src/vdbemem.c

   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 manipulate "Mem" structure.  A "Mem"
  14 ** stores a single value in the VDBE.  Mem is an opaque structure visible
  15 ** only within the VDBE.  Interface routines refer to a Mem using the
  16 ** name sqlite_value
  17 */
  18 #include "sqliteInt.h"
  19 #include "vdbeInt.h"
  20
  21 #ifdef SQLITE_DEBUG
  22 /*
  23 ** Check invariants on a Mem object.
  24 **
  25 ** This routine is intended for use inside of assert() statements, like
  26 ** this:    assert( sqlite3VdbeCheckMemInvariants(pMem) );
  27 */
  28 int sqlite3VdbeCheckMemInvariants(Mem *p){
  29   /* If MEM_Dyn is set then Mem.xDel!=0.
  30   ** Mem.xDel might not be initialized if MEM_Dyn is clear.
  31   */
  32   assert( (p->flags & MEM_Dyn)==0 || p->xDel!=0 );
  33
  34   /* MEM_Dyn may only be set if Mem.szMalloc==0.  In this way we
  35   ** ensure that if Mem.szMalloc>0 then it is safe to do
  36   ** Mem.z = Mem.zMalloc without having to check Mem.flags&MEM_Dyn.
  37   ** That saves a few cycles in inner loops. */
  38   assert( (p->flags & MEM_Dyn)==0 || p->szMalloc==0 );
  39
  40   /* Cannot be both MEM_Int and MEM_Real at the same time */
  41   assert( (p->flags & (MEM_Int|MEM_Real))!=(MEM_Int|MEM_Real) );
  42
  43   if( p->flags & MEM_Null ){
  44     /* Cannot be both MEM_Null and some other type */
  45     assert( (p->flags & (MEM_Int|MEM_Real|MEM_Str|MEM_Blob
  46                          |MEM_RowSet|MEM_Frame|MEM_Agg|MEM_Zero))==0 );
  47
  48     /* If MEM_Null is set, then either the value is a pure NULL (the usual
  49     ** case) or it is a pointer set using sqlite3_bind_pointer() or
  50     ** sqlite3_result_pointer().  If a pointer, then MEM_Term must also be
  51     ** set.
  52     */
  53     if( (p->flags & (MEM_Term|MEM_Subtype))==(MEM_Term|MEM_Subtype) ){
  54       /* This is a pointer type.  There may be a flag to indicate what to
  55       ** do with the pointer. */
  56       assert( ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
  57               ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
  58               ((p->flags&MEM_Static)!=0 ? 1 : 0) <= 1 );
  59
  60       /* No other bits set */
  61       assert( (p->flags & ~(MEM_Null|MEM_Term|MEM_Subtype
  62                            |MEM_Dyn|MEM_Ephem|MEM_Static))==0 );
  63     }else{
  64       /* A pure NULL might have other flags, such as MEM_Static, MEM_Dyn,
  65       ** MEM_Ephem, MEM_Cleared, or MEM_Subtype */
  66     }
  67   }else{
  68     /* The MEM_Cleared bit is only allowed on NULLs */
  69     assert( (p->flags & MEM_Cleared)==0 );
  70   }
  71
  72   /* The szMalloc field holds the correct memory allocation size */
  73   assert( p->szMalloc==0
  74        || p->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc) );
  75
  76   /* If p holds a string or blob, the Mem.z must point to exactly
  77   ** one of the following:
  78   **
  79   **   (1) Memory in Mem.zMalloc and managed by the Mem object
  80   **   (2) Memory to be freed using Mem.xDel
  81   **   (3) An ephemeral string or blob
  82   **   (4) A static string or blob
  83   */
  84   if( (p->flags & (MEM_Str|MEM_Blob)) && p->n>0 ){
  85     assert(
  86       ((p->szMalloc>0 && p->z==p->zMalloc)? 1 : 0) +
  87       ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
  88       ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
  89       ((p->flags&MEM_Static)!=0 ? 1 : 0) == 1
  90     );
  91   }
  92   return 1;
  93 }
  94 #endif
  95
  96
  97 /*
  98 ** If pMem is an object with a valid string representation, this routine
  99 ** ensures the internal encoding for the string representation is
 100 ** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
 101 **
 102 ** If pMem is not a string object, or the encoding of the string
 103 ** representation is already stored using the requested encoding, then this
 104 ** routine is a no-op.
 105 **
 106 ** SQLITE_OK is returned if the conversion is successful (or not required).
 107 ** SQLITE_NOMEM may be returned if a malloc() fails during conversion
 108 ** between formats.
 109 */
 110 int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
 111 #ifndef SQLITE_OMIT_UTF16
 112   int rc;
 113 #endif
 114   assert( (pMem->flags&MEM_RowSet)==0 );
 115   assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
 116            || desiredEnc==SQLITE_UTF16BE );
 117   if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
 118     return SQLITE_OK;
 119   }
 120   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 121 #ifdef SQLITE_OMIT_UTF16
 122   return SQLITE_ERROR;
 123 #else
 124
 125   /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
 126   ** then the encoding of the value may not have changed.
 127   */
 128   rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
 129   assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
 130   assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
 131   assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
 132   return rc;
 133 #endif
 134 }
 135
 136 /*
 137 ** Make sure pMem->z points to a writable allocation of at least
 138 ** min(n,32) bytes.
 139 **
 140 ** If the bPreserve argument is true, then copy of the content of
 141 ** pMem->z into the new allocation.  pMem must be either a string or
 142 ** blob if bPreserve is true.  If bPreserve is false, any prior content
 143 ** in pMem->z is discarded.
 144 */
 145 SQLITE_NOINLINE int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
 146   assert( sqlite3VdbeCheckMemInvariants(pMem) );
 147   assert( (pMem->flags&MEM_RowSet)==0 );
 148   testcase( pMem->db==0 );
 149
 150   /* If the bPreserve flag is set to true, then the memory cell must already
 151   ** contain a valid string or blob value.  */
 152   assert( bPreserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
 153   testcase( bPreserve && pMem->z==0 );
 154
 155   assert( pMem->szMalloc==0
 156        || pMem->szMalloc==sqlite3DbMallocSize(pMem->db, pMem->zMalloc) );
 157   if( n<32 ) n = 32;
 158   if( pMem->szMalloc>0 && bPreserve && pMem->z==pMem->zMalloc ){
 159     pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
 160     bPreserve = 0;
 161   }else{
 162     if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 163     pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
 164   }
 165   if( pMem->zMalloc==0 ){
 166     sqlite3VdbeMemSetNull(pMem);
 167     pMem->z = 0;
 168     pMem->szMalloc = 0;
 169     return SQLITE_NOMEM_BKPT;
 170   }else{
 171     pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
 172   }
 173
 174   if( bPreserve && pMem->z ){
 175     assert( pMem->z!=pMem->zMalloc );
 176     memcpy(pMem->zMalloc, pMem->z, pMem->n);
 177   }
 178   if( (pMem->flags&MEM_Dyn)!=0 ){
 179     assert( pMem->xDel!=0 && pMem->xDel!=SQLITE_DYNAMIC );
 180     pMem->xDel((void *)(pMem->z));
 181   }
 182
 183   pMem->z = pMem->zMalloc;
 184   pMem->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Static);
 185   return SQLITE_OK;
 186 }
 187
 188 /*
 189 ** Change the pMem->zMalloc allocation to be at least szNew bytes.
 190 ** If pMem->zMalloc already meets or exceeds the requested size, this
 191 ** routine is a no-op.
 192 **
 193 ** Any prior string or blob content in the pMem object may be discarded.
 194 ** The pMem->xDel destructor is called, if it exists.  Though MEM_Str
 195 ** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, and MEM_Null
 196 ** values are preserved.
 197 **
 198 ** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
 199 ** if unable to complete the resizing.
 200 */
 201 int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
 202   assert( szNew>0 );
 203   assert( (pMem->flags & MEM_Dyn)==0 || pMem->szMalloc==0 );
 204   if( pMem->szMalloc<szNew ){
 205     return sqlite3VdbeMemGrow(pMem, szNew, 0);
 206   }
 207   assert( (pMem->flags & MEM_Dyn)==0 );
 208   pMem->z = pMem->zMalloc;
 209   pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
 210   return SQLITE_OK;
 211 }
 212
 213 /*
 214 ** It is already known that pMem contains an unterminated string.
 215 ** Add the zero terminator.
 216 */
 217 static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
 218   if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
 219     return SQLITE_NOMEM_BKPT;
 220   }
 221   pMem->z[pMem->n] = 0;
 222   pMem->z[pMem->n+1] = 0;
 223   pMem->flags |= MEM_Term;
 224   return SQLITE_OK;
 225 }
 226
 227 /*
 228 ** Change pMem so that its MEM_Str or MEM_Blob value is stored in
 229 ** MEM.zMalloc, where it can be safely written.
 230 **
 231 ** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
 232 */
 233 int sqlite3VdbeMemMakeWriteable(Mem *pMem){
 234   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 235   assert( (pMem->flags&MEM_RowSet)==0 );
 236   if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
 237     if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
 238     if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
 239       int rc = vdbeMemAddTerminator(pMem);
 240       if( rc ) return rc;
 241     }
 242   }
 243   pMem->flags &= ~MEM_Ephem;
 244 #ifdef SQLITE_DEBUG
 245   pMem->pScopyFrom = 0;
 246 #endif
 247
 248   return SQLITE_OK;
 249 }
 250
 251 /*
 252 ** If the given Mem* has a zero-filled tail, turn it into an ordinary
 253 ** blob stored in dynamically allocated space.
 254 */
 255 #ifndef SQLITE_OMIT_INCRBLOB
 256 int sqlite3VdbeMemExpandBlob(Mem *pMem){
 257   int nByte;
 258   assert( pMem->flags & MEM_Zero );
 259   assert( pMem->flags&MEM_Blob );
 260   assert( (pMem->flags&MEM_RowSet)==0 );
 261   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 262
 263   /* Set nByte to the number of bytes required to store the expanded blob. */
 264   nByte = pMem->n + pMem->u.nZero;
 265   if( nByte<=0 ){
 266     nByte = 1;
 267   }
 268   if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
 269     return SQLITE_NOMEM_BKPT;
 270   }
 271
 272   memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
 273   pMem->n += pMem->u.nZero;
 274   pMem->flags &= ~(MEM_Zero|MEM_Term);
 275   return SQLITE_OK;
 276 }
 277 #endif
 278
 279 /*
 280 ** Make sure the given Mem is \u0000 terminated.
 281 */
 282 int sqlite3VdbeMemNulTerminate(Mem *pMem){
 283   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 284   testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
 285   testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
 286   if( (pMem->flags & (MEM_Term|MEM_Str))!=MEM_Str ){
 287     return SQLITE_OK;   /* Nothing to do */
 288   }else{
 289     return vdbeMemAddTerminator(pMem);
 290   }
 291 }
 292
 293 /*
 294 ** Add MEM_Str to the set of representations for the given Mem.  Numbers
 295 ** are converted using sqlite3_snprintf().  Converting a BLOB to a string
 296 ** is a no-op.
 297 **
 298 ** Existing representations MEM_Int and MEM_Real are invalidated if
 299 ** bForce is true but are retained if bForce is false.
 300 **
 301 ** A MEM_Null value will never be passed to this function. This function is
 302 ** used for converting values to text for returning to the user (i.e. via
 303 ** sqlite3_value_text()), or for ensuring that values to be used as btree
 304 ** keys are strings. In the former case a NULL pointer is returned the
 305 ** user and the latter is an internal programming error.
 306 */
 307 int sqlite3VdbeMemStringify(Mem *pMem, u8 enc, u8 bForce){
 308   int fg = pMem->flags;
 309   const int nByte = 32;
 310
 311   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 312   assert( !(fg&MEM_Zero) );
 313   assert( !(fg&(MEM_Str|MEM_Blob)) );
 314   assert( fg&(MEM_Int|MEM_Real) );
 315   assert( (pMem->flags&MEM_RowSet)==0 );
 316   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 317
 318
 319   if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
 320     pMem->enc = 0;
 321     return SQLITE_NOMEM_BKPT;
 322   }
 323
 324   /* For a Real or Integer, use sqlite3_snprintf() to produce the UTF-8
 325   ** string representation of the value. Then, if the required encoding
 326   ** is UTF-16le or UTF-16be do a translation.
 327   **
 328   ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.
 329   */
 330   if( fg & MEM_Int ){
 331     sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);
 332   }else{
 333     assert( fg & MEM_Real );
 334     sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->u.r);
 335   }
 336   pMem->n = sqlite3Strlen30(pMem->z);
 337   pMem->enc = SQLITE_UTF8;
 338   pMem->flags |= MEM_Str|MEM_Term;
 339   if( bForce ) pMem->flags &= ~(MEM_Int|MEM_Real);
 340   sqlite3VdbeChangeEncoding(pMem, enc);
 341   return SQLITE_OK;
 342 }
 343
 344 /*
 345 ** Memory cell pMem contains the context of an aggregate function.
 346 ** This routine calls the finalize method for that function.  The
 347 ** result of the aggregate is stored back into pMem.
 348 **
 349 ** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
 350 ** otherwise.
 351 */
 352 int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
 353   int rc = SQLITE_OK;
 354   if( ALWAYS(pFunc && pFunc->xFinalize) ){
 355     sqlite3_context ctx;
 356     Mem t;
 357     assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
 358     assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 359     memset(&ctx, 0, sizeof(ctx));
 360     memset(&t, 0, sizeof(t));
 361     t.flags = MEM_Null;
 362     t.db = pMem->db;
 363     ctx.pOut = &t;
 364     ctx.pMem = pMem;
 365     ctx.pFunc = pFunc;
 366     pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
 367     assert( (pMem->flags & MEM_Dyn)==0 );
 368     if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 369     memcpy(pMem, &t, sizeof(t));
 370     rc = ctx.isError;
 371   }
 372   return rc;
 373 }
 374
 375 /*
 376 ** If the memory cell contains a value that must be freed by
 377 ** invoking the external callback in Mem.xDel, then this routine
 378 ** will free that value.  It also sets Mem.flags to MEM_Null.
 379 **
 380 ** This is a helper routine for sqlite3VdbeMemSetNull() and
 381 ** for sqlite3VdbeMemRelease().  Use those other routines as the
 382 ** entry point for releasing Mem resources.
 383 */
 384 static SQLITE_NOINLINE void vdbeMemClearExternAndSetNull(Mem *p){
 385   assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
 386   assert( VdbeMemDynamic(p) );
 387   if( p->flags&MEM_Agg ){
 388     sqlite3VdbeMemFinalize(p, p->u.pDef);
 389     assert( (p->flags & MEM_Agg)==0 );
 390     testcase( p->flags & MEM_Dyn );
 391   }
 392   if( p->flags&MEM_Dyn ){
 393     assert( (p->flags&MEM_RowSet)==0 );
 394     assert( p->xDel!=SQLITE_DYNAMIC && p->xDel!=0 );
 395     p->xDel((void *)p->z);
 396   }else if( p->flags&MEM_RowSet ){
 397     sqlite3RowSetClear(p->u.pRowSet);
 398   }else if( p->flags&MEM_Frame ){
 399     VdbeFrame *pFrame = p->u.pFrame;
 400     pFrame->pParent = pFrame->v->pDelFrame;
 401     pFrame->v->pDelFrame = pFrame;
 402   }
 403   p->flags = MEM_Null;
 404 }
 405
 406 /*
 407 ** Release memory held by the Mem p, both external memory cleared
 408 ** by p->xDel and memory in p->zMalloc.
 409 **
 410 ** This is a helper routine invoked by sqlite3VdbeMemRelease() in
 411 ** the unusual case where there really is memory in p that needs
 412 ** to be freed.
 413 */
 414 static SQLITE_NOINLINE void vdbeMemClear(Mem *p){
 415   if( VdbeMemDynamic(p) ){
 416     vdbeMemClearExternAndSetNull(p);
 417   }
 418   if( p->szMalloc ){
 419     sqlite3DbFreeNN(p->db, p->zMalloc);
 420     p->szMalloc = 0;
 421   }
 422   p->z = 0;
 423 }
 424
 425 /*
 426 ** Release any memory resources held by the Mem.  Both the memory that is
 427 ** free by Mem.xDel and the Mem.zMalloc allocation are freed.
 428 **
 429 ** Use this routine prior to clean up prior to abandoning a Mem, or to
 430 ** reset a Mem back to its minimum memory utilization.
 431 **
 432 ** Use sqlite3VdbeMemSetNull() to release just the Mem.xDel space
 433 ** prior to inserting new content into the Mem.
 434 */
 435 void sqlite3VdbeMemRelease(Mem *p){
 436   assert( sqlite3VdbeCheckMemInvariants(p) );
 437   if( VdbeMemDynamic(p) || p->szMalloc ){
 438     vdbeMemClear(p);
 439   }
 440 }
 441
 442 /*
 443 ** Convert a 64-bit IEEE double into a 64-bit signed integer.
 444 ** If the double is out of range of a 64-bit signed integer then
 445 ** return the closest available 64-bit signed integer.
 446 */
 447 static SQLITE_NOINLINE i64 doubleToInt64(double r){
 448 #ifdef SQLITE_OMIT_FLOATING_POINT
 449   /* When floating-point is omitted, double and int64 are the same thing */
 450   return r;
 451 #else
 452   /*
 453   ** Many compilers we encounter do not define constants for the
 454   ** minimum and maximum 64-bit integers, or they define them
 455   ** inconsistently.  And many do not understand the "LL" notation.
 456   ** So we define our own static constants here using nothing
 457   ** larger than a 32-bit integer constant.
 458   */
 459   static const i64 maxInt = LARGEST_INT64;
 460   static const i64 minInt = SMALLEST_INT64;
 461
 462   if( r<=(double)minInt ){
 463     return minInt;
 464   }else if( r>=(double)maxInt ){
 465     return maxInt;
 466   }else{
 467     return (i64)r;
 468   }
 469 #endif
 470 }
 471
 472 /*
 473 ** Return some kind of integer value which is the best we can do
 474 ** at representing the value that *pMem describes as an integer.
 475 ** If pMem is an integer, then the value is exact.  If pMem is
 476 ** a floating-point then the value returned is the integer part.
 477 ** If pMem is a string or blob, then we make an attempt to convert
 478 ** it into an integer and return that.  If pMem represents an
 479 ** an SQL-NULL value, return 0.
 480 **
 481 ** If pMem represents a string value, its encoding might be changed.
 482 */
 483 static SQLITE_NOINLINE i64 memIntValue(Mem *pMem){
 484   i64 value = 0;
 485   sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
 486   return value;
 487 }
 488 i64 sqlite3VdbeIntValue(Mem *pMem){
 489   int flags;
 490   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 491   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 492   flags = pMem->flags;
 493   if( flags & MEM_Int ){
 494     return pMem->u.i;
 495   }else if( flags & MEM_Real ){
 496     return doubleToInt64(pMem->u.r);
 497   }else if( flags & (MEM_Str|MEM_Blob) ){
 498     assert( pMem->z || pMem->n==0 );
 499     return memIntValue(pMem);
 500   }else{
 501     return 0;
 502   }
 503 }
 504
 505 /*
 506 ** Return the best representation of pMem that we can get into a
 507 ** double.  If pMem is already a double or an integer, return its
 508 ** value.  If it is a string or blob, try to convert it to a double.
 509 ** If it is a NULL, return 0.0.
 510 */
 511 static SQLITE_NOINLINE double memRealValue(Mem *pMem){
 512   /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 513   double val = (double)0;
 514   sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
 515   return val;
 516 }
 517 double sqlite3VdbeRealValue(Mem *pMem){
 518   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 519   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 520   if( pMem->flags & MEM_Real ){
 521     return pMem->u.r;
 522   }else if( pMem->flags & MEM_Int ){
 523     return (double)pMem->u.i;
 524   }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
 525     return memRealValue(pMem);
 526   }else{
 527     /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 528     return (double)0;
 529   }
 530 }
 531
 532 /*
 533 ** The MEM structure is already a MEM_Real.  Try to also make it a
 534 ** MEM_Int if we can.
 535 */
 536 void sqlite3VdbeIntegerAffinity(Mem *pMem){
 537   i64 ix;
 538   assert( pMem->flags & MEM_Real );
 539   assert( (pMem->flags & MEM_RowSet)==0 );
 540   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 541   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 542
 543   ix = doubleToInt64(pMem->u.r);
 544
 545   /* Only mark the value as an integer if
 546   **
 547   **    (1) the round-trip conversion real->int->real is a no-op, and
 548   **    (2) The integer is neither the largest nor the smallest
 549   **        possible integer (ticket #3922)
 550   **
 551   ** The second and third terms in the following conditional enforces
 552   ** the second condition under the assumption that addition overflow causes
 553   ** values to wrap around.
 554   */
 555   if( pMem->u.r==ix && ix>SMALLEST_INT64 && ix<LARGEST_INT64 ){
 556     pMem->u.i = ix;
 557     MemSetTypeFlag(pMem, MEM_Int);
 558   }
 559 }
 560
 561 /*
 562 ** Convert pMem to type integer.  Invalidate any prior representations.
 563 */
 564 int sqlite3VdbeMemIntegerify(Mem *pMem){
 565   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 566   assert( (pMem->flags & MEM_RowSet)==0 );
 567   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 568
 569   pMem->u.i = sqlite3VdbeIntValue(pMem);
 570   MemSetTypeFlag(pMem, MEM_Int);
 571   return SQLITE_OK;
 572 }
 573
 574 /*
 575 ** Convert pMem so that it is of type MEM_Real.
 576 ** Invalidate any prior representations.
 577 */
 578 int sqlite3VdbeMemRealify(Mem *pMem){
 579   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 580   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 581
 582   pMem->u.r = sqlite3VdbeRealValue(pMem);
 583   MemSetTypeFlag(pMem, MEM_Real);
 584   return SQLITE_OK;
 585 }
 586
 587 /*
 588 ** Convert pMem so that it has types MEM_Real or MEM_Int or both.
 589 ** Invalidate any prior representations.
 590 **
 591 ** Every effort is made to force the conversion, even if the input
 592 ** is a string that does not look completely like a number.  Convert
 593 ** as much of the string as we can and ignore the rest.
 594 */
 595 int sqlite3VdbeMemNumerify(Mem *pMem){
 596   if( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 ){
 597     int rc;
 598     assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
 599     assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 600     rc = sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc);
 601     if( rc==0 ){
 602       MemSetTypeFlag(pMem, MEM_Int);
 603     }else{
 604       i64 i = pMem->u.i;
 605       sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
 606       if( rc==1 && pMem->u.r==(double)i ){
 607         pMem->u.i = i;
 608         MemSetTypeFlag(pMem, MEM_Int);
 609       }else{
 610         MemSetTypeFlag(pMem, MEM_Real);
 611       }
 612     }
 613   }
 614   assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))!=0 );
 615   pMem->flags &= ~(MEM_Str|MEM_Blob|MEM_Zero);
 616   return SQLITE_OK;
 617 }
 618
 619 /*
 620 ** Cast the datatype of the value in pMem according to the affinity
 621 ** "aff".  Casting is different from applying affinity in that a cast
 622 ** is forced.  In other words, the value is converted into the desired
 623 ** affinity even if that results in loss of data.  This routine is
 624 ** used (for example) to implement the SQL "cast()" operator.
 625 */
 626 void sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
 627   if( pMem->flags & MEM_Null ) return;
 628   switch( aff ){
 629     case SQLITE_AFF_BLOB: {   /* Really a cast to BLOB */
 630       if( (pMem->flags & MEM_Blob)==0 ){
 631         sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 632         assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 633         if( pMem->flags & MEM_Str ) MemSetTypeFlag(pMem, MEM_Blob);
 634       }else{
 635         pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
 636       }
 637       break;
 638     }
 639     case SQLITE_AFF_NUMERIC: {
 640       sqlite3VdbeMemNumerify(pMem);
 641       break;
 642     }
 643     case SQLITE_AFF_INTEGER: {
 644       sqlite3VdbeMemIntegerify(pMem);
 645       break;
 646     }
 647     case SQLITE_AFF_REAL: {
 648       sqlite3VdbeMemRealify(pMem);
 649       break;
 650     }
 651     default: {
 652       assert( aff==SQLITE_AFF_TEXT );
 653       assert( MEM_Str==(MEM_Blob>>3) );
 654       pMem->flags |= (pMem->flags&MEM_Blob)>>3;
 655       sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 656       assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 657       pMem->flags &= ~(MEM_Int|MEM_Real|MEM_Blob|MEM_Zero);
 658       break;
 659     }
 660   }
 661 }
 662
 663 /*
 664 ** Initialize bulk memory to be a consistent Mem object.
 665 **
 666 ** The minimum amount of initialization feasible is performed.
 667 */
 668 void sqlite3VdbeMemInit(Mem *pMem, sqlite3 *db, u16 flags){
 669   assert( (flags & ~MEM_TypeMask)==0 );
 670   pMem->flags = flags;
 671   pMem->db = db;
 672   pMem->szMalloc = 0;
 673 }
 674
 675
 676 /*
 677 ** Delete any previous value and set the value stored in *pMem to NULL.
 678 **
 679 ** This routine calls the Mem.xDel destructor to dispose of values that
 680 ** require the destructor.  But it preserves the Mem.zMalloc memory allocation.
 681 ** To free all resources, use sqlite3VdbeMemRelease(), which both calls this
 682 ** routine to invoke the destructor and deallocates Mem.zMalloc.
 683 **
 684 ** Use this routine to reset the Mem prior to insert a new value.
 685 **
 686 ** Use sqlite3VdbeMemRelease() to complete erase the Mem prior to abandoning it.
 687 */
 688 void sqlite3VdbeMemSetNull(Mem *pMem){
 689   if( VdbeMemDynamic(pMem) ){
 690     vdbeMemClearExternAndSetNull(pMem);
 691   }else{
 692     pMem->flags = MEM_Null;
 693   }
 694 }
 695 void sqlite3ValueSetNull(sqlite3_value *p){
 696   sqlite3VdbeMemSetNull((Mem*)p);
 697 }
 698
 699 /*
 700 ** Delete any previous value and set the value to be a BLOB of length
 701 ** n containing all zeros.
 702 */
 703 void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
 704   sqlite3VdbeMemRelease(pMem);
 705   pMem->flags = MEM_Blob|MEM_Zero;
 706   pMem->n = 0;
 707   if( n<0 ) n = 0;
 708   pMem->u.nZero = n;
 709   pMem->enc = SQLITE_UTF8;
 710   pMem->z = 0;
 711 }
 712
 713 /*
 714 ** The pMem is known to contain content that needs to be destroyed prior
 715 ** to a value change.  So invoke the destructor, then set the value to
 716 ** a 64-bit integer.
 717 */
 718 static SQLITE_NOINLINE void vdbeReleaseAndSetInt64(Mem *pMem, i64 val){
 719   sqlite3VdbeMemSetNull(pMem);
 720   pMem->u.i = val;
 721   pMem->flags = MEM_Int;
 722 }
 723
 724 /*
 725 ** Delete any previous value and set the value stored in *pMem to val,
 726 ** manifest type INTEGER.
 727 */
 728 void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
 729   if( VdbeMemDynamic(pMem) ){
 730     vdbeReleaseAndSetInt64(pMem, val);
 731   }else{
 732     pMem->u.i = val;
 733     pMem->flags = MEM_Int;
 734   }
 735 }
 736
 737 /* A no-op destructor */
 738 static void sqlite3NoopDestructor(void *p){ UNUSED_PARAMETER(p); }
 739
 740 /*
 741 ** Set the value stored in *pMem should already be a NULL.
 742 ** Also store a pointer to go with it.
 743 */
 744 void sqlite3VdbeMemSetPointer(
 745   Mem *pMem,
 746   void *pPtr,
 747   const char *zPType,
 748   void (*xDestructor)(void*)
 749 ){
 750   assert( pMem->flags==MEM_Null );
 751   pMem->u.zPType = zPType ? zPType : "";
 752   pMem->z = pPtr;
 753   pMem->flags = MEM_Null|MEM_Dyn|MEM_Subtype|MEM_Term;
 754   pMem->eSubtype = 'p';
 755   pMem->xDel = xDestructor ? xDestructor : sqlite3NoopDestructor;
 756 }
 757
 758 #ifndef SQLITE_OMIT_FLOATING_POINT
 759 /*
 760 ** Delete any previous value and set the value stored in *pMem to val,
 761 ** manifest type REAL.
 762 */
 763 void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
 764   sqlite3VdbeMemSetNull(pMem);
 765   if( !sqlite3IsNaN(val) ){
 766     pMem->u.r = val;
 767     pMem->flags = MEM_Real;
 768   }
 769 }
 770 #endif
 771
 772 /*
 773 ** Delete any previous value and set the value of pMem to be an
 774 ** empty boolean index.
 775 */
 776 void sqlite3VdbeMemSetRowSet(Mem *pMem){
 777   sqlite3 *db = pMem->db;
 778   assert( db!=0 );
 779   assert( (pMem->flags & MEM_RowSet)==0 );
 780   sqlite3VdbeMemRelease(pMem);
 781   pMem->zMalloc = sqlite3DbMallocRawNN(db, 64);
 782   if( db->mallocFailed ){
 783     pMem->flags = MEM_Null;
 784     pMem->szMalloc = 0;
 785   }else{
 786     assert( pMem->zMalloc );
 787     pMem->szMalloc = sqlite3DbMallocSize(db, pMem->zMalloc);
 788     pMem->u.pRowSet = sqlite3RowSetInit(db, pMem->zMalloc, pMem->szMalloc);
 789     assert( pMem->u.pRowSet!=0 );
 790     pMem->flags = MEM_RowSet;
 791   }
 792 }
 793
 794 /*
 795 ** Return true if the Mem object contains a TEXT or BLOB that is
 796 ** too large - whose size exceeds SQLITE_MAX_LENGTH.
 797 */
 798 int sqlite3VdbeMemTooBig(Mem *p){
 799   assert( p->db!=0 );
 800   if( p->flags & (MEM_Str|MEM_Blob) ){
 801     int n = p->n;
 802     if( p->flags & MEM_Zero ){
 803       n += p->u.nZero;
 804     }
 805     return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
 806   }
 807   return 0;
 808 }
 809
 810 #ifdef SQLITE_DEBUG
 811 /*
 812 ** This routine prepares a memory cell for modification by breaking
 813 ** its link to a shallow copy and by marking any current shallow
 814 ** copies of this cell as invalid.
 815 **
 816 ** This is used for testing and debugging only - to make sure shallow
 817 ** copies are not misused.
 818 */
 819 void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
 820   int i;
 821   Mem *pX;
 822   for(i=0, pX=pVdbe->aMem; i<pVdbe->nMem; i++, pX++){
 823     if( pX->pScopyFrom==pMem ){
 824       pX->flags |= MEM_Undefined;
 825       pX->pScopyFrom = 0;
 826     }
 827   }
 828   pMem->pScopyFrom = 0;
 829 }
 830 #endif /* SQLITE_DEBUG */
 831
 832
 833 /*
 834 ** Make an shallow copy of pFrom into pTo.  Prior contents of
 835 ** pTo are freed.  The pFrom->z field is not duplicated.  If
 836 ** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
 837 ** and flags gets srcType (either MEM_Ephem or MEM_Static).
 838 */
 839 static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){
 840   vdbeMemClearExternAndSetNull(pTo);
 841   assert( !VdbeMemDynamic(pTo) );
 842   sqlite3VdbeMemShallowCopy(pTo, pFrom, eType);
 843 }
 844 void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
 845   assert( (pFrom->flags & MEM_RowSet)==0 );
 846   assert( pTo->db==pFrom->db );
 847   if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; }
 848   memcpy(pTo, pFrom, MEMCELLSIZE);
 849   if( (pFrom->flags&MEM_Static)==0 ){
 850     pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
 851     assert( srcType==MEM_Ephem || srcType==MEM_Static );
 852     pTo->flags |= srcType;
 853   }
 854 }
 855
 856 /*
 857 ** Make a full copy of pFrom into pTo.  Prior contents of pTo are
 858 ** freed before the copy is made.
 859 */
 860 int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
 861   int rc = SQLITE_OK;
 862
 863   assert( (pFrom->flags & MEM_RowSet)==0 );
 864   if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
 865   memcpy(pTo, pFrom, MEMCELLSIZE);
 866   pTo->flags &= ~MEM_Dyn;
 867   if( pTo->flags&(MEM_Str|MEM_Blob) ){
 868     if( 0==(pFrom->flags&MEM_Static) ){
 869       pTo->flags |= MEM_Ephem;
 870       rc = sqlite3VdbeMemMakeWriteable(pTo);
 871     }
 872   }
 873
 874   return rc;
 875 }
 876
 877 /*
 878 ** Transfer the contents of pFrom to pTo. Any existing value in pTo is
 879 ** freed. If pFrom contains ephemeral data, a copy is made.
 880 **
 881 ** pFrom contains an SQL NULL when this routine returns.
 882 */
 883 void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
 884   assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
 885   assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
 886   assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
 887
 888   sqlite3VdbeMemRelease(pTo);
 889   memcpy(pTo, pFrom, sizeof(Mem));
 890   pFrom->flags = MEM_Null;
 891   pFrom->szMalloc = 0;
 892 }
 893
 894 /*
 895 ** Change the value of a Mem to be a string or a BLOB.
 896 **
 897 ** The memory management strategy depends on the value of the xDel
 898 ** parameter. If the value passed is SQLITE_TRANSIENT, then the
 899 ** string is copied into a (possibly existing) buffer managed by the
 900 ** Mem structure. Otherwise, any existing buffer is freed and the
 901 ** pointer copied.
 902 **
 903 ** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
 904 ** size limit) then no memory allocation occurs.  If the string can be
 905 ** stored without allocating memory, then it is.  If a memory allocation
 906 ** is required to store the string, then value of pMem is unchanged.  In
 907 ** either case, SQLITE_TOOBIG is returned.
 908 */
 909 int sqlite3VdbeMemSetStr(
 910   Mem *pMem,          /* Memory cell to set to string value */
 911   const char *z,      /* String pointer */
 912   int n,              /* Bytes in string, or negative */
 913   u8 enc,             /* Encoding of z.  0 for BLOBs */
 914   void (*xDel)(void*) /* Destructor function */
 915 ){
 916   int nByte = n;      /* New value for pMem->n */
 917   int iLimit;         /* Maximum allowed string or blob size */
 918   u16 flags = 0;      /* New value for pMem->flags */
 919
 920   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 921   assert( (pMem->flags & MEM_RowSet)==0 );
 922
 923   /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
 924   if( !z ){
 925     sqlite3VdbeMemSetNull(pMem);
 926     return SQLITE_OK;
 927   }
 928
 929   if( pMem->db ){
 930     iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
 931   }else{
 932     iLimit = SQLITE_MAX_LENGTH;
 933   }
 934   flags = (enc==0?MEM_Blob:MEM_Str);
 935   if( nByte<0 ){
 936     assert( enc!=0 );
 937     if( enc==SQLITE_UTF8 ){
 938       nByte = 0x7fffffff & (int)strlen(z);
 939       if( nByte>iLimit ) nByte = iLimit+1;
 940     }else{
 941       for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
 942     }
 943     flags |= MEM_Term;
 944   }
 945
 946   /* The following block sets the new values of Mem.z and Mem.xDel. It
 947   ** also sets a flag in local variable "flags" to indicate the memory
 948   ** management (one of MEM_Dyn or MEM_Static).
 949   */
 950   if( xDel==SQLITE_TRANSIENT ){
 951     int nAlloc = nByte;
 952     if( flags&MEM_Term ){
 953       nAlloc += (enc==SQLITE_UTF8?1:2);
 954     }
 955     if( nByte>iLimit ){
 956       return SQLITE_TOOBIG;
 957     }
 958     testcase( nAlloc==0 );
 959     testcase( nAlloc==31 );
 960     testcase( nAlloc==32 );
 961     if( sqlite3VdbeMemClearAndResize(pMem, MAX(nAlloc,32)) ){
 962       return SQLITE_NOMEM_BKPT;
 963     }
 964     memcpy(pMem->z, z, nAlloc);
 965   }else if( xDel==SQLITE_DYNAMIC ){
 966     sqlite3VdbeMemRelease(pMem);
 967     pMem->zMalloc = pMem->z = (char *)z;
 968     pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
 969   }else{
 970     sqlite3VdbeMemRelease(pMem);
 971     pMem->z = (char *)z;
 972     pMem->xDel = xDel;
 973     flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
 974   }
 975
 976   pMem->n = nByte;
 977   pMem->flags = flags;
 978   pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
 979
 980 #ifndef SQLITE_OMIT_UTF16
 981   if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
 982     return SQLITE_NOMEM_BKPT;
 983   }
 984 #endif
 985
 986   if( nByte>iLimit ){
 987     return SQLITE_TOOBIG;
 988   }
 989
 990   return SQLITE_OK;
 991 }
 992
 993 /*
 994 ** Move data out of a btree key or data field and into a Mem structure.
 995 ** The data is payload from the entry that pCur is currently pointing
 996 ** to.  offset and amt determine what portion of the data or key to retrieve.
 997 ** The result is written into the pMem element.
 998 **
 999 ** The pMem object must have been initialized.  This routine will use
1000 ** pMem->zMalloc to hold the content from the btree, if possible.  New
1001 ** pMem->zMalloc space will be allocated if necessary.  The calling routine
1002 ** is responsible for making sure that the pMem object is eventually
1003 ** destroyed.
1004 **
1005 ** If this routine fails for any reason (malloc returns NULL or unable
1006 ** to read from the disk) then the pMem is left in an inconsistent state.
1007 */
1008 static SQLITE_NOINLINE int vdbeMemFromBtreeResize(
1009   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1010   u32 offset,       /* Offset from the start of data to return bytes from. */
1011   u32 amt,          /* Number of bytes to return. */
1012   Mem *pMem         /* OUT: Return data in this Mem structure. */
1013 ){
1014   int rc;
1015   pMem->flags = MEM_Null;
1016   if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+1)) ){
1017     rc = sqlite3BtreePayload(pCur, offset, amt, pMem->z);
1018     if( rc==SQLITE_OK ){
1019       pMem->z[amt] = 0;   /* Overrun area used when reading malformed records */
1020       pMem->flags = MEM_Blob;
1021       pMem->n = (int)amt;
1022     }else{
1023       sqlite3VdbeMemRelease(pMem);
1024     }
1025   }
1026   return rc;
1027 }
1028 int sqlite3VdbeMemFromBtree(
1029   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1030   u32 offset,       /* Offset from the start of data to return bytes from. */
1031   u32 amt,          /* Number of bytes to return. */
1032   Mem *pMem         /* OUT: Return data in this Mem structure. */
1033 ){
1034   char *zData;        /* Data from the btree layer */
1035   u32 available = 0;  /* Number of bytes available on the local btree page */
1036   int rc = SQLITE_OK; /* Return code */
1037
1038   assert( sqlite3BtreeCursorIsValid(pCur) );
1039   assert( !VdbeMemDynamic(pMem) );
1040
1041   /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert()
1042   ** that both the BtShared and database handle mutexes are held. */
1043   assert( (pMem->flags & MEM_RowSet)==0 );
1044   zData = (char *)sqlite3BtreePayloadFetch(pCur, &available);
1045   assert( zData!=0 );
1046
1047   if( offset+amt<=available ){
1048     pMem->z = &zData[offset];
1049     pMem->flags = MEM_Blob|MEM_Ephem;
1050     pMem->n = (int)amt;
1051   }else{
1052     rc = vdbeMemFromBtreeResize(pCur, offset, amt, pMem);
1053   }
1054
1055   return rc;
1056 }
1057
1058 /*
1059 ** The pVal argument is known to be a value other than NULL.
1060 ** Convert it into a string with encoding enc and return a pointer
1061 ** to a zero-terminated version of that string.
1062 */
1063 static SQLITE_NOINLINE const void *valueToText(sqlite3_value* pVal, u8 enc){
1064   assert( pVal!=0 );
1065   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1066   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1067   assert( (pVal->flags & MEM_RowSet)==0 );
1068   assert( (pVal->flags & (MEM_Null))==0 );
1069   if( pVal->flags & (MEM_Blob|MEM_Str) ){
1070     if( ExpandBlob(pVal) ) return 0;
1071     pVal->flags |= MEM_Str;
1072     if( pVal->enc != (enc & ~SQLITE_UTF16_ALIGNED) ){
1073       sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
1074     }
1075     if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
1076       assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
1077       if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
1078         return 0;
1079       }
1080     }
1081     sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-31275-44060 */
1082   }else{
1083     sqlite3VdbeMemStringify(pVal, enc, 0);
1084     assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
1085   }
1086   assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
1087               || pVal->db->mallocFailed );
1088   if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
1089     return pVal->z;
1090   }else{
1091     return 0;
1092   }
1093 }
1094
1095 /* This function is only available internally, it is not part of the
1096 ** external API. It works in a similar way to sqlite3_value_text(),
1097 ** except the data returned is in the encoding specified by the second
1098 ** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
1099 ** SQLITE_UTF8.
1100 **
1101 ** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
1102 ** If that is the case, then the result must be aligned on an even byte
1103 ** boundary.
1104 */
1105 const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
1106   if( !pVal ) return 0;
1107   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1108   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1109   assert( (pVal->flags & MEM_RowSet)==0 );
1110   if( (pVal->flags&(MEM_Str|MEM_Term))==(MEM_Str|MEM_Term) && pVal->enc==enc ){
1111     return pVal->z;
1112   }
1113   if( pVal->flags&MEM_Null ){
1114     return 0;
1115   }
1116   return valueToText(pVal, enc);
1117 }
1118
1119 /*
1120 ** Create a new sqlite3_value object.
1121 */
1122 sqlite3_value *sqlite3ValueNew(sqlite3 *db){
1123   Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
1124   if( p ){
1125     p->flags = MEM_Null;
1126     p->db = db;
1127   }
1128   return p;
1129 }
1130
1131 /*
1132 ** Context object passed by sqlite3Stat4ProbeSetValue() through to
1133 ** valueNew(). See comments above valueNew() for details.
1134 */
1135 struct ValueNewStat4Ctx {
1136   Parse *pParse;
1137   Index *pIdx;
1138   UnpackedRecord **ppRec;
1139   int iVal;
1140 };
1141
1142 /*
1143 ** Allocate and return a pointer to a new sqlite3_value object. If
1144 ** the second argument to this function is NULL, the object is allocated
1145 ** by calling sqlite3ValueNew().
1146 **
1147 ** Otherwise, if the second argument is non-zero, then this function is
1148 ** being called indirectly by sqlite3Stat4ProbeSetValue(). If it has not
1149 ** already been allocated, allocate the UnpackedRecord structure that
1150 ** that function will return to its caller here. Then return a pointer to
1151 ** an sqlite3_value within the UnpackedRecord.a[] array.
1152 */
1153 static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
1154 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1155   if( p ){
1156     UnpackedRecord *pRec = p->ppRec[0];
1157
1158     if( pRec==0 ){
1159       Index *pIdx = p->pIdx;      /* Index being probed */
1160       int nByte;                  /* Bytes of space to allocate */
1161       int i;                      /* Counter variable */
1162       int nCol = pIdx->nColumn;   /* Number of index columns including rowid */
1163
1164       nByte = sizeof(Mem) * nCol + ROUND8(sizeof(UnpackedRecord));
1165       pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
1166       if( pRec ){
1167         pRec->pKeyInfo = sqlite3KeyInfoOfIndex(p->pParse, pIdx);
1168         if( pRec->pKeyInfo ){
1169           assert( pRec->pKeyInfo->nAllField==nCol );
1170           assert( pRec->pKeyInfo->enc==ENC(db) );
1171           pRec->aMem = (Mem *)((u8*)pRec + ROUND8(sizeof(UnpackedRecord)));
1172           for(i=0; i<nCol; i++){
1173             pRec->aMem[i].flags = MEM_Null;
1174             pRec->aMem[i].db = db;
1175           }
1176         }else{
1177           sqlite3DbFreeNN(db, pRec);
1178           pRec = 0;
1179         }
1180       }
1181       if( pRec==0 ) return 0;
1182       p->ppRec[0] = pRec;
1183     }
1184
1185     pRec->nField = p->iVal+1;
1186     return &pRec->aMem[p->iVal];
1187   }
1188 #else
1189   UNUSED_PARAMETER(p);
1190 #endif /* defined(SQLITE_ENABLE_STAT3_OR_STAT4) */
1191   return sqlite3ValueNew(db);
1192 }
1193
1194 /*
1195 ** The expression object indicated by the second argument is guaranteed
1196 ** to be a scalar SQL function. If
1197 **
1198 **   * all function arguments are SQL literals,
1199 **   * one of the SQLITE_FUNC_CONSTANT or _SLOCHNG function flags is set, and
1200 **   * the SQLITE_FUNC_NEEDCOLL function flag is not set,
1201 **
1202 ** then this routine attempts to invoke the SQL function. Assuming no
1203 ** error occurs, output parameter (*ppVal) is set to point to a value
1204 ** object containing the result before returning SQLITE_OK.
1205 **
1206 ** Affinity aff is applied to the result of the function before returning.
1207 ** If the result is a text value, the sqlite3_value object uses encoding
1208 ** enc.
1209 **
1210 ** If the conditions above are not met, this function returns SQLITE_OK
1211 ** and sets (*ppVal) to NULL. Or, if an error occurs, (*ppVal) is set to
1212 ** NULL and an SQLite error code returned.
1213 */
1214 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1215 static int valueFromFunction(
1216   sqlite3 *db,                    /* The database connection */
1217   Expr *p,                        /* The expression to evaluate */
1218   u8 enc,                         /* Encoding to use */
1219   u8 aff,                         /* Affinity to use */
1220   sqlite3_value **ppVal,          /* Write the new value here */
1221   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1222 ){
1223   sqlite3_context ctx;            /* Context object for function invocation */
1224   sqlite3_value **apVal = 0;      /* Function arguments */
1225   int nVal = 0;                   /* Size of apVal[] array */
1226   FuncDef *pFunc = 0;             /* Function definition */
1227   sqlite3_value *pVal = 0;        /* New value */
1228   int rc = SQLITE_OK;             /* Return code */
1229   ExprList *pList = 0;            /* Function arguments */
1230   int i;                          /* Iterator variable */
1231
1232   assert( pCtx!=0 );
1233   assert( (p->flags & EP_TokenOnly)==0 );
1234   pList = p->x.pList;
1235   if( pList ) nVal = pList->nExpr;
1236   pFunc = sqlite3FindFunction(db, p->u.zToken, nVal, enc, 0);
1237   assert( pFunc );
1238   if( (pFunc->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0
1239    || (pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
1240   ){
1241     return SQLITE_OK;
1242   }
1243
1244   if( pList ){
1245     apVal = (sqlite3_value**)sqlite3DbMallocZero(db, sizeof(apVal[0]) * nVal);
1246     if( apVal==0 ){
1247       rc = SQLITE_NOMEM_BKPT;
1248       goto value_from_function_out;
1249     }
1250     for(i=0; i<nVal; i++){
1251       rc = sqlite3ValueFromExpr(db, pList->a[i].pExpr, enc, aff, &apVal[i]);
1252       if( apVal[i]==0 || rc!=SQLITE_OK ) goto value_from_function_out;
1253     }
1254   }
1255
1256   pVal = valueNew(db, pCtx);
1257   if( pVal==0 ){
1258     rc = SQLITE_NOMEM_BKPT;
1259     goto value_from_function_out;
1260   }
1261
1262   assert( pCtx->pParse->rc==SQLITE_OK );
1263   memset(&ctx, 0, sizeof(ctx));
1264   ctx.pOut = pVal;
1265   ctx.pFunc = pFunc;
1266   pFunc->xSFunc(&ctx, nVal, apVal);
1267   if( ctx.isError ){
1268     rc = ctx.isError;
1269     sqlite3ErrorMsg(pCtx->pParse, "%s", sqlite3_value_text(pVal));
1270   }else{
1271     sqlite3ValueApplyAffinity(pVal, aff, SQLITE_UTF8);
1272     assert( rc==SQLITE_OK );
1273     rc = sqlite3VdbeChangeEncoding(pVal, enc);
1274     if( rc==SQLITE_OK && sqlite3VdbeMemTooBig(pVal) ){
1275       rc = SQLITE_TOOBIG;
1276       pCtx->pParse->nErr++;
1277     }
1278   }
1279   pCtx->pParse->rc = rc;
1280
1281  value_from_function_out:
1282   if( rc!=SQLITE_OK ){
1283     pVal = 0;
1284   }
1285   if( apVal ){
1286     for(i=0; i<nVal; i++){
1287       sqlite3ValueFree(apVal[i]);
1288     }
1289     sqlite3DbFreeNN(db, apVal);
1290   }
1291
1292   *ppVal = pVal;
1293   return rc;
1294 }
1295 #else
1296 # define valueFromFunction(a,b,c,d,e,f) SQLITE_OK
1297 #endif /* defined(SQLITE_ENABLE_STAT3_OR_STAT4) */
1298
1299 /*
1300 ** Extract a value from the supplied expression in the manner described
1301 ** above sqlite3ValueFromExpr(). Allocate the sqlite3_value object
1302 ** using valueNew().
1303 **
1304 ** If pCtx is NULL and an error occurs after the sqlite3_value object
1305 ** has been allocated, it is freed before returning. Or, if pCtx is not
1306 ** NULL, it is assumed that the caller will free any allocated object
1307 ** in all cases.
1308 */
1309 static int valueFromExpr(
1310   sqlite3 *db,                    /* The database connection */
1311   Expr *pExpr,                    /* The expression to evaluate */
1312   u8 enc,                         /* Encoding to use */
1313   u8 affinity,                    /* Affinity to use */
1314   sqlite3_value **ppVal,          /* Write the new value here */
1315   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1316 ){
1317   int op;
1318   char *zVal = 0;
1319   sqlite3_value *pVal = 0;
1320   int negInt = 1;
1321   const char *zNeg = "";
1322   int rc = SQLITE_OK;
1323
1324   assert( pExpr!=0 );
1325   while( (op = pExpr->op)==TK_UPLUS || op==TK_SPAN ) pExpr = pExpr->pLeft;
1326   if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
1327
1328   /* Compressed expressions only appear when parsing the DEFAULT clause
1329   ** on a table column definition, and hence only when pCtx==0.  This
1330   ** check ensures that an EP_TokenOnly expression is never passed down
1331   ** into valueFromFunction(). */
1332   assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );
1333
1334   if( op==TK_CAST ){
1335     u8 aff = sqlite3AffinityType(pExpr->u.zToken,0);
1336     rc = valueFromExpr(db, pExpr->pLeft, enc, aff, ppVal, pCtx);
1337     testcase( rc!=SQLITE_OK );
1338     if( *ppVal ){
1339       sqlite3VdbeMemCast(*ppVal, aff, SQLITE_UTF8);
1340       sqlite3ValueApplyAffinity(*ppVal, affinity, SQLITE_UTF8);
1341     }
1342     return rc;
1343   }
1344
1345   /* Handle negative integers in a single step.  This is needed in the
1346   ** case when the value is -9223372036854775808.
1347   */
1348   if( op==TK_UMINUS
1349    && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
1350     pExpr = pExpr->pLeft;
1351     op = pExpr->op;
1352     negInt = -1;
1353     zNeg = "-";
1354   }
1355
1356   if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
1357     pVal = valueNew(db, pCtx);
1358     if( pVal==0 ) goto no_mem;
1359     if( ExprHasProperty(pExpr, EP_IntValue) ){
1360       sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
1361     }else{
1362       zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
1363       if( zVal==0 ) goto no_mem;
1364       sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
1365     }
1366     if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_BLOB ){
1367       sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
1368     }else{
1369       sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
1370     }
1371     if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
1372     if( enc!=SQLITE_UTF8 ){
1373       rc = sqlite3VdbeChangeEncoding(pVal, enc);
1374     }
1375   }else if( op==TK_UMINUS ) {
1376     /* This branch happens for multiple negative signs.  Ex: -(-5) */
1377     if( SQLITE_OK==valueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal,pCtx)
1378      && pVal!=0
1379     ){
1380       sqlite3VdbeMemNumerify(pVal);
1381       if( pVal->flags & MEM_Real ){
1382         pVal->u.r = -pVal->u.r;
1383       }else if( pVal->u.i==SMALLEST_INT64 ){
1384         pVal->u.r = -(double)SMALLEST_INT64;
1385         MemSetTypeFlag(pVal, MEM_Real);
1386       }else{
1387         pVal->u.i = -pVal->u.i;
1388       }
1389       sqlite3ValueApplyAffinity(pVal, affinity, enc);
1390     }
1391   }else if( op==TK_NULL ){
1392     pVal = valueNew(db, pCtx);
1393     if( pVal==0 ) goto no_mem;
1394     sqlite3VdbeMemNumerify(pVal);
1395   }
1396 #ifndef SQLITE_OMIT_BLOB_LITERAL
1397   else if( op==TK_BLOB ){
1398     int nVal;
1399     assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
1400     assert( pExpr->u.zToken[1]=='\'' );
1401     pVal = valueNew(db, pCtx);
1402     if( !pVal ) goto no_mem;
1403     zVal = &pExpr->u.zToken[2];
1404     nVal = sqlite3Strlen30(zVal)-1;
1405     assert( zVal[nVal]=='\'' );
1406     sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
1407                          0, SQLITE_DYNAMIC);
1408   }
1409 #endif
1410
1411 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1412   else if( op==TK_FUNCTION && pCtx!=0 ){
1413     rc = valueFromFunction(db, pExpr, enc, affinity, &pVal, pCtx);
1414   }
1415 #endif
1416
1417   *ppVal = pVal;
1418   return rc;
1419
1420 no_mem:
1421   sqlite3OomFault(db);
1422   sqlite3DbFree(db, zVal);
1423   assert( *ppVal==0 );
1424 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1425   if( pCtx==0 ) sqlite3ValueFree(pVal);
1426 #else
1427   assert( pCtx==0 ); sqlite3ValueFree(pVal);
1428 #endif
1429   return SQLITE_NOMEM_BKPT;
1430 }
1431
1432 /*
1433 ** Create a new sqlite3_value object, containing the value of pExpr.
1434 **
1435 ** This only works for very simple expressions that consist of one constant
1436 ** token (i.e. "5", "5.1", "'a string'"). If the expression can
1437 ** be converted directly into a value, then the value is allocated and
1438 ** a pointer written to *ppVal. The caller is responsible for deallocating
1439 ** the value by passing it to sqlite3ValueFree() later on. If the expression
1440 ** cannot be converted to a value, then *ppVal is set to NULL.
1441 */
1442 int sqlite3ValueFromExpr(
1443   sqlite3 *db,              /* The database connection */
1444   Expr *pExpr,              /* The expression to evaluate */
1445   u8 enc,                   /* Encoding to use */
1446   u8 affinity,              /* Affinity to use */
1447   sqlite3_value **ppVal     /* Write the new value here */
1448 ){
1449   return pExpr ? valueFromExpr(db, pExpr, enc, affinity, ppVal, 0) : 0;
1450 }
1451
1452 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1453 /*
1454 ** The implementation of the sqlite_record() function. This function accepts
1455 ** a single argument of any type. The return value is a formatted database
1456 ** record (a blob) containing the argument value.
1457 **
1458 ** This is used to convert the value stored in the 'sample' column of the
1459 ** sqlite_stat3 table to the record format SQLite uses internally.
1460 */
1461 static void recordFunc(
1462   sqlite3_context *context,
1463   int argc,
1464   sqlite3_value **argv
1465 ){
1466   const int file_format = 1;
1467   u32 iSerial;                    /* Serial type */
1468   int nSerial;                    /* Bytes of space for iSerial as varint */
1469   u32 nVal;                       /* Bytes of space required for argv[0] */
1470   int nRet;
1471   sqlite3 *db;
1472   u8 *aRet;
1473
1474   UNUSED_PARAMETER( argc );
1475   iSerial = sqlite3VdbeSerialType(argv[0], file_format, &nVal);
1476   nSerial = sqlite3VarintLen(iSerial);
1477   db = sqlite3_context_db_handle(context);
1478
1479   nRet = 1 + nSerial + nVal;
1480   aRet = sqlite3DbMallocRawNN(db, nRet);
1481   if( aRet==0 ){
1482     sqlite3_result_error_nomem(context);
1483   }else{
1484     aRet[0] = nSerial+1;
1485     putVarint32(&aRet[1], iSerial);
1486     sqlite3VdbeSerialPut(&aRet[1+nSerial], argv[0], iSerial);
1487     sqlite3_result_blob(context, aRet, nRet, SQLITE_TRANSIENT);
1488     sqlite3DbFreeNN(db, aRet);
1489   }
1490 }
1491
1492 /*
1493 ** Register built-in functions used to help read ANALYZE data.
1494 */
1495 void sqlite3AnalyzeFunctions(void){
1496   static FuncDef aAnalyzeTableFuncs[] = {
1497     FUNCTION(sqlite_record,   1, 0, 0, recordFunc),
1498   };
1499   sqlite3InsertBuiltinFuncs(aAnalyzeTableFuncs, ArraySize(aAnalyzeTableFuncs));
1500 }
1501
1502 /*
1503 ** Attempt to extract a value from pExpr and use it to construct *ppVal.
1504 **
1505 ** If pAlloc is not NULL, then an UnpackedRecord object is created for
1506 ** pAlloc if one does not exist and the new value is added to the
1507 ** UnpackedRecord object.
1508 **
1509 ** A value is extracted in the following cases:
1510 **
1511 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1512 **
1513 **  * The expression is a bound variable, and this is a reprepare, or
1514 **
1515 **  * The expression is a literal value.
1516 **
1517 ** On success, *ppVal is made to point to the extracted value.  The caller
1518 ** is responsible for ensuring that the value is eventually freed.
1519 */
1520 static int stat4ValueFromExpr(
1521   Parse *pParse,                  /* Parse context */
1522   Expr *pExpr,                    /* The expression to extract a value from */
1523   u8 affinity,                    /* Affinity to use */
1524   struct ValueNewStat4Ctx *pAlloc,/* How to allocate space.  Or NULL */
1525   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1526 ){
1527   int rc = SQLITE_OK;
1528   sqlite3_value *pVal = 0;
1529   sqlite3 *db = pParse->db;
1530
1531   /* Skip over any TK_COLLATE nodes */
1532   pExpr = sqlite3ExprSkipCollate(pExpr);
1533
1534   assert( pExpr==0 || pExpr->op!=TK_REGISTER || pExpr->op2!=TK_VARIABLE );
1535   if( !pExpr ){
1536     pVal = valueNew(db, pAlloc);
1537     if( pVal ){
1538       sqlite3VdbeMemSetNull((Mem*)pVal);
1539     }
1540   }else if( pExpr->op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
1541     Vdbe *v;
1542     int iBindVar = pExpr->iColumn;
1543     sqlite3VdbeSetVarmask(pParse->pVdbe, iBindVar);
1544     if( (v = pParse->pReprepare)!=0 ){
1545       pVal = valueNew(db, pAlloc);
1546       if( pVal ){
1547         rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iBindVar-1]);
1548         sqlite3ValueApplyAffinity(pVal, affinity, ENC(db));
1549         pVal->db = pParse->db;
1550       }
1551     }
1552   }else{
1553     rc = valueFromExpr(db, pExpr, ENC(db), affinity, &pVal, pAlloc);
1554   }
1555
1556   assert( pVal==0 || pVal->db==db );
1557   *ppVal = pVal;
1558   return rc;
1559 }
1560
1561 /*
1562 ** This function is used to allocate and populate UnpackedRecord
1563 ** structures intended to be compared against sample index keys stored
1564 ** in the sqlite_stat4 table.
1565 **
1566 ** A single call to this function populates zero or more fields of the
1567 ** record starting with field iVal (fields are numbered from left to
1568 ** right starting with 0). A single field is populated if:
1569 **
1570 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1571 **
1572 **  * The expression is a bound variable, and this is a reprepare, or
1573 **
1574 **  * The sqlite3ValueFromExpr() function is able to extract a value
1575 **    from the expression (i.e. the expression is a literal value).
1576 **
1577 ** Or, if pExpr is a TK_VECTOR, one field is populated for each of the
1578 ** vector components that match either of the two latter criteria listed
1579 ** above.
1580 **
1581 ** Before any value is appended to the record, the affinity of the
1582 ** corresponding column within index pIdx is applied to it. Before
1583 ** this function returns, output parameter *pnExtract is set to the
1584 ** number of values appended to the record.
1585 **
1586 ** When this function is called, *ppRec must either point to an object
1587 ** allocated by an earlier call to this function, or must be NULL. If it
1588 ** is NULL and a value can be successfully extracted, a new UnpackedRecord
1589 ** is allocated (and *ppRec set to point to it) before returning.
1590 **
1591 ** Unless an error is encountered, SQLITE_OK is returned. It is not an
1592 ** error if a value cannot be extracted from pExpr. If an error does
1593 ** occur, an SQLite error code is returned.
1594 */
1595 int sqlite3Stat4ProbeSetValue(
1596   Parse *pParse,                  /* Parse context */
1597   Index *pIdx,                    /* Index being probed */
1598   UnpackedRecord **ppRec,         /* IN/OUT: Probe record */
1599   Expr *pExpr,                    /* The expression to extract a value from */
1600   int nElem,                      /* Maximum number of values to append */
1601   int iVal,                       /* Array element to populate */
1602   int *pnExtract                  /* OUT: Values appended to the record */
1603 ){
1604   int rc = SQLITE_OK;
1605   int nExtract = 0;
1606
1607   if( pExpr==0 || pExpr->op!=TK_SELECT ){
1608     int i;
1609     struct ValueNewStat4Ctx alloc;
1610
1611     alloc.pParse = pParse;
1612     alloc.pIdx = pIdx;
1613     alloc.ppRec = ppRec;
1614
1615     for(i=0; i<nElem; i++){
1616       sqlite3_value *pVal = 0;
1617       Expr *pElem = (pExpr ? sqlite3VectorFieldSubexpr(pExpr, i) : 0);
1618       u8 aff = sqlite3IndexColumnAffinity(pParse->db, pIdx, iVal+i);
1619       alloc.iVal = iVal+i;
1620       rc = stat4ValueFromExpr(pParse, pElem, aff, &alloc, &pVal);
1621       if( !pVal ) break;
1622       nExtract++;
1623     }
1624   }
1625
1626   *pnExtract = nExtract;
1627   return rc;
1628 }
1629
1630 /*
1631 ** Attempt to extract a value from expression pExpr using the methods
1632 ** as described for sqlite3Stat4ProbeSetValue() above.
1633 **
1634 ** If successful, set *ppVal to point to a new value object and return
1635 ** SQLITE_OK. If no value can be extracted, but no other error occurs
1636 ** (e.g. OOM), return SQLITE_OK and set *ppVal to NULL. Or, if an error
1637 ** does occur, return an SQLite error code. The final value of *ppVal
1638 ** is undefined in this case.
1639 */
1640 int sqlite3Stat4ValueFromExpr(
1641   Parse *pParse,                  /* Parse context */
1642   Expr *pExpr,                    /* The expression to extract a value from */
1643   u8 affinity,                    /* Affinity to use */
1644   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1645 ){
1646   return stat4ValueFromExpr(pParse, pExpr, affinity, 0, ppVal);
1647 }
1648
1649 /*
1650 ** Extract the iCol-th column from the nRec-byte record in pRec.  Write
1651 ** the column value into *ppVal.  If *ppVal is initially NULL then a new
1652 ** sqlite3_value object is allocated.
1653 **
1654 ** If *ppVal is initially NULL then the caller is responsible for
1655 ** ensuring that the value written into *ppVal is eventually freed.
1656 */
1657 int sqlite3Stat4Column(
1658   sqlite3 *db,                    /* Database handle */
1659   const void *pRec,               /* Pointer to buffer containing record */
1660   int nRec,                       /* Size of buffer pRec in bytes */
1661   int iCol,                       /* Column to extract */
1662   sqlite3_value **ppVal           /* OUT: Extracted value */
1663 ){
1664   u32 t;                          /* a column type code */
1665   int nHdr;                       /* Size of the header in the record */
1666   int iHdr;                       /* Next unread header byte */
1667   int iField;                     /* Next unread data byte */
1668   int szField;                    /* Size of the current data field */
1669   int i;                          /* Column index */
1670   u8 *a = (u8*)pRec;              /* Typecast byte array */
1671   Mem *pMem = *ppVal;             /* Write result into this Mem object */
1672
1673   assert( iCol>0 );
1674   iHdr = getVarint32(a, nHdr);
1675   if( nHdr>nRec || iHdr>=nHdr ) return SQLITE_CORRUPT_BKPT;
1676   iField = nHdr;
1677   for(i=0; i<=iCol; i++){
1678     iHdr += getVarint32(&a[iHdr], t);
1679     testcase( iHdr==nHdr );
1680     testcase( iHdr==nHdr+1 );
1681     if( iHdr>nHdr ) return SQLITE_CORRUPT_BKPT;
1682     szField = sqlite3VdbeSerialTypeLen(t);
1683     iField += szField;
1684   }
1685   testcase( iField==nRec );
1686   testcase( iField==nRec+1 );
1687   if( iField>nRec ) return SQLITE_CORRUPT_BKPT;
1688   if( pMem==0 ){
1689     pMem = *ppVal = sqlite3ValueNew(db);
1690     if( pMem==0 ) return SQLITE_NOMEM_BKPT;
1691   }
1692   sqlite3VdbeSerialGet(&a[iField-szField], t, pMem);
1693   pMem->enc = ENC(db);
1694   return SQLITE_OK;
1695 }
1696
1697 /*
1698 ** Unless it is NULL, the argument must be an UnpackedRecord object returned
1699 ** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
1700 ** the object.
1701 */
1702 void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
1703   if( pRec ){
1704     int i;
1705     int nCol = pRec->pKeyInfo->nAllField;
1706     Mem *aMem = pRec->aMem;
1707     sqlite3 *db = aMem[0].db;
1708     for(i=0; i<nCol; i++){
1709       sqlite3VdbeMemRelease(&aMem[i]);
1710     }
1711     sqlite3KeyInfoUnref(pRec->pKeyInfo);
1712     sqlite3DbFreeNN(db, pRec);
1713   }
1714 }
1715 #endif /* ifdef SQLITE_ENABLE_STAT4 */
1716
1717 /*
1718 ** Change the string value of an sqlite3_value object
1719 */
1720 void sqlite3ValueSetStr(
1721   sqlite3_value *v,     /* Value to be set */
1722   int n,                /* Length of string z */
1723   const void *z,        /* Text of the new string */
1724   u8 enc,               /* Encoding to use */
1725   void (*xDel)(void*)   /* Destructor for the string */
1726 ){
1727   if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
1728 }
1729
1730 /*
1731 ** Free an sqlite3_value object
1732 */
1733 void sqlite3ValueFree(sqlite3_value *v){
1734   if( !v ) return;
1735   sqlite3VdbeMemRelease((Mem *)v);
1736   sqlite3DbFreeNN(((Mem*)v)->db, v);
1737 }
1738
1739 /*
1740 ** The sqlite3ValueBytes() routine returns the number of bytes in the
1741 ** sqlite3_value object assuming that it uses the encoding "enc".
1742 ** The valueBytes() routine is a helper function.
1743 */
1744 static SQLITE_NOINLINE int valueBytes(sqlite3_value *pVal, u8 enc){
1745   return valueToText(pVal, enc)!=0 ? pVal->n : 0;
1746 }
1747 int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
1748   Mem *p = (Mem*)pVal;
1749   assert( (p->flags & MEM_Null)==0 || (p->flags & (MEM_Str|MEM_Blob))==0 );
1750   if( (p->flags & MEM_Str)!=0 && pVal->enc==enc ){
1751     return p->n;
1752   }
1753   if( (p->flags & MEM_Blob)!=0 ){
1754     if( p->flags & MEM_Zero ){
1755       return p->n + p->u.nZero;
1756     }else{
1757       return p->n;
1758     }
1759   }
1760   if( p->flags & MEM_Null ) return 0;
1761   return valueBytes(pVal, enc);
1762 }