third_party/sqlite/src/src/vdbemem.c

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This source file includes following definitions.
sqlite3VdbeChangeEncoding
sqlite3VdbeMemGrow
sqlite3VdbeMemMakeWriteable
sqlite3VdbeMemExpandBlob
sqlite3VdbeMemNulTerminate
sqlite3VdbeMemStringify
sqlite3VdbeMemFinalize
sqlite3VdbeMemReleaseExternal
sqlite3VdbeMemRelease
doubleToInt64
sqlite3VdbeIntValue
sqlite3VdbeRealValue
sqlite3VdbeIntegerAffinity
sqlite3VdbeMemIntegerify
sqlite3VdbeMemRealify
sqlite3VdbeMemNumerify
sqlite3VdbeMemSetNull
sqlite3VdbeMemSetZeroBlob
sqlite3VdbeMemSetInt64
sqlite3VdbeMemSetDouble
sqlite3VdbeMemSetRowSet
sqlite3VdbeMemTooBig
sqlite3VdbeMemPrepareToChange
sqlite3VdbeMemShallowCopy
sqlite3VdbeMemCopy
sqlite3VdbeMemMove
sqlite3VdbeMemSetStr
sqlite3MemCompare
sqlite3VdbeMemFromBtree
sqlite3ValueText
sqlite3ValueNew
sqlite3ValueFromExpr
sqlite3ValueSetStr
sqlite3ValueFree
sqlite3ValueBytes
/*
** 2004 May 26
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
** P if required.
*/
#define expandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)

/*
** If pMem is an object with a valid string representation, this routine
** ensures the internal encoding for the string representation is
** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
**
** If pMem is not a string object, or the encoding of the string
** representation is already stored using the requested encoding, then this
** routine is a no-op.
**
** SQLITE_OK is returned if the conversion is successful (or not required).
** SQLITE_NOMEM may be returned if a malloc() fails during conversion
** between formats.
*/
int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
  int rc;
  assert( (pMem->flags&MEM_RowSet)==0 );
  assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
           || desiredEnc==SQLITE_UTF16BE );
  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
    return SQLITE_OK;
  }
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
#ifdef SQLITE_OMIT_UTF16
  return SQLITE_ERROR;
#else

  /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
  ** then the encoding of the value may not have changed.
  */
  rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
  assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
  assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
  assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
  return rc;
#endif
}

/*
** Make sure pMem->z points to a writable allocation of at least 
** n bytes.
**
** If the memory cell currently contains string or blob data
** and the third argument passed to this function is true, the 
** current content of the cell is preserved. Otherwise, it may
** be discarded.  
**
** This function sets the MEM_Dyn flag and clears any xDel callback.
** It also clears MEM_Ephem and MEM_Static. If the preserve flag is 
** not set, Mem.n is zeroed.
*/
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve){
  assert( 1 >=
    ((pMem->zMalloc && pMem->zMalloc==pMem->z) ? 1 : 0) +
    (((pMem->flags&MEM_Dyn)&&pMem->xDel) ? 1 : 0) + 
    ((pMem->flags&MEM_Ephem) ? 1 : 0) + 
    ((pMem->flags&MEM_Static) ? 1 : 0)
  );
  assert( (pMem->flags&MEM_RowSet)==0 );

  if( n<32 ) n = 32;
  if( sqlite3DbMallocSize(pMem->db, pMem->zMalloc)<n ){
    if( preserve && pMem->z==pMem->zMalloc ){
      pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
      preserve = 0;
    }else{
      sqlite3DbFree(pMem->db, pMem->zMalloc);
      pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
    }
  }

  if( pMem->z && preserve && pMem->zMalloc && pMem->z!=pMem->zMalloc ){
    memcpy(pMem->zMalloc, pMem->z, pMem->n);
  }
  if( pMem->flags&MEM_Dyn && pMem->xDel ){
    pMem->xDel((void *)(pMem->z));
  }

  pMem->z = pMem->zMalloc;
  if( pMem->z==0 ){
    pMem->flags = MEM_Null;
  }else{
    pMem->flags &= ~(MEM_Ephem|MEM_Static);
  }
  pMem->xDel = 0;
  return (pMem->z ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** Make the given Mem object MEM_Dyn.  In other words, make it so
** that any TEXT or BLOB content is stored in memory obtained from
** malloc().  In this way, we know that the memory is safe to be
** overwritten or altered.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
int sqlite3VdbeMemMakeWriteable(Mem *pMem){
  int f;
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  expandBlob(pMem);
  f = pMem->flags;
  if( (f&(MEM_Str|MEM_Blob)) && pMem->z!=pMem->zMalloc ){
    if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
      return SQLITE_NOMEM;
    }
    pMem->z[pMem->n] = 0;
    pMem->z[pMem->n+1] = 0;
    pMem->flags |= MEM_Term;
#ifdef SQLITE_DEBUG
    pMem->pScopyFrom = 0;
#endif
  }

  return SQLITE_OK;
}

/*
** If the given Mem* has a zero-filled tail, turn it into an ordinary
** blob stored in dynamically allocated space.
*/
#ifndef SQLITE_OMIT_INCRBLOB
int sqlite3VdbeMemExpandBlob(Mem *pMem){
  if( pMem->flags & MEM_Zero ){
    int nByte;
    assert( pMem->flags&MEM_Blob );
    assert( (pMem->flags&MEM_RowSet)==0 );
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

    /* Set nByte to the number of bytes required to store the expanded blob. */
    nByte = pMem->n + pMem->u.nZero;
    if( nByte<=0 ){
      nByte = 1;
    }
    if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
      return SQLITE_NOMEM;
    }

    memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
    pMem->n += pMem->u.nZero;
    pMem->flags &= ~(MEM_Zero|MEM_Term);
  }
  return SQLITE_OK;
}
#endif


/*
** Make sure the given Mem is \u0000 terminated.
*/
int sqlite3VdbeMemNulTerminate(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  if( (pMem->flags & MEM_Term)!=0 || (pMem->flags & MEM_Str)==0 ){
    return SQLITE_OK;   /* Nothing to do */
  }
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Add MEM_Str to the set of representations for the given Mem.  Numbers
** are converted using sqlite3_snprintf().  Converting a BLOB to a string
** is a no-op.
**
** Existing representations MEM_Int and MEM_Real are *not* invalidated.
**
** A MEM_Null value will never be passed to this function. This function is
** used for converting values to text for returning to the user (i.e. via
** sqlite3_value_text()), or for ensuring that values to be used as btree
** keys are strings. In the former case a NULL pointer is returned the
** user and the later is an internal programming error.
*/
int sqlite3VdbeMemStringify(Mem *pMem, int enc){
  int rc = SQLITE_OK;
  int fg = pMem->flags;
  const int nByte = 32;

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( !(fg&MEM_Zero) );
  assert( !(fg&(MEM_Str|MEM_Blob)) );
  assert( fg&(MEM_Int|MEM_Real) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );


  if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){
    return SQLITE_NOMEM;
  }

  /* For a Real or Integer, use sqlite3_mprintf() to produce the UTF-8
  ** string representation of the value. Then, if the required encoding
  ** is UTF-16le or UTF-16be do a translation.
  ** 
  ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.
  */
  if( fg & MEM_Int ){
    sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);
  }else{
    assert( fg & MEM_Real );
    sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->r);
  }
  pMem->n = sqlite3Strlen30(pMem->z);
  pMem->enc = SQLITE_UTF8;
  pMem->flags |= MEM_Str|MEM_Term;
  sqlite3VdbeChangeEncoding(pMem, enc);
  return rc;
}

/*
** Memory cell pMem contains the context of an aggregate function.
** This routine calls the finalize method for that function.  The
** result of the aggregate is stored back into pMem.
**
** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
** otherwise.
*/
int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
  int rc = SQLITE_OK;
  if( ALWAYS(pFunc && pFunc->xFinalize) ){
    sqlite3_context ctx;
    assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
    memset(&ctx, 0, sizeof(ctx));
    ctx.s.flags = MEM_Null;
    ctx.s.db = pMem->db;
    ctx.pMem = pMem;
    ctx.pFunc = pFunc;
    pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
    assert( 0==(pMem->flags&MEM_Dyn) && !pMem->xDel );
    sqlite3DbFree(pMem->db, pMem->zMalloc);
    memcpy(pMem, &ctx.s, sizeof(ctx.s));
    rc = ctx.isError;
  }
  return rc;
}

/*
** If the memory cell contains a string value that must be freed by
** invoking an external callback, free it now. Calling this function
** does not free any Mem.zMalloc buffer.
*/
void sqlite3VdbeMemReleaseExternal(Mem *p){
  assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
  testcase( p->flags & MEM_Agg );
  testcase( p->flags & MEM_Dyn );
  testcase( p->flags & MEM_RowSet );
  testcase( p->flags & MEM_Frame );
  if( p->flags&(MEM_Agg|MEM_Dyn|MEM_RowSet|MEM_Frame) ){
    if( p->flags&MEM_Agg ){
      sqlite3VdbeMemFinalize(p, p->u.pDef);
      assert( (p->flags & MEM_Agg)==0 );
      sqlite3VdbeMemRelease(p);
    }else if( p->flags&MEM_Dyn && p->xDel ){
      assert( (p->flags&MEM_RowSet)==0 );
      p->xDel((void *)p->z);
      p->xDel = 0;
    }else if( p->flags&MEM_RowSet ){
      sqlite3RowSetClear(p->u.pRowSet);
    }else if( p->flags&MEM_Frame ){
      sqlite3VdbeMemSetNull(p);
    }
  }
}

/*
** Release any memory held by the Mem. This may leave the Mem in an
** inconsistent state, for example with (Mem.z==0) and
** (Mem.type==SQLITE_TEXT).
*/
void sqlite3VdbeMemRelease(Mem *p){
  sqlite3VdbeMemReleaseExternal(p);
  sqlite3DbFree(p->db, p->zMalloc);
  p->z = 0;
  p->zMalloc = 0;
  p->xDel = 0;
}

/*
** Convert a 64-bit IEEE double into a 64-bit signed integer.
** If the double is too large, return 0x8000000000000000.
**
** Most systems appear to do this simply by assigning
** variables and without the extra range tests.  But
** there are reports that windows throws an expection
** if the floating point value is out of range. (See ticket #2880.)
** Because we do not completely understand the problem, we will
** take the conservative approach and always do range tests
** before attempting the conversion.
*/
static i64 doubleToInt64(double r){
#ifdef SQLITE_OMIT_FLOATING_POINT
  /* When floating-point is omitted, double and int64 are the same thing */
  return r;
#else
  /*
  ** Many compilers we encounter do not define constants for the
  ** minimum and maximum 64-bit integers, or they define them
  ** inconsistently.  And many do not understand the "LL" notation.
  ** So we define our own static constants here using nothing
  ** larger than a 32-bit integer constant.
  */
  static const i64 maxInt = LARGEST_INT64;
  static const i64 minInt = SMALLEST_INT64;

  if( r<(double)minInt ){
    return minInt;
  }else if( r>(double)maxInt ){
    /* minInt is correct here - not maxInt.  It turns out that assigning
    ** a very large positive number to an integer results in a very large
    ** negative integer.  This makes no sense, but it is what x86 hardware
    ** does so for compatibility we will do the same in software. */
    return minInt;
  }else{
    return (i64)r;
  }
#endif
}

/*
** Return some kind of integer value which is the best we can do
** at representing the value that *pMem describes as an integer.
** If pMem is an integer, then the value is exact.  If pMem is
** a floating-point then the value returned is the integer part.
** If pMem is a string or blob, then we make an attempt to convert
** it into a integer and return that.  If pMem represents an
** an SQL-NULL value, return 0.
**
** If pMem represents a string value, its encoding might be changed.
*/
i64 sqlite3VdbeIntValue(Mem *pMem){
  int flags;
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  flags = pMem->flags;
  if( flags & MEM_Int ){
    return pMem->u.i;
  }else if( flags & MEM_Real ){
    return doubleToInt64(pMem->r);
  }else if( flags & (MEM_Str|MEM_Blob) ){
    i64 value = 0;
    assert( pMem->z || pMem->n==0 );
    testcase( pMem->z==0 );
    sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
    return value;
  }else{
    return 0;
  }
}

/*
** Return the best representation of pMem that we can get into a
** double.  If pMem is already a double or an integer, return its
** value.  If it is a string or blob, try to convert it to a double.
** If it is a NULL, return 0.0.
*/
double sqlite3VdbeRealValue(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  if( pMem->flags & MEM_Real ){
    return pMem->r;
  }else if( pMem->flags & MEM_Int ){
    return (double)pMem->u.i;
  }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
    double val = (double)0;
    sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
    return val;
  }else{
    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
    return (double)0;
  }
}

/*
** The MEM structure is already a MEM_Real.  Try to also make it a
** MEM_Int if we can.
*/
void sqlite3VdbeIntegerAffinity(Mem *pMem){
  assert( pMem->flags & MEM_Real );
  assert( (pMem->flags & MEM_RowSet)==0 );
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );

  pMem->u.i = doubleToInt64(pMem->r);

  /* Only mark the value as an integer if
  **
  **    (1) the round-trip conversion real->int->real is a no-op, and
  **    (2) The integer is neither the largest nor the smallest
  **        possible integer (ticket #3922)
  **
  ** The second and third terms in the following conditional enforces
  ** the second condition under the assumption that addition overflow causes
  ** values to wrap around.  On x86 hardware, the third term is always
  ** true and could be omitted.  But we leave it in because other
  ** architectures might behave differently.
  */
  if( pMem->r==(double)pMem->u.i && pMem->u.i>SMALLEST_INT64
      && ALWAYS(pMem->u.i<LARGEST_INT64) ){
    pMem->flags |= MEM_Int;
  }
}

/*
** Convert pMem to type integer.  Invalidate any prior representations.
*/
int sqlite3VdbeMemIntegerify(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags & MEM_RowSet)==0 );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );

  pMem->u.i = sqlite3VdbeIntValue(pMem);
  MemSetTypeFlag(pMem, MEM_Int);
  return SQLITE_OK;
}

/*
** Convert pMem so that it is of type MEM_Real.
** Invalidate any prior representations.
*/
int sqlite3VdbeMemRealify(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );

  pMem->r = sqlite3VdbeRealValue(pMem);
  MemSetTypeFlag(pMem, MEM_Real);
  return SQLITE_OK;
}

/*
** Convert pMem so that it has types MEM_Real or MEM_Int or both.
** Invalidate any prior representations.
**
** Every effort is made to force the conversion, even if the input
** is a string that does not look completely like a number.  Convert
** as much of the string as we can and ignore the rest.
*/
int sqlite3VdbeMemNumerify(Mem *pMem){
  if( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 ){
    assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
    if( 0==sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc) ){
      MemSetTypeFlag(pMem, MEM_Int);
    }else{
      pMem->r = sqlite3VdbeRealValue(pMem);
      MemSetTypeFlag(pMem, MEM_Real);
      sqlite3VdbeIntegerAffinity(pMem);
    }
  }
  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))!=0 );
  pMem->flags &= ~(MEM_Str|MEM_Blob);
  return SQLITE_OK;
}

/*
** Delete any previous value and set the value stored in *pMem to NULL.
*/
void sqlite3VdbeMemSetNull(Mem *pMem){
  if( pMem->flags & MEM_Frame ){
    VdbeFrame *pFrame = pMem->u.pFrame;
    pFrame->pParent = pFrame->v->pDelFrame;
    pFrame->v->pDelFrame = pFrame;
  }
  if( pMem->flags & MEM_RowSet ){
    sqlite3RowSetClear(pMem->u.pRowSet);
  }
  MemSetTypeFlag(pMem, MEM_Null);
  pMem->type = SQLITE_NULL;
}

/*
** Delete any previous value and set the value to be a BLOB of length
** n containing all zeros.
*/
void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
  sqlite3VdbeMemRelease(pMem);
  pMem->flags = MEM_Blob|MEM_Zero;
  pMem->type = SQLITE_BLOB;
  pMem->n = 0;
  if( n<0 ) n = 0;
  pMem->u.nZero = n;
  pMem->enc = SQLITE_UTF8;

#ifdef SQLITE_OMIT_INCRBLOB
  sqlite3VdbeMemGrow(pMem, n, 0);
  if( pMem->z ){
    pMem->n = n;
    memset(pMem->z, 0, n);
  }
#endif
}

/*
** Delete any previous value and set the value stored in *pMem to val,
** manifest type INTEGER.
*/
void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
  sqlite3VdbeMemRelease(pMem);
  pMem->u.i = val;
  pMem->flags = MEM_Int;
  pMem->type = SQLITE_INTEGER;
}

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Delete any previous value and set the value stored in *pMem to val,
** manifest type REAL.
*/
void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
  if( sqlite3IsNaN(val) ){
    sqlite3VdbeMemSetNull(pMem);
  }else{
    sqlite3VdbeMemRelease(pMem);
    pMem->r = val;
    pMem->flags = MEM_Real;
    pMem->type = SQLITE_FLOAT;
  }
}
#endif

/*
** Delete any previous value and set the value of pMem to be an
** empty boolean index.
*/
void sqlite3VdbeMemSetRowSet(Mem *pMem){
  sqlite3 *db = pMem->db;
  assert( db!=0 );
  assert( (pMem->flags & MEM_RowSet)==0 );
  sqlite3VdbeMemRelease(pMem);
  pMem->zMalloc = sqlite3DbMallocRaw(db, 64);
  if( db->mallocFailed ){
    pMem->flags = MEM_Null;
  }else{
    assert( pMem->zMalloc );
    pMem->u.pRowSet = sqlite3RowSetInit(db, pMem->zMalloc, 
                                       sqlite3DbMallocSize(db, pMem->zMalloc));
    assert( pMem->u.pRowSet!=0 );
    pMem->flags = MEM_RowSet;
  }
}

/*
** Return true if the Mem object contains a TEXT or BLOB that is
** too large - whose size exceeds SQLITE_MAX_LENGTH.
*/
int sqlite3VdbeMemTooBig(Mem *p){
  assert( p->db!=0 );
  if( p->flags & (MEM_Str|MEM_Blob) ){
    int n = p->n;
    if( p->flags & MEM_Zero ){
      n += p->u.nZero;
    }
    return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
  }
  return 0; 
}

#ifdef SQLITE_DEBUG
/*
** This routine prepares a memory cell for modication by breaking
** its link to a shallow copy and by marking any current shallow
** copies of this cell as invalid.
**
** This is used for testing and debugging only - to make sure shallow
** copies are not misused.
*/
void sqlite3VdbeMemPrepareToChange(Vdbe *pVdbe, Mem *pMem){
  int i;
  Mem *pX;
  for(i=1, pX=&pVdbe->aMem[1]; i<=pVdbe->nMem; i++, pX++){
    if( pX->pScopyFrom==pMem ){
      pX->flags |= MEM_Invalid;
      pX->pScopyFrom = 0;
    }
  }
  pMem->pScopyFrom = 0;
}
#endif /* SQLITE_DEBUG */

/*
** Size of struct Mem not including the Mem.zMalloc member.
*/
#define MEMCELLSIZE (size_t)(&(((Mem *)0)->zMalloc))

/*
** Make an shallow copy of pFrom into pTo.  Prior contents of
** pTo are freed.  The pFrom->z field is not duplicated.  If
** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
** and flags gets srcType (either MEM_Ephem or MEM_Static).
*/
void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
  assert( (pFrom->flags & MEM_RowSet)==0 );
  sqlite3VdbeMemReleaseExternal(pTo);
  memcpy(pTo, pFrom, MEMCELLSIZE);
  pTo->xDel = 0;
  if( (pFrom->flags&MEM_Static)==0 ){
    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
    assert( srcType==MEM_Ephem || srcType==MEM_Static );
    pTo->flags |= srcType;
  }
}

/*
** Make a full copy of pFrom into pTo.  Prior contents of pTo are
** freed before the copy is made.
*/
int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
  int rc = SQLITE_OK;

  assert( (pFrom->flags & MEM_RowSet)==0 );
  sqlite3VdbeMemReleaseExternal(pTo);
  memcpy(pTo, pFrom, MEMCELLSIZE);
  pTo->flags &= ~MEM_Dyn;

  if( pTo->flags&(MEM_Str|MEM_Blob) ){
    if( 0==(pFrom->flags&MEM_Static) ){
      pTo->flags |= MEM_Ephem;
      rc = sqlite3VdbeMemMakeWriteable(pTo);
    }
  }

  return rc;
}

/*
** Transfer the contents of pFrom to pTo. Any existing value in pTo is
** freed. If pFrom contains ephemeral data, a copy is made.
**
** pFrom contains an SQL NULL when this routine returns.
*/
void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
  assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
  assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
  assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );

  sqlite3VdbeMemRelease(pTo);
  memcpy(pTo, pFrom, sizeof(Mem));
  pFrom->flags = MEM_Null;
  pFrom->xDel = 0;
  pFrom->zMalloc = 0;
}

/*
** Change the value of a Mem to be a string or a BLOB.
**
** The memory management strategy depends on the value of the xDel
** parameter. If the value passed is SQLITE_TRANSIENT, then the 
** string is copied into a (possibly existing) buffer managed by the 
** Mem structure. Otherwise, any existing buffer is freed and the
** pointer copied.
**
** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
** size limit) then no memory allocation occurs.  If the string can be
** stored without allocating memory, then it is.  If a memory allocation
** is required to store the string, then value of pMem is unchanged.  In
** either case, SQLITE_TOOBIG is returned.
*/
int sqlite3VdbeMemSetStr(
  Mem *pMem,          /* Memory cell to set to string value */
  const char *z,      /* String pointer */
  int n,              /* Bytes in string, or negative */
  u8 enc,             /* Encoding of z.  0 for BLOBs */
  void (*xDel)(void*) /* Destructor function */
){
  int nByte = n;      /* New value for pMem->n */
  int iLimit;         /* Maximum allowed string or blob size */
  u16 flags = 0;      /* New value for pMem->flags */

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags & MEM_RowSet)==0 );

  /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
  if( !z ){
    sqlite3VdbeMemSetNull(pMem);
    return SQLITE_OK;
  }

  if( pMem->db ){
    iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
  }else{
    iLimit = SQLITE_MAX_LENGTH;
  }
  flags = (enc==0?MEM_Blob:MEM_Str);
  if( nByte<0 ){
    assert( enc!=0 );
    if( enc==SQLITE_UTF8 ){
      for(nByte=0; nByte<=iLimit && z[nByte]; nByte++){}
    }else{
      for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
    }
    flags |= MEM_Term;
  }

  /* The following block sets the new values of Mem.z and Mem.xDel. It
  ** also sets a flag in local variable "flags" to indicate the memory
  ** management (one of MEM_Dyn or MEM_Static).
  */
  if( xDel==SQLITE_TRANSIENT ){
    int nAlloc = nByte;
    if( flags&MEM_Term ){
      nAlloc += (enc==SQLITE_UTF8?1:2);
    }
    if( nByte>iLimit ){
      return SQLITE_TOOBIG;
    }
    if( sqlite3VdbeMemGrow(pMem, nAlloc, 0) ){
      return SQLITE_NOMEM;
    }
    memcpy(pMem->z, z, nAlloc);
  }else if( xDel==SQLITE_DYNAMIC ){
    sqlite3VdbeMemRelease(pMem);
    pMem->zMalloc = pMem->z = (char *)z;
    pMem->xDel = 0;
  }else{
    sqlite3VdbeMemRelease(pMem);
    pMem->z = (char *)z;
    pMem->xDel = xDel;
    flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
  }

  pMem->n = nByte;
  pMem->flags = flags;
  pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
  pMem->type = (enc==0 ? SQLITE_BLOB : SQLITE_TEXT);

#ifndef SQLITE_OMIT_UTF16
  if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
    return SQLITE_NOMEM;
  }
#endif

  if( nByte>iLimit ){
    return SQLITE_TOOBIG;
  }

  return SQLITE_OK;
}

/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater
** than pMem2. Sorting order is NULL's first, followed by numbers (integers
** and reals) sorted numerically, followed by text ordered by the collating
** sequence pColl and finally blob's ordered by memcmp().
**
** Two NULL values are considered equal by this function.
*/
int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
  int rc;
  int f1, f2;
  int combined_flags;

  f1 = pMem1->flags;
  f2 = pMem2->flags;
  combined_flags = f1|f2;
  assert( (combined_flags & MEM_RowSet)==0 );
 
  /* If one value is NULL, it is less than the other. If both values
  ** are NULL, return 0.
  */
  if( combined_flags&MEM_Null ){
    return (f2&MEM_Null) - (f1&MEM_Null);
  }

  /* If one value is a number and the other is not, the number is less.
  ** If both are numbers, compare as reals if one is a real, or as integers
  ** if both values are integers.
  */
  if( combined_flags&(MEM_Int|MEM_Real) ){
    if( !(f1&(MEM_Int|MEM_Real)) ){
      return 1;
    }
    if( !(f2&(MEM_Int|MEM_Real)) ){
      return -1;
    }
    if( (f1 & f2 & MEM_Int)==0 ){
      double r1, r2;
      if( (f1&MEM_Real)==0 ){
        r1 = (double)pMem1->u.i;
      }else{
        r1 = pMem1->r;
      }
      if( (f2&MEM_Real)==0 ){
        r2 = (double)pMem2->u.i;
      }else{
        r2 = pMem2->r;
      }
      if( r1<r2 ) return -1;
      if( r1>r2 ) return 1;
      return 0;
    }else{
      assert( f1&MEM_Int );
      assert( f2&MEM_Int );
      if( pMem1->u.i < pMem2->u.i ) return -1;
      if( pMem1->u.i > pMem2->u.i ) return 1;
      return 0;
    }
  }

  /* If one value is a string and the other is a blob, the string is less.
  ** If both are strings, compare using the collating functions.
  */
  if( combined_flags&MEM_Str ){
    if( (f1 & MEM_Str)==0 ){
      return 1;
    }
    if( (f2 & MEM_Str)==0 ){
      return -1;
    }

    assert( pMem1->enc==pMem2->enc );
    assert( pMem1->enc==SQLITE_UTF8 || 
            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );

    /* The collation sequence must be defined at this point, even if
    ** the user deletes the collation sequence after the vdbe program is
    ** compiled (this was not always the case).
    */
    assert( !pColl || pColl->xCmp );

    if( pColl ){
      if( pMem1->enc==pColl->enc ){
        /* The strings are already in the correct encoding.  Call the
        ** comparison function directly */
        return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
      }else{
        const void *v1, *v2;
        int n1, n2;
        Mem c1;
        Mem c2;
        memset(&c1, 0, sizeof(c1));
        memset(&c2, 0, sizeof(c2));
        sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
        sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
        v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
        n1 = v1==0 ? 0 : c1.n;
        v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
        n2 = v2==0 ? 0 : c2.n;
        rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
        sqlite3VdbeMemRelease(&c1);
        sqlite3VdbeMemRelease(&c2);
        return rc;
      }
    }
    /* If a NULL pointer was passed as the collate function, fall through
    ** to the blob case and use memcmp().  */
  }
 
  /* Both values must be blobs.  Compare using memcmp().  */
  rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
  if( rc==0 ){
    rc = pMem1->n - pMem2->n;
  }
  return rc;
}

/*
** Move data out of a btree key or data field and into a Mem structure.
** The data or key is taken from the entry that pCur is currently pointing
** to.  offset and amt determine what portion of the data or key to retrieve.
** key is true to get the key or false to get data.  The result is written
** into the pMem element.
**
** The pMem structure is assumed to be uninitialized.  Any prior content
** is overwritten without being freed.
**
** If this routine fails for any reason (malloc returns NULL or unable
** to read from the disk) then the pMem is left in an inconsistent state.
*/
int sqlite3VdbeMemFromBtree(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  int offset,       /* Offset from the start of data to return bytes from. */
  int amt,          /* Number of bytes to return. */
  int key,          /* If true, retrieve from the btree key, not data. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
  char *zData;        /* Data from the btree layer */
  int available = 0;  /* Number of bytes available on the local btree page */
  int rc = SQLITE_OK; /* Return code */

  assert( sqlite3BtreeCursorIsValid(pCur) );

  /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert() 
  ** that both the BtShared and database handle mutexes are held. */
  assert( (pMem->flags & MEM_RowSet)==0 );
  if( key ){
    zData = (char *)sqlite3BtreeKeyFetch(pCur, &available);
  }else{
    zData = (char *)sqlite3BtreeDataFetch(pCur, &available);
  }
  assert( zData!=0 );

  if( offset+amt<=available && (pMem->flags&MEM_Dyn)==0 ){
    sqlite3VdbeMemRelease(pMem);
    pMem->z = &zData[offset];
    pMem->flags = MEM_Blob|MEM_Ephem;
  }else if( SQLITE_OK==(rc = sqlite3VdbeMemGrow(pMem, amt+2, 0)) ){
    pMem->flags = MEM_Blob|MEM_Dyn|MEM_Term;
    pMem->enc = 0;
    pMem->type = SQLITE_BLOB;
    if( key ){
      rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
    }else{
      rc = sqlite3BtreeData(pCur, offset, amt, pMem->z);
    }
    pMem->z[amt] = 0;
    pMem->z[amt+1] = 0;
    if( rc!=SQLITE_OK ){
      sqlite3VdbeMemRelease(pMem);
    }
  }
  pMem->n = amt;

  return rc;
}

/* This function is only available internally, it is not part of the
** external API. It works in a similar way to sqlite3_value_text(),
** except the data returned is in the encoding specified by the second
** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
** SQLITE_UTF8.
**
** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
** If that is the case, then the result must be aligned on an even byte
** boundary.
*/
const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
  if( !pVal ) return 0;

  assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
  assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
  assert( (pVal->flags & MEM_RowSet)==0 );

  if( pVal->flags&MEM_Null ){
    return 0;
  }
  assert( (MEM_Blob>>3) == MEM_Str );
  pVal->flags |= (pVal->flags & MEM_Blob)>>3;
  expandBlob(pVal);
  if( pVal->flags&MEM_Str ){
    sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
    if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
      assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
      if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
        return 0;
      }
    }
    sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-59893-45467 */
  }else{
    assert( (pVal->flags&MEM_Blob)==0 );
    sqlite3VdbeMemStringify(pVal, enc);
    assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
  }
  assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
              || pVal->db->mallocFailed );
  if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
    return pVal->z;
  }else{
    return 0;
  }
}

/*
** Create a new sqlite3_value object.
*/
sqlite3_value *sqlite3ValueNew(sqlite3 *db){
  Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
  if( p ){
    p->flags = MEM_Null;
    p->type = SQLITE_NULL;
    p->db = db;
  }
  return p;
}

/*
** Create a new sqlite3_value object, containing the value of pExpr.
**
** This only works for very simple expressions that consist of one constant
** token (i.e. "5", "5.1", "'a string'"). If the expression can
** be converted directly into a value, then the value is allocated and
** a pointer written to *ppVal. The caller is responsible for deallocating
** the value by passing it to sqlite3ValueFree() later on. If the expression
** cannot be converted to a value, then *ppVal is set to NULL.
*/
int sqlite3ValueFromExpr(
  sqlite3 *db,              /* The database connection */
  Expr *pExpr,              /* The expression to evaluate */
  u8 enc,                   /* Encoding to use */
  u8 affinity,              /* Affinity to use */
  sqlite3_value **ppVal     /* Write the new value here */
){
  int op;
  char *zVal = 0;
  sqlite3_value *pVal = 0;
  int negInt = 1;
  const char *zNeg = "";

  if( !pExpr ){
    *ppVal = 0;
    return SQLITE_OK;
  }
  op = pExpr->op;

  /* op can only be TK_REGISTER if we have compiled with SQLITE_ENABLE_STAT2.
  ** The ifdef here is to enable us to achieve 100% branch test coverage even
  ** when SQLITE_ENABLE_STAT2 is omitted.
  */
#ifdef SQLITE_ENABLE_STAT2
  if( op==TK_REGISTER ) op = pExpr->op2;
#else
  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
#endif

  /* Handle negative integers in a single step.  This is needed in the
  ** case when the value is -9223372036854775808.
  */
  if( op==TK_UMINUS
   && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
    pExpr = pExpr->pLeft;
    op = pExpr->op;
    negInt = -1;
    zNeg = "-";
  }

  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
    pVal = sqlite3ValueNew(db);
    if( pVal==0 ) goto no_mem;
    if( ExprHasProperty(pExpr, EP_IntValue) ){
      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
    }else{
      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
      if( zVal==0 ) goto no_mem;
      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
      if( op==TK_FLOAT ) pVal->type = SQLITE_FLOAT;
    }
    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_NONE ){
      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
    }else{
      sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
    }
    if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
    if( enc!=SQLITE_UTF8 ){
      sqlite3VdbeChangeEncoding(pVal, enc);
    }
  }else if( op==TK_UMINUS ) {
    /* This branch happens for multiple negative signs.  Ex: -(-5) */
    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) ){
      sqlite3VdbeMemNumerify(pVal);
      if( pVal->u.i==SMALLEST_INT64 ){
        pVal->flags &= MEM_Int;
        pVal->flags |= MEM_Real;
        pVal->r = (double)LARGEST_INT64;
      }else{
        pVal->u.i = -pVal->u.i;
      }
      pVal->r = -pVal->r;
      sqlite3ValueApplyAffinity(pVal, affinity, enc);
    }
  }else if( op==TK_NULL ){
    pVal = sqlite3ValueNew(db);
    if( pVal==0 ) goto no_mem;
  }
#ifndef SQLITE_OMIT_BLOB_LITERAL
  else if( op==TK_BLOB ){
    int nVal;
    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
    assert( pExpr->u.zToken[1]=='\'' );
    pVal = sqlite3ValueNew(db);
    if( !pVal ) goto no_mem;
    zVal = &pExpr->u.zToken[2];
    nVal = sqlite3Strlen30(zVal)-1;
    assert( zVal[nVal]=='\'' );
    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
                         0, SQLITE_DYNAMIC);
  }
#endif

  if( pVal ){
    sqlite3VdbeMemStoreType(pVal);
  }
  *ppVal = pVal;
  return SQLITE_OK;

no_mem:
  db->mallocFailed = 1;
  sqlite3DbFree(db, zVal);
  sqlite3ValueFree(pVal);
  *ppVal = 0;
  return SQLITE_NOMEM;
}

/*
** Change the string value of an sqlite3_value object
*/
void sqlite3ValueSetStr(
  sqlite3_value *v,     /* Value to be set */
  int n,                /* Length of string z */
  const void *z,        /* Text of the new string */
  u8 enc,               /* Encoding to use */
  void (*xDel)(void*)   /* Destructor for the string */
){
  if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
}

/*
** Free an sqlite3_value object
*/
void sqlite3ValueFree(sqlite3_value *v){
  if( !v ) return;
  sqlite3VdbeMemRelease((Mem *)v);
  sqlite3DbFree(((Mem*)v)->db, v);
}

/*
** Return the number of bytes in the sqlite3_value object assuming
** that it uses the encoding "enc"
*/
int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
  Mem *p = (Mem*)pVal;
  if( (p->flags & MEM_Blob)!=0 || sqlite3ValueText(pVal, enc) ){
    if( p->flags & MEM_Zero ){
      return p->n + p->u.nZero;
    }else{
      return p->n;
    }
  }
  return 0;
}
/* [<][>][^][v][top][bottom][index][help] */
root/third_party/sqlite/src/src/vdbemem.c

DEFINITIONS
