_OK ){
604       rc = SQLITE_ERROR;
605     }
606   }
607 
608   db->errCode = rc;
609   if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
610     p->rc = SQLITE_NOMEM;
611   }
612 end_of_step:
613   /* At this point local variable rc holds the value that should be
614   ** returned if this statement was compiled using the legacy
615   ** sqlite3_prepare() interface. According to the docs, this can only
616   ** be one of the values in the first assert() below. Variable p->rc
617   ** contains the value that would be returned if sqlite3_finalize()
618   ** were called on statement p.
619   */
620   assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR
621        || (rc&0xff)==SQLITE_BUSY || rc==SQLITE_MISUSE
622   );
623   assert( (p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE) || p->rc==p->rcApp );
624   if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
625     /* If this statement was prepared using sqlite3_prepare_v2(), and an
626     ** error has occurred, then return the error code in p->rc to the
627     ** caller. Set the error code in the database handle to the same value.
628     */
629     rc = sqlite3VdbeTransferError(p);
630   }
631   return (rc&db->errMask);
632 }
633 
634 /*
635 ** This is the top-level implementation of sqlite3_step().  Call
636 ** sqlite3Step() to do most of the work.  If a schema error occurs,
637 ** call sqlite3Reprepare() and try again.
638 */
639 int sqlite3_step(sqlite3_stmt *pStmt){
640   int rc = SQLITE_OK;      /* Result from sqlite3Step() */
641   int rc2 = SQLITE_OK;     /* Result from sqlite3Reprepare() */
642   Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
643   int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
644   sqlite3 *db;             /* The database connection */
645 
646   if( vdbeSafetyNotNull(v) ){
647     return SQLITE_MISUSE_BKPT;
648   }
649   db = v->db;
650   sqlite3_mutex_enter(db->mutex);
651   v->doingRerun = 0;
652   while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
653          && cnt++ < SQLITE_MAX_SCHEMA_RETRY ){
654     int savedPc = v->pc;
655     rc2 = rc = sqlite3Reprepare(v);
656     if( rc!=SQLITE_OK) break;
657     sqlite3_reset(pStmt);
658     if( savedPc>=0 ) v->doingRerun = 1;
659     assert( v->expired==0 );
660   }
661   if( rc2!=SQLITE_OK ){
662     /* This case occurs after failing to recompile an sql statement.
663     ** The error message from the SQL compiler has already been loaded
664     ** into the database handle. This block copies the error message
665     ** from the database handle into the statement and sets the statement
666     ** program counter to 0 to ensure that when the statement is
667     ** finalized or reset the parser error message is available via
668     ** sqlite3_errmsg() and sqlite3_errcode().
669     */
670     const char *zErr = (const char *)sqlite3_value_text(db->pErr);
671     sqlite3DbFree(db, v->zErrMsg);
672     if( !db->mallocFailed ){
673       v->zErrMsg = sqlite3DbStrDup(db, zErr);
674       v->rc = rc2;
675     } else {
676       v->zErrMsg = 0;
677       v->rc = rc = SQLITE_NOMEM;
678     }
679   }
680   rc = sqlite3ApiExit(db, rc);
681   sqlite3_mutex_leave(db->mutex);
682   return rc;
683 }
684 
685 
686 /*
687 ** Extract the user data from a sqlite3_context structure and return a
688 ** pointer to it.
689 */
690 void *sqlite3_user_data(sqlite3_context *p){
691   assert( p && p->pFunc );
692   return p->pFunc->pUserData;
693 }
694 
695 /*
696 ** Extract the user data from a sqlite3_context structure and return a
697 ** pointer to it.
698 **
699 ** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
700 ** returns a copy of the pointer to the database connection (the 1st
701 ** parameter) of the sqlite3_create_function() and
702 ** sqlite3_create_function16() routines that originally registered the
703 ** application defined function.
704 */
705 sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
706   assert( p && p->pOut );
707   return p->pOut->db;
708 }
709 
710 /*
711 ** Return the current time for a statement.  If the current time
712 ** is requested more than once within the same run of a single prepared
713 ** statement, the exact same time is returned for each invocation regardless
714 ** of the amount of time that elapses between invocations.  In other words,
715 ** the time returned is always the time of the first call.
716 */
717 sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context *p){
718   int rc;
719 #ifndef SQLITE_ENABLE_STAT3_OR_STAT4
720   sqlite3_int64 *piTime = &p->pVdbe->iCurrentTime;
721   assert( p->pVdbe!=0 );
722 #else
723   sqlite3_int64 iTime = 0;
724   sqlite3_int64 *piTime = p->pVdbe!=0 ? &p->pVdbe->iCurrentTime : &iTime;
725 #endif
726   if( *piTime==0 ){
727     rc = sqlite3OsCurrentTimeInt64(p->pOut->db->pVfs, piTime);
728     if( rc ) *piTime = 0;
729   }
730   return *piTime;
731 }
732 
733 /*
734 ** The following is the implementation of an SQL function that always
735 ** fails with an error message stating that the function is used in the
736 ** wrong context.  The sqlite3_overload_function() API might construct
737 ** SQL function that use this routine so that the functions will exist
738 ** for name resolution but are actually overloaded by the xFindFunction
739 ** method of virtual tables.
740 */
741 void sqlite3InvalidFunction(
742   sqlite3_context *context,  /* The function calling context */
743   int NotUsed,               /* Number of arguments to the function */
744   sqlite3_value **NotUsed2   /* Value of each argument */
745 ){
746   const char *zName = context->pFunc->zName;
747   char *zErr;
748   UNUSED_PARAMETER2(NotUsed, NotUsed2);
749   zErr = sqlite3_mprintf(
750       "unable to use function %s in the requested context", zName);
751   sqlite3_result_error(context, zErr, -1);
752   sqlite3_free(zErr);
753 }
754 
755 /*
756 ** Create a new aggregate context for p and return a pointer to
757 ** its pMem->z element.
758 */
759 static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
760   Mem *pMem = p->pMem;
761   assert( (pMem->flags & MEM_Agg)==0 );
762   if( nByte<=0 ){
763     sqlite3VdbeMemSetNull(pMem);
764     pMem->z = 0;
765   }else{
766     sqlite3VdbeMemClearAndResize(pMem, nByte);
767     pMem->flags = MEM_Agg;
768     pMem->u.pDef = p->pFunc;
769     if( pMem->z ){
770       memset(pMem->z, 0, nByte);
771     }
772   }
773   return (void*)pMem->z;
774 }
775 
776 /*
777 ** Allocate or return the aggregate context for a user function.  A new
778 ** context is allocated on the first call.  Subsequent calls return the
779 ** same context that was returned on prior calls.
780 */
781 void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
782   assert( p && p->pFunc && p->pFunc->xStep );
783   assert( sqlite3_mutex_held(p->pOut->db->mutex) );
784   testcase( nByte<0 );
785   if( (p->pMem->flags & MEM_Agg)==0 ){
786     return createAggContext(p, nByte);
787   }else{
788     return (void*)p->pMem->z;
789   }
790 }
791 
792 /*
793 ** Return the auxiliary data pointer, if any, for the iArg'th argument to
794 ** the user-function defined by pCtx.
795 */
796 void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
797   AuxData *pAuxData;
798 
799   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
800 #if SQLITE_ENABLE_STAT3_OR_STAT4
801   if( pCtx->pVdbe==0 ) return 0;
802 #else
803   assert( pCtx->pVdbe!=0 );
804 #endif
805   for(pAuxData=pCtx->pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
806     if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;
807   }
808 
809   return (pAuxData ? pAuxData->pAux : 0);
810 }
811 
812 /*
813 ** Set the auxiliary data pointer and delete function, for the iArg'th
814 ** argument to the user-function defined by pCtx. Any previous value is
815 ** deleted by calling the delete function specified when it was set.
816 */
817 void sqlite3_set_auxdata(
818   sqlite3_context *pCtx,
819   int iArg,
820   void *pAux,
821   void (*xDelete)(void*)
822 ){
823   AuxData *pAuxData;
824   Vdbe *pVdbe = pCtx->pVdbe;
825 
826   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
827   if( iArg<0 ) goto failed;
828 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
829   if( pVdbe==0 ) goto failed;
830 #else
831   assert( pVdbe!=0 );
832 #endif
833 
834   for(pAuxData=pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
835     if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;
836   }
837   if( pAuxData==0 ){
838     pAuxData = sqlite3DbMallocZero(pVdbe->db, sizeof(AuxData));
839     if( !pAuxData ) goto failed;
840     pAuxData->iOp = pCtx->iOp;
841     pAuxData->iArg = iArg;
842     pAuxData->pNext = pVdbe->pAuxData;
843     pVdbe->pAuxData = pAuxData;
844     if( pCtx->fErrorOrAux==0 ){
845       pCtx->isError = 0;
846       pCtx->fErrorOrAux = 1;
847     }
848   }else if( pAuxData->xDelete ){
849     pAuxData->xDelete(pAuxData->pAux);
850   }
851 
852   pAuxData->pAux = pAux;
853   pAuxData->xDelete = xDelete;
854   return;
855 
856 failed:
857   if( xDelete ){
858     xDelete(pAux);
859   }
860 }
861 
862 #ifndef SQLITE_OMIT_DEPRECATED
863 /*
864 ** Return the number of times the Step function of an aggregate has been
865 ** called.
866 **
867 ** This function is deprecated.  Do not use it for new code.  It is
868 ** provide only to avoid breaking legacy code.  New aggregate function
869 ** implementations should keep their own counts within their aggregate
870 ** context.
871 */
872 int sqlite3_aggregate_count(sqlite3_context *p){
873   assert( p && p->pMem && p->pFunc && p->pFunc->xStep );
874   return p->pMem->n;
875 }
876 #endif
877 
878 /*
879 ** Return the number of columns in the result set for the statement pStmt.
880 */
881 int sqlite3_column_count(sqlite3_stmt *pStmt){
882   Vdbe *pVm = (Vdbe *)pStmt;
883   return pVm ? pVm->nResColumn : 0;
884 }
885 
886 /*
887 ** Return the number of values available from the current row of the
888 ** currently executing statement pStmt.
889 */
890 int sqlite3_data_count(sqlite3_stmt *pStmt){
891   Vdbe *pVm = (Vdbe *)pStmt;
892   if( pVm==0 || pVm->pResultSet==0 ) return 0;
893   return pVm->nResColumn;
894 }
895 
896 /*
897 ** Return a pointer to static memory containing an SQL NULL value.
898 */
899 static const Mem *columnNullValue(void){
900   /* Even though the Mem structure contains an element
901   ** of type i64, on certain architectures (x86) with certain compiler
902   ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
903   ** instead of an 8-byte one. This all works fine, except that when
904   ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
905   ** that a Mem structure is located on an 8-byte boundary. To prevent
906   ** these assert()s from failing, when building with SQLITE_DEBUG defined
907   ** using gcc, we force nullMem to be 8-byte aligned using the magical
908   ** __attribute__((aligned(8))) macro.  */
909   static const Mem nullMem
910 #if defined(SQLITE_DEBUG) && defined(__GNUC__)
911     __attribute__((aligned(8)))
912 #endif
913     = {
914         /* .u          = */ {0},
915         /* .flags      = */ (u16)MEM_Null,
916         /* .enc        = */ (u8)0,
917         /* .eSubtype   = */ (u8)0,
918         /* .n          = */ (int)0,
919         /* .z          = */ (char*)0,
920         /* .zMalloc    = */ (char*)0,
921         /* .szMalloc   = */ (int)0,
922         /* .uTemp      = */ (u32)0,
923         /* .db         = */ (sqlite3*)0,
924         /* .xDel       = */ (void(*)(void*))0,
925 #ifdef SQLITE_DEBUG
926         /* .pScopyFrom = */ (Mem*)0,
927         /* .pFiller    = */ (void*)0,
928 #endif
929       };
930   return &nullMem;
931 }
932 
933 /*
934 ** Check to see if column iCol of the given statement is valid.  If
935 ** it is, return a pointer to the Mem for the value of that column.
936 ** If iCol is not valid, return a pointer to a Mem which has a value
937 ** of NULL.
938 */
939 static Mem *columnMem(sqlite3_stmt *pStmt, int i){
940   Vdbe *pVm;
941   Mem *pOut;
942 
943   pVm = (Vdbe *)pStmt;
944   if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
945     sqlite3_mutex_enter(pVm->db->mutex);
946     pOut = &pVm->pResultSet[i];
947   }else{
948     if( pVm && ALWAYS(pVm->db) ){
949       sqlite3_mutex_enter(pVm->db->mutex);
950       sqlite3Error(pVm->db, SQLITE_RANGE);
951     }
952     pOut = (Mem*)columnNullValue();
953   }
954   return pOut;
955 }
956 
957 /*
958 ** This function is called after invoking an sqlite3_value_XXX function on a
959 ** column value (i.e. a value returned by evaluating an SQL expression in the
960 ** select list of a SELECT statement) that may cause a malloc() failure. If
961 ** malloc() has failed, the threads mallocFailed flag is cleared and the result
962 ** code of statement pStmt set to SQLITE_NOMEM.
963 **
964 ** Specifically, this is called from within:
965 **
966 **     sqlite3_column_int()
967 **     sqlite3_column_int64()
968 **     sqlite3_column_text()
969 **     sqlite3_column_text16()
970 **     sqlite3_column_real()
971 **     sqlite3_column_bytes()
972 **     sqlite3_column_bytes16()
973 **     sqiite3_column_blob()
974 */
975 static void columnMallocFailure(sqlite3_stmt *pStmt)
976 {
977   /* If malloc() failed during an encoding conversion within an
978   ** sqlite3_column_XXX API, then set the return code of the statement to
979   ** SQLITE_NOMEM. The next call to _step() (if any) will return SQLITE_ERROR
980   ** and _finalize() will return NOMEM.
981   */
982   Vdbe *p = (Vdbe *)pStmt;
983   if( p ){
984     p->rc = sqlite3ApiExit(p->db, p->rc);
985     sqlite3_mutex_leave(p->db->mutex);
986   }
987 }
988 
989 /**************************** sqlite3_column_  *******************************
990 ** The following routines are used to access elements of the current row
991 ** in the result set.
992 */
993 const void *sqlite3_column_blob(sqlite3_stmt *pStmt, int i){
994   const void *val;
995   val = sqlite3_value_blob( columnMem(pStmt,i) );
996   /* Even though there is no encoding conversion, value_blob() might
997   ** need to call malloc() to expand the result of a zeroblob()
998   ** expression.
999   */
1000   columnMallocFailure(pStmt);
1001   return val;
1002 }
1003 int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
1004   int val = sqlite3_value_bytes( columnMem(pStmt,i) );
1005   columnMallocFailure(pStmt);
1006   return val;
1007 }
1008 int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
1009   int val = sqlite3_value_bytes16( columnMem(pStmt,i) );
1010   columnMallocFailure(pStmt);
1011   return val;
1012 }
1013 double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
1014   double val = sqlite3_value_double( columnMem(pStmt,i) );
1015   columnMallocFailure(pStmt);
1016   return val;
1017 }
1018 int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
1019   int val = sqlite3_value_int( columnMem(pStmt,i) );
1020   columnMallocFailure(pStmt);
1021   return val;
1022 }
1023 sqlite_int64 sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
1024   sqlite_int64 val = sqlite3_value_int64( columnMem(pStmt,i) );
1025   columnMallocFailure(pStmt);
1026   return val;
1027 }
1028 const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
1029   const unsigned char *val = sqlite3_value_text( columnMem(pStmt,i) );
1030   columnMallocFailure(pStmt);
1031   return val;
1032 }
1033 sqlite3_value *sqlite3_column_value(sqlite3_stmt *pStmt, int i){
1034   Mem *pOut = columnMem(pStmt, i);
1035   if( pOut->flags&MEM_Static ){
1036     pOut->flags &= ~MEM_Static;
1037     pOut->flags |= MEM_Ephem;
1038   }
1039   columnMallocFailure(pStmt);
1040   return (sqlite3_value *)pOut;
1041 }
1042 #ifndef SQLITE_OMIT_UTF16
1043 const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
1044   const void *val = sqlite3_value_text16( columnMem(pStmt,i) );
1045   columnMallocFailure(pStmt);
1046   return val;
1047 }
1048 #endif /* SQLITE_OMIT_UTF16 */
1049 int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
1050   int iType = sqlite3_value_type( columnMem(pStmt,i) );
1051   columnMallocFailure(pStmt);
1052   return iType;
1053 }
1054 
1055 /*
1056 ** Convert the N-th element of pStmt->pColName[] into a string using
1057 ** xFunc() then return that string.  If N is out of range, return 0.
1058 **
1059 ** There are up to 5 names for each column.  useType determines which
1060 ** name is returned.  Here are the names:
1061 **
1062 **    0      The column name as it should be displayed for output
1063 **    1      The datatype name for the column
1064 **    2      The name of the database that the column derives from
1065 **    3      The name of the table that the column derives from
1066 **    4      The name of the table column that the result column derives from
1067 **
1068 ** If the result is not a simple column reference (if it is an expression
1069 ** or a constant) then useTypes 2, 3, and 4 return NULL.
1070 */
1071 static const void *columnName(
1072   sqlite3_stmt *pStmt,
1073   int N,
1074   const void *(*xFunc)(Mem*),
1075   int useType
1076 ){
1077   const void *ret;
1078   Vdbe *p;
1079   int n;
1080   sqlite3 *db;
1081 #ifdef SQLITE_ENABLE_API_ARMOR
1082   if( pStmt==0 ){
1083     (void)SQLITE_MISUSE_BKPT;
1084     return 0;
1085   }
1086 #endif
1087   ret = 0;
1088   p = (Vdbe *)pStmt;
1089   db = p->db;
1090   assert( db!=0 );
1091   n = sqlite3_column_count(pStmt);
1092   if( N<n && N>=0 ){
1093     N += useType*n;
1094     sqlite3_mutex_enter(db->mutex);
1095     assert( db->mallocFailed==0 );
1096     ret = xFunc(&p->aColName[N]);
1097      /* A malloc may have failed inside of the xFunc() call. If this
1098     ** is the case, clear the mallocFailed flag and return NULL.
1099     */
1100     if( db->mallocFailed ){
1101       db->mallocFailed = 0;
1102       ret = 0;
1103     }
1104     sqlite3_mutex_leave(db->mutex);
1105   }
1106   return ret;
1107 }
1108 
1109 /*
1110 ** Return the name of the Nth column of the result set returned by SQL
1111 ** statement pStmt.
1112 */
1113 const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
1114   return columnName(
1115       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_NAME);
1116 }
1117 #ifndef SQLITE_OMIT_UTF16
1118 const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
1119   return columnName(
1120       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_NAME);
1121 }
1122 #endif
1123 
1124 /*
1125 ** Constraint:  If you have ENABLE_COLUMN_METADATA then you must
1126 ** not define OMIT_DECLTYPE.
1127 */
1128 #if defined(SQLITE_OMIT_DECLTYPE) && defined(SQLITE_ENABLE_COLUMN_METADATA)
1129 # error "Must not define both SQLITE_OMIT_DECLTYPE \
1130          and SQLITE_ENABLE_COLUMN_METADATA"
1131 #endif
1132 
1133 #ifndef SQLITE_OMIT_DECLTYPE
1134 /*
1135 ** Return the column declaration type (if applicable) of the 'i'th column
1136 ** of the result set of SQL statement pStmt.
1137 */
1138 const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int N){
1139   return columnName(
1140       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DECLTYPE);
1141 }
1142 #ifndef SQLITE_OMIT_UTF16
1143 const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int N){
1144   return columnName(
1145       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DECLTYPE);
1146 }
1147 #endif /* SQLITE_OMIT_UTF16 */
1148 #endif /* SQLITE_OMIT_DECLTYPE */
1149 
1150 #ifdef SQLITE_ENABLE_COLUMN_METADATA
1151 /*
1152 ** Return the name of the database from which a result column derives.
1153 ** NULL is returned if the result column is an expression or constant or
1154 ** anything else which is not an unambiguous reference to a database column.
1155 */
1156 const char *sqlite3_column_database_name(sqlite3_stmt *pStmt, int N){
1157   return columnName(
1158       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DATABASE);
1159 }
1160 #ifndef SQLITE_OMIT_UTF16
1161 const void *sqlite3_column_database_name16(sqlite3_stmt *pStmt, int N){
1162   return columnName(
1163       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DATABASE);
1164 }
1165 #endif /* SQLITE_OMIT_UTF16 */
1166 
1167 /*
1168 ** Return the name of the table from which a result column derives.
1169 ** NULL is returned if the result column is an expression or constant or
1170 ** anything else which is not an unambiguous reference to a database column.
1171 */
1172 const char *sqlite3_column_table_name(sqlite3_stmt *pStmt, int N){
1173   return columnName(
1174       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_TABLE);
1175 }
1176 #ifndef SQLITE_OMIT_UTF16
1177 const void *sqlite3_column_table_name16(sqlite3_stmt *pStmt, int N){
1178   return columnName(
1179       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_TABLE);
1180 }
1181 #endif /* SQLITE_OMIT_UTF16 */
1182 
1183 /*
1184 ** Return the name of the table column from which a result column derives.
1185 ** NULL is returned if the result column is an expression or constant or
1186 ** anything else which is not an unambiguous reference to a database column.
1187 */
1188 const char *sqlite3_column_origin_name(sqlite3_stmt *pStmt, int N){
1189   return columnName(
1190       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_COLUMN);
1191 }
1192 #ifndef SQLITE_OMIT_UTF16
1193 const void *sqlite3_column_origin_name16(sqlite3_stmt *pStmt, int N){
1194   return columnName(
1195       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_COLUMN);
1196 }
1197 #endif /* SQLITE_OMIT_UTF16 */
1198 #endif /* SQLITE_ENABLE_COLUMN_METADATA */
1199 
1200 
1201 /******************************* sqlite3_bind_  ***************************
1202 **
1203 ** Routines used to attach values to wildcards in a compiled SQL statement.
1204 */
1205 /*
1206 ** Unbind the value bound to variable i in virtual machine p. This is the
1207 ** the same as binding a NULL value to the column. If the "i" parameter is
1208 ** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
1209 **
1210 ** A successful evaluation of this routine acquires the mutex on p.
1211 ** the mutex is released if any kind of error occurs.
1212 **
1213 ** The error code stored in database p->db is overwritten with the return
1214 ** value in any case.
1215 */
1216 static int vdbeUnbind(Vdbe *p, int i){
1217   Mem *pVar;
1218   if( vdbeSafetyNotNull(p) ){
1219     return SQLITE_MISUSE_BKPT;
1220   }
1221   sqlite3_mutex_enter(p->db->mutex);
1222   if( p->magic!=VDBE_MAGIC_RUN || p->pc>=0 ){
1223     sqlite3Error(p->db, SQLITE_MISUSE);
1224     sqlite3_mutex_leave(p->db->mutex);
1225     sqlite3_log(SQLITE_MISUSE,
1226         "bind on a busy prepared statement: [%s]", p->zSql);
1227     return SQLITE_MISUSE_BKPT;
1228   }
1229   if( i<1 || i>p->nVar ){
1230     sqlite3Error(p->db, SQLITE_RANGE);
1231     sqlite3_mutex_leave(p->db->mutex);
1232     return SQLITE_RANGE;
1233   }
1234   i--;
1235   pVar = &p->aVar[i];
1236   sqlite3VdbeMemRelease(pVar);
1237   pVar->flags = MEM_Null;
1238   sqlite3Error(p->db, SQLITE_OK);
1239 
1240   /* If the bit corresponding to this variable in Vdbe.expmask is set, then
1241   ** binding a new value to this variable invalidates the current query plan.
1242   **
1243   ** IMPLEMENTATION-OF: R-48440-37595 If the specific value bound to host
1244   ** parameter in the WHERE clause might influence the choice of query plan
1245   ** for a statement, then the statement will be automatically recompiled,
1246   ** as if there had been a schema change, on the first sqlite3_step() call
1247   ** following any change to the bindings of that parameter.
1248   */
1249   if( p->isPrepareV2 &&
1250      ((i<32 && p->expmask & ((u32)1 << i)) || p->expmask==0xffffffff)
1251   ){
1252     p->expired = 1;
1253   }
1254   return SQLITE_OK;
1255 }
1256 
1257 /*
1258 ** Bind a text or BLOB value.
1259 */
1260 static int bindText(
1261   sqlite3_stmt *pStmt,   /* The statement to bind against */
1262   int i,                 /* Index of the parameter to bind */
1263   const void *zData,     /* Pointer to the data to be bound */
1264   int nData,             /* Number of bytes of data to be bound */
1265   void (*xDel)(void*),   /* Destructor for the data */
1266   u8 encoding            /* Encoding for the data */
1267 ){
1268   Vdbe *p = (Vdbe *)pStmt;
1269   Mem *pVar;
1270   int rc;
1271 
1272   rc = vdbeUnbind(p, i);
1273   if( rc==SQLITE_OK ){
1274     if( zData!=0 ){
1275       pVar = &p->aVar[i-1];
1276       rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
1277       if( rc==SQLITE_OK && encoding!=0 ){
1278         rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
1279       }
1280       sqlite3Error(p->db, rc);
1281       rc = sqlite3ApiExit(p->db, rc);
1282     }
1283     sqlite3_mutex_leave(p->db->mutex);
1284   }else if( xDel!=SQLITE_STATIC && xDel!=SQLITE_TRANSIENT ){
1285     xDel((void*)zData);
1286   }
1287   return rc;
1288 }
1289 
1290 
1291 /*
1292 ** Bind a blob value to an SQL statement variable.
1293 */
1294 int sqlite3_bind_blob(
1295   sqlite3_stmt *pStmt,
1296   int i,
1297   const void *zData,
1298   int nData,
1299   void (*xDel)(void*)
1300 ){
1301   return bindText(pStmt, i, zData, nData, xDel, 0);
1302 }
1303 int sqlite3_bind_blob64(
1304   sqlite3_stmt *pStmt,
1305   int i,
1306   const void *zData,
1307   sqlite3_uint64 nData,
1308   void (*xDel)(void*)
1309 ){
1310   assert( xDel!=SQLITE_DYNAMIC );
1311   if( nData>0x7fffffff ){
1312     return invokeValueDestructor(zData, xDel, 0);
1313   }else{
1314     return bindText(pStmt, i, zData, (int)nData, xDel, 0);
1315   }
1316 }
1317 int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
1318   int rc;
1319   Vdbe *p = (Vdbe *)pStmt;
1320   rc = vdbeUnbind(p, i);
1321   if( rc==SQLITE_OK ){
1322     sqlite3VdbeMemSetDouble(&p->aVar[i-1], rValue);
1323     sqlite3_mutex_leave(p->db->mutex);
1324   }
1325   return rc;
1326 }
1327 int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
1328   return sqlite3_bind_int64(p, i, (i64)iValue);
1329 }
1330 int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, sqlite_int64 iValue){
1331   int rc;
1332   Vdbe *p = (Vdbe *)pStmt;
1333   rc = vdbeUnbind(p, i);
1334   if( rc==SQLITE_OK ){
1335     sqlite3VdbeMemSetInt64(&p->aVar[i-1], iValue);
1336     sqlite3_mutex_leave(p->db->mutex);
1337   }
1338   return rc;
1339 }
1340 int sqlite3_bind_null(sqlite3_stmt *pStmt, int i){
1341   int rc;
1342   Vdbe *p = (Vdbe*)pStmt;
1343   rc = vdbeUnbind(p, i);
1344   if( rc==SQLITE_OK ){
1345     sqlite3_mutex_leave(p->db->mutex);
1346   }
1347   return rc;
1348 }
1349 int sqlite3_bind_text(
1350   sqlite3_stmt *pStmt,
1351   int i,
1352   const char *zData,
1353   int nData,
1354   void (*xDel)(void*)
1355 ){
1356   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF8);
1357 }
1358 int sqlite3_bind_text64(
1359   sqlite3_stmt *pStmt,
1360   int i,
1361   const char *zData,
1362   sqlite3_uint64 nData,
1363   void (*xDel)(void*),
1364   unsigned char enc
1365 ){
1366   assert( xDel!=SQLITE_DYNAMIC );
1367   if( nData>0x7fffffff ){
1368     return invokeValueDestructor(zData, xDel, 0);
1369   }else{
1370     if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
1371     return bindText(pStmt, i, zData, (int)nData, xDel, enc);
1372   }
1373 }
1374 #ifndef SQLITE_OMIT_UTF16
1375 int sqlite3_bind_text16(
1376   sqlite3_stmt *pStmt,
1377   int i,
1378   const void *zData,
1379   int nData,
1380   void (*xDel)(void*)
1381 ){
1382   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF16NATIVE);
1383 }
1384 #endif /* SQLITE_OMIT_UTF16 */
1385 int sqlite3_bind_value(sqlite3_stmt *pStmt, int i, const sqlite3_value *pValue){
1386   int rc;
1387   switch( sqlite3_value_type((sqlite3_value*)pValue) ){
1388     case SQLITE_INTEGER: {
1389       rc = sqlite3_bind_int64(pStmt, i, pValue->u.i);
1390       break;
1391     }
1392     case SQLITE_FLOAT: {
1393       rc = sqlite3_bind_double(pStmt, i, pValue->u.r);
1394       break;
1395     }
1396     case SQLITE_BLOB: {
1397       if( pValue->flags & MEM_Zero ){
1398         rc = sqlite3_bind_zeroblob(pStmt, i, pValue->u.nZero);
1399       }else{
1400         rc = sqlite3_bind_blob(pStmt, i, pValue->z, pValue->n,SQLITE_TRANSIENT);
1401       }
1402       break;
1403     }
1404     case SQLITE_TEXT: {
1405       rc = bindText(pStmt,i,  pValue->z, pValue->n, SQLITE_TRANSIENT,
1406                               pValue->enc);
1407       break;
1408     }
1409     default: {
1410       rc = sqlite3_bind_null(pStmt, i);
1411       break;
1412     }
1413   }
1414   return rc;
1415 }
1416 int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
1417   int rc;
1418   Vdbe *p = (Vdbe *)pStmt;
1419   rc = vdbeUnbind(p, i);
1420   if( rc==SQLITE_OK ){
1421     sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
1422     sqlite3_mutex_leave(p->db->mutex);
1423   }
1424   return rc;
1425 }
1426 int sqlite3_bind_zeroblob64(sqlite3_stmt *pStmt, int i, sqlite3_uint64 n){
1427   int rc;
1428   Vdbe *p = (Vdbe *)pStmt;
1429   sqlite3_mutex_enter(p->db->mutex);
1430   if( n>(u64)p->db->aLimit[SQLITE_LIMIT_LENGTH] ){
1431     rc = SQLITE_TOOBIG;
1432   }else{
1433     assert( (n & 0x7FFFFFFF)==n );
1434     rc = sqlite3_bind_zeroblob(pStmt, i, n);
1435   }
1436   rc = sqlite3ApiExit(p->db, rc);
1437   sqlite3_mutex_leave(p->db->mutex);
1438   return rc;
1439 }
1440 
1441 /*
1442 ** Return the number of wildcards that can be potentially bound to.
1443 ** This routine is added to support DBD::SQLite.
1444 */
1445 int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
1446   Vdbe *p = (Vdbe*)pStmt;
1447   return p ? p->nVar : 0;
1448 }
1449 
1450 /*
1451 ** Return the name of a wildcard parameter.  Return NULL if the index
1452 ** is out of range or if the wildcard is unnamed.
1453 **
1454 ** The result is always UTF-8.
1455 */
1456 const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
1457   Vdbe *p = (Vdbe*)pStmt;
1458   if( p==0 || i<1 || i>p->nzVar ){
1459     return 0;
1460   }
1461   return p->azVar[i-1];
1462 }
1463 
1464 /*
1465 ** Given a wildcard parameter name, return the index of the variable
1466 ** with that name.  If there is no variable with the given name,
1467 ** return 0.
1468 */
1469 int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
1470   int i;
1471   if( p==0 ){
1472     return 0;
1473   }
1474   if( zName ){
1475     for(i=0; i<p->nzVar; i++){
1476       const char *z = p->azVar[i];
1477       if( z && strncmp(z,zName,nName)==0 && z[nName]==0 ){
1478         return i+1;
1479       }
1480     }
1481   }
1482   return 0;
1483 }
1484 int sqlite3_bind_parameter_index(sqlite3_stmt *pStmt, const char *zName){
1485   return sqlite3VdbeParameterIndex((Vdbe*)pStmt, zName, sqlite3Strlen30(zName));
1486 }
1487 
1488 /*
1489 ** Transfer all bindings from the first statement over to the second.
1490 */
1491 int sqlite3TransferBindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1492   Vdbe *pFrom = (Vdbe*)pFromStmt;
1493   Vdbe *pTo = (Vdbe*)pToStmt;
1494   int i;
1495   assert( pTo->db==pFrom->db );
1496   assert( pTo->nVar==pFrom->nVar );
1497   sqlite3_mutex_enter(pTo->db->mutex);
1498   for(i=0; i<pFrom->nVar; i++){
1499     sqlite3VdbeMemMove(&pTo->aVar[i], &pFrom->aVar[i]);
1500   }
1501   sqlite3_mutex_leave(pTo->db->mutex);
1502   return SQLITE_OK;
1503 }
1504 
1505 #ifndef SQLITE_OMIT_DEPRECATED
1506 /*
1507 ** Deprecated external interface.  Internal/core SQLite code
1508 ** should call sqlite3TransferBindings.
1509 **
1510 ** It is misuse to call this routine with statements from different
1511 ** database connections.  But as this is a deprecated interface, we
1512 ** will not bother to check for that condition.
1513 **
1514 ** If the two statements contain a different number of bindings, then
1515 ** an SQLITE_ERROR is returned.  Nothing else can go wrong, so otherwise
1516 ** SQLITE_OK is returned.
1517 */
1518 int sqlite3_transfer_bindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1519   Vdbe *pFrom = (Vdbe*)pFromStmt;
1520   Vdbe *pTo = (Vdbe*)pToStmt;
1521   if( pFrom->nVar!=pTo->nVar ){
1522     return SQLITE_ERROR;
1523   }
1524   if( pTo->isPrepareV2 && pTo->expmask ){
1525     pTo->expired = 1;
1526   }
1527   if( pFrom->isPrepareV2 && pFrom->expmask ){
1528     pFrom->expired = 1;
1529   }
1530   return sqlite3TransferBindings(pFromStmt, pToStmt);
1531 }
1532 #endif
1533 
1534 /*
1535 ** Return the sqlite3* database handle to which the prepared statement given
1536 ** in the argument belongs.  This is the same database handle that was
1537 ** the first argument to the sqlite3_prepare() that was used to create
1538 ** the statement in the first place.
1539 */
1540 sqlite3 *sqlite3_db_handle(sqlite3_stmt *pStmt){
1541   return pStmt ? ((Vdbe*)pStmt)->db : 0;
1542 }
1543 
1544 /*
1545 ** Return true if the prepared statement is guaranteed to not modify the
1546 ** database.
1547 */
1548 int sqlite3_stmt_readonly(sqlite3_stmt *pStmt){
1549   return pStmt ? ((Vdbe*)pStmt)->readOnly : 1;
1550 }
1551 
1552 /*
1553 ** Return true if the prepared statement is in need of being reset.
1554 */
1555 int sqlite3_stmt_busy(sqlite3_stmt *pStmt){
1556   Vdbe *v = (Vdbe*)pStmt;
1557   return v!=0 && v->pc>=0 && v->magic==VDBE_MAGIC_RUN;
1558 }
1559 
1560 /*
1561 ** Return a pointer to the next prepared statement after pStmt associated
1562 ** with database connection pDb.  If pStmt is NULL, return the first
1563 ** prepared statement for the database connection.  Return NULL if there
1564 ** are no more.
1565 */
1566 sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt){
1567   sqlite3_stmt *pNext;
1568 #ifdef SQLITE_ENABLE_API_ARMOR
1569   if( !sqlite3SafetyCheckOk(pDb) ){
1570     (void)SQLITE_MISUSE_BKPT;
1571     return 0;
1572   }
1573 #endif
1574   sqlite3_mutex_enter(pDb->mutex);
1575   if( pStmt==0 ){
1576     pNext = (sqlite3_stmt*)pDb->pVdbe;
1577   }else{
1578     pNext = (sqlite3_stmt*)((Vdbe*)pStmt)->pNext;
1579   }
1580   sqlite3_mutex_leave(pDb->mutex);
1581   return pNext;
1582 }
1583 
1584 /*
1585 ** Return the value of a status counter for a prepared statement
1586 */
1587 int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
1588   Vdbe *pVdbe = (Vdbe*)pStmt;
1589   u32 v;
1590 #ifdef SQLITE_ENABLE_API_ARMOR
1591   if( !pStmt ){
1592     (void)SQLITE_MISUSE_BKPT;
1593     return 0;
1594   }
1595 #endif
1596   v = pVdbe->aCounter[op];
1597   if( resetFlag ) pVdbe->aCounter[op] = 0;
1598   return (int)v;
1599 }
1600 
1601 #ifdef SQLITE_ENABLE_STMT_SCANSTATUS
1602 /*
1603 ** Return status data for a single loop within query pStmt.
1604 */
1605 int sqlite3_stmt_scanstatus(
1606   sqlite3_stmt *pStmt,            /* Prepared statement being queried */
1607   int idx,                        /* Index of loop to report on */
1608   int iScanStatusOp,              /* Which metric to return */
1609   void *pOut                      /* OUT: Write the answer here */
1610 ){
1611   Vdbe *p = (Vdbe*)pStmt;
1612   ScanStatus *pScan;
1613   if( idx<0 || idx>=p->nScan ) return 1;
1614   pScan = &p->aScan[idx];
1615   switch( iScanStatusOp ){
1616     case SQLITE_SCANSTAT_NLOOP: {
1617       *(sqlite3_int64*)pOut = p->anExec[pScan->addrLoop];
1618       break;
1619     }
1620     case SQLITE_SCANSTAT_NVISIT: {
1621       *(sqlite3_int64*)pOut = p->anExec[pScan->addrVisit];
1622       break;
1623     }
1624     case SQLITE_SCANSTAT_EST: {
1625       double r = 1.0;
1626       LogEst x = pScan->nEst;
1627       while( x<100 ){
1628         x += 10;
1629         r *= 0.5;
1630       }
1631       *(double*)pOut = r*sqlite3LogEstToInt(x);
1632       break;
1633     }
1634     case SQLITE_SCANSTAT_NAME: {
1635       *(const char**)pOut = pScan->zName;
1636       break;
1637     }
1638     case SQLITE_SCANSTAT_EXPLAIN: {
1639       if( pScan->addrExplain ){
1640         *(const char**)pOut = p->aOp[ pScan->addrExplain ].p4.z;
1641       }else{
1642         *(const char**)pOut = 0;
1643       }
1644       break;
1645     }
1646     case SQLITE_SCANSTAT_SELECTID: {
1647       if( pScan->addrExplain ){
1648         *(int*)pOut = p->aOp[ pScan->addrExplain ].p1;
1649       }else{
1650         *(int*)pOut = -1;
1651       }
1652       break;
1653     }
1654     default: {
1655       return 1;
1656     }
1657   }
1658   return 0;
1659 }
1660 
1661 /*
1662 ** Zero all counters associated with the sqlite3_stmt_scanstatus() data.
1663 */
1664 void sqlite3_stmt_scanstatus_reset(sqlite3_stmt *pStmt){
1665   Vdbe *p = (Vdbe*)pStmt;
1666   memset(p->anExec, 0, p->nOp * sizeof(i64));
1667 }
1668 #endif /* SQLITE_ENABLE_STMT_SCANSTATUS */
1669