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->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc) );
  79
  80   /* If p holds a string or blob, the Mem.z must point to exactly
  81   ** one of the following:
  82   **
  83   **   (1) Memory in Mem.zMalloc and managed by the Mem object
  84   **   (2) Memory to be freed using Mem.xDel
  85   **   (3) An ephemeral string or blob
  86   **   (4) A static string or blob
  87   */
  88   if( (p->flags & (MEM_Str|MEM_Blob)) && p->n>0 ){
  89     assert(
  90       ((p->szMalloc>0 && p->z==p->zMalloc)? 1 : 0) +
  91       ((p->flags&MEM_Dyn)!=0 ? 1 : 0) +
  92       ((p->flags&MEM_Ephem)!=0 ? 1 : 0) +
  93       ((p->flags&MEM_Static)!=0 ? 1 : 0) == 1
  94     );
  95   }
  96   return 1;
  97 }
  98 #endif
  99
 100 /*
 101 ** Render a Mem object which is one of MEM_Int, MEM_Real, or MEM_IntReal
 102 ** into a buffer.
 103 */
 104 static void vdbeMemRenderNum(int sz, char *zBuf, Mem *p){
 105   StrAccum acc;
 106   assert( p->flags & (MEM_Int|MEM_Real|MEM_IntReal) );
 107   sqlite3StrAccumInit(&acc, 0, zBuf, sz, 0);
 108   if( p->flags & MEM_Int ){
 109     sqlite3_str_appendf(&acc, "%lld", p->u.i);
 110   }else if( p->flags & MEM_IntReal ){
 111     sqlite3_str_appendf(&acc, "%!.15g", (double)p->u.i);
 112   }else{
 113     sqlite3_str_appendf(&acc, "%!.15g", p->u.r);
 114   }
 115   assert( acc.zText==zBuf && acc.mxAlloc<=0 );
 116   zBuf[acc.nChar] = 0; /* Fast version of sqlite3StrAccumFinish(&acc) */
 117 }
 118
 119 #ifdef SQLITE_DEBUG
 120 /*
 121 ** Validity checks on pMem.  pMem holds a string.
 122 **
 123 ** (1) Check that string value of pMem agrees with its integer or real value.
 124 ** (2) Check that the string is correctly zero terminated
 125 **
 126 ** A single int or real value always converts to the same strings.  But
 127 ** many different strings can be converted into the same int or real.
 128 ** If a table contains a numeric value and an index is based on the
 129 ** corresponding string value, then it is important that the string be
 130 ** derived from the numeric value, not the other way around, to ensure
 131 ** that the index and table are consistent.  See ticket
 132 ** https://www.sqlite.org/src/info/343634942dd54ab (2018-01-31) for
 133 ** an example.
 134 **
 135 ** This routine looks at pMem to verify that if it has both a numeric
 136 ** representation and a string representation then the string rep has
 137 ** been derived from the numeric and not the other way around.  It returns
 138 ** true if everything is ok and false if there is a problem.
 139 **
 140 ** This routine is for use inside of assert() statements only.
 141 */
 142 int sqlite3VdbeMemValidStrRep(Mem *p){
 143   char zBuf[100];
 144   char *z;
 145   int i, j, incr;
 146   if( (p->flags & MEM_Str)==0 ) return 1;
 147   if( p->flags & MEM_Term ){
 148     /* Insure that the string is properly zero-terminated.  Pay particular
 149     ** attention to the case where p->n is odd */
 150     if( p->szMalloc>0 && p->z==p->zMalloc ){
 151       assert( p->enc==SQLITE_UTF8 || p->szMalloc >= ((p->n+1)&~1)+2 );
 152       assert( p->enc!=SQLITE_UTF8 || p->szMalloc >= p->n+1 );
 153     }
 154     assert( p->z[p->n]==0 );
 155     assert( p->enc==SQLITE_UTF8 || p->z[(p->n+1)&~1]==0 );
 156     assert( p->enc==SQLITE_UTF8 || p->z[((p->n+1)&~1)+1]==0 );
 157   }
 158   if( (p->flags & (MEM_Int|MEM_Real|MEM_IntReal))==0 ) return 1;
 159   vdbeMemRenderNum(sizeof(zBuf), zBuf, p);
 160   z = p->z;
 161   i = j = 0;
 162   incr = 1;
 163   if( p->enc!=SQLITE_UTF8 ){
 164     incr = 2;
 165     if( p->enc==SQLITE_UTF16BE ) z++;
 166   }
 167   while( zBuf[j] ){
 168     if( zBuf[j++]!=z[i] ) return 0;
 169     i += incr;
 170   }
 171   return 1;
 172 }
 173 #endif /* SQLITE_DEBUG */
 174
 175 /*
 176 ** If pMem is an object with a valid string representation, this routine
 177 ** ensures the internal encoding for the string representation is
 178 ** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
 179 **
 180 ** If pMem is not a string object, or the encoding of the string
 181 ** representation is already stored using the requested encoding, then this
 182 ** routine is a no-op.
 183 **
 184 ** SQLITE_OK is returned if the conversion is successful (or not required).
 185 ** SQLITE_NOMEM may be returned if a malloc() fails during conversion
 186 ** between formats.
 187 */
 188 int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
 189 #ifndef SQLITE_OMIT_UTF16
 190   int rc;
 191 #endif
 192   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 193   assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
 194            || desiredEnc==SQLITE_UTF16BE );
 195   if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
 196     return SQLITE_OK;
 197   }
 198   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 199 #ifdef SQLITE_OMIT_UTF16
 200   return SQLITE_ERROR;
 201 #else
 202
 203   /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
 204   ** then the encoding of the value may not have changed.
 205   */
 206   rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
 207   assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
 208   assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
 209   assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
 210   return rc;
 211 #endif
 212 }
 213
 214 /*
 215 ** Make sure pMem->z points to a writable allocation of at least n bytes.
 216 **
 217 ** If the bPreserve argument is true, then copy of the content of
 218 ** pMem->z into the new allocation.  pMem must be either a string or
 219 ** blob if bPreserve is true.  If bPreserve is false, any prior content
 220 ** in pMem->z is discarded.
 221 */
 222 SQLITE_NOINLINE int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
 223   assert( sqlite3VdbeCheckMemInvariants(pMem) );
 224   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 225   testcase( pMem->db==0 );
 226
 227   /* If the bPreserve flag is set to true, then the memory cell must already
 228   ** contain a valid string or blob value.  */
 229   assert( bPreserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
 230   testcase( bPreserve && pMem->z==0 );
 231
 232   assert( pMem->szMalloc==0
 233        || pMem->szMalloc==sqlite3DbMallocSize(pMem->db, pMem->zMalloc) );
 234   if( pMem->szMalloc>0 && bPreserve && pMem->z==pMem->zMalloc ){
 235     if( pMem->db ){
 236       pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
 237     }else{
 238       pMem->zMalloc = sqlite3Realloc(pMem->z, n);
 239       if( pMem->zMalloc==0 ) sqlite3_free(pMem->z);
 240       pMem->z = pMem->zMalloc;
 241     }
 242     bPreserve = 0;
 243   }else{
 244     if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 245     pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
 246   }
 247   if( pMem->zMalloc==0 ){
 248     sqlite3VdbeMemSetNull(pMem);
 249     pMem->z = 0;
 250     pMem->szMalloc = 0;
 251     return SQLITE_NOMEM_BKPT;
 252   }else{
 253     pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
 254   }
 255
 256   if( bPreserve && pMem->z ){
 257     assert( pMem->z!=pMem->zMalloc );
 258     memcpy(pMem->zMalloc, pMem->z, pMem->n);
 259   }
 260   if( (pMem->flags&MEM_Dyn)!=0 ){
 261     assert( pMem->xDel!=0 && pMem->xDel!=SQLITE_DYNAMIC );
 262     pMem->xDel((void *)(pMem->z));
 263   }
 264
 265   pMem->z = pMem->zMalloc;
 266   pMem->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Static);
 267   return SQLITE_OK;
 268 }
 269
 270 /*
 271 ** Change the pMem->zMalloc allocation to be at least szNew bytes.
 272 ** If pMem->zMalloc already meets or exceeds the requested size, this
 273 ** routine is a no-op.
 274 **
 275 ** Any prior string or blob content in the pMem object may be discarded.
 276 ** The pMem->xDel destructor is called, if it exists.  Though MEM_Str
 277 ** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, MEM_IntReal,
 278 ** and MEM_Null values are preserved.
 279 **
 280 ** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
 281 ** if unable to complete the resizing.
 282 */
 283 int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
 284   assert( CORRUPT_DB || szNew>0 );
 285   assert( (pMem->flags & MEM_Dyn)==0 || pMem->szMalloc==0 );
 286   if( pMem->szMalloc<szNew ){
 287     return sqlite3VdbeMemGrow(pMem, szNew, 0);
 288   }
 289   assert( (pMem->flags & MEM_Dyn)==0 );
 290   pMem->z = pMem->zMalloc;
 291   pMem->flags &= (MEM_Null|MEM_Int|MEM_Real|MEM_IntReal);
 292   return SQLITE_OK;
 293 }
 294
 295 /*
 296 ** It is already known that pMem contains an unterminated string.
 297 ** Add the zero terminator.
 298 **
 299 ** Three bytes of zero are added.  In this way, there is guaranteed
 300 ** to be a double-zero byte at an even byte boundary in order to
 301 ** terminate a UTF16 string, even if the initial size of the buffer
 302 ** is an odd number of bytes.
 303 */
 304 static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
 305   if( sqlite3VdbeMemGrow(pMem, pMem->n+3, 1) ){
 306     return SQLITE_NOMEM_BKPT;
 307   }
 308   pMem->z[pMem->n] = 0;
 309   pMem->z[pMem->n+1] = 0;
 310   pMem->z[pMem->n+2] = 0;
 311   pMem->flags |= MEM_Term;
 312   return SQLITE_OK;
 313 }
 314
 315 /*
 316 ** Change pMem so that its MEM_Str or MEM_Blob value is stored in
 317 ** MEM.zMalloc, where it can be safely written.
 318 **
 319 ** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
 320 */
 321 int sqlite3VdbeMemMakeWriteable(Mem *pMem){
 322   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 323   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 324   if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
 325     if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
 326     if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
 327       int rc = vdbeMemAddTerminator(pMem);
 328       if( rc ) return rc;
 329     }
 330   }
 331   pMem->flags &= ~MEM_Ephem;
 332 #ifdef SQLITE_DEBUG
 333   pMem->pScopyFrom = 0;
 334 #endif
 335
 336   return SQLITE_OK;
 337 }
 338
 339 /*
 340 ** If the given Mem* has a zero-filled tail, turn it into an ordinary
 341 ** blob stored in dynamically allocated space.
 342 */
 343 #ifndef SQLITE_OMIT_INCRBLOB
 344 int sqlite3VdbeMemExpandBlob(Mem *pMem){
 345   int nByte;
 346   assert( pMem->flags & MEM_Zero );
 347   assert( (pMem->flags&MEM_Blob)!=0 || MemNullNochng(pMem) );
 348   testcase( sqlite3_value_nochange(pMem) );
 349   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 350   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 351
 352   /* Set nByte to the number of bytes required to store the expanded blob. */
 353   nByte = pMem->n + pMem->u.nZero;
 354   if( nByte<=0 ){
 355     if( (pMem->flags & MEM_Blob)==0 ) return SQLITE_OK;
 356     nByte = 1;
 357   }
 358   if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
 359     return SQLITE_NOMEM_BKPT;
 360   }
 361
 362   memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
 363   pMem->n += pMem->u.nZero;
 364   pMem->flags &= ~(MEM_Zero|MEM_Term);
 365   return SQLITE_OK;
 366 }
 367 #endif
 368
 369 /*
 370 ** Make sure the given Mem is \u0000 terminated.
 371 */
 372 int sqlite3VdbeMemNulTerminate(Mem *pMem){
 373   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 374   testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
 375   testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
 376   if( (pMem->flags & (MEM_Term|MEM_Str))!=MEM_Str ){
 377     return SQLITE_OK;   /* Nothing to do */
 378   }else{
 379     return vdbeMemAddTerminator(pMem);
 380   }
 381 }
 382
 383 /*
 384 ** Add MEM_Str to the set of representations for the given Mem.  This
 385 ** routine is only called if pMem is a number of some kind, not a NULL
 386 ** or a BLOB.
 387 **
 388 ** Existing representations MEM_Int, MEM_Real, or MEM_IntReal are invalidated
 389 ** if bForce is true but are retained if bForce is false.
 390 **
 391 ** A MEM_Null value will never be passed to this function. This function is
 392 ** used for converting values to text for returning to the user (i.e. via
 393 ** sqlite3_value_text()), or for ensuring that values to be used as btree
 394 ** keys are strings. In the former case a NULL pointer is returned the
 395 ** user and the latter is an internal programming error.
 396 */
 397 int sqlite3VdbeMemStringify(Mem *pMem, u8 enc, u8 bForce){
 398   const int nByte = 32;
 399
 400   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 401   assert( !(pMem->flags&MEM_Zero) );
 402   assert( !(pMem->flags&(MEM_Str|MEM_Blob)) );
 403   assert( pMem->flags&(MEM_Int|MEM_Real|MEM_IntReal) );
 404   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 405   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 406
 407
 408   if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
 409     pMem->enc = 0;
 410     return SQLITE_NOMEM_BKPT;
 411   }
 412
 413   vdbeMemRenderNum(nByte, pMem->z, pMem);
 414   assert( pMem->z!=0 );
 415   pMem->n = sqlite3Strlen30NN(pMem->z);
 416   pMem->enc = SQLITE_UTF8;
 417   pMem->flags |= MEM_Str|MEM_Term;
 418   if( bForce ) pMem->flags &= ~(MEM_Int|MEM_Real|MEM_IntReal);
 419   sqlite3VdbeChangeEncoding(pMem, enc);
 420   return SQLITE_OK;
 421 }
 422
 423 /*
 424 ** Memory cell pMem contains the context of an aggregate function.
 425 ** This routine calls the finalize method for that function.  The
 426 ** result of the aggregate is stored back into pMem.
 427 **
 428 ** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
 429 ** otherwise.
 430 */
 431 int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
 432   sqlite3_context ctx;
 433   Mem t;
 434   assert( pFunc!=0 );
 435   assert( pFunc->xFinalize!=0 );
 436   assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
 437   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 438   memset(&ctx, 0, sizeof(ctx));
 439   memset(&t, 0, sizeof(t));
 440   t.flags = MEM_Null;
 441   t.db = pMem->db;
 442   ctx.pOut = &t;
 443   ctx.pMem = pMem;
 444   ctx.pFunc = pFunc;
 445   pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
 446   assert( (pMem->flags & MEM_Dyn)==0 );
 447   if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
 448   memcpy(pMem, &t, sizeof(t));
 449   return ctx.isError;
 450 }
 451
 452 /*
 453 ** Memory cell pAccum contains the context of an aggregate function.
 454 ** This routine calls the xValue method for that function and stores
 455 ** the results in memory cell pMem.
 456 **
 457 ** SQLITE_ERROR is returned if xValue() reports an error. SQLITE_OK
 458 ** otherwise.
 459 */
 460 #ifndef SQLITE_OMIT_WINDOWFUNC
 461 int sqlite3VdbeMemAggValue(Mem *pAccum, Mem *pOut, FuncDef *pFunc){
 462   sqlite3_context ctx;
 463   assert( pFunc!=0 );
 464   assert( pFunc->xValue!=0 );
 465   assert( (pAccum->flags & MEM_Null)!=0 || pFunc==pAccum->u.pDef );
 466   assert( pAccum->db==0 || sqlite3_mutex_held(pAccum->db->mutex) );
 467   memset(&ctx, 0, sizeof(ctx));
 468   sqlite3VdbeMemSetNull(pOut);
 469   ctx.pOut = pOut;
 470   ctx.pMem = pAccum;
 471   ctx.pFunc = pFunc;
 472   pFunc->xValue(&ctx);
 473   return ctx.isError;
 474 }
 475 #endif /* SQLITE_OMIT_WINDOWFUNC */
 476
 477 /*
 478 ** If the memory cell contains a value that must be freed by
 479 ** invoking the external callback in Mem.xDel, then this routine
 480 ** will free that value.  It also sets Mem.flags to MEM_Null.
 481 **
 482 ** This is a helper routine for sqlite3VdbeMemSetNull() and
 483 ** for sqlite3VdbeMemRelease().  Use those other routines as the
 484 ** entry point for releasing Mem resources.
 485 */
 486 static SQLITE_NOINLINE void vdbeMemClearExternAndSetNull(Mem *p){
 487   assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
 488   assert( VdbeMemDynamic(p) );
 489   if( p->flags&MEM_Agg ){
 490     sqlite3VdbeMemFinalize(p, p->u.pDef);
 491     assert( (p->flags & MEM_Agg)==0 );
 492     testcase( p->flags & MEM_Dyn );
 493   }
 494   if( p->flags&MEM_Dyn ){
 495     assert( p->xDel!=SQLITE_DYNAMIC && p->xDel!=0 );
 496     p->xDel((void *)p->z);
 497   }
 498   p->flags = MEM_Null;
 499 }
 500
 501 /*
 502 ** Release memory held by the Mem p, both external memory cleared
 503 ** by p->xDel and memory in p->zMalloc.
 504 **
 505 ** This is a helper routine invoked by sqlite3VdbeMemRelease() in
 506 ** the unusual case where there really is memory in p that needs
 507 ** to be freed.
 508 */
 509 static SQLITE_NOINLINE void vdbeMemClear(Mem *p){
 510   if( VdbeMemDynamic(p) ){
 511     vdbeMemClearExternAndSetNull(p);
 512   }
 513   if( p->szMalloc ){
 514     sqlite3DbFreeNN(p->db, p->zMalloc);
 515     p->szMalloc = 0;
 516   }
 517   p->z = 0;
 518 }
 519
 520 /*
 521 ** Release any memory resources held by the Mem.  Both the memory that is
 522 ** free by Mem.xDel and the Mem.zMalloc allocation are freed.
 523 **
 524 ** Use this routine prior to clean up prior to abandoning a Mem, or to
 525 ** reset a Mem back to its minimum memory utilization.
 526 **
 527 ** Use sqlite3VdbeMemSetNull() to release just the Mem.xDel space
 528 ** prior to inserting new content into the Mem.
 529 */
 530 void sqlite3VdbeMemRelease(Mem *p){
 531   assert( sqlite3VdbeCheckMemInvariants(p) );
 532   if( VdbeMemDynamic(p) || p->szMalloc ){
 533     vdbeMemClear(p);
 534   }
 535 }
 536
 537 /*
 538 ** Convert a 64-bit IEEE double into a 64-bit signed integer.
 539 ** If the double is out of range of a 64-bit signed integer then
 540 ** return the closest available 64-bit signed integer.
 541 */
 542 static SQLITE_NOINLINE i64 doubleToInt64(double r){
 543 #ifdef SQLITE_OMIT_FLOATING_POINT
 544   /* When floating-point is omitted, double and int64 are the same thing */
 545   return r;
 546 #else
 547   /*
 548   ** Many compilers we encounter do not define constants for the
 549   ** minimum and maximum 64-bit integers, or they define them
 550   ** inconsistently.  And many do not understand the "LL" notation.
 551   ** So we define our own static constants here using nothing
 552   ** larger than a 32-bit integer constant.
 553   */
 554   static const i64 maxInt = LARGEST_INT64;
 555   static const i64 minInt = SMALLEST_INT64;
 556
 557   if( r<=(double)minInt ){
 558     return minInt;
 559   }else if( r>=(double)maxInt ){
 560     return maxInt;
 561   }else{
 562     return (i64)r;
 563   }
 564 #endif
 565 }
 566
 567 /*
 568 ** Return some kind of integer value which is the best we can do
 569 ** at representing the value that *pMem describes as an integer.
 570 ** If pMem is an integer, then the value is exact.  If pMem is
 571 ** a floating-point then the value returned is the integer part.
 572 ** If pMem is a string or blob, then we make an attempt to convert
 573 ** it into an integer and return that.  If pMem represents an
 574 ** an SQL-NULL value, return 0.
 575 **
 576 ** If pMem represents a string value, its encoding might be changed.
 577 */
 578 static SQLITE_NOINLINE i64 memIntValue(Mem *pMem){
 579   i64 value = 0;
 580   sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
 581   return value;
 582 }
 583 i64 sqlite3VdbeIntValue(Mem *pMem){
 584   int flags;
 585   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 586   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 587   flags = pMem->flags;
 588   if( flags & (MEM_Int|MEM_IntReal) ){
 589     testcase( flags & MEM_IntReal );
 590     return pMem->u.i;
 591   }else if( flags & MEM_Real ){
 592     return doubleToInt64(pMem->u.r);
 593   }else if( (flags & (MEM_Str|MEM_Blob))!=0 && pMem->z!=0 ){
 594     return memIntValue(pMem);
 595   }else{
 596     return 0;
 597   }
 598 }
 599
 600 /*
 601 ** Return the best representation of pMem that we can get into a
 602 ** double.  If pMem is already a double or an integer, return its
 603 ** value.  If it is a string or blob, try to convert it to a double.
 604 ** If it is a NULL, return 0.0.
 605 */
 606 static SQLITE_NOINLINE double memRealValue(Mem *pMem){
 607   /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 608   double val = (double)0;
 609   sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
 610   return val;
 611 }
 612 double sqlite3VdbeRealValue(Mem *pMem){
 613   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 614   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 615   if( pMem->flags & MEM_Real ){
 616     return pMem->u.r;
 617   }else if( pMem->flags & (MEM_Int|MEM_IntReal) ){
 618     testcase( pMem->flags & MEM_IntReal );
 619     return (double)pMem->u.i;
 620   }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
 621     return memRealValue(pMem);
 622   }else{
 623     /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
 624     return (double)0;
 625   }
 626 }
 627
 628 /*
 629 ** Return 1 if pMem represents true, and return 0 if pMem represents false.
 630 ** Return the value ifNull if pMem is NULL.
 631 */
 632 int sqlite3VdbeBooleanValue(Mem *pMem, int ifNull){
 633   testcase( pMem->flags & MEM_IntReal );
 634   if( pMem->flags & (MEM_Int|MEM_IntReal) ) return pMem->u.i!=0;
 635   if( pMem->flags & MEM_Null ) return ifNull;
 636   return sqlite3VdbeRealValue(pMem)!=0.0;
 637 }
 638
 639 /*
 640 ** The MEM structure is already a MEM_Real.  Try to also make it a
 641 ** MEM_Int if we can.
 642 */
 643 void sqlite3VdbeIntegerAffinity(Mem *pMem){
 644   i64 ix;
 645   assert( pMem->flags & MEM_Real );
 646   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 647   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 648   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 649
 650   ix = doubleToInt64(pMem->u.r);
 651
 652   /* Only mark the value as an integer if
 653   **
 654   **    (1) the round-trip conversion real->int->real is a no-op, and
 655   **    (2) The integer is neither the largest nor the smallest
 656   **        possible integer (ticket #3922)
 657   **
 658   ** The second and third terms in the following conditional enforces
 659   ** the second condition under the assumption that addition overflow causes
 660   ** values to wrap around.
 661   */
 662   if( pMem->u.r==ix && ix>SMALLEST_INT64 && ix<LARGEST_INT64 ){
 663     pMem->u.i = ix;
 664     MemSetTypeFlag(pMem, MEM_Int);
 665   }
 666 }
 667
 668 /*
 669 ** Convert pMem to type integer.  Invalidate any prior representations.
 670 */
 671 int sqlite3VdbeMemIntegerify(Mem *pMem){
 672   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 673   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 674   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 675
 676   pMem->u.i = sqlite3VdbeIntValue(pMem);
 677   MemSetTypeFlag(pMem, MEM_Int);
 678   return SQLITE_OK;
 679 }
 680
 681 /*
 682 ** Convert pMem so that it is of type MEM_Real.
 683 ** Invalidate any prior representations.
 684 */
 685 int sqlite3VdbeMemRealify(Mem *pMem){
 686   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 687   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 688
 689   pMem->u.r = sqlite3VdbeRealValue(pMem);
 690   MemSetTypeFlag(pMem, MEM_Real);
 691   return SQLITE_OK;
 692 }
 693
 694 /* Compare a floating point value to an integer.  Return true if the two
 695 ** values are the same within the precision of the floating point value.
 696 **
 697 ** This function assumes that i was obtained by assignment from r1.
 698 **
 699 ** For some versions of GCC on 32-bit machines, if you do the more obvious
 700 ** comparison of "r1==(double)i" you sometimes get an answer of false even
 701 ** though the r1 and (double)i values are bit-for-bit the same.
 702 */
 703 int sqlite3RealSameAsInt(double r1, sqlite3_int64 i){
 704   double r2 = (double)i;
 705   return r1==0.0
 706       || (memcmp(&r1, &r2, sizeof(r1))==0
 707           && i >= -2251799813685248LL && i < 2251799813685248LL);
 708 }
 709
 710 /*
 711 ** Convert pMem so that it has type MEM_Real or MEM_Int.
 712 ** Invalidate any prior representations.
 713 **
 714 ** Every effort is made to force the conversion, even if the input
 715 ** is a string that does not look completely like a number.  Convert
 716 ** as much of the string as we can and ignore the rest.
 717 */
 718 int sqlite3VdbeMemNumerify(Mem *pMem){
 719   testcase( pMem->flags & MEM_Int );
 720   testcase( pMem->flags & MEM_Real );
 721   testcase( pMem->flags & MEM_IntReal );
 722   testcase( pMem->flags & MEM_Null );
 723   if( (pMem->flags & (MEM_Int|MEM_Real|MEM_IntReal|MEM_Null))==0 ){
 724     int rc;
 725     sqlite3_int64 ix;
 726     assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
 727     assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
 728     rc = sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
 729     if( ((rc==0 || rc==1) && sqlite3Atoi64(pMem->z, &ix, pMem->n, pMem->enc)<=1)
 730      || sqlite3RealSameAsInt(pMem->u.r, (ix = (i64)pMem->u.r))
 731     ){
 732       pMem->u.i = ix;
 733       MemSetTypeFlag(pMem, MEM_Int);
 734     }else{
 735       MemSetTypeFlag(pMem, MEM_Real);
 736     }
 737   }
 738   assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_IntReal|MEM_Null))!=0 );
 739   pMem->flags &= ~(MEM_Str|MEM_Blob|MEM_Zero);
 740   return SQLITE_OK;
 741 }
 742
 743 /*
 744 ** Cast the datatype of the value in pMem according to the affinity
 745 ** "aff".  Casting is different from applying affinity in that a cast
 746 ** is forced.  In other words, the value is converted into the desired
 747 ** affinity even if that results in loss of data.  This routine is
 748 ** used (for example) to implement the SQL "cast()" operator.
 749 */
 750 int sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
 751   if( pMem->flags & MEM_Null ) return SQLITE_OK;
 752   switch( aff ){
 753     case SQLITE_AFF_BLOB: {   /* Really a cast to BLOB */
 754       if( (pMem->flags & MEM_Blob)==0 ){
 755         sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 756         assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 757         if( pMem->flags & MEM_Str ) MemSetTypeFlag(pMem, MEM_Blob);
 758       }else{
 759         pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
 760       }
 761       break;
 762     }
 763     case SQLITE_AFF_NUMERIC: {
 764       sqlite3VdbeMemNumerify(pMem);
 765       break;
 766     }
 767     case SQLITE_AFF_INTEGER: {
 768       sqlite3VdbeMemIntegerify(pMem);
 769       break;
 770     }
 771     case SQLITE_AFF_REAL: {
 772       sqlite3VdbeMemRealify(pMem);
 773       break;
 774     }
 775     default: {
 776       assert( aff==SQLITE_AFF_TEXT );
 777       assert( MEM_Str==(MEM_Blob>>3) );
 778       pMem->flags |= (pMem->flags&MEM_Blob)>>3;
 779       sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
 780       assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
 781       pMem->flags &= ~(MEM_Int|MEM_Real|MEM_IntReal|MEM_Blob|MEM_Zero);
 782       return sqlite3VdbeChangeEncoding(pMem, encoding);
 783     }
 784   }
 785   return SQLITE_OK;
 786 }
 787
 788 /*
 789 ** Initialize bulk memory to be a consistent Mem object.
 790 **
 791 ** The minimum amount of initialization feasible is performed.
 792 */
 793 void sqlite3VdbeMemInit(Mem *pMem, sqlite3 *db, u16 flags){
 794   assert( (flags & ~MEM_TypeMask)==0 );
 795   pMem->flags = flags;
 796   pMem->db = db;
 797   pMem->szMalloc = 0;
 798 }
 799
 800
 801 /*
 802 ** Delete any previous value and set the value stored in *pMem to NULL.
 803 **
 804 ** This routine calls the Mem.xDel destructor to dispose of values that
 805 ** require the destructor.  But it preserves the Mem.zMalloc memory allocation.
 806 ** To free all resources, use sqlite3VdbeMemRelease(), which both calls this
 807 ** routine to invoke the destructor and deallocates Mem.zMalloc.
 808 **
 809 ** Use this routine to reset the Mem prior to insert a new value.
 810 **
 811 ** Use sqlite3VdbeMemRelease() to complete erase the Mem prior to abandoning it.
 812 */
 813 void sqlite3VdbeMemSetNull(Mem *pMem){
 814   if( VdbeMemDynamic(pMem) ){
 815     vdbeMemClearExternAndSetNull(pMem);
 816   }else{
 817     pMem->flags = MEM_Null;
 818   }
 819 }
 820 void sqlite3ValueSetNull(sqlite3_value *p){
 821   sqlite3VdbeMemSetNull((Mem*)p);
 822 }
 823
 824 /*
 825 ** Delete any previous value and set the value to be a BLOB of length
 826 ** n containing all zeros.
 827 */
 828 void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
 829   sqlite3VdbeMemRelease(pMem);
 830   pMem->flags = MEM_Blob|MEM_Zero;
 831   pMem->n = 0;
 832   if( n<0 ) n = 0;
 833   pMem->u.nZero = n;
 834   pMem->enc = SQLITE_UTF8;
 835   pMem->z = 0;
 836 }
 837
 838 /*
 839 ** The pMem is known to contain content that needs to be destroyed prior
 840 ** to a value change.  So invoke the destructor, then set the value to
 841 ** a 64-bit integer.
 842 */
 843 static SQLITE_NOINLINE void vdbeReleaseAndSetInt64(Mem *pMem, i64 val){
 844   sqlite3VdbeMemSetNull(pMem);
 845   pMem->u.i = val;
 846   pMem->flags = MEM_Int;
 847 }
 848
 849 /*
 850 ** Delete any previous value and set the value stored in *pMem to val,
 851 ** manifest type INTEGER.
 852 */
 853 void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
 854   if( VdbeMemDynamic(pMem) ){
 855     vdbeReleaseAndSetInt64(pMem, val);
 856   }else{
 857     pMem->u.i = val;
 858     pMem->flags = MEM_Int;
 859   }
 860 }
 861
 862 /* A no-op destructor */
 863 void sqlite3NoopDestructor(void *p){ UNUSED_PARAMETER(p); }
 864
 865 /*
 866 ** Set the value stored in *pMem should already be a NULL.
 867 ** Also store a pointer to go with it.
 868 */
 869 void sqlite3VdbeMemSetPointer(
 870   Mem *pMem,
 871   void *pPtr,
 872   const char *zPType,
 873   void (*xDestructor)(void*)
 874 ){
 875   assert( pMem->flags==MEM_Null );
 876   pMem->u.zPType = zPType ? zPType : "";
 877   pMem->z = pPtr;
 878   pMem->flags = MEM_Null|MEM_Dyn|MEM_Subtype|MEM_Term;
 879   pMem->eSubtype = 'p';
 880   pMem->xDel = xDestructor ? xDestructor : sqlite3NoopDestructor;
 881 }
 882
 883 #ifndef SQLITE_OMIT_FLOATING_POINT
 884 /*
 885 ** Delete any previous value and set the value stored in *pMem to val,
 886 ** manifest type REAL.
 887 */
 888 void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
 889   sqlite3VdbeMemSetNull(pMem);
 890   if( !sqlite3IsNaN(val) ){
 891     pMem->u.r = val;
 892     pMem->flags = MEM_Real;
 893   }
 894 }
 895 #endif
 896
 897 #ifdef SQLITE_DEBUG
 898 /*
 899 ** Return true if the Mem holds a RowSet object.  This routine is intended
 900 ** for use inside of assert() statements.
 901 */
 902 int sqlite3VdbeMemIsRowSet(const Mem *pMem){
 903   return (pMem->flags&(MEM_Blob|MEM_Dyn))==(MEM_Blob|MEM_Dyn)
 904          && pMem->xDel==sqlite3RowSetDelete;
 905 }
 906 #endif
 907
 908 /*
 909 ** Delete any previous value and set the value of pMem to be an
 910 ** empty boolean index.
 911 **
 912 ** Return SQLITE_OK on success and SQLITE_NOMEM if a memory allocation
 913 ** error occurs.
 914 */
 915 int sqlite3VdbeMemSetRowSet(Mem *pMem){
 916   sqlite3 *db = pMem->db;
 917   RowSet *p;
 918   assert( db!=0 );
 919   assert( !sqlite3VdbeMemIsRowSet(pMem) );
 920   sqlite3VdbeMemRelease(pMem);
 921   p = sqlite3RowSetInit(db);
 922   if( p==0 ) return SQLITE_NOMEM;
 923   pMem->z = (char*)p;
 924   pMem->flags = MEM_Blob|MEM_Dyn;
 925   pMem->xDel = sqlite3RowSetDelete;
 926   return SQLITE_OK;
 927 }
 928
 929 /*
 930 ** Return true if the Mem object contains a TEXT or BLOB that is
 931 ** too large - whose size exceeds SQLITE_MAX_LENGTH.
 932 */
 933 int sqlite3VdbeMemTooBig(Mem *p){
 934   assert( p->db!=0 );
 935   if( p->flags & (MEM_Str|MEM_Blob) ){
 936     int n = p->n;
 937     if( p->flags & MEM_Zero ){
 938       n += p->u.nZero;
 939     }
 940     return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
 941   }
 942   return 0;
 943 }
 944
 945 #ifdef SQLITE_DEBUG
 946 /*
 947 ** This routine prepares a memory cell for modification by breaking
 948 ** its link to a shallow copy and by marking any current shallow
 949 ** copies of this cell as invalid.
 950 **
 951 ** This is used for testing and debugging only - to help ensure that shallow
 952 ** copies (created by OP_SCopy) are not misused.
 953 */
 954 void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
 955   int i;
 956   Mem *pX;
 957   for(i=1, pX=pVdbe->aMem+1; i<pVdbe->nMem; i++, pX++){
 958     if( pX->pScopyFrom==pMem ){
 959       u16 mFlags;
 960       if( pVdbe->db->flags & SQLITE_VdbeTrace ){
 961         sqlite3DebugPrintf("Invalidate R[%d] due to change in R[%d]\n",
 962           (int)(pX - pVdbe->aMem), (int)(pMem - pVdbe->aMem));
 963       }
 964       /* If pX is marked as a shallow copy of pMem, then verify that
 965       ** no significant changes have been made to pX since the OP_SCopy.
 966       ** A significant change would indicated a missed call to this
 967       ** function for pX.  Minor changes, such as adding or removing a
 968       ** dual type, are allowed, as long as the underlying value is the
 969       ** same. */
 970       mFlags = pMem->flags & pX->flags & pX->mScopyFlags;
 971       assert( (mFlags&(MEM_Int|MEM_IntReal))==0 || pMem->u.i==pX->u.i );
 972       /* assert( (mFlags&MEM_Real)==0 || pMem->u.r==pX->u.r ); */
 973       /*                                          ^^           */
 974       /*       Cannot reliably compare doubles for equality    */
 975       assert( (mFlags&MEM_Str)==0  || (pMem->n==pX->n && pMem->z==pX->z) );
 976       assert( (mFlags&MEM_Blob)==0  || sqlite3BlobCompare(pMem,pX)==0 );
 977
 978       /* pMem is the register that is changing.  But also mark pX as
 979       ** undefined so that we can quickly detect the shallow-copy error */
 980       pX->flags = MEM_Undefined;
 981       pX->pScopyFrom = 0;
 982     }
 983   }
 984   pMem->pScopyFrom = 0;
 985 }
 986 #endif /* SQLITE_DEBUG */
 987
 988 /*
 989 ** Make an shallow copy of pFrom into pTo.  Prior contents of
 990 ** pTo are freed.  The pFrom->z field is not duplicated.  If
 991 ** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
 992 ** and flags gets srcType (either MEM_Ephem or MEM_Static).
 993 */
 994 static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){
 995   vdbeMemClearExternAndSetNull(pTo);
 996   assert( !VdbeMemDynamic(pTo) );
 997   sqlite3VdbeMemShallowCopy(pTo, pFrom, eType);
 998 }
 999 void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
1000   assert( !sqlite3VdbeMemIsRowSet(pFrom) );
1001   assert( pTo->db==pFrom->db );
1002   if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; }
1003   memcpy(pTo, pFrom, MEMCELLSIZE);
1004   if( (pFrom->flags&MEM_Static)==0 ){
1005     pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
1006     assert( srcType==MEM_Ephem || srcType==MEM_Static );
1007     pTo->flags |= srcType;
1008   }
1009 }
1010
1011 /*
1012 ** Make a full copy of pFrom into pTo.  Prior contents of pTo are
1013 ** freed before the copy is made.
1014 */
1015 int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
1016   int rc = SQLITE_OK;
1017
1018   assert( !sqlite3VdbeMemIsRowSet(pFrom) );
1019   if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
1020   memcpy(pTo, pFrom, MEMCELLSIZE);
1021   pTo->flags &= ~MEM_Dyn;
1022   if( pTo->flags&(MEM_Str|MEM_Blob) ){
1023     if( 0==(pFrom->flags&MEM_Static) ){
1024       pTo->flags |= MEM_Ephem;
1025       rc = sqlite3VdbeMemMakeWriteable(pTo);
1026     }
1027   }
1028
1029   return rc;
1030 }
1031
1032 /*
1033 ** Transfer the contents of pFrom to pTo. Any existing value in pTo is
1034 ** freed. If pFrom contains ephemeral data, a copy is made.
1035 **
1036 ** pFrom contains an SQL NULL when this routine returns.
1037 */
1038 void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
1039   assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
1040   assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
1041   assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
1042
1043   sqlite3VdbeMemRelease(pTo);
1044   memcpy(pTo, pFrom, sizeof(Mem));
1045   pFrom->flags = MEM_Null;
1046   pFrom->szMalloc = 0;
1047 }
1048
1049 /*
1050 ** Change the value of a Mem to be a string or a BLOB.
1051 **
1052 ** The memory management strategy depends on the value of the xDel
1053 ** parameter. If the value passed is SQLITE_TRANSIENT, then the
1054 ** string is copied into a (possibly existing) buffer managed by the
1055 ** Mem structure. Otherwise, any existing buffer is freed and the
1056 ** pointer copied.
1057 **
1058 ** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
1059 ** size limit) then no memory allocation occurs.  If the string can be
1060 ** stored without allocating memory, then it is.  If a memory allocation
1061 ** is required to store the string, then value of pMem is unchanged.  In
1062 ** either case, SQLITE_TOOBIG is returned.
1063 */
1064 int sqlite3VdbeMemSetStr(
1065   Mem *pMem,          /* Memory cell to set to string value */
1066   const char *z,      /* String pointer */
1067   int n,              /* Bytes in string, or negative */
1068   u8 enc,             /* Encoding of z.  0 for BLOBs */
1069   void (*xDel)(void*) /* Destructor function */
1070 ){
1071   int nByte = n;      /* New value for pMem->n */
1072   int iLimit;         /* Maximum allowed string or blob size */
1073   u16 flags = 0;      /* New value for pMem->flags */
1074
1075   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
1076   assert( !sqlite3VdbeMemIsRowSet(pMem) );
1077
1078   /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
1079   if( !z ){
1080     sqlite3VdbeMemSetNull(pMem);
1081     return SQLITE_OK;
1082   }
1083
1084   if( pMem->db ){
1085     iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
1086   }else{
1087     iLimit = SQLITE_MAX_LENGTH;
1088   }
1089   flags = (enc==0?MEM_Blob:MEM_Str);
1090   if( nByte<0 ){
1091     assert( enc!=0 );
1092     if( enc==SQLITE_UTF8 ){
1093       nByte = 0x7fffffff & (int)strlen(z);
1094     }else{
1095       for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
1096     }
1097     flags |= MEM_Term;
1098   }
1099
1100   /* The following block sets the new values of Mem.z and Mem.xDel. It
1101   ** also sets a flag in local variable "flags" to indicate the memory
1102   ** management (one of MEM_Dyn or MEM_Static).
1103   */
1104   if( xDel==SQLITE_TRANSIENT ){
1105     u32 nAlloc = nByte;
1106     if( flags&MEM_Term ){
1107       nAlloc += (enc==SQLITE_UTF8?1:2);
1108     }
1109     if( nByte>iLimit ){
1110       return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
1111     }
1112     testcase( nAlloc==0 );
1113     testcase( nAlloc==31 );
1114     testcase( nAlloc==32 );
1115     if( sqlite3VdbeMemClearAndResize(pMem, (int)MAX(nAlloc,32)) ){
1116       return SQLITE_NOMEM_BKPT;
1117     }
1118     memcpy(pMem->z, z, nAlloc);
1119   }else{
1120     sqlite3VdbeMemRelease(pMem);
1121     pMem->z = (char *)z;
1122     if( xDel==SQLITE_DYNAMIC ){
1123       pMem->zMalloc = pMem->z;
1124       pMem->szMalloc = sqlite3DbMallocSize(pMem->db, pMem->zMalloc);
1125     }else{
1126       pMem->xDel = xDel;
1127       flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
1128     }
1129   }
1130
1131   pMem->n = nByte;
1132   pMem->flags = flags;
1133   if( enc ){
1134     pMem->enc = enc;
1135 #ifdef SQLITE_ENABLE_SESSION
1136   }else if( pMem->db==0 ){
1137     pMem->enc = SQLITE_UTF8;
1138 #endif
1139   }else{
1140     assert( pMem->db!=0 );
1141     pMem->enc = ENC(pMem->db);
1142   }
1143
1144 #ifndef SQLITE_OMIT_UTF16
1145   if( enc>SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
1146     return SQLITE_NOMEM_BKPT;
1147   }
1148 #endif
1149
1150   if( nByte>iLimit ){
1151     return SQLITE_TOOBIG;
1152   }
1153
1154   return SQLITE_OK;
1155 }
1156
1157 /*
1158 ** Move data out of a btree key or data field and into a Mem structure.
1159 ** The data is payload from the entry that pCur is currently pointing
1160 ** to.  offset and amt determine what portion of the data or key to retrieve.
1161 ** The result is written into the pMem element.
1162 **
1163 ** The pMem object must have been initialized.  This routine will use
1164 ** pMem->zMalloc to hold the content from the btree, if possible.  New
1165 ** pMem->zMalloc space will be allocated if necessary.  The calling routine
1166 ** is responsible for making sure that the pMem object is eventually
1167 ** destroyed.
1168 **
1169 ** If this routine fails for any reason (malloc returns NULL or unable
1170 ** to read from the disk) then the pMem is left in an inconsistent state.
1171 */
1172 int sqlite3VdbeMemFromBtree(
1173   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1174   u32 offset,       /* Offset from the start of data to return bytes from. */
1175   u32 amt,          /* Number of bytes to return. */
1176   Mem *pMem         /* OUT: Return data in this Mem structure. */
1177 ){
1178   int rc;
1179   pMem->flags = MEM_Null;
1180   if( sqlite3BtreeMaxRecordSize(pCur)<offset+amt ){
1181     return SQLITE_CORRUPT_BKPT;
1182   }
1183   if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+1)) ){
1184     rc = sqlite3BtreePayload(pCur, offset, amt, pMem->z);
1185     if( rc==SQLITE_OK ){
1186       pMem->z[amt] = 0;   /* Overrun area used when reading malformed records */
1187       pMem->flags = MEM_Blob;
1188       pMem->n = (int)amt;
1189     }else{
1190       sqlite3VdbeMemRelease(pMem);
1191     }
1192   }
1193   return rc;
1194 }
1195 int sqlite3VdbeMemFromBtreeZeroOffset(
1196   BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
1197   u32 amt,          /* Number of bytes to return. */
1198   Mem *pMem         /* OUT: Return data in this Mem structure. */
1199 ){
1200   u32 available = 0;  /* Number of bytes available on the local btree page */
1201   int rc = SQLITE_OK; /* Return code */
1202
1203   assert( sqlite3BtreeCursorIsValid(pCur) );
1204   assert( !VdbeMemDynamic(pMem) );
1205
1206   /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert()
1207   ** that both the BtShared and database handle mutexes are held. */
1208   assert( !sqlite3VdbeMemIsRowSet(pMem) );
1209   pMem->z = (char *)sqlite3BtreePayloadFetch(pCur, &available);
1210   assert( pMem->z!=0 );
1211
1212   if( amt<=available ){
1213     pMem->flags = MEM_Blob|MEM_Ephem;
1214     pMem->n = (int)amt;
1215   }else{
1216     rc = sqlite3VdbeMemFromBtree(pCur, 0, amt, pMem);
1217   }
1218
1219   return rc;
1220 }
1221
1222 /*
1223 ** The pVal argument is known to be a value other than NULL.
1224 ** Convert it into a string with encoding enc and return a pointer
1225 ** to a zero-terminated version of that string.
1226 */
1227 static SQLITE_NOINLINE const void *valueToText(sqlite3_value* pVal, u8 enc){
1228   assert( pVal!=0 );
1229   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1230   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1231   assert( !sqlite3VdbeMemIsRowSet(pVal) );
1232   assert( (pVal->flags & (MEM_Null))==0 );
1233   if( pVal->flags & (MEM_Blob|MEM_Str) ){
1234     if( ExpandBlob(pVal) ) return 0;
1235     pVal->flags |= MEM_Str;
1236     if( pVal->enc != (enc & ~SQLITE_UTF16_ALIGNED) ){
1237       sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
1238     }
1239     if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
1240       assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
1241       if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
1242         return 0;
1243       }
1244     }
1245     sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-31275-44060 */
1246   }else{
1247     sqlite3VdbeMemStringify(pVal, enc, 0);
1248     assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
1249   }
1250   assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
1251               || pVal->db->mallocFailed );
1252   if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
1253     assert( sqlite3VdbeMemValidStrRep(pVal) );
1254     return pVal->z;
1255   }else{
1256     return 0;
1257   }
1258 }
1259
1260 /* This function is only available internally, it is not part of the
1261 ** external API. It works in a similar way to sqlite3_value_text(),
1262 ** except the data returned is in the encoding specified by the second
1263 ** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
1264 ** SQLITE_UTF8.
1265 **
1266 ** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
1267 ** If that is the case, then the result must be aligned on an even byte
1268 ** boundary.
1269 */
1270 const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
1271   if( !pVal ) return 0;
1272   assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
1273   assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
1274   assert( !sqlite3VdbeMemIsRowSet(pVal) );
1275   if( (pVal->flags&(MEM_Str|MEM_Term))==(MEM_Str|MEM_Term) && pVal->enc==enc ){
1276     assert( sqlite3VdbeMemValidStrRep(pVal) );
1277     return pVal->z;
1278   }
1279   if( pVal->flags&MEM_Null ){
1280     return 0;
1281   }
1282   return valueToText(pVal, enc);
1283 }
1284
1285 /*
1286 ** Create a new sqlite3_value object.
1287 */
1288 sqlite3_value *sqlite3ValueNew(sqlite3 *db){
1289   Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
1290   if( p ){
1291     p->flags = MEM_Null;
1292     p->db = db;
1293   }
1294   return p;
1295 }
1296
1297 /*
1298 ** Context object passed by sqlite3Stat4ProbeSetValue() through to
1299 ** valueNew(). See comments above valueNew() for details.
1300 */
1301 struct ValueNewStat4Ctx {
1302   Parse *pParse;
1303   Index *pIdx;
1304   UnpackedRecord **ppRec;
1305   int iVal;
1306 };
1307
1308 /*
1309 ** Allocate and return a pointer to a new sqlite3_value object. If
1310 ** the second argument to this function is NULL, the object is allocated
1311 ** by calling sqlite3ValueNew().
1312 **
1313 ** Otherwise, if the second argument is non-zero, then this function is
1314 ** being called indirectly by sqlite3Stat4ProbeSetValue(). If it has not
1315 ** already been allocated, allocate the UnpackedRecord structure that
1316 ** that function will return to its caller here. Then return a pointer to
1317 ** an sqlite3_value within the UnpackedRecord.a[] array.
1318 */
1319 static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
1320 #ifdef SQLITE_ENABLE_STAT4
1321   if( p ){
1322     UnpackedRecord *pRec = p->ppRec[0];
1323
1324     if( pRec==0 ){
1325       Index *pIdx = p->pIdx;      /* Index being probed */
1326       int nByte;                  /* Bytes of space to allocate */
1327       int i;                      /* Counter variable */
1328       int nCol = pIdx->nColumn;   /* Number of index columns including rowid */
1329
1330       nByte = sizeof(Mem) * nCol + ROUND8(sizeof(UnpackedRecord));
1331       pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
1332       if( pRec ){
1333         pRec->pKeyInfo = sqlite3KeyInfoOfIndex(p->pParse, pIdx);
1334         if( pRec->pKeyInfo ){
1335           assert( pRec->pKeyInfo->nAllField==nCol );
1336           assert( pRec->pKeyInfo->enc==ENC(db) );
1337           pRec->aMem = (Mem *)((u8*)pRec + ROUND8(sizeof(UnpackedRecord)));
1338           for(i=0; i<nCol; i++){
1339             pRec->aMem[i].flags = MEM_Null;
1340             pRec->aMem[i].db = db;
1341           }
1342         }else{
1343           sqlite3DbFreeNN(db, pRec);
1344           pRec = 0;
1345         }
1346       }
1347       if( pRec==0 ) return 0;
1348       p->ppRec[0] = pRec;
1349     }
1350
1351     pRec->nField = p->iVal+1;
1352     return &pRec->aMem[p->iVal];
1353   }
1354 #else
1355   UNUSED_PARAMETER(p);
1356 #endif /* defined(SQLITE_ENABLE_STAT4) */
1357   return sqlite3ValueNew(db);
1358 }
1359
1360 /*
1361 ** The expression object indicated by the second argument is guaranteed
1362 ** to be a scalar SQL function. If
1363 **
1364 **   * all function arguments are SQL literals,
1365 **   * one of the SQLITE_FUNC_CONSTANT or _SLOCHNG function flags is set, and
1366 **   * the SQLITE_FUNC_NEEDCOLL function flag is not set,
1367 **
1368 ** then this routine attempts to invoke the SQL function. Assuming no
1369 ** error occurs, output parameter (*ppVal) is set to point to a value
1370 ** object containing the result before returning SQLITE_OK.
1371 **
1372 ** Affinity aff is applied to the result of the function before returning.
1373 ** If the result is a text value, the sqlite3_value object uses encoding
1374 ** enc.
1375 **
1376 ** If the conditions above are not met, this function returns SQLITE_OK
1377 ** and sets (*ppVal) to NULL. Or, if an error occurs, (*ppVal) is set to
1378 ** NULL and an SQLite error code returned.
1379 */
1380 #ifdef SQLITE_ENABLE_STAT4
1381 static int valueFromFunction(
1382   sqlite3 *db,                    /* The database connection */
1383   Expr *p,                        /* The expression to evaluate */
1384   u8 enc,                         /* Encoding to use */
1385   u8 aff,                         /* Affinity to use */
1386   sqlite3_value **ppVal,          /* Write the new value here */
1387   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1388 ){
1389   sqlite3_context ctx;            /* Context object for function invocation */
1390   sqlite3_value **apVal = 0;      /* Function arguments */
1391   int nVal = 0;                   /* Size of apVal[] array */
1392   FuncDef *pFunc = 0;             /* Function definition */
1393   sqlite3_value *pVal = 0;        /* New value */
1394   int rc = SQLITE_OK;             /* Return code */
1395   ExprList *pList = 0;            /* Function arguments */
1396   int i;                          /* Iterator variable */
1397
1398   assert( pCtx!=0 );
1399   assert( (p->flags & EP_TokenOnly)==0 );
1400   pList = p->x.pList;
1401   if( pList ) nVal = pList->nExpr;
1402   pFunc = sqlite3FindFunction(db, p->u.zToken, nVal, enc, 0);
1403   assert( pFunc );
1404   if( (pFunc->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0
1405    || (pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
1406   ){
1407     return SQLITE_OK;
1408   }
1409
1410   if( pList ){
1411     apVal = (sqlite3_value**)sqlite3DbMallocZero(db, sizeof(apVal[0]) * nVal);
1412     if( apVal==0 ){
1413       rc = SQLITE_NOMEM_BKPT;
1414       goto value_from_function_out;
1415     }
1416     for(i=0; i<nVal; i++){
1417       rc = sqlite3ValueFromExpr(db, pList->a[i].pExpr, enc, aff, &apVal[i]);
1418       if( apVal[i]==0 || rc!=SQLITE_OK ) goto value_from_function_out;
1419     }
1420   }
1421
1422   pVal = valueNew(db, pCtx);
1423   if( pVal==0 ){
1424     rc = SQLITE_NOMEM_BKPT;
1425     goto value_from_function_out;
1426   }
1427
1428   assert( pCtx->pParse->rc==SQLITE_OK );
1429   memset(&ctx, 0, sizeof(ctx));
1430   ctx.pOut = pVal;
1431   ctx.pFunc = pFunc;
1432   pFunc->xSFunc(&ctx, nVal, apVal);
1433   if( ctx.isError ){
1434     rc = ctx.isError;
1435     sqlite3ErrorMsg(pCtx->pParse, "%s", sqlite3_value_text(pVal));
1436   }else{
1437     sqlite3ValueApplyAffinity(pVal, aff, SQLITE_UTF8);
1438     assert( rc==SQLITE_OK );
1439     rc = sqlite3VdbeChangeEncoding(pVal, enc);
1440     if( rc==SQLITE_OK && sqlite3VdbeMemTooBig(pVal) ){
1441       rc = SQLITE_TOOBIG;
1442       pCtx->pParse->nErr++;
1443     }
1444   }
1445   pCtx->pParse->rc = rc;
1446
1447  value_from_function_out:
1448   if( rc!=SQLITE_OK ){
1449     pVal = 0;
1450   }
1451   if( apVal ){
1452     for(i=0; i<nVal; i++){
1453       sqlite3ValueFree(apVal[i]);
1454     }
1455     sqlite3DbFreeNN(db, apVal);
1456   }
1457
1458   *ppVal = pVal;
1459   return rc;
1460 }
1461 #else
1462 # define valueFromFunction(a,b,c,d,e,f) SQLITE_OK
1463 #endif /* defined(SQLITE_ENABLE_STAT4) */
1464
1465 /*
1466 ** Extract a value from the supplied expression in the manner described
1467 ** above sqlite3ValueFromExpr(). Allocate the sqlite3_value object
1468 ** using valueNew().
1469 **
1470 ** If pCtx is NULL and an error occurs after the sqlite3_value object
1471 ** has been allocated, it is freed before returning. Or, if pCtx is not
1472 ** NULL, it is assumed that the caller will free any allocated object
1473 ** in all cases.
1474 */
1475 static int valueFromExpr(
1476   sqlite3 *db,                    /* The database connection */
1477   Expr *pExpr,                    /* The expression to evaluate */
1478   u8 enc,                         /* Encoding to use */
1479   u8 affinity,                    /* Affinity to use */
1480   sqlite3_value **ppVal,          /* Write the new value here */
1481   struct ValueNewStat4Ctx *pCtx   /* Second argument for valueNew() */
1482 ){
1483   int op;
1484   char *zVal = 0;
1485   sqlite3_value *pVal = 0;
1486   int negInt = 1;
1487   const char *zNeg = "";
1488   int rc = SQLITE_OK;
1489
1490   assert( pExpr!=0 );
1491   while( (op = pExpr->op)==TK_UPLUS || op==TK_SPAN ) pExpr = pExpr->pLeft;
1492 #if defined(SQLITE_ENABLE_STAT4)
1493   if( op==TK_REGISTER ) op = pExpr->op2;
1494 #else
1495   if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
1496 #endif
1497
1498   /* Compressed expressions only appear when parsing the DEFAULT clause
1499   ** on a table column definition, and hence only when pCtx==0.  This
1500   ** check ensures that an EP_TokenOnly expression is never passed down
1501   ** into valueFromFunction(). */
1502   assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );
1503
1504   if( op==TK_CAST ){
1505     u8 aff = sqlite3AffinityType(pExpr->u.zToken,0);
1506     rc = valueFromExpr(db, pExpr->pLeft, enc, aff, ppVal, pCtx);
1507     testcase( rc!=SQLITE_OK );
1508     if( *ppVal ){
1509       sqlite3VdbeMemCast(*ppVal, aff, SQLITE_UTF8);
1510       sqlite3ValueApplyAffinity(*ppVal, affinity, SQLITE_UTF8);
1511     }
1512     return rc;
1513   }
1514
1515   /* Handle negative integers in a single step.  This is needed in the
1516   ** case when the value is -9223372036854775808.
1517   */
1518   if( op==TK_UMINUS
1519    && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
1520     pExpr = pExpr->pLeft;
1521     op = pExpr->op;
1522     negInt = -1;
1523     zNeg = "-";
1524   }
1525
1526   if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
1527     pVal = valueNew(db, pCtx);
1528     if( pVal==0 ) goto no_mem;
1529     if( ExprHasProperty(pExpr, EP_IntValue) ){
1530       sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
1531     }else{
1532       zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
1533       if( zVal==0 ) goto no_mem;
1534       sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
1535     }
1536     if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_BLOB ){
1537       sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
1538     }else{
1539       sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
1540     }
1541     assert( (pVal->flags & MEM_IntReal)==0 );
1542     if( pVal->flags & (MEM_Int|MEM_IntReal|MEM_Real) ){
1543       testcase( pVal->flags & MEM_Int );
1544       testcase( pVal->flags & MEM_Real );
1545       pVal->flags &= ~MEM_Str;
1546     }
1547     if( enc!=SQLITE_UTF8 ){
1548       rc = sqlite3VdbeChangeEncoding(pVal, enc);
1549     }
1550   }else if( op==TK_UMINUS ) {
1551     /* This branch happens for multiple negative signs.  Ex: -(-5) */
1552     if( SQLITE_OK==valueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal,pCtx)
1553      && pVal!=0
1554     ){
1555       sqlite3VdbeMemNumerify(pVal);
1556       if( pVal->flags & MEM_Real ){
1557         pVal->u.r = -pVal->u.r;
1558       }else if( pVal->u.i==SMALLEST_INT64 ){
1559 #ifndef SQLITE_OMIT_FLOATING_POINT
1560         pVal->u.r = -(double)SMALLEST_INT64;
1561 #else
1562         pVal->u.r = LARGEST_INT64;
1563 #endif
1564         MemSetTypeFlag(pVal, MEM_Real);
1565       }else{
1566         pVal->u.i = -pVal->u.i;
1567       }
1568       sqlite3ValueApplyAffinity(pVal, affinity, enc);
1569     }
1570   }else if( op==TK_NULL ){
1571     pVal = valueNew(db, pCtx);
1572     if( pVal==0 ) goto no_mem;
1573     sqlite3VdbeMemSetNull(pVal);
1574   }
1575 #ifndef SQLITE_OMIT_BLOB_LITERAL
1576   else if( op==TK_BLOB ){
1577     int nVal;
1578     assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
1579     assert( pExpr->u.zToken[1]=='\'' );
1580     pVal = valueNew(db, pCtx);
1581     if( !pVal ) goto no_mem;
1582     zVal = &pExpr->u.zToken[2];
1583     nVal = sqlite3Strlen30(zVal)-1;
1584     assert( zVal[nVal]=='\'' );
1585     sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
1586                          0, SQLITE_DYNAMIC);
1587   }
1588 #endif
1589 #ifdef SQLITE_ENABLE_STAT4
1590   else if( op==TK_FUNCTION && pCtx!=0 ){
1591     rc = valueFromFunction(db, pExpr, enc, affinity, &pVal, pCtx);
1592   }
1593 #endif
1594   else if( op==TK_TRUEFALSE ){
1595     pVal = valueNew(db, pCtx);
1596     if( pVal ){
1597       pVal->flags = MEM_Int;
1598       pVal->u.i = pExpr->u.zToken[4]==0;
1599     }
1600   }
1601
1602   *ppVal = pVal;
1603   return rc;
1604
1605 no_mem:
1606 #ifdef SQLITE_ENABLE_STAT4
1607   if( pCtx==0 || pCtx->pParse->nErr==0 )
1608 #endif
1609     sqlite3OomFault(db);
1610   sqlite3DbFree(db, zVal);
1611   assert( *ppVal==0 );
1612 #ifdef SQLITE_ENABLE_STAT4
1613   if( pCtx==0 ) sqlite3ValueFree(pVal);
1614 #else
1615   assert( pCtx==0 ); sqlite3ValueFree(pVal);
1616 #endif
1617   return SQLITE_NOMEM_BKPT;
1618 }
1619
1620 /*
1621 ** Create a new sqlite3_value object, containing the value of pExpr.
1622 **
1623 ** This only works for very simple expressions that consist of one constant
1624 ** token (i.e. "5", "5.1", "'a string'"). If the expression can
1625 ** be converted directly into a value, then the value is allocated and
1626 ** a pointer written to *ppVal. The caller is responsible for deallocating
1627 ** the value by passing it to sqlite3ValueFree() later on. If the expression
1628 ** cannot be converted to a value, then *ppVal is set to NULL.
1629 */
1630 int sqlite3ValueFromExpr(
1631   sqlite3 *db,              /* The database connection */
1632   Expr *pExpr,              /* The expression to evaluate */
1633   u8 enc,                   /* Encoding to use */
1634   u8 affinity,              /* Affinity to use */
1635   sqlite3_value **ppVal     /* Write the new value here */
1636 ){
1637   return pExpr ? valueFromExpr(db, pExpr, enc, affinity, ppVal, 0) : 0;
1638 }
1639
1640 #ifdef SQLITE_ENABLE_STAT4
1641 /*
1642 ** Attempt to extract a value from pExpr and use it to construct *ppVal.
1643 **
1644 ** If pAlloc is not NULL, then an UnpackedRecord object is created for
1645 ** pAlloc if one does not exist and the new value is added to the
1646 ** UnpackedRecord object.
1647 **
1648 ** A value is extracted in the following cases:
1649 **
1650 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1651 **
1652 **  * The expression is a bound variable, and this is a reprepare, or
1653 **
1654 **  * The expression is a literal value.
1655 **
1656 ** On success, *ppVal is made to point to the extracted value.  The caller
1657 ** is responsible for ensuring that the value is eventually freed.
1658 */
1659 static int stat4ValueFromExpr(
1660   Parse *pParse,                  /* Parse context */
1661   Expr *pExpr,                    /* The expression to extract a value from */
1662   u8 affinity,                    /* Affinity to use */
1663   struct ValueNewStat4Ctx *pAlloc,/* How to allocate space.  Or NULL */
1664   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1665 ){
1666   int rc = SQLITE_OK;
1667   sqlite3_value *pVal = 0;
1668   sqlite3 *db = pParse->db;
1669
1670   /* Skip over any TK_COLLATE nodes */
1671   pExpr = sqlite3ExprSkipCollate(pExpr);
1672
1673   assert( pExpr==0 || pExpr->op!=TK_REGISTER || pExpr->op2!=TK_VARIABLE );
1674   if( !pExpr ){
1675     pVal = valueNew(db, pAlloc);
1676     if( pVal ){
1677       sqlite3VdbeMemSetNull((Mem*)pVal);
1678     }
1679   }else if( pExpr->op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
1680     Vdbe *v;
1681     int iBindVar = pExpr->iColumn;
1682     sqlite3VdbeSetVarmask(pParse->pVdbe, iBindVar);
1683     if( (v = pParse->pReprepare)!=0 ){
1684       pVal = valueNew(db, pAlloc);
1685       if( pVal ){
1686         rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iBindVar-1]);
1687         sqlite3ValueApplyAffinity(pVal, affinity, ENC(db));
1688         pVal->db = pParse->db;
1689       }
1690     }
1691   }else{
1692     rc = valueFromExpr(db, pExpr, ENC(db), affinity, &pVal, pAlloc);
1693   }
1694
1695   assert( pVal==0 || pVal->db==db );
1696   *ppVal = pVal;
1697   return rc;
1698 }
1699
1700 /*
1701 ** This function is used to allocate and populate UnpackedRecord
1702 ** structures intended to be compared against sample index keys stored
1703 ** in the sqlite_stat4 table.
1704 **
1705 ** A single call to this function populates zero or more fields of the
1706 ** record starting with field iVal (fields are numbered from left to
1707 ** right starting with 0). A single field is populated if:
1708 **
1709 **  * (pExpr==0). In this case the value is assumed to be an SQL NULL,
1710 **
1711 **  * The expression is a bound variable, and this is a reprepare, or
1712 **
1713 **  * The sqlite3ValueFromExpr() function is able to extract a value
1714 **    from the expression (i.e. the expression is a literal value).
1715 **
1716 ** Or, if pExpr is a TK_VECTOR, one field is populated for each of the
1717 ** vector components that match either of the two latter criteria listed
1718 ** above.
1719 **
1720 ** Before any value is appended to the record, the affinity of the
1721 ** corresponding column within index pIdx is applied to it. Before
1722 ** this function returns, output parameter *pnExtract is set to the
1723 ** number of values appended to the record.
1724 **
1725 ** When this function is called, *ppRec must either point to an object
1726 ** allocated by an earlier call to this function, or must be NULL. If it
1727 ** is NULL and a value can be successfully extracted, a new UnpackedRecord
1728 ** is allocated (and *ppRec set to point to it) before returning.
1729 **
1730 ** Unless an error is encountered, SQLITE_OK is returned. It is not an
1731 ** error if a value cannot be extracted from pExpr. If an error does
1732 ** occur, an SQLite error code is returned.
1733 */
1734 int sqlite3Stat4ProbeSetValue(
1735   Parse *pParse,                  /* Parse context */
1736   Index *pIdx,                    /* Index being probed */
1737   UnpackedRecord **ppRec,         /* IN/OUT: Probe record */
1738   Expr *pExpr,                    /* The expression to extract a value from */
1739   int nElem,                      /* Maximum number of values to append */
1740   int iVal,                       /* Array element to populate */
1741   int *pnExtract                  /* OUT: Values appended to the record */
1742 ){
1743   int rc = SQLITE_OK;
1744   int nExtract = 0;
1745
1746   if( pExpr==0 || pExpr->op!=TK_SELECT ){
1747     int i;
1748     struct ValueNewStat4Ctx alloc;
1749
1750     alloc.pParse = pParse;
1751     alloc.pIdx = pIdx;
1752     alloc.ppRec = ppRec;
1753
1754     for(i=0; i<nElem; i++){
1755       sqlite3_value *pVal = 0;
1756       Expr *pElem = (pExpr ? sqlite3VectorFieldSubexpr(pExpr, i) : 0);
1757       u8 aff = sqlite3IndexColumnAffinity(pParse->db, pIdx, iVal+i);
1758       alloc.iVal = iVal+i;
1759       rc = stat4ValueFromExpr(pParse, pElem, aff, &alloc, &pVal);
1760       if( !pVal ) break;
1761       nExtract++;
1762     }
1763   }
1764
1765   *pnExtract = nExtract;
1766   return rc;
1767 }
1768
1769 /*
1770 ** Attempt to extract a value from expression pExpr using the methods
1771 ** as described for sqlite3Stat4ProbeSetValue() above.
1772 **
1773 ** If successful, set *ppVal to point to a new value object and return
1774 ** SQLITE_OK. If no value can be extracted, but no other error occurs
1775 ** (e.g. OOM), return SQLITE_OK and set *ppVal to NULL. Or, if an error
1776 ** does occur, return an SQLite error code. The final value of *ppVal
1777 ** is undefined in this case.
1778 */
1779 int sqlite3Stat4ValueFromExpr(
1780   Parse *pParse,                  /* Parse context */
1781   Expr *pExpr,                    /* The expression to extract a value from */
1782   u8 affinity,                    /* Affinity to use */
1783   sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
1784 ){
1785   return stat4ValueFromExpr(pParse, pExpr, affinity, 0, ppVal);
1786 }
1787
1788 /*
1789 ** Extract the iCol-th column from the nRec-byte record in pRec.  Write
1790 ** the column value into *ppVal.  If *ppVal is initially NULL then a new
1791 ** sqlite3_value object is allocated.
1792 **
1793 ** If *ppVal is initially NULL then the caller is responsible for
1794 ** ensuring that the value written into *ppVal is eventually freed.
1795 */
1796 int sqlite3Stat4Column(
1797   sqlite3 *db,                    /* Database handle */
1798   const void *pRec,               /* Pointer to buffer containing record */
1799   int nRec,                       /* Size of buffer pRec in bytes */
1800   int iCol,                       /* Column to extract */
1801   sqlite3_value **ppVal           /* OUT: Extracted value */
1802 ){
1803   u32 t = 0;                      /* a column type code */
1804   int nHdr;                       /* Size of the header in the record */
1805   int iHdr;                       /* Next unread header byte */
1806   int iField;                     /* Next unread data byte */
1807   int szField = 0;                /* Size of the current data field */
1808   int i;                          /* Column index */
1809   u8 *a = (u8*)pRec;              /* Typecast byte array */
1810   Mem *pMem = *ppVal;             /* Write result into this Mem object */
1811
1812   assert( iCol>0 );
1813   iHdr = getVarint32(a, nHdr);
1814   if( nHdr>nRec || iHdr>=nHdr ) return SQLITE_CORRUPT_BKPT;
1815   iField = nHdr;
1816   for(i=0; i<=iCol; i++){
1817     iHdr += getVarint32(&a[iHdr], t);
1818     testcase( iHdr==nHdr );
1819     testcase( iHdr==nHdr+1 );
1820     if( iHdr>nHdr ) return SQLITE_CORRUPT_BKPT;
1821     szField = sqlite3VdbeSerialTypeLen(t);
1822     iField += szField;
1823   }
1824   testcase( iField==nRec );
1825   testcase( iField==nRec+1 );
1826   if( iField>nRec ) return SQLITE_CORRUPT_BKPT;
1827   if( pMem==0 ){
1828     pMem = *ppVal = sqlite3ValueNew(db);
1829     if( pMem==0 ) return SQLITE_NOMEM_BKPT;
1830   }
1831   sqlite3VdbeSerialGet(&a[iField-szField], t, pMem);
1832   pMem->enc = ENC(db);
1833   return SQLITE_OK;
1834 }
1835
1836 /*
1837 ** Unless it is NULL, the argument must be an UnpackedRecord object returned
1838 ** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
1839 ** the object.
1840 */
1841 void sqlite3Stat4ProbeFree(UnpackedRecord *pRec){
1842   if( pRec ){
1843     int i;
1844     int nCol = pRec->pKeyInfo->nAllField;
1845     Mem *aMem = pRec->aMem;
1846     sqlite3 *db = aMem[0].db;
1847     for(i=0; i<nCol; i++){
1848       sqlite3VdbeMemRelease(&aMem[i]);
1849     }
1850     sqlite3KeyInfoUnref(pRec->pKeyInfo);
1851     sqlite3DbFreeNN(db, pRec);
1852   }
1853 }
1854 #endif /* ifdef SQLITE_ENABLE_STAT4 */
1855
1856 /*
1857 ** Change the string value of an sqlite3_value object
1858 */
1859 void sqlite3ValueSetStr(
1860   sqlite3_value *v,     /* Value to be set */
1861   int n,                /* Length of string z */
1862   const void *z,        /* Text of the new string */
1863   u8 enc,               /* Encoding to use */
1864   void (*xDel)(void*)   /* Destructor for the string */
1865 ){
1866   if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
1867 }
1868
1869 /*
1870 ** Free an sqlite3_value object
1871 */
1872 void sqlite3ValueFree(sqlite3_value *v){
1873   if( !v ) return;
1874   sqlite3VdbeMemRelease((Mem *)v);
1875   sqlite3DbFreeNN(((Mem*)v)->db, v);
1876 }
1877
1878 /*
1879 ** The sqlite3ValueBytes() routine returns the number of bytes in the
1880 ** sqlite3_value object assuming that it uses the encoding "enc".
1881 ** The valueBytes() routine is a helper function.
1882 */
1883 static SQLITE_NOINLINE int valueBytes(sqlite3_value *pVal, u8 enc){
1884   return valueToText(pVal, enc)!=0 ? pVal->n : 0;
1885 }
1886 int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
1887   Mem *p = (Mem*)pVal;
1888   assert( (p->flags & MEM_Null)==0 || (p->flags & (MEM_Str|MEM_Blob))==0 );
1889   if( (p->flags & MEM_Str)!=0 && pVal->enc==enc ){
1890     return p->n;
1891   }
1892   if( (p->flags & MEM_Blob)!=0 ){
1893     if( p->flags & MEM_Zero ){
1894       return p->n + p->u.nZero;
1895     }else{
1896       return p->n;
1897     }
1898   }
1899   if( p->flags & MEM_Null ) return 0;
1900   return valueBytes(pVal, enc);
1901 }