xref: /sqlite-3.40.0/src/vdbeapi.c (revision 8c53b4e7)
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   sqlite3_int64 iElapse;
64   assert( p->startTime>0 );
65   assert( db->xProfile!=0 || (db->mTrace & SQLITE_TRACE_PROFILE)!=0 );
66   assert( db->init.busy==0 );
67   assert( p->zSql!=0 );
68   sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
69   iElapse = (iNow - p->startTime)*1000000;
70   if( db->xProfile ){
71     db->xProfile(db->pProfileArg, p->zSql, iElapse);
72   }
73   if( db->mTrace & SQLITE_TRACE_PROFILE ){
74     db->xTrace(SQLITE_TRACE_PROFILE, db->pTraceArg, p, (void*)&iElapse);
75   }
76   p->startTime = 0;
77 }
78 /*
79 ** The checkProfileCallback(DB,P) macro checks to see if a profile callback
80 ** is needed, and it invokes the callback if it is needed.
81 */
82 # define checkProfileCallback(DB,P) \
83    if( ((P)->startTime)>0 ){ invokeProfileCallback(DB,P); }
84 #else
85 # define checkProfileCallback(DB,P)  /*no-op*/
86 #endif
87 
88 /*
89 ** The following routine destroys a virtual machine that is created by
90 ** the sqlite3_compile() routine. The integer returned is an SQLITE_
91 ** success/failure code that describes the result of executing the virtual
92 ** machine.
93 **
94 ** This routine sets the error code and string returned by
95 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
96 */
97 int sqlite3_finalize(sqlite3_stmt *pStmt){
98   int rc;
99   if( pStmt==0 ){
100     /* IMPLEMENTATION-OF: R-57228-12904 Invoking sqlite3_finalize() on a NULL
101     ** pointer is a harmless no-op. */
102     rc = SQLITE_OK;
103   }else{
104     Vdbe *v = (Vdbe*)pStmt;
105     sqlite3 *db = v->db;
106     if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
107     sqlite3_mutex_enter(db->mutex);
108     checkProfileCallback(db, v);
109     rc = sqlite3VdbeFinalize(v);
110     rc = sqlite3ApiExit(db, rc);
111     sqlite3LeaveMutexAndCloseZombie(db);
112   }
113   return rc;
114 }
115 
116 /*
117 ** Terminate the current execution of an SQL statement and reset it
118 ** back to its starting state so that it can be reused. A success code from
119 ** the prior execution is returned.
120 **
121 ** This routine sets the error code and string returned by
122 ** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
123 */
124 int sqlite3_reset(sqlite3_stmt *pStmt){
125   int rc;
126   if( pStmt==0 ){
127     rc = SQLITE_OK;
128   }else{
129     Vdbe *v = (Vdbe*)pStmt;
130     sqlite3 *db = v->db;
131     sqlite3_mutex_enter(db->mutex);
132     checkProfileCallback(db, v);
133     rc = sqlite3VdbeReset(v);
134     sqlite3VdbeRewind(v);
135     assert( (rc & (db->errMask))==rc );
136     rc = sqlite3ApiExit(db, rc);
137     sqlite3_mutex_leave(db->mutex);
138   }
139   return rc;
140 }
141 
142 /*
143 ** Set all the parameters in the compiled SQL statement to NULL.
144 */
145 int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
146   int i;
147   int rc = SQLITE_OK;
148   Vdbe *p = (Vdbe*)pStmt;
149 #if SQLITE_THREADSAFE
150   sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
151 #endif
152   sqlite3_mutex_enter(mutex);
153   for(i=0; i<p->nVar; i++){
154     sqlite3VdbeMemRelease(&p->aVar[i]);
155     p->aVar[i].flags = MEM_Null;
156   }
157   assert( (p->prepFlags & SQLITE_PREPARE_SAVESQL)!=0 || p->expmask==0 );
158   if( p->expmask ){
159     p->expired = 1;
160   }
161   sqlite3_mutex_leave(mutex);
162   return rc;
163 }
164 
165 
166 /**************************** sqlite3_value_  *******************************
167 ** The following routines extract information from a Mem or sqlite3_value
168 ** structure.
169 */
170 const void *sqlite3_value_blob(sqlite3_value *pVal){
171   Mem *p = (Mem*)pVal;
172   if( p->flags & (MEM_Blob|MEM_Str) ){
173     if( ExpandBlob(p)!=SQLITE_OK ){
174       assert( p->flags==MEM_Null && p->z==0 );
175       return 0;
176     }
177     p->flags |= MEM_Blob;
178     return p->n ? p->z : 0;
179   }else{
180     return sqlite3_value_text(pVal);
181   }
182 }
183 int sqlite3_value_bytes(sqlite3_value *pVal){
184   return sqlite3ValueBytes(pVal, SQLITE_UTF8);
185 }
186 int sqlite3_value_bytes16(sqlite3_value *pVal){
187   return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
188 }
189 double sqlite3_value_double(sqlite3_value *pVal){
190   return sqlite3VdbeRealValue((Mem*)pVal);
191 }
192 int sqlite3_value_int(sqlite3_value *pVal){
193   return (int)sqlite3VdbeIntValue((Mem*)pVal);
194 }
195 sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
196   return sqlite3VdbeIntValue((Mem*)pVal);
197 }
198 unsigned int sqlite3_value_subtype(sqlite3_value *pVal){
199   Mem *pMem = (Mem*)pVal;
200   return ((pMem->flags & MEM_Subtype) ? pMem->eSubtype : 0);
201 }
202 void *sqlite3_value_pointer(sqlite3_value *pVal, const char *zPType){
203   Mem *p = (Mem*)pVal;
204   if( (p->flags&(MEM_TypeMask|MEM_Term|MEM_Subtype)) ==
205                  (MEM_Null|MEM_Term|MEM_Subtype)
206    && zPType!=0
207    && p->eSubtype=='p'
208    && strcmp(p->u.zPType, zPType)==0
209   ){
210     return (void*)p->z;
211   }else{
212     return 0;
213   }
214 }
215 const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
216   return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
217 }
218 #ifndef SQLITE_OMIT_UTF16
219 const void *sqlite3_value_text16(sqlite3_value* pVal){
220   return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
221 }
222 const void *sqlite3_value_text16be(sqlite3_value *pVal){
223   return sqlite3ValueText(pVal, SQLITE_UTF16BE);
224 }
225 const void *sqlite3_value_text16le(sqlite3_value *pVal){
226   return sqlite3ValueText(pVal, SQLITE_UTF16LE);
227 }
228 #endif /* SQLITE_OMIT_UTF16 */
229 /* EVIDENCE-OF: R-12793-43283 Every value in SQLite has one of five
230 ** fundamental datatypes: 64-bit signed integer 64-bit IEEE floating
231 ** point number string BLOB NULL
232 */
233 int sqlite3_value_type(sqlite3_value* pVal){
234   static const u8 aType[] = {
235      SQLITE_BLOB,     /* 0x00 */
236      SQLITE_NULL,     /* 0x01 */
237      SQLITE_TEXT,     /* 0x02 */
238      SQLITE_NULL,     /* 0x03 */
239      SQLITE_INTEGER,  /* 0x04 */
240      SQLITE_NULL,     /* 0x05 */
241      SQLITE_INTEGER,  /* 0x06 */
242      SQLITE_NULL,     /* 0x07 */
243      SQLITE_FLOAT,    /* 0x08 */
244      SQLITE_NULL,     /* 0x09 */
245      SQLITE_FLOAT,    /* 0x0a */
246      SQLITE_NULL,     /* 0x0b */
247      SQLITE_INTEGER,  /* 0x0c */
248      SQLITE_NULL,     /* 0x0d */
249      SQLITE_INTEGER,  /* 0x0e */
250      SQLITE_NULL,     /* 0x0f */
251      SQLITE_BLOB,     /* 0x10 */
252      SQLITE_NULL,     /* 0x11 */
253      SQLITE_TEXT,     /* 0x12 */
254      SQLITE_NULL,     /* 0x13 */
255      SQLITE_INTEGER,  /* 0x14 */
256      SQLITE_NULL,     /* 0x15 */
257      SQLITE_INTEGER,  /* 0x16 */
258      SQLITE_NULL,     /* 0x17 */
259      SQLITE_FLOAT,    /* 0x18 */
260      SQLITE_NULL,     /* 0x19 */
261      SQLITE_FLOAT,    /* 0x1a */
262      SQLITE_NULL,     /* 0x1b */
263      SQLITE_INTEGER,  /* 0x1c */
264      SQLITE_NULL,     /* 0x1d */
265      SQLITE_INTEGER,  /* 0x1e */
266      SQLITE_NULL,     /* 0x1f */
267   };
268   return aType[pVal->flags&MEM_AffMask];
269 }
270 
271 /* Return true if a parameter to xUpdate represents an unchanged column */
272 int sqlite3_value_nochange(sqlite3_value *pVal){
273   return (pVal->flags&(MEM_Null|MEM_Zero))==(MEM_Null|MEM_Zero);
274 }
275 
276 /* Make a copy of an sqlite3_value object
277 */
278 sqlite3_value *sqlite3_value_dup(const sqlite3_value *pOrig){
279   sqlite3_value *pNew;
280   if( pOrig==0 ) return 0;
281   pNew = sqlite3_malloc( sizeof(*pNew) );
282   if( pNew==0 ) return 0;
283   memset(pNew, 0, sizeof(*pNew));
284   memcpy(pNew, pOrig, MEMCELLSIZE);
285   pNew->flags &= ~MEM_Dyn;
286   pNew->db = 0;
287   if( pNew->flags&(MEM_Str|MEM_Blob) ){
288     pNew->flags &= ~(MEM_Static|MEM_Dyn);
289     pNew->flags |= MEM_Ephem;
290     if( sqlite3VdbeMemMakeWriteable(pNew)!=SQLITE_OK ){
291       sqlite3ValueFree(pNew);
292       pNew = 0;
293     }
294   }
295   return pNew;
296 }
297 
298 /* Destroy an sqlite3_value object previously obtained from
299 ** sqlite3_value_dup().
300 */
301 void sqlite3_value_free(sqlite3_value *pOld){
302   sqlite3ValueFree(pOld);
303 }
304 
305 
306 /**************************** sqlite3_result_  *******************************
307 ** The following routines are used by user-defined functions to specify
308 ** the function result.
309 **
310 ** The setStrOrError() function calls sqlite3VdbeMemSetStr() to store the
311 ** result as a string or blob but if the string or blob is too large, it
312 ** then sets the error code to SQLITE_TOOBIG
313 **
314 ** The invokeValueDestructor(P,X) routine invokes destructor function X()
315 ** on value P is not going to be used and need to be destroyed.
316 */
317 static void setResultStrOrError(
318   sqlite3_context *pCtx,  /* Function context */
319   const char *z,          /* String pointer */
320   int n,                  /* Bytes in string, or negative */
321   u8 enc,                 /* Encoding of z.  0 for BLOBs */
322   void (*xDel)(void*)     /* Destructor function */
323 ){
324   if( sqlite3VdbeMemSetStr(pCtx->pOut, z, n, enc, xDel)==SQLITE_TOOBIG ){
325     sqlite3_result_error_toobig(pCtx);
326   }
327 }
328 static int invokeValueDestructor(
329   const void *p,             /* Value to destroy */
330   void (*xDel)(void*),       /* The destructor */
331   sqlite3_context *pCtx      /* Set a SQLITE_TOOBIG error if no NULL */
332 ){
333   assert( xDel!=SQLITE_DYNAMIC );
334   if( xDel==0 ){
335     /* noop */
336   }else if( xDel==SQLITE_TRANSIENT ){
337     /* noop */
338   }else{
339     xDel((void*)p);
340   }
341   if( pCtx ) sqlite3_result_error_toobig(pCtx);
342   return SQLITE_TOOBIG;
343 }
344 void sqlite3_result_blob(
345   sqlite3_context *pCtx,
346   const void *z,
347   int n,
348   void (*xDel)(void *)
349 ){
350   assert( n>=0 );
351   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
352   setResultStrOrError(pCtx, z, n, 0, xDel);
353 }
354 void sqlite3_result_blob64(
355   sqlite3_context *pCtx,
356   const void *z,
357   sqlite3_uint64 n,
358   void (*xDel)(void *)
359 ){
360   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
361   assert( xDel!=SQLITE_DYNAMIC );
362   if( n>0x7fffffff ){
363     (void)invokeValueDestructor(z, xDel, pCtx);
364   }else{
365     setResultStrOrError(pCtx, z, (int)n, 0, xDel);
366   }
367 }
368 void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
369   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
370   sqlite3VdbeMemSetDouble(pCtx->pOut, rVal);
371 }
372 void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
373   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
374   pCtx->isError = SQLITE_ERROR;
375   sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
376 }
377 #ifndef SQLITE_OMIT_UTF16
378 void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
379   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
380   pCtx->isError = SQLITE_ERROR;
381   sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
382 }
383 #endif
384 void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
385   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
386   sqlite3VdbeMemSetInt64(pCtx->pOut, (i64)iVal);
387 }
388 void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
389   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
390   sqlite3VdbeMemSetInt64(pCtx->pOut, iVal);
391 }
392 void sqlite3_result_null(sqlite3_context *pCtx){
393   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
394   sqlite3VdbeMemSetNull(pCtx->pOut);
395 }
396 void sqlite3_result_pointer(
397   sqlite3_context *pCtx,
398   void *pPtr,
399   const char *zPType,
400   void (*xDestructor)(void*)
401 ){
402   Mem *pOut = pCtx->pOut;
403   assert( sqlite3_mutex_held(pOut->db->mutex) );
404   sqlite3VdbeMemRelease(pOut);
405   pOut->flags = MEM_Null;
406   sqlite3VdbeMemSetPointer(pOut, pPtr, zPType, xDestructor);
407 }
408 void sqlite3_result_subtype(sqlite3_context *pCtx, unsigned int eSubtype){
409   Mem *pOut = pCtx->pOut;
410   assert( sqlite3_mutex_held(pOut->db->mutex) );
411   pOut->eSubtype = eSubtype & 0xff;
412   pOut->flags |= MEM_Subtype;
413 }
414 void sqlite3_result_text(
415   sqlite3_context *pCtx,
416   const char *z,
417   int n,
418   void (*xDel)(void *)
419 ){
420   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
421   setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel);
422 }
423 void sqlite3_result_text64(
424   sqlite3_context *pCtx,
425   const char *z,
426   sqlite3_uint64 n,
427   void (*xDel)(void *),
428   unsigned char enc
429 ){
430   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
431   assert( xDel!=SQLITE_DYNAMIC );
432   if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
433   if( n>0x7fffffff ){
434     (void)invokeValueDestructor(z, xDel, pCtx);
435   }else{
436     setResultStrOrError(pCtx, z, (int)n, enc, xDel);
437   }
438 }
439 #ifndef SQLITE_OMIT_UTF16
440 void sqlite3_result_text16(
441   sqlite3_context *pCtx,
442   const void *z,
443   int n,
444   void (*xDel)(void *)
445 ){
446   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
447   setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel);
448 }
449 void sqlite3_result_text16be(
450   sqlite3_context *pCtx,
451   const void *z,
452   int n,
453   void (*xDel)(void *)
454 ){
455   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
456   setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel);
457 }
458 void sqlite3_result_text16le(
459   sqlite3_context *pCtx,
460   const void *z,
461   int n,
462   void (*xDel)(void *)
463 ){
464   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
465   setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel);
466 }
467 #endif /* SQLITE_OMIT_UTF16 */
468 void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
469   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
470   sqlite3VdbeMemCopy(pCtx->pOut, pValue);
471 }
472 void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
473   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
474   sqlite3VdbeMemSetZeroBlob(pCtx->pOut, n);
475 }
476 int sqlite3_result_zeroblob64(sqlite3_context *pCtx, u64 n){
477   Mem *pOut = pCtx->pOut;
478   assert( sqlite3_mutex_held(pOut->db->mutex) );
479   if( n>(u64)pOut->db->aLimit[SQLITE_LIMIT_LENGTH] ){
480     return SQLITE_TOOBIG;
481   }
482   sqlite3VdbeMemSetZeroBlob(pCtx->pOut, (int)n);
483   return SQLITE_OK;
484 }
485 void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
486   pCtx->isError = errCode ? errCode : -1;
487 #ifdef SQLITE_DEBUG
488   if( pCtx->pVdbe ) pCtx->pVdbe->rcApp = errCode;
489 #endif
490   if( pCtx->pOut->flags & MEM_Null ){
491     sqlite3VdbeMemSetStr(pCtx->pOut, sqlite3ErrStr(errCode), -1,
492                          SQLITE_UTF8, SQLITE_STATIC);
493   }
494 }
495 
496 /* Force an SQLITE_TOOBIG error. */
497 void sqlite3_result_error_toobig(sqlite3_context *pCtx){
498   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
499   pCtx->isError = SQLITE_TOOBIG;
500   sqlite3VdbeMemSetStr(pCtx->pOut, "string or blob too big", -1,
501                        SQLITE_UTF8, SQLITE_STATIC);
502 }
503 
504 /* An SQLITE_NOMEM error. */
505 void sqlite3_result_error_nomem(sqlite3_context *pCtx){
506   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
507   sqlite3VdbeMemSetNull(pCtx->pOut);
508   pCtx->isError = SQLITE_NOMEM_BKPT;
509   sqlite3OomFault(pCtx->pOut->db);
510 }
511 
512 /*
513 ** This function is called after a transaction has been committed. It
514 ** invokes callbacks registered with sqlite3_wal_hook() as required.
515 */
516 static int doWalCallbacks(sqlite3 *db){
517   int rc = SQLITE_OK;
518 #ifndef SQLITE_OMIT_WAL
519   int i;
520   for(i=0; i<db->nDb; i++){
521     Btree *pBt = db->aDb[i].pBt;
522     if( pBt ){
523       int nEntry;
524       sqlite3BtreeEnter(pBt);
525       nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
526       sqlite3BtreeLeave(pBt);
527       if( nEntry>0 && db->xWalCallback && rc==SQLITE_OK ){
528         rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zDbSName, nEntry);
529       }
530     }
531   }
532 #endif
533   return rc;
534 }
535 
536 
537 /*
538 ** Execute the statement pStmt, either until a row of data is ready, the
539 ** statement is completely executed or an error occurs.
540 **
541 ** This routine implements the bulk of the logic behind the sqlite_step()
542 ** API.  The only thing omitted is the automatic recompile if a
543 ** schema change has occurred.  That detail is handled by the
544 ** outer sqlite3_step() wrapper procedure.
545 */
546 static int sqlite3Step(Vdbe *p){
547   sqlite3 *db;
548   int rc;
549 
550   assert(p);
551   if( p->magic!=VDBE_MAGIC_RUN ){
552     /* We used to require that sqlite3_reset() be called before retrying
553     ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
554     ** with version 3.7.0, we changed this so that sqlite3_reset() would
555     ** be called automatically instead of throwing the SQLITE_MISUSE error.
556     ** This "automatic-reset" change is not technically an incompatibility,
557     ** since any application that receives an SQLITE_MISUSE is broken by
558     ** definition.
559     **
560     ** Nevertheless, some published applications that were originally written
561     ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE
562     ** returns, and those were broken by the automatic-reset change.  As a
563     ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
564     ** legacy behavior of returning SQLITE_MISUSE for cases where the
565     ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
566     ** or SQLITE_BUSY error.
567     */
568 #ifdef SQLITE_OMIT_AUTORESET
569     if( (rc = p->rc&0xff)==SQLITE_BUSY || rc==SQLITE_LOCKED ){
570       sqlite3_reset((sqlite3_stmt*)p);
571     }else{
572       return SQLITE_MISUSE_BKPT;
573     }
574 #else
575     sqlite3_reset((sqlite3_stmt*)p);
576 #endif
577   }
578 
579   /* Check that malloc() has not failed. If it has, return early. */
580   db = p->db;
581   if( db->mallocFailed ){
582     p->rc = SQLITE_NOMEM;
583     return SQLITE_NOMEM_BKPT;
584   }
585 
586   if( p->pc<=0 && p->expired ){
587     p->rc = SQLITE_SCHEMA;
588     rc = SQLITE_ERROR;
589     goto end_of_step;
590   }
591   if( p->pc<0 ){
592     /* If there are no other statements currently running, then
593     ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
594     ** from interrupting a statement that has not yet started.
595     */
596     if( db->nVdbeActive==0 ){
597       db->u1.isInterrupted = 0;
598     }
599 
600     assert( db->nVdbeWrite>0 || db->autoCommit==0
601         || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
602     );
603 
604 #ifndef SQLITE_OMIT_TRACE
605     if( (db->xProfile || (db->mTrace & SQLITE_TRACE_PROFILE)!=0)
606         && !db->init.busy && p->zSql ){
607       sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
608     }else{
609       assert( p->startTime==0 );
610     }
611 #endif
612 
613     db->nVdbeActive++;
614     if( p->readOnly==0 ) db->nVdbeWrite++;
615     if( p->bIsReader ) db->nVdbeRead++;
616     p->pc = 0;
617   }
618 #ifdef SQLITE_DEBUG
619   p->rcApp = SQLITE_OK;
620 #endif
621 #ifndef SQLITE_OMIT_EXPLAIN
622   if( p->explain ){
623     rc = sqlite3VdbeList(p);
624   }else
625 #endif /* SQLITE_OMIT_EXPLAIN */
626   {
627     db->nVdbeExec++;
628     rc = sqlite3VdbeExec(p);
629     db->nVdbeExec--;
630   }
631 
632 #ifndef SQLITE_OMIT_TRACE
633   /* If the statement completed successfully, invoke the profile callback */
634   if( rc!=SQLITE_ROW ) checkProfileCallback(db, p);
635 #endif
636 
637   if( rc==SQLITE_DONE && db->autoCommit ){
638     assert( p->rc==SQLITE_OK );
639     p->rc = doWalCallbacks(db);
640     if( p->rc!=SQLITE_OK ){
641       rc = SQLITE_ERROR;
642     }
643   }
644 
645   db->errCode = rc;
646   if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
647     p->rc = SQLITE_NOMEM_BKPT;
648   }
649 end_of_step:
650   /* At this point local variable rc holds the value that should be
651   ** returned if this statement was compiled using the legacy
652   ** sqlite3_prepare() interface. According to the docs, this can only
653   ** be one of the values in the first assert() below. Variable p->rc
654   ** contains the value that would be returned if sqlite3_finalize()
655   ** were called on statement p.
656   */
657   assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR
658        || (rc&0xff)==SQLITE_BUSY || rc==SQLITE_MISUSE
659   );
660   assert( (p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE) || p->rc==p->rcApp );
661   if( (p->prepFlags & SQLITE_PREPARE_SAVESQL)!=0
662    && rc!=SQLITE_ROW
663    && rc!=SQLITE_DONE
664   ){
665     /* If this statement was prepared using saved SQL and an
666     ** error has occurred, then return the error code in p->rc to the
667     ** caller. Set the error code in the database handle to the same value.
668     */
669     rc = sqlite3VdbeTransferError(p);
670   }
671   return (rc&db->errMask);
672 }
673 
674 /*
675 ** This is the top-level implementation of sqlite3_step().  Call
676 ** sqlite3Step() to do most of the work.  If a schema error occurs,
677 ** call sqlite3Reprepare() and try again.
678 */
679 int sqlite3_step(sqlite3_stmt *pStmt){
680   int rc = SQLITE_OK;      /* Result from sqlite3Step() */
681   Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
682   int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
683   sqlite3 *db;             /* The database connection */
684 
685   if( vdbeSafetyNotNull(v) ){
686     return SQLITE_MISUSE_BKPT;
687   }
688   db = v->db;
689   sqlite3_mutex_enter(db->mutex);
690   v->doingRerun = 0;
691   while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
692          && cnt++ < SQLITE_MAX_SCHEMA_RETRY ){
693     int savedPc = v->pc;
694     rc = sqlite3Reprepare(v);
695     if( rc!=SQLITE_OK ){
696       /* This case occurs after failing to recompile an sql statement.
697       ** The error message from the SQL compiler has already been loaded
698       ** into the database handle. This block copies the error message
699       ** from the database handle into the statement and sets the statement
700       ** program counter to 0 to ensure that when the statement is
701       ** finalized or reset the parser error message is available via
702       ** sqlite3_errmsg() and sqlite3_errcode().
703       */
704       const char *zErr = (const char *)sqlite3_value_text(db->pErr);
705       sqlite3DbFree(db, v->zErrMsg);
706       if( !db->mallocFailed ){
707         v->zErrMsg = sqlite3DbStrDup(db, zErr);
708         v->rc = rc = sqlite3ApiExit(db, rc);
709       } else {
710         v->zErrMsg = 0;
711         v->rc = rc = SQLITE_NOMEM_BKPT;
712       }
713       break;
714     }
715     sqlite3_reset(pStmt);
716     if( savedPc>=0 ) v->doingRerun = 1;
717     assert( v->expired==0 );
718   }
719   sqlite3_mutex_leave(db->mutex);
720   return rc;
721 }
722 
723 
724 /*
725 ** Extract the user data from a sqlite3_context structure and return a
726 ** pointer to it.
727 */
728 void *sqlite3_user_data(sqlite3_context *p){
729   assert( p && p->pFunc );
730   return p->pFunc->pUserData;
731 }
732 
733 /*
734 ** Extract the user data from a sqlite3_context structure and return a
735 ** pointer to it.
736 **
737 ** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
738 ** returns a copy of the pointer to the database connection (the 1st
739 ** parameter) of the sqlite3_create_function() and
740 ** sqlite3_create_function16() routines that originally registered the
741 ** application defined function.
742 */
743 sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
744   assert( p && p->pOut );
745   return p->pOut->db;
746 }
747 
748 /*
749 ** If this routine is invoked from within an xColumn method of a virtual
750 ** table, then it returns true if and only if the the call is during an
751 ** UPDATE operation and the value of the column will not be modified
752 ** by the UPDATE.
753 **
754 ** If this routine is called from any context other than within the
755 ** xColumn method of a virtual table, then the return value is meaningless
756 ** and arbitrary.
757 **
758 ** Virtual table implements might use this routine to optimize their
759 ** performance by substituting a NULL result, or some other light-weight
760 ** value, as a signal to the xUpdate routine that the column is unchanged.
761 */
762 int sqlite3_vtab_nochange(sqlite3_context *p){
763   assert( p );
764   return sqlite3_value_nochange(p->pOut);
765 }
766 
767 /*
768 ** Return the current time for a statement.  If the current time
769 ** is requested more than once within the same run of a single prepared
770 ** statement, the exact same time is returned for each invocation regardless
771 ** of the amount of time that elapses between invocations.  In other words,
772 ** the time returned is always the time of the first call.
773 */
774 sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context *p){
775   int rc;
776 #ifndef SQLITE_ENABLE_STAT3_OR_STAT4
777   sqlite3_int64 *piTime = &p->pVdbe->iCurrentTime;
778   assert( p->pVdbe!=0 );
779 #else
780   sqlite3_int64 iTime = 0;
781   sqlite3_int64 *piTime = p->pVdbe!=0 ? &p->pVdbe->iCurrentTime : &iTime;
782 #endif
783   if( *piTime==0 ){
784     rc = sqlite3OsCurrentTimeInt64(p->pOut->db->pVfs, piTime);
785     if( rc ) *piTime = 0;
786   }
787   return *piTime;
788 }
789 
790 /*
791 ** Create a new aggregate context for p and return a pointer to
792 ** its pMem->z element.
793 */
794 static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
795   Mem *pMem = p->pMem;
796   assert( (pMem->flags & MEM_Agg)==0 );
797   if( nByte<=0 ){
798     sqlite3VdbeMemSetNull(pMem);
799     pMem->z = 0;
800   }else{
801     sqlite3VdbeMemClearAndResize(pMem, nByte);
802     pMem->flags = MEM_Agg;
803     pMem->u.pDef = p->pFunc;
804     if( pMem->z ){
805       memset(pMem->z, 0, nByte);
806     }
807   }
808   return (void*)pMem->z;
809 }
810 
811 /*
812 ** Allocate or return the aggregate context for a user function.  A new
813 ** context is allocated on the first call.  Subsequent calls return the
814 ** same context that was returned on prior calls.
815 */
816 void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
817   assert( p && p->pFunc && p->pFunc->xFinalize );
818   assert( sqlite3_mutex_held(p->pOut->db->mutex) );
819   testcase( nByte<0 );
820   if( (p->pMem->flags & MEM_Agg)==0 ){
821     return createAggContext(p, nByte);
822   }else{
823     return (void*)p->pMem->z;
824   }
825 }
826 
827 /*
828 ** Return the auxiliary data pointer, if any, for the iArg'th argument to
829 ** the user-function defined by pCtx.
830 **
831 ** The left-most argument is 0.
832 **
833 ** Undocumented behavior:  If iArg is negative then access a cache of
834 ** auxiliary data pointers that is available to all functions within a
835 ** single prepared statement.  The iArg values must match.
836 */
837 void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
838   AuxData *pAuxData;
839 
840   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
841 #if SQLITE_ENABLE_STAT3_OR_STAT4
842   if( pCtx->pVdbe==0 ) return 0;
843 #else
844   assert( pCtx->pVdbe!=0 );
845 #endif
846   for(pAuxData=pCtx->pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNextAux){
847     if(  pAuxData->iAuxArg==iArg && (pAuxData->iAuxOp==pCtx->iOp || iArg<0) ){
848       return pAuxData->pAux;
849     }
850   }
851   return 0;
852 }
853 
854 /*
855 ** Set the auxiliary data pointer and delete function, for the iArg'th
856 ** argument to the user-function defined by pCtx. Any previous value is
857 ** deleted by calling the delete function specified when it was set.
858 **
859 ** The left-most argument is 0.
860 **
861 ** Undocumented behavior:  If iArg is negative then make the data available
862 ** to all functions within the current prepared statement using iArg as an
863 ** access code.
864 */
865 void sqlite3_set_auxdata(
866   sqlite3_context *pCtx,
867   int iArg,
868   void *pAux,
869   void (*xDelete)(void*)
870 ){
871   AuxData *pAuxData;
872   Vdbe *pVdbe = pCtx->pVdbe;
873 
874   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
875 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
876   if( pVdbe==0 ) goto failed;
877 #else
878   assert( pVdbe!=0 );
879 #endif
880 
881   for(pAuxData=pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNextAux){
882     if( pAuxData->iAuxArg==iArg && (pAuxData->iAuxOp==pCtx->iOp || iArg<0) ){
883       break;
884     }
885   }
886   if( pAuxData==0 ){
887     pAuxData = sqlite3DbMallocZero(pVdbe->db, sizeof(AuxData));
888     if( !pAuxData ) goto failed;
889     pAuxData->iAuxOp = pCtx->iOp;
890     pAuxData->iAuxArg = iArg;
891     pAuxData->pNextAux = pVdbe->pAuxData;
892     pVdbe->pAuxData = pAuxData;
893     if( pCtx->isError==0 ) pCtx->isError = -1;
894   }else if( pAuxData->xDeleteAux ){
895     pAuxData->xDeleteAux(pAuxData->pAux);
896   }
897 
898   pAuxData->pAux = pAux;
899   pAuxData->xDeleteAux = xDelete;
900   return;
901 
902 failed:
903   if( xDelete ){
904     xDelete(pAux);
905   }
906 }
907 
908 #ifndef SQLITE_OMIT_DEPRECATED
909 /*
910 ** Return the number of times the Step function of an aggregate has been
911 ** called.
912 **
913 ** This function is deprecated.  Do not use it for new code.  It is
914 ** provide only to avoid breaking legacy code.  New aggregate function
915 ** implementations should keep their own counts within their aggregate
916 ** context.
917 */
918 int sqlite3_aggregate_count(sqlite3_context *p){
919   assert( p && p->pMem && p->pFunc && p->pFunc->xFinalize );
920   return p->pMem->n;
921 }
922 #endif
923 
924 /*
925 ** Return the number of columns in the result set for the statement pStmt.
926 */
927 int sqlite3_column_count(sqlite3_stmt *pStmt){
928   Vdbe *pVm = (Vdbe *)pStmt;
929   return pVm ? pVm->nResColumn : 0;
930 }
931 
932 /*
933 ** Return the number of values available from the current row of the
934 ** currently executing statement pStmt.
935 */
936 int sqlite3_data_count(sqlite3_stmt *pStmt){
937   Vdbe *pVm = (Vdbe *)pStmt;
938   if( pVm==0 || pVm->pResultSet==0 ) return 0;
939   return pVm->nResColumn;
940 }
941 
942 /*
943 ** Return a pointer to static memory containing an SQL NULL value.
944 */
945 static const Mem *columnNullValue(void){
946   /* Even though the Mem structure contains an element
947   ** of type i64, on certain architectures (x86) with certain compiler
948   ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
949   ** instead of an 8-byte one. This all works fine, except that when
950   ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
951   ** that a Mem structure is located on an 8-byte boundary. To prevent
952   ** these assert()s from failing, when building with SQLITE_DEBUG defined
953   ** using gcc, we force nullMem to be 8-byte aligned using the magical
954   ** __attribute__((aligned(8))) macro.  */
955   static const Mem nullMem
956 #if defined(SQLITE_DEBUG) && defined(__GNUC__)
957     __attribute__((aligned(8)))
958 #endif
959     = {
960         /* .u          = */ {0},
961         /* .flags      = */ (u16)MEM_Null,
962         /* .enc        = */ (u8)0,
963         /* .eSubtype   = */ (u8)0,
964         /* .n          = */ (int)0,
965         /* .z          = */ (char*)0,
966         /* .zMalloc    = */ (char*)0,
967         /* .szMalloc   = */ (int)0,
968         /* .uTemp      = */ (u32)0,
969         /* .db         = */ (sqlite3*)0,
970         /* .xDel       = */ (void(*)(void*))0,
971 #ifdef SQLITE_DEBUG
972         /* .pScopyFrom = */ (Mem*)0,
973         /* .mScopyFlags= */ 0,
974 #endif
975       };
976   return &nullMem;
977 }
978 
979 /*
980 ** Check to see if column iCol of the given statement is valid.  If
981 ** it is, return a pointer to the Mem for the value of that column.
982 ** If iCol is not valid, return a pointer to a Mem which has a value
983 ** of NULL.
984 */
985 static Mem *columnMem(sqlite3_stmt *pStmt, int i){
986   Vdbe *pVm;
987   Mem *pOut;
988 
989   pVm = (Vdbe *)pStmt;
990   if( pVm==0 ) return (Mem*)columnNullValue();
991   assert( pVm->db );
992   sqlite3_mutex_enter(pVm->db->mutex);
993   if( pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
994     pOut = &pVm->pResultSet[i];
995   }else{
996     sqlite3Error(pVm->db, SQLITE_RANGE);
997     pOut = (Mem*)columnNullValue();
998   }
999   return pOut;
1000 }
1001 
1002 /*
1003 ** This function is called after invoking an sqlite3_value_XXX function on a
1004 ** column value (i.e. a value returned by evaluating an SQL expression in the
1005 ** select list of a SELECT statement) that may cause a malloc() failure. If
1006 ** malloc() has failed, the threads mallocFailed flag is cleared and the result
1007 ** code of statement pStmt set to SQLITE_NOMEM.
1008 **
1009 ** Specifically, this is called from within:
1010 **
1011 **     sqlite3_column_int()
1012 **     sqlite3_column_int64()
1013 **     sqlite3_column_text()
1014 **     sqlite3_column_text16()
1015 **     sqlite3_column_real()
1016 **     sqlite3_column_bytes()
1017 **     sqlite3_column_bytes16()
1018 **     sqiite3_column_blob()
1019 */
1020 static void columnMallocFailure(sqlite3_stmt *pStmt)
1021 {
1022   /* If malloc() failed during an encoding conversion within an
1023   ** sqlite3_column_XXX API, then set the return code of the statement to
1024   ** SQLITE_NOMEM. The next call to _step() (if any) will return SQLITE_ERROR
1025   ** and _finalize() will return NOMEM.
1026   */
1027   Vdbe *p = (Vdbe *)pStmt;
1028   if( p ){
1029     assert( p->db!=0 );
1030     assert( sqlite3_mutex_held(p->db->mutex) );
1031     p->rc = sqlite3ApiExit(p->db, p->rc);
1032     sqlite3_mutex_leave(p->db->mutex);
1033   }
1034 }
1035 
1036 /**************************** sqlite3_column_  *******************************
1037 ** The following routines are used to access elements of the current row
1038 ** in the result set.
1039 */
1040 const void *sqlite3_column_blob(sqlite3_stmt *pStmt, int i){
1041   const void *val;
1042   val = sqlite3_value_blob( columnMem(pStmt,i) );
1043   /* Even though there is no encoding conversion, value_blob() might
1044   ** need to call malloc() to expand the result of a zeroblob()
1045   ** expression.
1046   */
1047   columnMallocFailure(pStmt);
1048   return val;
1049 }
1050 int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
1051   int val = sqlite3_value_bytes( columnMem(pStmt,i) );
1052   columnMallocFailure(pStmt);
1053   return val;
1054 }
1055 int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
1056   int val = sqlite3_value_bytes16( columnMem(pStmt,i) );
1057   columnMallocFailure(pStmt);
1058   return val;
1059 }
1060 double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
1061   double val = sqlite3_value_double( columnMem(pStmt,i) );
1062   columnMallocFailure(pStmt);
1063   return val;
1064 }
1065 int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
1066   int val = sqlite3_value_int( columnMem(pStmt,i) );
1067   columnMallocFailure(pStmt);
1068   return val;
1069 }
1070 sqlite_int64 sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
1071   sqlite_int64 val = sqlite3_value_int64( columnMem(pStmt,i) );
1072   columnMallocFailure(pStmt);
1073   return val;
1074 }
1075 const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
1076   const unsigned char *val = sqlite3_value_text( columnMem(pStmt,i) );
1077   columnMallocFailure(pStmt);
1078   return val;
1079 }
1080 sqlite3_value *sqlite3_column_value(sqlite3_stmt *pStmt, int i){
1081   Mem *pOut = columnMem(pStmt, i);
1082   if( pOut->flags&MEM_Static ){
1083     pOut->flags &= ~MEM_Static;
1084     pOut->flags |= MEM_Ephem;
1085   }
1086   columnMallocFailure(pStmt);
1087   return (sqlite3_value *)pOut;
1088 }
1089 #ifndef SQLITE_OMIT_UTF16
1090 const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
1091   const void *val = sqlite3_value_text16( columnMem(pStmt,i) );
1092   columnMallocFailure(pStmt);
1093   return val;
1094 }
1095 #endif /* SQLITE_OMIT_UTF16 */
1096 int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
1097   int iType = sqlite3_value_type( columnMem(pStmt,i) );
1098   columnMallocFailure(pStmt);
1099   return iType;
1100 }
1101 
1102 /*
1103 ** Convert the N-th element of pStmt->pColName[] into a string using
1104 ** xFunc() then return that string.  If N is out of range, return 0.
1105 **
1106 ** There are up to 5 names for each column.  useType determines which
1107 ** name is returned.  Here are the names:
1108 **
1109 **    0      The column name as it should be displayed for output
1110 **    1      The datatype name for the column
1111 **    2      The name of the database that the column derives from
1112 **    3      The name of the table that the column derives from
1113 **    4      The name of the table column that the result column derives from
1114 **
1115 ** If the result is not a simple column reference (if it is an expression
1116 ** or a constant) then useTypes 2, 3, and 4 return NULL.
1117 */
1118 static const void *columnName(
1119   sqlite3_stmt *pStmt,
1120   int N,
1121   const void *(*xFunc)(Mem*),
1122   int useType
1123 ){
1124   const void *ret;
1125   Vdbe *p;
1126   int n;
1127   sqlite3 *db;
1128 #ifdef SQLITE_ENABLE_API_ARMOR
1129   if( pStmt==0 ){
1130     (void)SQLITE_MISUSE_BKPT;
1131     return 0;
1132   }
1133 #endif
1134   ret = 0;
1135   p = (Vdbe *)pStmt;
1136   db = p->db;
1137   assert( db!=0 );
1138   n = sqlite3_column_count(pStmt);
1139   if( N<n && N>=0 ){
1140     N += useType*n;
1141     sqlite3_mutex_enter(db->mutex);
1142     assert( db->mallocFailed==0 );
1143     ret = xFunc(&p->aColName[N]);
1144      /* A malloc may have failed inside of the xFunc() call. If this
1145     ** is the case, clear the mallocFailed flag and return NULL.
1146     */
1147     if( db->mallocFailed ){
1148       sqlite3OomClear(db);
1149       ret = 0;
1150     }
1151     sqlite3_mutex_leave(db->mutex);
1152   }
1153   return ret;
1154 }
1155 
1156 /*
1157 ** Return the name of the Nth column of the result set returned by SQL
1158 ** statement pStmt.
1159 */
1160 const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
1161   return columnName(
1162       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_NAME);
1163 }
1164 #ifndef SQLITE_OMIT_UTF16
1165 const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
1166   return columnName(
1167       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_NAME);
1168 }
1169 #endif
1170 
1171 /*
1172 ** Constraint:  If you have ENABLE_COLUMN_METADATA then you must
1173 ** not define OMIT_DECLTYPE.
1174 */
1175 #if defined(SQLITE_OMIT_DECLTYPE) && defined(SQLITE_ENABLE_COLUMN_METADATA)
1176 # error "Must not define both SQLITE_OMIT_DECLTYPE \
1177          and SQLITE_ENABLE_COLUMN_METADATA"
1178 #endif
1179 
1180 #ifndef SQLITE_OMIT_DECLTYPE
1181 /*
1182 ** Return the column declaration type (if applicable) of the 'i'th column
1183 ** of the result set of SQL statement pStmt.
1184 */
1185 const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int N){
1186   return columnName(
1187       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DECLTYPE);
1188 }
1189 #ifndef SQLITE_OMIT_UTF16
1190 const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int N){
1191   return columnName(
1192       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DECLTYPE);
1193 }
1194 #endif /* SQLITE_OMIT_UTF16 */
1195 #endif /* SQLITE_OMIT_DECLTYPE */
1196 
1197 #ifdef SQLITE_ENABLE_COLUMN_METADATA
1198 /*
1199 ** Return the name of the database from which a result column derives.
1200 ** NULL is returned if the result column is an expression or constant or
1201 ** anything else which is not an unambiguous reference to a database column.
1202 */
1203 const char *sqlite3_column_database_name(sqlite3_stmt *pStmt, int N){
1204   return columnName(
1205       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DATABASE);
1206 }
1207 #ifndef SQLITE_OMIT_UTF16
1208 const void *sqlite3_column_database_name16(sqlite3_stmt *pStmt, int N){
1209   return columnName(
1210       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DATABASE);
1211 }
1212 #endif /* SQLITE_OMIT_UTF16 */
1213 
1214 /*
1215 ** Return the name of the table from which a result column derives.
1216 ** NULL is returned if the result column is an expression or constant or
1217 ** anything else which is not an unambiguous reference to a database column.
1218 */
1219 const char *sqlite3_column_table_name(sqlite3_stmt *pStmt, int N){
1220   return columnName(
1221       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_TABLE);
1222 }
1223 #ifndef SQLITE_OMIT_UTF16
1224 const void *sqlite3_column_table_name16(sqlite3_stmt *pStmt, int N){
1225   return columnName(
1226       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_TABLE);
1227 }
1228 #endif /* SQLITE_OMIT_UTF16 */
1229 
1230 /*
1231 ** Return the name of the table column from which a result column derives.
1232 ** NULL is returned if the result column is an expression or constant or
1233 ** anything else which is not an unambiguous reference to a database column.
1234 */
1235 const char *sqlite3_column_origin_name(sqlite3_stmt *pStmt, int N){
1236   return columnName(
1237       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_COLUMN);
1238 }
1239 #ifndef SQLITE_OMIT_UTF16
1240 const void *sqlite3_column_origin_name16(sqlite3_stmt *pStmt, int N){
1241   return columnName(
1242       pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_COLUMN);
1243 }
1244 #endif /* SQLITE_OMIT_UTF16 */
1245 #endif /* SQLITE_ENABLE_COLUMN_METADATA */
1246 
1247 
1248 /******************************* sqlite3_bind_  ***************************
1249 **
1250 ** Routines used to attach values to wildcards in a compiled SQL statement.
1251 */
1252 /*
1253 ** Unbind the value bound to variable i in virtual machine p. This is the
1254 ** the same as binding a NULL value to the column. If the "i" parameter is
1255 ** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
1256 **
1257 ** A successful evaluation of this routine acquires the mutex on p.
1258 ** the mutex is released if any kind of error occurs.
1259 **
1260 ** The error code stored in database p->db is overwritten with the return
1261 ** value in any case.
1262 */
1263 static int vdbeUnbind(Vdbe *p, int i){
1264   Mem *pVar;
1265   if( vdbeSafetyNotNull(p) ){
1266     return SQLITE_MISUSE_BKPT;
1267   }
1268   sqlite3_mutex_enter(p->db->mutex);
1269   if( p->magic!=VDBE_MAGIC_RUN || p->pc>=0 ){
1270     sqlite3Error(p->db, SQLITE_MISUSE);
1271     sqlite3_mutex_leave(p->db->mutex);
1272     sqlite3_log(SQLITE_MISUSE,
1273         "bind on a busy prepared statement: [%s]", p->zSql);
1274     return SQLITE_MISUSE_BKPT;
1275   }
1276   if( i<1 || i>p->nVar ){
1277     sqlite3Error(p->db, SQLITE_RANGE);
1278     sqlite3_mutex_leave(p->db->mutex);
1279     return SQLITE_RANGE;
1280   }
1281   i--;
1282   pVar = &p->aVar[i];
1283   sqlite3VdbeMemRelease(pVar);
1284   pVar->flags = MEM_Null;
1285   sqlite3Error(p->db, SQLITE_OK);
1286 
1287   /* If the bit corresponding to this variable in Vdbe.expmask is set, then
1288   ** binding a new value to this variable invalidates the current query plan.
1289   **
1290   ** IMPLEMENTATION-OF: R-48440-37595 If the specific value bound to host
1291   ** parameter in the WHERE clause might influence the choice of query plan
1292   ** for a statement, then the statement will be automatically recompiled,
1293   ** as if there had been a schema change, on the first sqlite3_step() call
1294   ** following any change to the bindings of that parameter.
1295   */
1296   assert( (p->prepFlags & SQLITE_PREPARE_SAVESQL)!=0 || p->expmask==0 );
1297   if( p->expmask!=0 && (p->expmask & (i>=31 ? 0x80000000 : (u32)1<<i))!=0 ){
1298     p->expired = 1;
1299   }
1300   return SQLITE_OK;
1301 }
1302 
1303 /*
1304 ** Bind a text or BLOB value.
1305 */
1306 static int bindText(
1307   sqlite3_stmt *pStmt,   /* The statement to bind against */
1308   int i,                 /* Index of the parameter to bind */
1309   const void *zData,     /* Pointer to the data to be bound */
1310   int nData,             /* Number of bytes of data to be bound */
1311   void (*xDel)(void*),   /* Destructor for the data */
1312   u8 encoding            /* Encoding for the data */
1313 ){
1314   Vdbe *p = (Vdbe *)pStmt;
1315   Mem *pVar;
1316   int rc;
1317 
1318   rc = vdbeUnbind(p, i);
1319   if( rc==SQLITE_OK ){
1320     if( zData!=0 ){
1321       pVar = &p->aVar[i-1];
1322       rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
1323       if( rc==SQLITE_OK && encoding!=0 ){
1324         rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
1325       }
1326       if( rc ){
1327         sqlite3Error(p->db, rc);
1328         rc = sqlite3ApiExit(p->db, rc);
1329       }
1330     }
1331     sqlite3_mutex_leave(p->db->mutex);
1332   }else if( xDel!=SQLITE_STATIC && xDel!=SQLITE_TRANSIENT ){
1333     xDel((void*)zData);
1334   }
1335   return rc;
1336 }
1337 
1338 
1339 /*
1340 ** Bind a blob value to an SQL statement variable.
1341 */
1342 int sqlite3_bind_blob(
1343   sqlite3_stmt *pStmt,
1344   int i,
1345   const void *zData,
1346   int nData,
1347   void (*xDel)(void*)
1348 ){
1349 #ifdef SQLITE_ENABLE_API_ARMOR
1350   if( nData<0 ) return SQLITE_MISUSE_BKPT;
1351 #endif
1352   return bindText(pStmt, i, zData, nData, xDel, 0);
1353 }
1354 int sqlite3_bind_blob64(
1355   sqlite3_stmt *pStmt,
1356   int i,
1357   const void *zData,
1358   sqlite3_uint64 nData,
1359   void (*xDel)(void*)
1360 ){
1361   assert( xDel!=SQLITE_DYNAMIC );
1362   if( nData>0x7fffffff ){
1363     return invokeValueDestructor(zData, xDel, 0);
1364   }else{
1365     return bindText(pStmt, i, zData, (int)nData, xDel, 0);
1366   }
1367 }
1368 int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
1369   int rc;
1370   Vdbe *p = (Vdbe *)pStmt;
1371   rc = vdbeUnbind(p, i);
1372   if( rc==SQLITE_OK ){
1373     sqlite3VdbeMemSetDouble(&p->aVar[i-1], rValue);
1374     sqlite3_mutex_leave(p->db->mutex);
1375   }
1376   return rc;
1377 }
1378 int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
1379   return sqlite3_bind_int64(p, i, (i64)iValue);
1380 }
1381 int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, sqlite_int64 iValue){
1382   int rc;
1383   Vdbe *p = (Vdbe *)pStmt;
1384   rc = vdbeUnbind(p, i);
1385   if( rc==SQLITE_OK ){
1386     sqlite3VdbeMemSetInt64(&p->aVar[i-1], iValue);
1387     sqlite3_mutex_leave(p->db->mutex);
1388   }
1389   return rc;
1390 }
1391 int sqlite3_bind_null(sqlite3_stmt *pStmt, int i){
1392   int rc;
1393   Vdbe *p = (Vdbe*)pStmt;
1394   rc = vdbeUnbind(p, i);
1395   if( rc==SQLITE_OK ){
1396     sqlite3_mutex_leave(p->db->mutex);
1397   }
1398   return rc;
1399 }
1400 int sqlite3_bind_pointer(
1401   sqlite3_stmt *pStmt,
1402   int i,
1403   void *pPtr,
1404   const char *zPTtype,
1405   void (*xDestructor)(void*)
1406 ){
1407   int rc;
1408   Vdbe *p = (Vdbe*)pStmt;
1409   rc = vdbeUnbind(p, i);
1410   if( rc==SQLITE_OK ){
1411     sqlite3VdbeMemSetPointer(&p->aVar[i-1], pPtr, zPTtype, xDestructor);
1412     sqlite3_mutex_leave(p->db->mutex);
1413   }else if( xDestructor ){
1414     xDestructor(pPtr);
1415   }
1416   return rc;
1417 }
1418 int sqlite3_bind_text(
1419   sqlite3_stmt *pStmt,
1420   int i,
1421   const char *zData,
1422   int nData,
1423   void (*xDel)(void*)
1424 ){
1425   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF8);
1426 }
1427 int sqlite3_bind_text64(
1428   sqlite3_stmt *pStmt,
1429   int i,
1430   const char *zData,
1431   sqlite3_uint64 nData,
1432   void (*xDel)(void*),
1433   unsigned char enc
1434 ){
1435   assert( xDel!=SQLITE_DYNAMIC );
1436   if( nData>0x7fffffff ){
1437     return invokeValueDestructor(zData, xDel, 0);
1438   }else{
1439     if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE;
1440     return bindText(pStmt, i, zData, (int)nData, xDel, enc);
1441   }
1442 }
1443 #ifndef SQLITE_OMIT_UTF16
1444 int sqlite3_bind_text16(
1445   sqlite3_stmt *pStmt,
1446   int i,
1447   const void *zData,
1448   int nData,
1449   void (*xDel)(void*)
1450 ){
1451   return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF16NATIVE);
1452 }
1453 #endif /* SQLITE_OMIT_UTF16 */
1454 int sqlite3_bind_value(sqlite3_stmt *pStmt, int i, const sqlite3_value *pValue){
1455   int rc;
1456   switch( sqlite3_value_type((sqlite3_value*)pValue) ){
1457     case SQLITE_INTEGER: {
1458       rc = sqlite3_bind_int64(pStmt, i, pValue->u.i);
1459       break;
1460     }
1461     case SQLITE_FLOAT: {
1462       rc = sqlite3_bind_double(pStmt, i, pValue->u.r);
1463       break;
1464     }
1465     case SQLITE_BLOB: {
1466       if( pValue->flags & MEM_Zero ){
1467         rc = sqlite3_bind_zeroblob(pStmt, i, pValue->u.nZero);
1468       }else{
1469         rc = sqlite3_bind_blob(pStmt, i, pValue->z, pValue->n,SQLITE_TRANSIENT);
1470       }
1471       break;
1472     }
1473     case SQLITE_TEXT: {
1474       rc = bindText(pStmt,i,  pValue->z, pValue->n, SQLITE_TRANSIENT,
1475                               pValue->enc);
1476       break;
1477     }
1478     default: {
1479       rc = sqlite3_bind_null(pStmt, i);
1480       break;
1481     }
1482   }
1483   return rc;
1484 }
1485 int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
1486   int rc;
1487   Vdbe *p = (Vdbe *)pStmt;
1488   rc = vdbeUnbind(p, i);
1489   if( rc==SQLITE_OK ){
1490     sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
1491     sqlite3_mutex_leave(p->db->mutex);
1492   }
1493   return rc;
1494 }
1495 int sqlite3_bind_zeroblob64(sqlite3_stmt *pStmt, int i, sqlite3_uint64 n){
1496   int rc;
1497   Vdbe *p = (Vdbe *)pStmt;
1498   sqlite3_mutex_enter(p->db->mutex);
1499   if( n>(u64)p->db->aLimit[SQLITE_LIMIT_LENGTH] ){
1500     rc = SQLITE_TOOBIG;
1501   }else{
1502     assert( (n & 0x7FFFFFFF)==n );
1503     rc = sqlite3_bind_zeroblob(pStmt, i, n);
1504   }
1505   rc = sqlite3ApiExit(p->db, rc);
1506   sqlite3_mutex_leave(p->db->mutex);
1507   return rc;
1508 }
1509 
1510 /*
1511 ** Return the number of wildcards that can be potentially bound to.
1512 ** This routine is added to support DBD::SQLite.
1513 */
1514 int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
1515   Vdbe *p = (Vdbe*)pStmt;
1516   return p ? p->nVar : 0;
1517 }
1518 
1519 /*
1520 ** Return the name of a wildcard parameter.  Return NULL if the index
1521 ** is out of range or if the wildcard is unnamed.
1522 **
1523 ** The result is always UTF-8.
1524 */
1525 const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
1526   Vdbe *p = (Vdbe*)pStmt;
1527   if( p==0 ) return 0;
1528   return sqlite3VListNumToName(p->pVList, i);
1529 }
1530 
1531 /*
1532 ** Given a wildcard parameter name, return the index of the variable
1533 ** with that name.  If there is no variable with the given name,
1534 ** return 0.
1535 */
1536 int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
1537   if( p==0 || zName==0 ) return 0;
1538   return sqlite3VListNameToNum(p->pVList, zName, nName);
1539 }
1540 int sqlite3_bind_parameter_index(sqlite3_stmt *pStmt, const char *zName){
1541   return sqlite3VdbeParameterIndex((Vdbe*)pStmt, zName, sqlite3Strlen30(zName));
1542 }
1543 
1544 /*
1545 ** Transfer all bindings from the first statement over to the second.
1546 */
1547 int sqlite3TransferBindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1548   Vdbe *pFrom = (Vdbe*)pFromStmt;
1549   Vdbe *pTo = (Vdbe*)pToStmt;
1550   int i;
1551   assert( pTo->db==pFrom->db );
1552   assert( pTo->nVar==pFrom->nVar );
1553   sqlite3_mutex_enter(pTo->db->mutex);
1554   for(i=0; i<pFrom->nVar; i++){
1555     sqlite3VdbeMemMove(&pTo->aVar[i], &pFrom->aVar[i]);
1556   }
1557   sqlite3_mutex_leave(pTo->db->mutex);
1558   return SQLITE_OK;
1559 }
1560 
1561 #ifndef SQLITE_OMIT_DEPRECATED
1562 /*
1563 ** Deprecated external interface.  Internal/core SQLite code
1564 ** should call sqlite3TransferBindings.
1565 **
1566 ** It is misuse to call this routine with statements from different
1567 ** database connections.  But as this is a deprecated interface, we
1568 ** will not bother to check for that condition.
1569 **
1570 ** If the two statements contain a different number of bindings, then
1571 ** an SQLITE_ERROR is returned.  Nothing else can go wrong, so otherwise
1572 ** SQLITE_OK is returned.
1573 */
1574 int sqlite3_transfer_bindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
1575   Vdbe *pFrom = (Vdbe*)pFromStmt;
1576   Vdbe *pTo = (Vdbe*)pToStmt;
1577   if( pFrom->nVar!=pTo->nVar ){
1578     return SQLITE_ERROR;
1579   }
1580   assert( (pTo->prepFlags & SQLITE_PREPARE_SAVESQL)!=0 || pTo->expmask==0 );
1581   if( pTo->expmask ){
1582     pTo->expired = 1;
1583   }
1584   assert( (pFrom->prepFlags & SQLITE_PREPARE_SAVESQL)!=0 || pFrom->expmask==0 );
1585   if( pFrom->expmask ){
1586     pFrom->expired = 1;
1587   }
1588   return sqlite3TransferBindings(pFromStmt, pToStmt);
1589 }
1590 #endif
1591 
1592 /*
1593 ** Return the sqlite3* database handle to which the prepared statement given
1594 ** in the argument belongs.  This is the same database handle that was
1595 ** the first argument to the sqlite3_prepare() that was used to create
1596 ** the statement in the first place.
1597 */
1598 sqlite3 *sqlite3_db_handle(sqlite3_stmt *pStmt){
1599   return pStmt ? ((Vdbe*)pStmt)->db : 0;
1600 }
1601 
1602 /*
1603 ** Return true if the prepared statement is guaranteed to not modify the
1604 ** database.
1605 */
1606 int sqlite3_stmt_readonly(sqlite3_stmt *pStmt){
1607   return pStmt ? ((Vdbe*)pStmt)->readOnly : 1;
1608 }
1609 
1610 /*
1611 ** Return true if the prepared statement is in need of being reset.
1612 */
1613 int sqlite3_stmt_busy(sqlite3_stmt *pStmt){
1614   Vdbe *v = (Vdbe*)pStmt;
1615   return v!=0 && v->magic==VDBE_MAGIC_RUN && v->pc>=0;
1616 }
1617 
1618 /*
1619 ** Return a pointer to the next prepared statement after pStmt associated
1620 ** with database connection pDb.  If pStmt is NULL, return the first
1621 ** prepared statement for the database connection.  Return NULL if there
1622 ** are no more.
1623 */
1624 sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt){
1625   sqlite3_stmt *pNext;
1626 #ifdef SQLITE_ENABLE_API_ARMOR
1627   if( !sqlite3SafetyCheckOk(pDb) ){
1628     (void)SQLITE_MISUSE_BKPT;
1629     return 0;
1630   }
1631 #endif
1632   sqlite3_mutex_enter(pDb->mutex);
1633   if( pStmt==0 ){
1634     pNext = (sqlite3_stmt*)pDb->pVdbe;
1635   }else{
1636     pNext = (sqlite3_stmt*)((Vdbe*)pStmt)->pNext;
1637   }
1638   sqlite3_mutex_leave(pDb->mutex);
1639   return pNext;
1640 }
1641 
1642 /*
1643 ** Return the value of a status counter for a prepared statement
1644 */
1645 int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
1646   Vdbe *pVdbe = (Vdbe*)pStmt;
1647   u32 v;
1648 #ifdef SQLITE_ENABLE_API_ARMOR
1649   if( !pStmt
1650    || (op!=SQLITE_STMTSTATUS_MEMUSED && (op<0||op>=ArraySize(pVdbe->aCounter)))
1651   ){
1652     (void)SQLITE_MISUSE_BKPT;
1653     return 0;
1654   }
1655 #endif
1656   if( op==SQLITE_STMTSTATUS_MEMUSED ){
1657     sqlite3 *db = pVdbe->db;
1658     sqlite3_mutex_enter(db->mutex);
1659     v = 0;
1660     db->pnBytesFreed = (int*)&v;
1661     sqlite3VdbeClearObject(db, pVdbe);
1662     sqlite3DbFree(db, pVdbe);
1663     db->pnBytesFreed = 0;
1664     sqlite3_mutex_leave(db->mutex);
1665   }else{
1666     v = pVdbe->aCounter[op];
1667     if( resetFlag ) pVdbe->aCounter[op] = 0;
1668   }
1669   return (int)v;
1670 }
1671 
1672 /*
1673 ** Return the SQL associated with a prepared statement
1674 */
1675 const char *sqlite3_sql(sqlite3_stmt *pStmt){
1676   Vdbe *p = (Vdbe *)pStmt;
1677   return p ? p->zSql : 0;
1678 }
1679 
1680 /*
1681 ** Return the SQL associated with a prepared statement with
1682 ** bound parameters expanded.  Space to hold the returned string is
1683 ** obtained from sqlite3_malloc().  The caller is responsible for
1684 ** freeing the returned string by passing it to sqlite3_free().
1685 **
1686 ** The SQLITE_TRACE_SIZE_LIMIT puts an upper bound on the size of
1687 ** expanded bound parameters.
1688 */
1689 char *sqlite3_expanded_sql(sqlite3_stmt *pStmt){
1690 #ifdef SQLITE_OMIT_TRACE
1691   return 0;
1692 #else
1693   char *z = 0;
1694   const char *zSql = sqlite3_sql(pStmt);
1695   if( zSql ){
1696     Vdbe *p = (Vdbe *)pStmt;
1697     sqlite3_mutex_enter(p->db->mutex);
1698     z = sqlite3VdbeExpandSql(p, zSql);
1699     sqlite3_mutex_leave(p->db->mutex);
1700   }
1701   return z;
1702 #endif
1703 }
1704 
1705 #ifdef SQLITE_ENABLE_NORMALIZE
1706 /*
1707 ** Return the normalized SQL associated with a prepared statement.
1708 */
1709 const char *sqlite3_normalized_sql(sqlite3_stmt *pStmt){
1710   Vdbe *p = (Vdbe *)pStmt;
1711   return p ? p->zNormSql : 0;
1712 }
1713 #endif /* SQLITE_ENABLE_NORMALIZE */
1714 
1715 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1716 /*
1717 ** Allocate and populate an UnpackedRecord structure based on the serialized
1718 ** record in nKey/pKey. Return a pointer to the new UnpackedRecord structure
1719 ** if successful, or a NULL pointer if an OOM error is encountered.
1720 */
1721 static UnpackedRecord *vdbeUnpackRecord(
1722   KeyInfo *pKeyInfo,
1723   int nKey,
1724   const void *pKey
1725 ){
1726   UnpackedRecord *pRet;           /* Return value */
1727 
1728   pRet = sqlite3VdbeAllocUnpackedRecord(pKeyInfo);
1729   if( pRet ){
1730     memset(pRet->aMem, 0, sizeof(Mem)*(pKeyInfo->nKeyField+1));
1731     sqlite3VdbeRecordUnpack(pKeyInfo, nKey, pKey, pRet);
1732   }
1733   return pRet;
1734 }
1735 
1736 /*
1737 ** This function is called from within a pre-update callback to retrieve
1738 ** a field of the row currently being updated or deleted.
1739 */
1740 int sqlite3_preupdate_old(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
1741   PreUpdate *p = db->pPreUpdate;
1742   Mem *pMem;
1743   int rc = SQLITE_OK;
1744 
1745   /* Test that this call is being made from within an SQLITE_DELETE or
1746   ** SQLITE_UPDATE pre-update callback, and that iIdx is within range. */
1747   if( !p || p->op==SQLITE_INSERT ){
1748     rc = SQLITE_MISUSE_BKPT;
1749     goto preupdate_old_out;
1750   }
1751   if( p->pPk ){
1752     iIdx = sqlite3ColumnOfIndex(p->pPk, iIdx);
1753   }
1754   if( iIdx>=p->pCsr->nField || iIdx<0 ){
1755     rc = SQLITE_RANGE;
1756     goto preupdate_old_out;
1757   }
1758 
1759   /* If the old.* record has not yet been loaded into memory, do so now. */
1760   if( p->pUnpacked==0 ){
1761     u32 nRec;
1762     u8 *aRec;
1763 
1764     nRec = sqlite3BtreePayloadSize(p->pCsr->uc.pCursor);
1765     aRec = sqlite3DbMallocRaw(db, nRec);
1766     if( !aRec ) goto preupdate_old_out;
1767     rc = sqlite3BtreePayload(p->pCsr->uc.pCursor, 0, nRec, aRec);
1768     if( rc==SQLITE_OK ){
1769       p->pUnpacked = vdbeUnpackRecord(&p->keyinfo, nRec, aRec);
1770       if( !p->pUnpacked ) rc = SQLITE_NOMEM;
1771     }
1772     if( rc!=SQLITE_OK ){
1773       sqlite3DbFree(db, aRec);
1774       goto preupdate_old_out;
1775     }
1776     p->aRecord = aRec;
1777   }
1778 
1779   pMem = *ppValue = &p->pUnpacked->aMem[iIdx];
1780   if( iIdx==p->pTab->iPKey ){
1781     sqlite3VdbeMemSetInt64(pMem, p->iKey1);
1782   }else if( iIdx>=p->pUnpacked->nField ){
1783     *ppValue = (sqlite3_value *)columnNullValue();
1784   }else if( p->pTab->aCol[iIdx].affinity==SQLITE_AFF_REAL ){
1785     if( pMem->flags & MEM_Int ){
1786       sqlite3VdbeMemRealify(pMem);
1787     }
1788   }
1789 
1790  preupdate_old_out:
1791   sqlite3Error(db, rc);
1792   return sqlite3ApiExit(db, rc);
1793 }
1794 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
1795 
1796 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1797 /*
1798 ** This function is called from within a pre-update callback to retrieve
1799 ** the number of columns in the row being updated, deleted or inserted.
1800 */
1801 int sqlite3_preupdate_count(sqlite3 *db){
1802   PreUpdate *p = db->pPreUpdate;
1803   return (p ? p->keyinfo.nKeyField : 0);
1804 }
1805 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
1806 
1807 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1808 /*
1809 ** This function is designed to be called from within a pre-update callback
1810 ** only. It returns zero if the change that caused the callback was made
1811 ** immediately by a user SQL statement. Or, if the change was made by a
1812 ** trigger program, it returns the number of trigger programs currently
1813 ** on the stack (1 for a top-level trigger, 2 for a trigger fired by a
1814 ** top-level trigger etc.).
1815 **
1816 ** For the purposes of the previous paragraph, a foreign key CASCADE, SET NULL
1817 ** or SET DEFAULT action is considered a trigger.
1818 */
1819 int sqlite3_preupdate_depth(sqlite3 *db){
1820   PreUpdate *p = db->pPreUpdate;
1821   return (p ? p->v->nFrame : 0);
1822 }
1823 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
1824 
1825 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1826 /*
1827 ** This function is called from within a pre-update callback to retrieve
1828 ** a field of the row currently being updated or inserted.
1829 */
1830 int sqlite3_preupdate_new(sqlite3 *db, int iIdx, sqlite3_value **ppValue){
1831   PreUpdate *p = db->pPreUpdate;
1832   int rc = SQLITE_OK;
1833   Mem *pMem;
1834 
1835   if( !p || p->op==SQLITE_DELETE ){
1836     rc = SQLITE_MISUSE_BKPT;
1837     goto preupdate_new_out;
1838   }
1839   if( p->pPk && p->op!=SQLITE_UPDATE ){
1840     iIdx = sqlite3ColumnOfIndex(p->pPk, iIdx);
1841   }
1842   if( iIdx>=p->pCsr->nField || iIdx<0 ){
1843     rc = SQLITE_RANGE;
1844     goto preupdate_new_out;
1845   }
1846 
1847   if( p->op==SQLITE_INSERT ){
1848     /* For an INSERT, memory cell p->iNewReg contains the serialized record
1849     ** that is being inserted. Deserialize it. */
1850     UnpackedRecord *pUnpack = p->pNewUnpacked;
1851     if( !pUnpack ){
1852       Mem *pData = &p->v->aMem[p->iNewReg];
1853       rc = ExpandBlob(pData);
1854       if( rc!=SQLITE_OK ) goto preupdate_new_out;
1855       pUnpack = vdbeUnpackRecord(&p->keyinfo, pData->n, pData->z);
1856       if( !pUnpack ){
1857         rc = SQLITE_NOMEM;
1858         goto preupdate_new_out;
1859       }
1860       p->pNewUnpacked = pUnpack;
1861     }
1862     pMem = &pUnpack->aMem[iIdx];
1863     if( iIdx==p->pTab->iPKey ){
1864       sqlite3VdbeMemSetInt64(pMem, p->iKey2);
1865     }else if( iIdx>=pUnpack->nField ){
1866       pMem = (sqlite3_value *)columnNullValue();
1867     }
1868   }else{
1869     /* For an UPDATE, memory cell (p->iNewReg+1+iIdx) contains the required
1870     ** value. Make a copy of the cell contents and return a pointer to it.
1871     ** It is not safe to return a pointer to the memory cell itself as the
1872     ** caller may modify the value text encoding.
1873     */
1874     assert( p->op==SQLITE_UPDATE );
1875     if( !p->aNew ){
1876       p->aNew = (Mem *)sqlite3DbMallocZero(db, sizeof(Mem) * p->pCsr->nField);
1877       if( !p->aNew ){
1878         rc = SQLITE_NOMEM;
1879         goto preupdate_new_out;
1880       }
1881     }
1882     assert( iIdx>=0 && iIdx<p->pCsr->nField );
1883     pMem = &p->aNew[iIdx];
1884     if( pMem->flags==0 ){
1885       if( iIdx==p->pTab->iPKey ){
1886         sqlite3VdbeMemSetInt64(pMem, p->iKey2);
1887       }else{
1888         rc = sqlite3VdbeMemCopy(pMem, &p->v->aMem[p->iNewReg+1+iIdx]);
1889         if( rc!=SQLITE_OK ) goto preupdate_new_out;
1890       }
1891     }
1892   }
1893   *ppValue = pMem;
1894 
1895  preupdate_new_out:
1896   sqlite3Error(db, rc);
1897   return sqlite3ApiExit(db, rc);
1898 }
1899 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
1900 
1901 #ifdef SQLITE_ENABLE_STMT_SCANSTATUS
1902 /*
1903 ** Return status data for a single loop within query pStmt.
1904 */
1905 int sqlite3_stmt_scanstatus(
1906   sqlite3_stmt *pStmt,            /* Prepared statement being queried */
1907   int idx,                        /* Index of loop to report on */
1908   int iScanStatusOp,              /* Which metric to return */
1909   void *pOut                      /* OUT: Write the answer here */
1910 ){
1911   Vdbe *p = (Vdbe*)pStmt;
1912   ScanStatus *pScan;
1913   if( idx<0 || idx>=p->nScan ) return 1;
1914   pScan = &p->aScan[idx];
1915   switch( iScanStatusOp ){
1916     case SQLITE_SCANSTAT_NLOOP: {
1917       *(sqlite3_int64*)pOut = p->anExec[pScan->addrLoop];
1918       break;
1919     }
1920     case SQLITE_SCANSTAT_NVISIT: {
1921       *(sqlite3_int64*)pOut = p->anExec[pScan->addrVisit];
1922       break;
1923     }
1924     case SQLITE_SCANSTAT_EST: {
1925       double r = 1.0;
1926       LogEst x = pScan->nEst;
1927       while( x<100 ){
1928         x += 10;
1929         r *= 0.5;
1930       }
1931       *(double*)pOut = r*sqlite3LogEstToInt(x);
1932       break;
1933     }
1934     case SQLITE_SCANSTAT_NAME: {
1935       *(const char**)pOut = pScan->zName;
1936       break;
1937     }
1938     case SQLITE_SCANSTAT_EXPLAIN: {
1939       if( pScan->addrExplain ){
1940         *(const char**)pOut = p->aOp[ pScan->addrExplain ].p4.z;
1941       }else{
1942         *(const char**)pOut = 0;
1943       }
1944       break;
1945     }
1946     case SQLITE_SCANSTAT_SELECTID: {
1947       if( pScan->addrExplain ){
1948         *(int*)pOut = p->aOp[ pScan->addrExplain ].p1;
1949       }else{
1950         *(int*)pOut = -1;
1951       }
1952       break;
1953     }
1954     default: {
1955       return 1;
1956     }
1957   }
1958   return 0;
1959 }
1960 
1961 /*
1962 ** Zero all counters associated with the sqlite3_stmt_scanstatus() data.
1963 */
1964 void sqlite3_stmt_scanstatus_reset(sqlite3_stmt *pStmt){
1965   Vdbe *p = (Vdbe*)pStmt;
1966   memset(p->anExec, 0, p->nOp * sizeof(i64));
1967 }
1968 #endif /* SQLITE_ENABLE_STMT_SCANSTATUS */
1969