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 /* True if X is a power of two.  0 is considered a power of two here.
  22 ** In other words, return true if X has at most one bit set.
  23 */
  24 #define ISPOWEROF2(X)  (((X)&((X)-1))==0)
  25
  26 #ifdef SQLITE_DEBUG
  27 /*
  28 ** Check invariants on a Mem object.
  29 **
  30 ** This routine is intended for use inside of assert() statements, like
  31 ** this:    assert( sqlite3VdbeCheckMemInvariants(pMem) );
  32 */
  33 int sqlite3VdbeCheckMemInvariants(Mem *p){
  34   /* If MEM_Dyn is set then Mem.xDel!=0.
  35   ** Mem.xDel might not be initialized if MEM_Dyn is clear.
  36   */
  37   assert( (p->flags & MEM_Dyn)==0 || p->xDel!=0 );
  38
  39   /* MEM_Dyn may only be set if Mem.szMalloc==0.  In this way we
  40   ** ensure that if Mem.szMalloc>0 then it is safe to do
  41   ** Mem.z = Mem.zMalloc without having to check Mem.flags&MEM_Dyn.
  42   ** That saves a few cycles in inner loops. */
  43   assert( (p->flags & MEM_Dyn)==0 || p->szMalloc==0 );
  44
  45   /* Cannot have more than one of MEM_Int, MEM_Real, or MEM_IntReal */
  46   assert( ISPOWEROF2(p->flags & (MEM_Int|MEM_Real|MEM_IntReal)) );
  47
  48   if( p->flags & MEM_Null ){
  49     /* Cannot be both MEM_Null and some other type */
  50     assert( (p->flags & (MEM_Int|MEM_Real|MEM_Str|MEM_Blob|MEM_Agg))==0 );
  51
  52     /* If MEM_Null is set, then either the value is a pure NULL (the usual
  53     ** case) or it is a pointer set using sqlite3_bind_pointer() or
  54     ** sqlite3_result_pointer().  If a pointer, then MEM_Term must also be
  55     ** set.
  56     */
  57     if( (p->flags & (MEM_Term|MEM_Subtype))==(MEM_Term|MEM_Subtype) ){
  58       /* This is a pointer type.  There may be a flag to indicate what to
  59       ** do with the pointer. */
  60       assert( ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
  61               ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
  62               ((p->flags&MEM_Static)!=0 ? 1 : 0) <= 1 );
  63
  64       /* No other bits set */
  65       assert( (p->flags & ~(MEM_Null|MEM_Term|MEM_Subtype|MEM_FromBind
  66                            |MEM_Dyn|MEM_Ephem|MEM_Static))==0 );
  67     }else{
  68       /* A pure NULL might have other flags, such as MEM_Static, MEM_Dyn,
  69       ** MEM_Ephem, MEM_Cleared, or MEM_Subtype */
  70     }
  71   }else{
  72     /* The MEM_Cleared bit is only allowed on NULLs */
  73     assert( (p->flags & MEM_Cleared)==0 );
  74   }
  75
  76   /* The szMalloc field holds the correct memory allocation size */
  77   assert( p->szMalloc==0
  78        || (p->flags==MEM_Undefined
  79            && p->szMalloc<=sqlite3DbMallocSize(p->db,p->zMalloc))
  80        || p->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc));
  81
  82   /* If p holds a string or blob, the Mem.z must point to exactly
  83   ** one of the following:
  84   **
  85   **   (1) Memory in Mem.zMalloc and managed by the Mem object
  86   **   (2) Memory to be freed using Mem.xDel
  87   **   (3) An ephemeral string or blob
  88   **   (4) A static string or blob
  89   */
  90   if( (p->flags & (MEM_Str|MEM_Blob)) && p->n>0 ){
  91     assert(
  92       ((p->szMalloc>0 && p->z==p->zMalloc)? 1 : 0) +
  93       ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
  94       ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
  95       ((p->flags&MEM_Static)!=0 ? 1 : 0) == 1
  96     );
  97   }
  98   return 1;
  99 }
 100 #endif
 101
 102 /*
 103 ** Render a Mem object which is one of MEM_Int, MEM_Real, or MEM_IntReal
 104 ** into a buffer.
 105 */
 106 static void vdbeMemRenderNum(int sz, char *zBuf, Mem *p){
 107   StrAccum acc;
 108   assert( p->flags & (MEM_Int|MEM_Real|MEM_IntReal) );
 109   assert( sz>22 );
 110   if( p->flags & MEM_Int ){
 111 #if GCC_VERSION>=7000000
 112     /* Work-around for GCC bug
 113     ** https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96270 */
 114     i64 x;
 115     assert( (p->flags&MEM_Int)*2==sizeof(x) );
 116     memcpy(&x, (char*)&p->u, (p->flags&MEM_Int)*2);
 117     sqlite3Int64ToText(x, zBuf);
 118 #else
 119     sqlite3Int64ToText(p->u.i, zBuf);
 120 #endif
 121   }else{
 122     sqlite3StrAccumInit(&acc, 0, zBuf, sz, 0);
 123     sqlite3_str_appendf(&acc, "%!.15g",
 124          (p->flags & MEM_IntReal)!=0 ? (double)p->u.i : p->u.r);
 125     assert( acc.zText==zBuf && acc.mxAlloc<=0 );
 126     zBuf[acc.nChar] = 0; /* Fast version of sqlite3StrAccumFinish(&acc) */
 127   }
 128 }
 129
 130 #ifdef SQLITE_DEBUG
 131 /*
 132 ** Validity checks on pMem.  pMem holds a string.
 133 **
 134 ** (1) Check that string value of pMem agrees with its integer or real value.
 135 ** (2) Check that the string is correctly zero terminated
 136 **
 137 ** A single int or real value always converts to the same strings.  But
 138 ** many different strings can be converted into the same int or real.
 139 ** If a table contains a numeric value and an index is based on the
 140 ** corresponding string value, then it is important that the string be
 141 ** derived from the numeric value, not the other way around, to ensure
 142 ** that the index and table are consistent.  See ticket
 143 ** https://www.sqlite.org/src/info/343634942dd54ab (2018-01-31) for
 144 ** an example.
 145 **
 146 ** This routine looks at pMem to verify that if it has both a numeric
 147 ** representation and a string representation then the string rep has
 148 ** been derived from the numeric and not the other way around.  It returns
 149 ** true if everything is ok and false if there is a problem.
 150 **
 151 ** This routine is for use inside of assert() statements only.
 152 */
 153 int sqlite3VdbeMemValidStrRep(Mem *p){
 154   char zBuf[100];
 155   char *z;
 156   int i, j, incr;
 157   if( (p->flags & MEM_Str)==0 ) return 1;
 158   if( p->flags & MEM_Term ){
 159     /* Insure that the string is properly zero-terminated.  Pay particular
 160     ** attention to the case where p->n is odd */
 161     if( p->szMalloc>0 && p->z==p->zMalloc ){
 162       assert( p->enc==SQLITE_UTF8 || p->szMalloc >= ((p->n+1)&~1)+2 );
 163       assert( p->enc!=SQLITE_UTF8 || p->szMalloc >= p->n+1 );
 164     }
 165     assert( p->z[p->n]==0 );
 166     assert( p->enc==SQLITE_UTF8 || p->z[(p->n+1)&~1]==0 );
 167     assert( p->enc==SQLITE_UTF8 || p->z[((p->n+1)&~1)+1]==0 );
 168   }
 169   if( (p->flags & (MEM_Int|MEM_Real|MEM_IntReal))==0 ) return 1;
 170   vdbeMemRenderNum(sizeof(zBuf), zBuf, p);
 171   z = p->z;
 172   i = j = 0;
 173   incr = 1;
 174   if( p->enc!=SQLITE_UTF8 ){
 175     incr = 2;
 176     if( p->enc==SQLITE_UTF16BE ) z++;
 177   }
 178   while( zBuf[j] ){
 179     if( zBuf[j++]!=z[i] ) return 0;
 180     i += incr;
 181   }
 182   return 1;
 183 }
 184 #endif /* SQLITE_DEBUG */
 185
 186 /*
 187 ** If pMem is an object with a valid string representation, this routine
 188 ** ensures the internal encoding for the string representation is
 189 ** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
 190 **
 191 ** If pMem is not a string object, or the encoding of the string
 192 ** representation is already stored using the requested encoding, then this
 193 ** routine is a no-op.
 194 **
 195 ** SQLITE_OK is returned if the conversion is successful (or not required).
 196 ** SQLITE_NOMEM may be returned if a malloc() fails during conversion
 197 ** between formats.
 198 */
 199 int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
 200 #ifndef SQLITE_OMIT_UTF16
 201   int rc;
 202 #endif
 203   assert( pMem!=0 );
 204   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 205   assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
 206            || desiredEnc==SQLITE_UTF16BE );
 207   if( !(pMem->flags&MEM_Str) ){
 208     pMem->enc = desiredEnc;
 209     return SQLITE_OK;
 210   }
 211   if( pMem->enc==desiredEnc ){
 212     return SQLITE_OK;
 213   }
 214   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 215 #ifdef SQLITE_OMIT_UTF16
 216   return SQLITE_ERROR;
 217 #else
 218
 219   /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
 220   ** then the encoding of the value may not have changed.
 221   */
 222   rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
 223   assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
 224   assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
 225   assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
 226   return rc;
 227 #endif
 228 }
 229
 230 /*
 231 ** Make sure pMem->z points to a writable allocation of at least n bytes.
 232 **
 233 ** If the bPreserve argument is true, then copy of the content of
 234 ** pMem->z into the new allocation.  pMem must be either a string or
 235 ** blob if bPreserve is true.  If bPreserve is false, any prior content
 236 ** in pMem->z is discarded.
 237 */
 238 SQLITE_NOINLINE int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
 239   assert( sqlite3VdbeCheckMemInvariants(pMem) );
 240   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 241   testcase( pMem->db==0 );
 242
 243   /* If the bPreserve flag is set to true, then the memory cell must already
 244   ** contain a valid string or blob value.  */
 245   assert( bPreserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
 246   testcase( bPreserve && pMem->z==0 );
 247
 248   assert( pMem->szMalloc==0
 249        || (pMem->flags==MEM_Undefined
 250            && pMem->szMalloc<=sqlite3DbMallocSize(pMem->db,pMem->zMalloc))
 251        || pMem->szMalloc==sqlite3DbMallocSize(pMem->db,pMem->zMalloc));
 252   if( pMem->szMalloc>0 && bPreserve && pMem->z==pMem->zMalloc ){
 253     if( pMem->db ){
 254       pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
 255     }else{
 256       pMem->zMalloc = sqlite3Realloc(pMem->z, n);
 257       if( pMem->zMalloc==0 ) sqlite3_free(pMem->z);
 258       pMem->z = pMem->zMalloc;
 259     }
 260     bPreserve = 0;
 261   }else{
 262     if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 263     pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
 264   }
 265   if( pMem->zMalloc==0 ){
 266     sqlite3VdbeMemSetNull(pMem);
 267     pMem->z = 0;
 268     pMem->szMalloc = 0;
 269     return SQLITE_NOMEM_BKPT;
 270   }else{
 271     pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
 272   }
 273
 274   if( bPreserve && pMem->z ){
 275     assert( pMem->z!=pMem->zMalloc );
 276     memcpy(pMem->zMalloc, pMem->z, pMem->n);
 277   }
 278   if( (pMem->flags&MEM_Dyn)!=0 ){
 279     assert( pMem->xDel!=0 && pMem->xDel!=SQLITE_DYNAMIC );
 280     pMem->xDel((void *)(pMem->z));
 281   }
 282
 283   pMem->z = pMem->zMalloc;
 284   pMem->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Static);
 285   return SQLITE_OK;
 286 }
 287
 288 /*
 289 ** Change the pMem->zMalloc allocation to be at least szNew bytes.
 290 ** If pMem->zMalloc already meets or exceeds the requested size, this
 291 ** routine is a no-op.
 292 **
 293 ** Any prior string or blob content in the pMem object may be discarded.
 294 ** The pMem->xDel destructor is called, if it exists.  Though MEM_Str
 295 ** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, MEM_IntReal,
 296 ** and MEM_Null values are preserved.
 297 **
 298 ** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
 299 ** if unable to complete the resizing.
 300 */
 301 int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
 302   assert( CORRUPT_DB || szNew>0 );
 303   assert( (pMem->flags & MEM_Dyn)==0 || pMem->szMalloc==0 );
 304   if( pMem->szMalloc<szNew ){
 305     return sqlite3VdbeMemGrow(pMem, szNew, 0);
 306   }
 307   assert( (pMem->flags & MEM_Dyn)==0 );
 308   pMem->z = pMem->zMalloc;
 309   pMem->flags &= (MEM_Null|MEM_Int|MEM_Real|MEM_IntReal);
 310   return SQLITE_OK;
 311 }
 312
 313 /*
 314 ** It is already known that pMem contains an unterminated string.
 315 ** Add the zero terminator.
 316 **
 317 ** Three bytes of zero are added.  In this way, there is guaranteed
 318 ** to be a double-zero byte at an even byte boundary in order to
 319 ** terminate a UTF16 string, even if the initial size of the buffer
 320 ** is an odd number of bytes.
 321 */
 322 static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
 323   if( sqlite3VdbeMemGrow(pMem, pMem->n+3, 1) ){
 324     return SQLITE_NOMEM_BKPT;
 325   }
 326   pMem->z[pMem->n] = 0;
 327   pMem->z[pMem->n+1] = 0;
 328   pMem->z[pMem->n+2] = 0;
 329   pMem->flags |= MEM_Term;
 330   return SQLITE_OK;
 331 }
 332
 333 /*
 334 ** Change pMem so that its MEM_Str or MEM_Blob value is stored in
 335 ** MEM.zMalloc, where it can be safely written.
 336 **
 337 ** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
 338 */
 339 int sqlite3VdbeMemMakeWriteable(Mem *pMem){
 340   assert( pMem!=0 );
 341   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 342   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 343   if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
 344     if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
 345     if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
 346       int rc = vdbeMemAddTerminator(pMem);
 347       if( rc ) return rc;
 348     }
 349   }
 350   pMem->flags &= ~MEM_Ephem;
 351 #ifdef SQLITE_DEBUG
 352   pMem->pScopyFrom = 0;
 353 #endif
 354
 355   return SQLITE_OK;
 356 }
 357
 358 /*
 359 ** If the given Mem* has a zero-filled tail, turn it into an ordinary
 360 ** blob stored in dynamically allocated space.
 361 */
 362 #ifndef SQLITE_OMIT_INCRBLOB
 363 int sqlite3VdbeMemExpandBlob(Mem *pMem){
 364   int nByte;
 365   assert( pMem!=0 );
 366   assert( pMem->flags & MEM_Zero );
 367   assert( (pMem->flags&MEM_Blob)!=0 || MemNullNochng(pMem) );
 368   testcase( sqlite3_value_nochange(pMem) );
 369   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 370   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 371
 372   /* Set nByte to the number of bytes required to store the expanded blob. */
 373   nByte = pMem->n + pMem->u.nZero;
 374   if( nByte<=0 ){
 375     if( (pMem->flags & MEM_Blob)==0 ) return SQLITE_OK;
 376     nByte = 1;
 377   }
 378   if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
 379     return SQLITE_NOMEM_BKPT;
 380   }
 381   assert( pMem->z!=0 );
 382   assert( sqlite3DbMallocSize(pMem->db,pMem->z) >= nByte );
 383
 384   memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
 385   pMem->n += pMem->u.nZero;
 386   pMem->flags &= ~(MEM_Zero|MEM_Term);
 387   return SQLITE_OK;
 388 }
 389 #endif
 390
 391 /*
 392 ** Make sure the given Mem is \u0000 terminated.
 393 */
 394 int sqlite3VdbeMemNulTerminate(Mem *pMem){
 395   assert( pMem!=0 );
 396   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 397   testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
 398   testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
 399   if( (pMem->flags & (MEM_Term|MEM_Str))!=MEM_Str ){
 400     return SQLITE_OK;   /* Nothing to do */
 401   }else{
 402     return vdbeMemAddTerminator(pMem);
 403   }
 404 }
 405
 406 /*
 407 ** Add MEM_Str to the set of representations for the given Mem.  This
 408 ** routine is only called if pMem is a number of some kind, not a NULL
 409 ** or a BLOB.
 410 **
 411 ** Existing representations MEM_Int, MEM_Real, or MEM_IntReal are invalidated
 412 ** if bForce is true but are retained if bForce is false.
 413 **
 414 ** A MEM_Null value will never be passed to this function. This function is
 415 ** used for converting values to text for returning to the user (i.e. via
 416 ** sqlite3_value_text()), or for ensuring that values to be used as btree
 417 ** keys are strings. In the former case a NULL pointer is returned the
 418 ** user and the latter is an internal programming error.
 419 */
 420 int sqlite3VdbeMemStringify(Mem *pMem, u8 enc, u8 bForce){
 421   const int nByte = 32;
 422
 423   assert( pMem!=0 );
 424   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 425   assert( !(pMem->flags&MEM_Zero) );
 426   assert( !(pMem->flags&(MEM_Str|MEM_Blob)) );
 427   assert( pMem->flags&(MEM_Int|MEM_Real|MEM_IntReal) );
 428   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 429   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 430
 431
 432   if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
 433     pMem->enc = 0;
 434     return SQLITE_NOMEM_BKPT;
 435   }
 436
 437   vdbeMemRenderNum(nByte, pMem->z, pMem);
 438   assert( pMem->z!=0 );
 439   pMem->n = sqlite3Strlen30NN(pMem->z);
 440   pMem->enc = SQLITE_UTF8;
 441   pMem->flags |= MEM_Str|MEM_Term;
 442   if( bForce ) pMem->flags &= ~(MEM_Int|MEM_Real|MEM_IntReal);
 443   sqlite3VdbeChangeEncoding(pMem, enc);
 444   return SQLITE_OK;
 445 }
 446
 447 /*
 448 ** Memory cell pMem contains the context of an aggregate function.
 449 ** This routine calls the finalize method for that function.  The
 450 ** result of the aggregate is stored back into pMem.
 451 **
 452 ** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
 453 ** otherwise.
 454 */
 455 int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
 456   sqlite3_context ctx;
 457   Mem t;
 458   assert( pFunc!=0 );
 459   assert( pMem!=0 );
 460   assert( pFunc->xFinalize!=0 );
 461   assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
 462   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 463   memset(&ctx, 0, sizeof(ctx));
 464   memset(&t, 0, sizeof(t));
 465   t.flags = MEM_Null;
 466   t.db = pMem->db;
 467   ctx.pOut = &t;
 468   ctx.pMem = pMem;
 469   ctx.pFunc = pFunc;
 470   pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
 471   assert( (pMem->flags & MEM_Dyn)==0 );
 472   if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 473   memcpy(pMem, &t, sizeof(t));
 474   return ctx.isError;
 475 }
 476
 477 /*
 478 ** Memory cell pAccum contains the context of an aggregate function.
 479 ** This routine calls the xValue method for that function and stores
 480 ** the results in memory cell pMem.
 481 **
 482 ** SQLITE_ERROR is returned if xValue() reports an error. SQLITE_OK
 483 ** otherwise.
 484 */
 485 #ifndef SQLITE_OMIT_WINDOWFUNC
 486 int sqlite3VdbeMemAggValue(Mem *pAccum, Mem *pOut, FuncDef *pFunc){
 487   sqlite3_context ctx;
 488   assert( pFunc!=0 );
 489   assert( pFunc->xValue!=0 );
 490   assert( (pAccum->flags & MEM_Null)!=0 || pFunc==pAccum->u.pDef );
 491   assert( pAccum->db==0 || sqlite3_mutex_held(pAccum->db->mutex) );
 492   memset(&ctx, 0, sizeof(ctx));
 493   sqlite3VdbeMemSetNull(pOut);
 494   ctx.pOut = pOut;
 495   ctx.pMem = pAccum;
 496   ctx.pFunc = pFunc;
 497   pFunc->xValue(&ctx);
 498   return ctx.isError;
 499 }
 500 #endif /* SQLITE_OMIT_WINDOWFUNC */
 501
 502 /*
 503 ** If the memory cell contains a value that must be freed by
 504 ** invoking the external callback in Mem.xDel, then this routine
 505 ** will free that value.  It also sets Mem.flags to MEM_Null.
 506 **
 507 ** This is a helper routine for sqlite3VdbeMemSetNull() and
 508 ** for sqlite3VdbeMemRelease().  Use those other routines as the
 509 ** entry point for releasing Mem resources.
 510 */
 511 static SQLITE_NOINLINE void vdbeMemClearExternAndSetNull(Mem *p){
 512   assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
 513   assert( VdbeMemDynamic(p) );
 514   if( p->flags&MEM_Agg ){
 515     sqlite3VdbeMemFinalize(p, p->u.pDef);
 516     assert( (p->flags & MEM_Agg)==0 );
 517     testcase( p->flags & MEM_Dyn );
 518   }
 519   if( p->flags&MEM_Dyn ){
 520     assert( p->xDel!=SQLITE_DYNAMIC && p->xDel!=0 );
 521     p->xDel((void *)p->z);
 522   }
 523   p->flags = MEM_Null;
 524 }
 525
 526 /*
 527 ** Release memory held by the Mem p, both external memory cleared
 528 ** by p->xDel and memory in p->zMalloc.
 529 **
 530 ** This is a helper routine invoked by sqlite3VdbeMemRelease() in
 531 ** the unusual case where there really is memory in p that needs
 532 ** to be freed.
 533 */
 534 static SQLITE_NOINLINE void vdbeMemClear(Mem *p){
 535   if( VdbeMemDynamic(p) ){
 536     vdbeMemClearExternAndSetNull(p);
 537   }
 538   if( p->szMalloc ){
 539     sqlite3DbFreeNN(p->db, p->zMalloc);
 540     p->szMalloc = 0;
 541   }
 542   p->z = 0;
 543 }
 544
 545 /*
 546 ** Release any memory resources held by the Mem.  Both the memory that is
 547 ** free by Mem.xDel and the Mem.zMalloc allocation are freed.
 548 **
 549 ** Use this routine prior to clean up prior to abandoning a Mem, or to
 550 ** reset a Mem back to its minimum memory utilization.
 551 **
 552 ** Use sqlite3VdbeMemSetNull() to release just the Mem.xDel space
 553 ** prior to inserting new content into the Mem.
 554 */
 555 void sqlite3VdbeMemRelease(Mem *p){
 556   assert( sqlite3VdbeCheckMemInvariants(p) );
 557   if( VdbeMemDynamic(p) || p->szMalloc ){
 558     vdbeMemClear(p);
 559   }
 560 }
 561
 562 /*
 563 ** Convert a 64-bit IEEE double into a 64-bit signed integer.
 564 ** If the double is out of range of a 64-bit signed integer then
 565 ** return the closest available 64-bit signed integer.
 566 */
 567 static SQLITE_NOINLINE i64 doubleToInt64(double r){
 568 #ifdef SQLITE_OMIT_FLOATING_POINT
 569   /* When floating-point is omitted, double and int64 are the same thing */
 570   return r;
 571 #else
 572   /*
 573   ** Many compilers we encounter do not define constants for the
 574   ** minimum and maximum 64-bit integers, or they define them
 575   ** inconsistently.  And many do not understand the "LL" notation.
 576   ** So we define our own static constants here using nothing
 577   ** larger than a 32-bit integer constant.
 578   */
 579   static const i64 maxInt = LARGEST_INT64;
 580   static const i64 minInt = SMALLEST_INT64;
 581
 582   if( r<=(double)minInt ){
 583     return minInt;
 584   }else if( r>=(double)maxInt ){
 585     return maxInt;
 586   }else{
 587     return (i64)r;
 588   }
 589 #endif
 590 }
 591
 592 /*
 593 ** Return some kind of integer value which is the best we can do
 594 ** at representing the value that *pMem describes as an integer.
 595 ** If pMem is an integer, then the value is exact.  If pMem is
 596 ** a floating-point then the value returned is the integer part.
 597 ** If pMem is a string or blob, then we make an attempt to convert
 598 ** it into an integer and return that.  If pMem represents an
 599 ** an SQL-NULL value, return 0.
 600 **
 601 ** If pMem represents a string value, its encoding might be changed.
 602 */
 603 static SQLITE_NOINLINE i64 memIntValue(const Mem *pMem){
 604   i64 value = 0;
 605   sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
 606   return value;
 607 }
 608 i64 sqlite3VdbeIntValue(const Mem *pMem){
 609   int flags;
 610   assert( pMem!=0 );
 611   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 612   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 613   flags = pMem->flags;
 614   if( flags & (MEM_Int|MEM_IntReal) ){
 615     testcase( flags & MEM_IntReal );
 616     return pMem->u.i;
 617   }else if( flags & MEM_Real ){
 618     return doubleToInt64(pMem->u.r);
 619   }else if( (flags & (MEM_Str|MEM_Blob))!=0 && pMem->z!=0 ){
 620     return memIntValue(pMem);
 621   }else{
 622     return 0;
 623   }
 624 }
 625
 626 /*
 627 ** Return the best representation of pMem that we can get into a
 628 ** double.  If pMem is already a double or an integer, return its
 629 ** value.  If it is a string or blob, try to convert it to a double.
 630 ** If it is a NULL, return 0.0.
 631 */
 632 static SQLITE_NOINLINE double memRealValue(Mem *pMem){
 633   /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 634   double val = (double)0;
 635   sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
 636   return val;
 637 }
 638 double sqlite3VdbeRealValue(Mem *pMem){
 639   assert( pMem!=0 );
 640   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 641   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 642   if( pMem->flags & MEM_Real ){
 643     return pMem->u.r;
 644   }else if( pMem->flags & (MEM_Int|MEM_IntReal) ){
 645     testcase( pMem->flags & MEM_IntReal );
 646     return (double)pMem->u.i;
 647   }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
 648     return memRealValue(pMem);
 649   }else{
 650     /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 651     return (double)0;
 652   }
 653 }
 654
 655 /*
 656 ** Return 1 if pMem represents true, and return 0 if pMem represents false.
 657 ** Return the value ifNull if pMem is NULL.
 658 */
 659 int sqlite3VdbeBooleanValue(Mem *pMem, int ifNull){
 660   testcase( pMem->flags & MEM_IntReal );
 661   if( pMem->flags & (MEM_Int|MEM_IntReal) ) return pMem->u.i!=0;
 662   if( pMem->flags & MEM_Null ) return ifNull;
 663   return sqlite3VdbeRealValue(pMem)!=0.0;
 664 }
 665
 666 /*
 667 ** The MEM structure is already a MEM_Real.  Try to also make it a
 668 ** MEM_Int if we can.
 669 */
 670 void sqlite3VdbeIntegerAffinity(Mem *pMem){
 671   i64 ix;
 672   assert( pMem!=0 );
 673   assert( pMem->flags & MEM_Real );
 674   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 675   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 676   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 677
 678   ix = doubleToInt64(pMem->u.r);
 679
 680   /* Only mark the value as an integer if
 681   **
 682   **    (1) the round-trip conversion real->int->real is a no-op, and
 683   **    (2) The integer is neither the largest nor the smallest
 684   **        possible integer (ticket #3922)
 685   **
 686   ** The second and third terms in the following conditional enforces
 687   ** the second condition under the assumption that addition overflow causes
 688   ** values to wrap around.
 689   */
 690   if( pMem->u.r==ix && ix>SMALLEST_INT64 && ix<LARGEST_INT64 ){
 691     pMem->u.i = ix;
 692     MemSetTypeFlag(pMem, MEM_Int);
 693   }
 694 }
 695
 696 /*
 697 ** Convert pMem to type integer.  Invalidate any prior representations.
 698 */
 699 int sqlite3VdbeMemIntegerify(Mem *pMem){
 700   assert( pMem!=0 );
 701   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 702   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 703   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 704
 705   pMem->u.i = sqlite3VdbeIntValue(pMem);
 706   MemSetTypeFlag(pMem, MEM_Int);
 707   return SQLITE_OK;
 708 }
 709
 710 /*
 711 ** Convert pMem so that it is of type MEM_Real.
 712 ** Invalidate any prior representations.
 713 */
 714 int sqlite3VdbeMemRealify(Mem *pMem){
 715   assert( pMem!=0 );
 716   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 717   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 718
 719   pMem->u.r = sqlite3VdbeRealValue(pMem);
 720   MemSetTypeFlag(pMem, MEM_Real);
 721   return SQLITE_OK;
 722 }
 723
 724 /* Compare a floating point value to an integer.  Return true if the two
 725 ** values are the same within the precision of the floating point value.
 726 **
 727 ** This function assumes that i was obtained by assignment from r1.
 728 **
 729 ** For some versions of GCC on 32-bit machines, if you do the more obvious
 730 ** comparison of "r1==(double)i" you sometimes get an answer of false even
 731 ** though the r1 and (double)i values are bit-for-bit the same.
 732 */
 733 int sqlite3RealSameAsInt(double r1, sqlite3_int64 i){
 734   double r2 = (double)i;
 735   return r1==0.0
 736       || (memcmp(&r1, &r2, sizeof(r1))==0
 737           && i >= -2251799813685248LL && i < 2251799813685248LL);
 738 }
 739
 740 /*
 741 ** Convert pMem so that it has type MEM_Real or MEM_Int.
 742 ** Invalidate any prior representations.
 743 **
 744 ** Every effort is made to force the conversion, even if the input
 745 ** is a string that does not look completely like a number.  Convert
 746 ** as much of the string as we can and ignore the rest.
 747 */
 748 int sqlite3VdbeMemNumerify(Mem *pMem){
 749   assert( pMem!=0 );
 750   testcase( pMem->flags & MEM_Int );
 751   testcase( pMem->flags & MEM_Real );
 752   testcase( pMem->flags & MEM_IntReal );
 753   testcase( pMem->flags & MEM_Null );
 754   if( (pMem->flags & (MEM_Int|MEM_Real|MEM_IntReal|MEM_Null))==0 ){
 755     int rc;
 756     sqlite3_int64 ix;
 757     assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
 758     assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 759     rc = sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
 760     if( ((rc==0 || rc==1) && sqlite3Atoi64(pMem->z, &ix, pMem->n, pMem->enc)<=1)
 761      || sqlite3RealSameAsInt(pMem->u.r, (ix = (i64)pMem->u.r))
 762     ){
 763       pMem->u.i = ix;
 764       MemSetTypeFlag(pMem, MEM_Int);
 765     }else{
 766       MemSetTypeFlag(pMem, MEM_Real);
 767     }
 768   }
 769   assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_IntReal|MEM_Null))!=0 );
 770   pMem->flags &= ~(MEM_Str|MEM_Blob|MEM_Zero);
 771   return SQLITE_OK;
 772 }
 773
 774 /*
 775 ** Cast the datatype of the value in pMem according to the affinity
 776 ** "aff".  Casting is different from applying affinity in that a cast
 777 ** is forced.  In other words, the value is converted into the desired
 778 ** affinity even if that results in loss of data.  This routine is
 779 ** used (for example) to implement the SQL "cast()" operator.
 780 */
 781 int sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
 782   if( pMem->flags & MEM_Null ) return SQLITE_OK;
 783   switch( aff ){
 784     case SQLITE_AFF_BLOB: {   /* Really a cast to BLOB */
 785       if( (pMem->flags & MEM_Blob)==0 ){
 786         sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 787         assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 788         if( pMem->flags & MEM_Str ) MemSetTypeFlag(pMem, MEM_Blob);
 789       }else{
 790         pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
 791       }
 792       break;
 793     }
 794     case SQLITE_AFF_NUMERIC: {
 795       sqlite3VdbeMemNumerify(pMem);
 796       break;
 797     }
 798     case SQLITE_AFF_INTEGER: {
 799       sqlite3VdbeMemIntegerify(pMem);
 800       break;
 801     }
 802     case SQLITE_AFF_REAL: {
 803       sqlite3VdbeMemRealify(pMem);
 804       break;
 805     }
 806     default: {
 807       assert( aff==SQLITE_AFF_TEXT );
 808       assert( MEM_Str==(MEM_Blob>>3) );
 809       pMem->flags |= (pMem->flags&MEM_Blob)>>3;
 810       sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 811       assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 812       pMem->flags &= ~(MEM_Int|MEM_Real|MEM_IntReal|MEM_Blob|MEM_Zero);
 813       return sqlite3VdbeChangeEncoding(pMem, encoding);
 814     }
 815   }
 816   return SQLITE_OK;
 817 }
 818
 819 /*
 820 ** Initialize bulk memory to be a consistent Mem object.
 821 **
 822 ** The minimum amount of initialization feasible is performed.
 823 */
 824 void sqlite3VdbeMemInit(Mem *pMem, sqlite3 *db, u16 flags){
 825   assert( (flags & ~MEM_TypeMask)==0 );
 826   pMem->flags = flags;
 827   pMem->db = db;
 828   pMem->szMalloc = 0;
 829 }
 830
 831
 832 /*
 833 ** Delete any previous value and set the value stored in *pMem to NULL.
 834 **
 835 ** This routine calls the Mem.xDel destructor to dispose of values that
 836 ** require the destructor.  But it preserves the Mem.zMalloc memory allocation.
 837 ** To free all resources, use sqlite3VdbeMemRelease(), which both calls this
 838 ** routine to invoke the destructor and deallocates Mem.zMalloc.
 839 **
 840 ** Use this routine to reset the Mem prior to insert a new value.
 841 **
 842 ** Use sqlite3VdbeMemRelease() to complete erase the Mem prior to abandoning it.
 843 */
 844 void sqlite3VdbeMemSetNull(Mem *pMem){
 845   if( VdbeMemDynamic(pMem) ){
 846     vdbeMemClearExternAndSetNull(pMem);
 847   }else{
 848     pMem->flags = MEM_Null;
 849   }
 850 }
 851 void sqlite3ValueSetNull(sqlite3_value *p){
 852   sqlite3VdbeMemSetNull((Mem*)p);
 853 }
 854
 855 /*
 856 ** Delete any previous value and set the value to be a BLOB of length
 857 ** n containing all zeros.
 858 */
 859 #ifndef SQLITE_OMIT_INCRBLOB
 860 void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
 861   sqlite3VdbeMemRelease(pMem);
 862   pMem->flags = MEM_Blob|MEM_Zero;
 863   pMem->n = 0;
 864   if( n<0 ) n = 0;
 865   pMem->u.nZero = n;
 866   pMem->enc = SQLITE_UTF8;
 867   pMem->z = 0;
 868 }
 869 #else
 870 int sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
 871   int nByte = n>0?n:1;
 872   if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){
 873     return SQLITE_NOMEM_BKPT;
 874   }
 875   assert( pMem->z!=0 );
 876   assert( sqlite3DbMallocSize(pMem->db, pMem->z)>=nByte );
 877   memset(pMem->z, 0, nByte);
 878   pMem->n = n>0?n:0;
 879   pMem->flags = MEM_Blob;
 880   pMem->enc = SQLITE_UTF8;
 881   return SQLITE_OK;
 882 }
 883 #endif
 884
 885 /*
 886 ** The pMem is known to contain content that needs to be destroyed prior
 887 ** to a value change.  So invoke the destructor, then set the value to
 888 ** a 64-bit integer.
 889 */
 890 static SQLITE_NOINLINE void vdbeReleaseAndSetInt64(Mem *pMem, i64 val){
 891   sqlite3VdbeMemSetNull(pMem);
 892   pMem->u.i = val;
 893   pMem->flags = MEM_Int;
 894 }
 895
 896 /*
 897 ** Delete any previous value and set the value stored in *pMem to val,
 898 ** manifest type INTEGER.
 899 */
 900 void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
 901   if( VdbeMemDynamic(pMem) ){
 902     vdbeReleaseAndSetInt64(pMem, val);
 903   }else{
 904     pMem->u.i = val;
 905     pMem->flags = MEM_Int;
 906   }
 907 }
 908
 909 /* A no-op destructor */
 910 void sqlite3NoopDestructor(void *p){ UNUSED_PARAMETER(p); }
 911
 912 /*
 913 ** Set the value stored in *pMem should already be a NULL.
 914 ** Also store a pointer to go with it.
 915 */
 916 void sqlite3VdbeMemSetPointer(
 917   Mem *pMem,
 918   void *pPtr,
 919   const char *zPType,
 920   void (*xDestructor)(void*)
 921 ){
 922   assert( pMem->flags==MEM_Null );
 923   vdbeMemClear(pMem);
 924   pMem->u.zPType = zPType ? zPType : "";
 925   pMem->z = pPtr;
 926   pMem->flags = MEM_Null|MEM_Dyn|MEM_Subtype|MEM_Term;
 927   pMem->eSubtype = 'p';
 928   pMem->xDel = xDestructor ? xDestructor : sqlite3NoopDestructor;
 929 }
 930
 931 #ifndef SQLITE_OMIT_FLOATING_POINT
 932 /*
 933 ** Delete any previous value and set the value stored in *pMem to val,
 934 ** manifest type REAL.
 935 */
 936 void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
 937   sqlite3VdbeMemSetNull(pMem);
 938   if( !sqlite3IsNaN(val) ){
 939     pMem->u.r = val;
 940     pMem->flags = MEM_Real;
 941   }
 942 }
 943 #endif
 944
 945 #ifdef SQLITE_DEBUG
 946 /*
 947 ** Return true if the Mem holds a RowSet object.  This routine is intended
 948 ** for use inside of assert() statements.
 949 */
 950 int sqlite3VdbeMemIsRowSet(const Mem *pMem){
 951   return (pMem->flags&(MEM_Blob|MEM_Dyn))==(MEM_Blob|MEM_Dyn)
 952          && pMem->xDel==sqlite3RowSetDelete;
 953 }
 954 #endif
 955
 956 /*
 957 ** Delete any previous value and set the value of pMem to be an
 958 ** empty boolean index.
 959 **
 960 ** Return SQLITE_OK on success and SQLITE_NOMEM if a memory allocation
 961 ** error occurs.
 962 */
 963 int sqlite3VdbeMemSetRowSet(Mem *pMem){
 964   sqlite3 *db = pMem->db;
 965   RowSet *p;
 966   assert( db!=0 );
 967   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 968   sqlite3VdbeMemRelease(pMem);
 969   p = sqlite3RowSetInit(db);
 970   if( p==0 ) return SQLITE_NOMEM;
 971   pMem->z = (char*)p;
 972   pMem->flags = MEM_Blob|MEM_Dyn;
 973   pMem->xDel = sqlite3RowSetDelete;
 974   return SQLITE_OK;
 975 }
 976
 977 /*
 978 ** Return true if the Mem object contains a TEXT or BLOB that is
 979 ** too large - whose size exceeds SQLITE_MAX_LENGTH.
 980 */
 981 int sqlite3VdbeMemTooBig(Mem *p){
 982   assert( p->db!=0 );
 983   if( p->flags & (MEM_Str|MEM_Blob) ){
 984     int n = p->n;
 985     if( p->flags & MEM_Zero ){
 986       n += p->u.nZero;
 987     }
 988     return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
 989   }
 990   return 0;
 991 }
 992
 993 #ifdef SQLITE_DEBUG
 994 /*
 995 ** This routine prepares a memory cell for modification by breaking
 996 ** its link to a shallow copy and by marking any current shallow
 997 ** copies of this cell as invalid.
 998 **
 999 ** This is used for testing and debugging only - to help ensure that shallow
1000 ** copies (created by OP_SCopy) are not misused.
1001 */
1002 void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
1003   int i;
1004   Mem *pX;
1005   for(i=1, pX=pVdbe->aMem+1; i<pVdbe->nMem; i++, pX++){
1006     if( pX->pScopyFrom==pMem ){
1007       u16 mFlags;
1008       if( pVdbe->db->flags & SQLITE_VdbeTrace ){
1009         sqlite3DebugPrintf("Invalidate R[%d] due to change in R[%d]\n",
1010           (int)(pX - pVdbe->aMem), (int)(pMem - pVdbe->aMem));
1011       }
1012       /* If pX is marked as a shallow copy of pMem, then try to verify that
1013       ** no significant changes have been made to pX since the OP_SCopy.
1014       ** A significant change would indicated a missed call to this
1015       ** function for pX.  Minor changes, such as adding or removing a
1016       ** dual type, are allowed, as long as the underlying value is the
1017       ** same. */
1018       mFlags = pMem->flags & pX->flags & pX->mScopyFlags;
1019       assert( (mFlags&(MEM_Int|MEM_IntReal))==0 || pMem->u.i==pX->u.i );
1020
1021       /* pMem is the register that is changing.  But also mark pX as
1022       ** undefined so that we can quickly detect the shallow-copy error */
1023       pX->flags = MEM_Undefined;
1024       pX->pScopyFrom = 0;
1025     }
1026   }
1027   pMem->pScopyFrom = 0;
1028 }
1029 #endif /* SQLITE_DEBUG */
1030
1031 /*
1032 ** Make an shallow copy of pFrom into pTo.  Prior contents of
1033 ** pTo are freed.  The pFrom->z field is not duplicated.  If
1034 ** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
1035 ** and flags gets srcType (either MEM_Ephem or MEM_Static).
1036 */
1037 static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){
1038   vdbeMemClearExternAndSetNull(pTo);
1039   assert( !VdbeMemDynamic(pTo) );
1040   sqlite3VdbeMemShallowCopy(pTo, pFrom, eType);
1041 }
1042 void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
1043   assert( !sqlite3VdbeMemIsRowSet(pFrom) );
1044   assert( pTo->db==pFrom->db );
1045   if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; }
1046   memcpy(pTo, pFrom, MEMCELLSIZE);
1047   if( (pFrom->flags&MEM_Static)==0 ){
1048     pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
1049     assert( srcType==MEM_Ephem || srcType==MEM_Static );
1050     pTo->flags |= srcType;
1051   }
1052 }
1053
1054 /*
1055 ** Make a full copy of pFrom into pTo.  Prior contents of pTo are
1056 ** freed before the copy is made.
1057 */
1058 int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
1059   int rc = SQLITE_OK;
1060
1061   assert( !sqlite3VdbeMemIsRowSet(pFrom) );
1062   if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
1063   memcpy(pTo, pFrom, MEMCELLSIZE);
1064   pTo->flags &= ~MEM_Dyn;
1065   if( pTo->flags&(MEM_Str|MEM_Blob) ){
1066     if( 0==(pFrom->flags&MEM_Static) ){
1067       pTo->flags |= MEM_Ephem;
1068       rc = sqlite3VdbeMemMakeWriteable(pTo);
1069     }
1070   }
1071
1072   return rc;
1073 }
1074
1075 /*
1076 ** Transfer the contents of pFrom to pTo. Any existing value in pTo is
1077 ** freed. If pFrom contains ephemeral data, a copy is made.
1078 **
1079 ** pFrom contains an SQL NULL when this routine returns.
1080 */
1081 void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
1082   assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
1083   assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
1084   assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
1085
1086   sqlite3VdbeMemRelease(pTo);
1087   memcpy(pTo, pFrom, sizeof(Mem));
1088   pFrom->flags = MEM_Null;
1089   pFrom->szMalloc = 0;
1090 }
1091
1092 /*
1093 ** Change the value of a Mem to be a string or a BLOB.
1094 **
1095 ** The memory management strategy depends on the value of the xDel
1096 ** parameter. If the value passed is SQLITE_TRANSIENT, then the
1097 ** string is copied into a (possibly existing) buffer managed by the
1098 ** Mem structure. Otherwise, any existing buffer is freed and the
1099 ** pointer copied.
1100 **
1101 ** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
1102 ** size limit) then no memory allocation occurs.  If the string can be
1103 ** stored without allocating memory, then it is.  If a memory allocation
1104 ** is required to store the string, then value of pMem is unchanged.  In
1105 ** either case, SQLITE_TOOBIG is returned.
1106 */
1107 int sqlite3VdbeMemSetStr(
1108   Mem *pMem,          /* Memory cell to set to string value */
1109   const char *z,      /* String pointer */
1110   i64 n,              /* Bytes in string, or negative */
1111   u8 enc,             /* Encoding of z.  0 for BLOBs */
1112   void (*xDel)(void*) /* Destructor function */
1113 ){
1114   i64 nByte = n;      /* New value for pMem->n */
1115   int iLimit;         /* Maximum allowed string or blob size */
1116   u16 flags = 0;      /* New value for pMem->flags */
1117
1118   assert( pMem!=0 );
1119   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
1120   assert( !sqlite3VdbeMemIsRowSet(pMem) );
1121
1122   /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
1123   if( !z ){
1124     sqlite3VdbeMemSetNull(pMem);
1125     return SQLITE_OK;
1126   }
1127
1128   if( pMem->db ){
1129     iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
1130   }else{
1131     iLimit = SQLITE_MAX_LENGTH;
1132   }
1133   flags = (enc==0?MEM_Blob:MEM_Str);
1134   if( nByte<0 ){
1135     assert( enc!=0 );
1136     if( enc==SQLITE_UTF8 ){
1137       nByte = strlen(z);
1138     }else{
1139       for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
1140     }
1141     flags |= MEM_Term;
1142   }
1143
1144   /* The following block sets the new values of Mem.z and Mem.xDel. It
1145   ** also sets a flag in local variable "flags" to indicate the memory
1146   ** management (one of MEM_Dyn or MEM_Static).
1147   */
1148   if( xDel==SQLITE_TRANSIENT ){
1149     i64 nAlloc = nByte;
1150     if( flags&MEM_Term ){
1151       nAlloc += (enc==SQLITE_UTF8?1:2);
1152     }
1153     if( nByte>iLimit ){
1154       return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
1155     }
1156     testcase( nAlloc==0 );
1157     testcase( nAlloc==31 );
1158     testcase( nAlloc==32 );
1159     if( sqlite3VdbeMemClearAndResize(pMem, (int)MAX(nAlloc,32)) ){
1160       return SQLITE_NOMEM_BKPT;
1161     }
1162     memcpy(pMem->z, z, nAlloc);
1163   }else{
1164     sqlite3VdbeMemRelease(pMem);
1165     pMem->z = (char *)z;
1166     if( xDel==SQLITE_DYNAMIC ){
1167       pMem->zMalloc = pMem->z;
1168       pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
1169     }else{
1170       pMem->xDel = xDel;
1171       flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
1172     }
1173   }
1174
1175   pMem->n = (int)(nByte & 0x7fffffff);
1176   pMem->flags = flags;
1177   if( enc ){
1178     pMem->enc = enc;
1179 #ifdef SQLITE_ENABLE_SESSION
1180   }else if( pMem->db==0 ){
1181     pMem->enc = SQLITE_UTF8;
1182 #endif
1183   }else{
1184     assert( pMem->db!=0 );
1185     pMem->enc = ENC(pMem->db);
1186   }
1187
1188 #ifndef SQLITE_OMIT_UTF16
1189   if( enc>SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
1190     return SQLITE_NOMEM_BKPT;
1191   }
1192 #endif
1193
1194   if( nByte>iLimit ){
1195     return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
1196   }
1197
1198   return SQLITE_OK;
1199 }
1200
1201 /*
1202 ** Move data out of a btree key or data field and into a Mem structure.
1203 ** The data is payload from the entry that pCur is currently pointing
1204 ** to.  offset and amt determine what portion of the data or key to retrieve.
1205 ** The result is written into the pMem element.
1206 **
1207 ** The pMem object must have been initialized.  This routine will use
1208 ** pMem->zMalloc to hold the content from the btree, if possible.  New
1209 ** pMem->zMalloc space will be allocated if necessary.  The calling routine
1210 ** is responsible for making sure that the pMem object is eventually
1211 ** destroyed.
1212 **
1213 ** If this routine fails for any reason (malloc returns NULL or unable
1214 ** to read from the disk) then the pMem is left in an inconsistent state.
1215 */
1216 int sqlite3VdbeMemFromBtree(
1217   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1218   u32 offset,       /* Offset from the start of data to return bytes from. */
1219   u32 amt,          /* Number of bytes to return. */
1220   Mem *pMem         /* OUT: Return data in this Mem structure. */
1221 ){
1222   int rc;
1223   pMem->flags = MEM_Null;
1224   if( sqlite3BtreeMaxRecordSize(pCur)<offset+amt ){
1225     return SQLITE_CORRUPT_BKPT;
1226   }
1227   if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+1)) ){
1228     rc = sqlite3BtreePayload(pCur, offset, amt, pMem->z);
1229     if( rc==SQLITE_OK ){
1230       pMem->z[amt] = 0;   /* Overrun area used when reading malformed records */
1231       pMem->flags = MEM_Blob;
1232       pMem->n = (int)amt;
1233     }else{
1234       sqlite3VdbeMemRelease(pMem);
1235     }
1236   }
1237   return rc;
1238 }
1239 int sqlite3VdbeMemFromBtreeZeroOffset(
1240   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1241   u32 amt,          /* Number of bytes to return. */
1242   Mem *pMem         /* OUT: Return data in this Mem structure. */
1243 ){
1244   u32 available = 0;  /* Number of bytes available on the local btree page */
1245   int rc = SQLITE_OK; /* Return code */
1246
1247   assert( sqlite3BtreeCursorIsValid(pCur) );
1248   assert( !VdbeMemDynamic(pMem) );
1249
1250   /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert()
1251   ** that both the BtShared and database handle mutexes are held. */
1252   assert( !sqlite3VdbeMemIsRowSet(pMem) );
1253   pMem->z = (char *)sqlite3BtreePayloadFetch(pCur, &available);
1254   assert( pMem->z!=0 );
1255
1256   if( amt<=available ){
1257     pMem->flags = MEM_Blob|MEM_Ephem;
1258     pMem->n = (int)amt;
1259   }else{
1260     rc = sqlite3VdbeMemFromBtree(pCur, 0, amt, pMem);
1261   }
1262
1263   return rc;
1264 }
1265
1266 /*
1267 ** The pVal argument is known to be a value other than NULL.
1268 ** Convert it into a string with encoding enc and return a pointer
1269 ** to a zero-terminated version of that string.
1270 */
1271 static SQLITE_NOINLINE const void *valueToText(sqlite3_value* pVal, u8 enc){
1272   assert( pVal!=0 );
1273   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1274   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1275   assert( !sqlite3VdbeMemIsRowSet(pVal) );
1276   assert( (pVal->flags & (MEM_Null))==0 );
1277   if( pVal->flags & (MEM_Blob|MEM_Str) ){
1278     if( ExpandBlob(pVal) ) return 0;
1279     pVal->flags |= MEM_Str;
1280     if( pVal->enc != (enc & ~SQLITE_UTF16_ALIGNED) ){
1281       sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
1282     }
1283     if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
1284       assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
1285       if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
1286         return 0;
1287       }
1288     }
1289     sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-31275-44060 */
1290   }else{
1291     sqlite3VdbeMemStringify(pVal, enc, 0);
1292     assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
1293   }
1294   assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
1295               || pVal->db->mallocFailed );
1296   if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
1297     assert( sqlite3VdbeMemValidStrRep(pVal) );
1298     return pVal->z;
1299   }else{
1300     return 0;
1301   }
1302 }
1303
1304 /* This function is only available internally, it is not part of the
1305 ** external API. It works in a similar way to sqlite3_value_text(),
1306 ** except the data returned is in the encoding specified by the second
1307 ** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
1308 ** SQLITE_UTF8.
1309 **
1310 ** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
1311 ** If that is the case, then the result must be aligned on an even byte
1312 ** boundary.
1313 */
1314 const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
1315   if( !pVal ) return 0;
1316   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1317   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1318   assert( !sqlite3VdbeMemIsRowSet(pVal) );
1319   if( (pVal->flags&(MEM_Str|MEM_Term))==(MEM_Str|MEM_Term) && pVal->enc==enc ){
1320     assert( sqlite3VdbeMemValidStrRep(pVal) );
1321     return pVal->z;
1322   }
1323   if( pVal->flags&MEM_Null ){
1324     return 0;
1325   }
1326   return valueToText(pVal, enc);
1327 }
1328
1329 /*
1330 ** Create a new sqlite3_value object.
1331 */
1332 sqlite3_value *sqlite3ValueNew(sqlite3 *db){
1333   Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
1334   if( p ){
1335     p->flags = MEM_Null;
1336     p->db = db;
1337   }
1338   return p;
1339 }
1340
1341 /*
1342 ** Context object passed by sqlite3Stat4ProbeSetValue() through to
1343 ** valueNew(). See comments above valueNew() for details.
1344 */
1345 struct ValueNewStat4Ctx {
1346   Parse *pParse;
1347   Index *pIdx;
1348   UnpackedRecord **ppRec;
1349   int iVal;
1350 };
1351
1352 /*
1353 ** Allocate and return a pointer to a new sqlite3_value object. If
1354 ** the second argument to this function is NULL, the object is allocated
1355 ** by calling sqlite3ValueNew().
1356 **
1357 ** Otherwise, if the second argument is non-zero, then this function is
1358 ** being called indirectly by sqlite3Stat4ProbeSetValue(). If it has not
1359 ** already been allocated, allocate the UnpackedRecord structure that
1360 ** that function will return to its caller here. Then return a pointer to
1361 ** an sqlite3_value within the UnpackedRecord.a[] array.
1362 */
1363 static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
1364 #ifdef SQLITE_ENABLE_STAT4
1365   if( p ){
1366     UnpackedRecord *pRec = p->ppRec[0];
1367
1368     if( pRec==0 ){
1369       Index *pIdx = p->pIdx;      /* Index being probed */
1370       int nByte;                  /* Bytes of space to allocate */
1371       int i;                      /* Counter variable */
1372       int nCol = pIdx->nColumn;   /* Number of index columns including rowid */
1373
1374       nByte = sizeof(Mem) * nCol + ROUND8(sizeof(UnpackedRecord));
1375       pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
1376       if( pRec ){
1377         pRec->pKeyInfo = sqlite3KeyInfoOfIndex(p->pParse, pIdx);
1378         if( pRec->pKeyInfo ){
1379           assert( pRec->pKeyInfo->nAllField==nCol );
1380           assert( pRec->pKeyInfo->enc==ENC(db) );
1381           pRec->aMem = (Mem *)((u8*)pRec + ROUND8(sizeof(UnpackedRecord)));
1382           for(i=0; i<nCol; i++){
1383             pRec->aMem[i].flags = MEM_Null;
1384             pRec->aMem[i].db = db;
1385           }
1386         }else{
1387           sqlite3DbFreeNN(db, pRec);
1388           pRec = 0;
1389         }
1390       }
1391       if( pRec==0 ) return 0;
1392       p->ppRec[0] = pRec;
1393     }
1394
1395     pRec->nField = p->iVal+1;
1396     return &pRec->aMem[p->iVal];
1397   }
1398 #else
1399   UNUSED_PARAMETER(p);
1400 #endif /* defined(SQLITE_ENABLE_STAT4) */
1401   return sqlite3ValueNew(db);
1402 }
1403
1404 /*
1405 ** The expression object indicated by the second argument is guaranteed
1406 ** to be a scalar SQL function. If
1407 **
1408 **   * all function arguments are SQL literals,
1409 **   * one of the SQLITE_FUNC_CONSTANT or _SLOCHNG function flags is set, and
1410 **   * the SQLITE_FUNC_NEEDCOLL function flag is not set,
1411 **
1412 ** then this routine attempts to invoke the SQL function. Assuming no
1413 ** error occurs, output parameter (*ppVal) is set to point to a value
1414 ** object containing the result before returning SQLITE_OK.
1415 **
1416 ** Affinity aff is applied to the result of the function before returning.
1417 ** If the result is a text value, the sqlite3_value object uses encoding
1418 ** enc.
1419 **
1420 ** If the conditions above are not met, this function returns SQLITE_OK
1421 ** and sets (*ppVal) to NULL. Or, if an error occurs, (*ppVal) is set to
1422 ** NULL and an SQLite error code returned.
1423 */
1424 #ifdef SQLITE_ENABLE_STAT4
1425 static int valueFromFunction(
1426   sqlite3 *db,                    /* The database connection */
1427   const Expr *p,                  /* The expression to evaluate */
1428   u8 enc,                         /* Encoding to use */
1429   u8 aff,                         /* Affinity to use */
1430   sqlite3_value **ppVal,          /* Write the new value here */
1431   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1432 ){
1433   sqlite3_context ctx;            /* Context object for function invocation */
1434   sqlite3_value **apVal = 0;      /* Function arguments */
1435   int nVal = 0;                   /* Size of apVal[] array */
1436   FuncDef *pFunc = 0;             /* Function definition */
1437   sqlite3_value *pVal = 0;        /* New value */
1438   int rc = SQLITE_OK;             /* Return code */
1439   ExprList *pList = 0;            /* Function arguments */
1440   int i;                          /* Iterator variable */
1441
1442   assert( pCtx!=0 );
1443   assert( (p->flags & EP_TokenOnly)==0 );
1444   assert( ExprUseXList(p) );
1445   pList = p->x.pList;
1446   if( pList ) nVal = pList->nExpr;
1447   assert( !ExprHasProperty(p, EP_IntValue) );
1448   pFunc = sqlite3FindFunction(db, p->u.zToken, nVal, enc, 0);
1449   assert( pFunc );
1450   if( (pFunc->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0
1451    || (pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
1452   ){
1453     return SQLITE_OK;
1454   }
1455
1456   if( pList ){
1457     apVal = (sqlite3_value**)sqlite3DbMallocZero(db, sizeof(apVal[0]) * nVal);
1458     if( apVal==0 ){
1459       rc = SQLITE_NOMEM_BKPT;
1460       goto value_from_function_out;
1461     }
1462     for(i=0; i<nVal; i++){
1463       rc = sqlite3ValueFromExpr(db, pList->a[i].pExpr, enc, aff, &apVal[i]);
1464       if( apVal[i]==0 || rc!=SQLITE_OK ) goto value_from_function_out;
1465     }
1466   }
1467
1468   pVal = valueNew(db, pCtx);
1469   if( pVal==0 ){
1470     rc = SQLITE_NOMEM_BKPT;
1471     goto value_from_function_out;
1472   }
1473
1474   assert( pCtx->pParse->rc==SQLITE_OK );
1475   memset(&ctx, 0, sizeof(ctx));
1476   ctx.pOut = pVal;
1477   ctx.pFunc = pFunc;
1478   pFunc->xSFunc(&ctx, nVal, apVal);
1479   if( ctx.isError ){
1480     rc = ctx.isError;
1481     sqlite3ErrorMsg(pCtx->pParse, "%s", sqlite3_value_text(pVal));
1482   }else{
1483     sqlite3ValueApplyAffinity(pVal, aff, SQLITE_UTF8);
1484     assert( rc==SQLITE_OK );
1485     rc = sqlite3VdbeChangeEncoding(pVal, enc);
1486     if( rc==SQLITE_OK && sqlite3VdbeMemTooBig(pVal) ){
1487       rc = SQLITE_TOOBIG;
1488       pCtx->pParse->nErr++;
1489     }
1490   }
1491   pCtx->pParse->rc = rc;
1492
1493  value_from_function_out:
1494   if( rc!=SQLITE_OK ){
1495     pVal = 0;
1496   }
1497   if( apVal ){
1498     for(i=0; i<nVal; i++){
1499       sqlite3ValueFree(apVal[i]);
1500     }
1501     sqlite3DbFreeNN(db, apVal);
1502   }
1503
1504   *ppVal = pVal;
1505   return rc;
1506 }
1507 #else
1508 # define valueFromFunction(a,b,c,d,e,f) SQLITE_OK
1509 #endif /* defined(SQLITE_ENABLE_STAT4) */
1510
1511 /*
1512 ** Extract a value from the supplied expression in the manner described
1513 ** above sqlite3ValueFromExpr(). Allocate the sqlite3_value object
1514 ** using valueNew().
1515 **
1516 ** If pCtx is NULL and an error occurs after the sqlite3_value object
1517 ** has been allocated, it is freed before returning. Or, if pCtx is not
1518 ** NULL, it is assumed that the caller will free any allocated object
1519 ** in all cases.
1520 */
1521 static int valueFromExpr(
1522   sqlite3 *db,                    /* The database connection */
1523   const Expr *pExpr,              /* The expression to evaluate */
1524   u8 enc,                         /* Encoding to use */
1525   u8 affinity,                    /* Affinity to use */
1526   sqlite3_value **ppVal,          /* Write the new value here */
1527   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1528 ){
1529   int op;
1530   char *zVal = 0;
1531   sqlite3_value *pVal = 0;
1532   int negInt = 1;
1533   const char *zNeg = "";
1534   int rc = SQLITE_OK;
1535
1536   assert( pExpr!=0 );
1537   while( (op = pExpr->op)==TK_UPLUS || op==TK_SPAN ) pExpr = pExpr->pLeft;
1538   if( op==TK_REGISTER ) op = pExpr->op2;
1539
1540   /* Compressed expressions only appear when parsing the DEFAULT clause
1541   ** on a table column definition, and hence only when pCtx==0.  This
1542   ** check ensures that an EP_TokenOnly expression is never passed down
1543   ** into valueFromFunction(). */
1544   assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );
1545
1546   if( op==TK_CAST ){
1547     u8 aff;
1548     assert( !ExprHasProperty(pExpr, EP_IntValue) );
1549     aff = sqlite3AffinityType(pExpr->u.zToken,0);
1550     rc = valueFromExpr(db, pExpr->pLeft, enc, aff, ppVal, pCtx);
1551     testcase( rc!=SQLITE_OK );
1552     if( *ppVal ){
1553       sqlite3VdbeMemCast(*ppVal, aff, SQLITE_UTF8);
1554       sqlite3ValueApplyAffinity(*ppVal, affinity, SQLITE_UTF8);
1555     }
1556     return rc;
1557   }
1558
1559   /* Handle negative integers in a single step.  This is needed in the
1560   ** case when the value is -9223372036854775808.
1561   */
1562   if( op==TK_UMINUS
1563    && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
1564     pExpr = pExpr->pLeft;
1565     op = pExpr->op;
1566     negInt = -1;
1567     zNeg = "-";
1568   }
1569
1570   if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
1571     pVal = valueNew(db, pCtx);
1572     if( pVal==0 ) goto no_mem;
1573     if( ExprHasProperty(pExpr, EP_IntValue) ){
1574       sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
1575     }else{
1576       zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
1577       if( zVal==0 ) goto no_mem;
1578       sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
1579     }
1580     if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_BLOB ){
1581       sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
1582     }else{
1583       sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
1584     }
1585     assert( (pVal->flags & MEM_IntReal)==0 );
1586     if( pVal->flags & (MEM_Int|MEM_IntReal|MEM_Real) ){
1587       testcase( pVal->flags & MEM_Int );
1588       testcase( pVal->flags & MEM_Real );
1589       pVal->flags &= ~MEM_Str;
1590     }
1591     if( enc!=SQLITE_UTF8 ){
1592       rc = sqlite3VdbeChangeEncoding(pVal, enc);
1593     }
1594   }else if( op==TK_UMINUS ) {
1595     /* This branch happens for multiple negative signs.  Ex: -(-5) */
1596     if( SQLITE_OK==valueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal,pCtx)
1597      && pVal!=0
1598     ){
1599       sqlite3VdbeMemNumerify(pVal);
1600       if( pVal->flags & MEM_Real ){
1601         pVal->u.r = -pVal->u.r;
1602       }else if( pVal->u.i==SMALLEST_INT64 ){
1603 #ifndef SQLITE_OMIT_FLOATING_POINT
1604         pVal->u.r = -(double)SMALLEST_INT64;
1605 #else
1606         pVal->u.r = LARGEST_INT64;
1607 #endif
1608         MemSetTypeFlag(pVal, MEM_Real);
1609       }else{
1610         pVal->u.i = -pVal->u.i;
1611       }
1612       sqlite3ValueApplyAffinity(pVal, affinity, enc);
1613     }
1614   }else if( op==TK_NULL ){
1615     pVal = valueNew(db, pCtx);
1616     if( pVal==0 ) goto no_mem;
1617     sqlite3VdbeMemSetNull(pVal);
1618   }
1619 #ifndef SQLITE_OMIT_BLOB_LITERAL
1620   else if( op==TK_BLOB ){
1621     int nVal;
1622     assert( !ExprHasProperty(pExpr, EP_IntValue) );
1623     assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
1624     assert( pExpr->u.zToken[1]=='\'' );
1625     pVal = valueNew(db, pCtx);
1626     if( !pVal ) goto no_mem;
1627     zVal = &pExpr->u.zToken[2];
1628     nVal = sqlite3Strlen30(zVal)-1;
1629     assert( zVal[nVal]=='\'' );
1630     sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
1631                          0, SQLITE_DYNAMIC);
1632   }
1633 #endif
1634 #ifdef SQLITE_ENABLE_STAT4
1635   else if( op==TK_FUNCTION && pCtx!=0 ){
1636     rc = valueFromFunction(db, pExpr, enc, affinity, &pVal, pCtx);
1637   }
1638 #endif
1639   else if( op==TK_TRUEFALSE ){
1640     assert( !ExprHasProperty(pExpr, EP_IntValue) );
1641     pVal = valueNew(db, pCtx);
1642     if( pVal ){
1643       pVal->flags = MEM_Int;
1644       pVal->u.i = pExpr->u.zToken[4]==0;
1645     }
1646   }
1647
1648   *ppVal = pVal;
1649   return rc;
1650
1651 no_mem:
1652 #ifdef SQLITE_ENABLE_STAT4
1653   if( pCtx==0 || NEVER(pCtx->pParse->nErr==0) )
1654 #endif
1655     sqlite3OomFault(db);
1656   sqlite3DbFree(db, zVal);
1657   assert( *ppVal==0 );
1658 #ifdef SQLITE_ENABLE_STAT4
1659   if( pCtx==0 ) sqlite3ValueFree(pVal);
1660 #else
1661   assert( pCtx==0 ); sqlite3ValueFree(pVal);
1662 #endif
1663   return SQLITE_NOMEM_BKPT;
1664 }
1665
1666 /*
1667 ** Create a new sqlite3_value object, containing the value of pExpr.
1668 **
1669 ** This only works for very simple expressions that consist of one constant
1670 ** token (i.e. "5", "5.1", "'a string'"). If the expression can
1671 ** be converted directly into a value, then the value is allocated and
1672 ** a pointer written to *ppVal. The caller is responsible for deallocating
1673 ** the value by passing it to sqlite3ValueFree() later on. If the expression
1674 ** cannot be converted to a value, then *ppVal is set to NULL.
1675 */
1676 int sqlite3ValueFromExpr(
1677   sqlite3 *db,              /* The database connection */
1678   const Expr *pExpr,        /* The expression to evaluate */
1679   u8 enc,                   /* Encoding to use */
1680   u8 affinity,              /* Affinity to use */
1681   sqlite3_value **ppVal     /* Write the new value here */
1682 ){
1683   return pExpr ? valueFromExpr(db, pExpr, enc, affinity, ppVal, 0) : 0;
1684 }
1685
1686 #ifdef SQLITE_ENABLE_STAT4
1687 /*
1688 ** Attempt to extract a value from pExpr and use it to construct *ppVal.
1689 **
1690 ** If pAlloc is not NULL, then an UnpackedRecord object is created for
1691 ** pAlloc if one does not exist and the new value is added to the
1692 ** UnpackedRecord object.
1693 **
1694 ** A value is extracted in the following cases:
1695 **
1696 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1697 **
1698 **  * The expression is a bound variable, and this is a reprepare, or
1699 **
1700 **  * The expression is a literal value.
1701 **
1702 ** On success, *ppVal is made to point to the extracted value.  The caller
1703 ** is responsible for ensuring that the value is eventually freed.
1704 */
1705 static int stat4ValueFromExpr(
1706   Parse *pParse,                  /* Parse context */
1707   Expr *pExpr,                    /* The expression to extract a value from */
1708   u8 affinity,                    /* Affinity to use */
1709   struct ValueNewStat4Ctx *pAlloc,/* How to allocate space.  Or NULL */
1710   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1711 ){
1712   int rc = SQLITE_OK;
1713   sqlite3_value *pVal = 0;
1714   sqlite3 *db = pParse->db;
1715
1716   /* Skip over any TK_COLLATE nodes */
1717   pExpr = sqlite3ExprSkipCollate(pExpr);
1718
1719   assert( pExpr==0 || pExpr->op!=TK_REGISTER || pExpr->op2!=TK_VARIABLE );
1720   if( !pExpr ){
1721     pVal = valueNew(db, pAlloc);
1722     if( pVal ){
1723       sqlite3VdbeMemSetNull((Mem*)pVal);
1724     }
1725   }else if( pExpr->op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
1726     Vdbe *v;
1727     int iBindVar = pExpr->iColumn;
1728     sqlite3VdbeSetVarmask(pParse->pVdbe, iBindVar);
1729     if( (v = pParse->pReprepare)!=0 ){
1730       pVal = valueNew(db, pAlloc);
1731       if( pVal ){
1732         rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iBindVar-1]);
1733         sqlite3ValueApplyAffinity(pVal, affinity, ENC(db));
1734         pVal->db = pParse->db;
1735       }
1736     }
1737   }else{
1738     rc = valueFromExpr(db, pExpr, ENC(db), affinity, &pVal, pAlloc);
1739   }
1740
1741   assert( pVal==0 || pVal->db==db );
1742   *ppVal = pVal;
1743   return rc;
1744 }
1745
1746 /*
1747 ** This function is used to allocate and populate UnpackedRecord
1748 ** structures intended to be compared against sample index keys stored
1749 ** in the sqlite_stat4 table.
1750 **
1751 ** A single call to this function populates zero or more fields of the
1752 ** record starting with field iVal (fields are numbered from left to
1753 ** right starting with 0). A single field is populated if:
1754 **
1755 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1756 **
1757 **  * The expression is a bound variable, and this is a reprepare, or
1758 **
1759 **  * The sqlite3ValueFromExpr() function is able to extract a value
1760 **    from the expression (i.e. the expression is a literal value).
1761 **
1762 ** Or, if pExpr is a TK_VECTOR, one field is populated for each of the
1763 ** vector components that match either of the two latter criteria listed
1764 ** above.
1765 **
1766 ** Before any value is appended to the record, the affinity of the
1767 ** corresponding column within index pIdx is applied to it. Before
1768 ** this function returns, output parameter *pnExtract is set to the
1769 ** number of values appended to the record.
1770 **
1771 ** When this function is called, *ppRec must either point to an object
1772 ** allocated by an earlier call to this function, or must be NULL. If it
1773 ** is NULL and a value can be successfully extracted, a new UnpackedRecord
1774 ** is allocated (and *ppRec set to point to it) before returning.
1775 **
1776 ** Unless an error is encountered, SQLITE_OK is returned. It is not an
1777 ** error if a value cannot be extracted from pExpr. If an error does
1778 ** occur, an SQLite error code is returned.
1779 */
1780 int sqlite3Stat4ProbeSetValue(
1781   Parse *pParse,                  /* Parse context */
1782   Index *pIdx,                    /* Index being probed */
1783   UnpackedRecord **ppRec,         /* IN/OUT: Probe record */
1784   Expr *pExpr,                    /* The expression to extract a value from */
1785   int nElem,                      /* Maximum number of values to append */
1786   int iVal,                       /* Array element to populate */
1787   int *pnExtract                  /* OUT: Values appended to the record */
1788 ){
1789   int rc = SQLITE_OK;
1790   int nExtract = 0;
1791
1792   if( pExpr==0 || pExpr->op!=TK_SELECT ){
1793     int i;
1794     struct ValueNewStat4Ctx alloc;
1795
1796     alloc.pParse = pParse;
1797     alloc.pIdx = pIdx;
1798     alloc.ppRec = ppRec;
1799
1800     for(i=0; i<nElem; i++){
1801       sqlite3_value *pVal = 0;
1802       Expr *pElem = (pExpr ? sqlite3VectorFieldSubexpr(pExpr, i) : 0);
1803       u8 aff = sqlite3IndexColumnAffinity(pParse->db, pIdx, iVal+i);
1804       alloc.iVal = iVal+i;
1805       rc = stat4ValueFromExpr(pParse, pElem, aff, &alloc, &pVal);
1806       if( !pVal ) break;
1807       nExtract++;
1808     }
1809   }
1810
1811   *pnExtract = nExtract;
1812   return rc;
1813 }
1814
1815 /*
1816 ** Attempt to extract a value from expression pExpr using the methods
1817 ** as described for sqlite3Stat4ProbeSetValue() above.
1818 **
1819 ** If successful, set *ppVal to point to a new value object and return
1820 ** SQLITE_OK. If no value can be extracted, but no other error occurs
1821 ** (e.g. OOM), return SQLITE_OK and set *ppVal to NULL. Or, if an error
1822 ** does occur, return an SQLite error code. The final value of *ppVal
1823 ** is undefined in this case.
1824 */
1825 int sqlite3Stat4ValueFromExpr(
1826   Parse *pParse,                  /* Parse context */
1827   Expr *pExpr,                    /* The expression to extract a value from */
1828   u8 affinity,                    /* Affinity to use */
1829   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1830 ){
1831   return stat4ValueFromExpr(pParse, pExpr, affinity, 0, ppVal);
1832 }
1833
1834 /*
1835 ** Extract the iCol-th column from the nRec-byte record in pRec.  Write
1836 ** the column value into *ppVal.  If *ppVal is initially NULL then a new
1837 ** sqlite3_value object is allocated.
1838 **
1839 ** If *ppVal is initially NULL then the caller is responsible for
1840 ** ensuring that the value written into *ppVal is eventually freed.
1841 */
1842 int sqlite3Stat4Column(
1843   sqlite3 *db,                    /* Database handle */
1844   const void *pRec,               /* Pointer to buffer containing record */
1845   int nRec,                       /* Size of buffer pRec in bytes */
1846   int iCol,                       /* Column to extract */
1847   sqlite3_value **ppVal           /* OUT: Extracted value */
1848 ){
1849   u32 t = 0;                      /* a column type code */
1850   int nHdr;                       /* Size of the header in the record */
1851   int iHdr;                       /* Next unread header byte */
1852   int iField;                     /* Next unread data byte */
1853   int szField = 0;                /* Size of the current data field */
1854   int i;                          /* Column index */
1855   u8 *a = (u8*)pRec;              /* Typecast byte array */
1856   Mem *pMem = *ppVal;             /* Write result into this Mem object */
1857
1858   assert( iCol>0 );
1859   iHdr = getVarint32(a, nHdr);
1860   if( nHdr>nRec || iHdr>=nHdr ) return SQLITE_CORRUPT_BKPT;
1861   iField = nHdr;
1862   for(i=0; i<=iCol; i++){
1863     iHdr += getVarint32(&a[iHdr], t);
1864     testcase( iHdr==nHdr );
1865     testcase( iHdr==nHdr+1 );
1866     if( iHdr>nHdr ) return SQLITE_CORRUPT_BKPT;
1867     szField = sqlite3VdbeSerialTypeLen(t);
1868     iField += szField;
1869   }
1870   testcase( iField==nRec );
1871   testcase( iField==nRec+1 );
1872   if( iField>nRec ) return SQLITE_CORRUPT_BKPT;
1873   if( pMem==0 ){
1874     pMem = *ppVal = sqlite3ValueNew(db);
1875     if( pMem==0 ) return SQLITE_NOMEM_BKPT;
1876   }
1877   sqlite3VdbeSerialGet(&a[iField-szField], t, pMem);
1878   pMem->enc = ENC(db);
1879   return SQLITE_OK;
1880 }
1881
1882 /*
1883 ** Unless it is NULL, the argument must be an UnpackedRecord object returned
1884 ** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
1885 ** the object.
1886 */
1887 void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
1888   if( pRec ){
1889     int i;
1890     int nCol = pRec->pKeyInfo->nAllField;
1891     Mem *aMem = pRec->aMem;
1892     sqlite3 *db = aMem[0].db;
1893     for(i=0; i<nCol; i++){
1894       sqlite3VdbeMemRelease(&aMem[i]);
1895     }
1896     sqlite3KeyInfoUnref(pRec->pKeyInfo);
1897     sqlite3DbFreeNN(db, pRec);
1898   }
1899 }
1900 #endif /* ifdef SQLITE_ENABLE_STAT4 */
1901
1902 /*
1903 ** Change the string value of an sqlite3_value object
1904 */
1905 void sqlite3ValueSetStr(
1906   sqlite3_value *v,     /* Value to be set */
1907   int n,                /* Length of string z */
1908   const void *z,        /* Text of the new string */
1909   u8 enc,               /* Encoding to use */
1910   void (*xDel)(void*)   /* Destructor for the string */
1911 ){
1912   if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
1913 }
1914
1915 /*
1916 ** Free an sqlite3_value object
1917 */
1918 void sqlite3ValueFree(sqlite3_value *v){
1919   if( !v ) return;
1920   sqlite3VdbeMemRelease((Mem *)v);
1921   sqlite3DbFreeNN(((Mem*)v)->db, v);
1922 }
1923
1924 /*
1925 ** The sqlite3ValueBytes() routine returns the number of bytes in the
1926 ** sqlite3_value object assuming that it uses the encoding "enc".
1927 ** The valueBytes() routine is a helper function.
1928 */
1929 static SQLITE_NOINLINE int valueBytes(sqlite3_value *pVal, u8 enc){
1930   return valueToText(pVal, enc)!=0 ? pVal->n : 0;
1931 }
1932 int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
1933   Mem *p = (Mem*)pVal;
1934   assert( (p->flags & MEM_Null)==0 || (p->flags & (MEM_Str|MEM_Blob))==0 );
1935   if( (p->flags & MEM_Str)!=0 && pVal->enc==enc ){
1936     return p->n;
1937   }
1938   if( (p->flags & MEM_Blob)!=0 ){
1939     if( p->flags & MEM_Zero ){
1940       return p->n + p->u.nZero;
1941     }else{
1942       return p->n;
1943     }
1944   }
1945   if( p->flags & MEM_Null ) return 0;
1946   return valueBytes(pVal, enc);
1947 }