SQLite

typedef struct Fts5Buffer Fts5Buffer;
struct Fts5Buffer {
  u8 *p;
  int n;
  int nSpace;
};


int sqlite3Fts5BufferGrow(int*, Fts5Buffer*, int);
void sqlite3Fts5BufferAppendVarint(int*, Fts5Buffer*, i64);
void sqlite3Fts5BufferAppendBlob(int*, Fts5Buffer*, int, const u8*);
void sqlite3Fts5BufferAppendString(int *, Fts5Buffer*, const char*);
void sqlite3Fts5BufferFree(Fts5Buffer*);
void sqlite3Fts5BufferZero(Fts5Buffer*);
void sqlite3Fts5BufferSet(int*, Fts5Buffer*, int, const u8*);
void sqlite3Fts5BufferAppendPrintf(int *, Fts5Buffer*, char *zFmt, ...);
void sqlite3Fts5BufferAppend32(int*, Fts5Buffer*, int);

char *sqlite3Fts5Mprintf(int *pRc, const char *zFmt, ...);

#define fts5BufferZero(x)             sqlite3Fts5BufferZero(x)
#define fts5BufferGrow(a,b,c)         sqlite3Fts5BufferGrow(a,b,c)
#define fts5BufferAppendVarint(a,b,c) sqlite3Fts5BufferAppendVarint(a,b,c)
#define fts5BufferFree(a)             sqlite3Fts5BufferFree(a)
#define fts5BufferAppendBlob(a,b,c,d) sqlite3Fts5BufferAppendBlob(a,b,c,d)
#define fts5BufferSet(a,b,c,d)        sqlite3Fts5BufferSet(a,b,c,d)
#define fts5BufferAppend32(a,b,c)     sqlite3Fts5BufferAppend32(a,b,c)






/* Write and decode big-endian 32-bit integer values */
void sqlite3Fts5Put32(u8*, int);
int sqlite3Fts5Get32(const u8*);

#define FTS5_POS2COLUMN(iPos) (int)(iPos >> 32)
#define FTS5_POS2OFFSET(iPos) (int)(iPos & 0xFFFFFFFF)

******************************************************************************
*/



#include "fts5Int.h"

int sqlite3Fts5BufferGrow(int *pRc, Fts5Buffer *pBuf, int nByte){

  if( (pBuf->n + nByte) > pBuf->nSpace ){
    u8 *pNew;
    int nNew = pBuf->nSpace ? pBuf->nSpace*2 : 64;

    /* A no-op if an error has already occurred */
    if( *pRc ) return 1;

    while( nNew<(pBuf->n + nByte) ){
      nNew = nNew * 2;
    }
    pNew = sqlite3_realloc(pBuf->p, nNew);
    if( pNew==0 ){
      *pRc = SQLITE_NOMEM;
      return 1;
    }else{
      pBuf->nSpace = nNew;
      pBuf->p = pNew;
    }
  }
  return 0;
}


/*
** Encode value iVal as an SQLite varint and append it to the buffer object
** pBuf. If an OOM error occurs, set the error code in p.
*/
void sqlite3Fts5BufferAppendVarint(int *pRc, Fts5Buffer *pBuf, i64 iVal){
  if( sqlite3Fts5BufferGrow(pRc, pBuf, 9) ) return;
  pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], iVal);
}

void sqlite3Fts5Put32(u8 *aBuf, int iVal){
  aBuf[0] = (iVal>>24) & 0x00FF;
  aBuf[1] = (iVal>>16) & 0x00FF;
  aBuf[2] = (iVal>> 8) & 0x00FF;
  aBuf[3] = (iVal>> 0) & 0x00FF;
}

int sqlite3Fts5Get32(const u8 *aBuf){
  return (aBuf[0] << 24) + (aBuf[1] << 16) + (aBuf[2] << 8) + aBuf[3];
}

void sqlite3Fts5BufferAppend32(int *pRc, Fts5Buffer *pBuf, int iVal){
  if( sqlite3Fts5BufferGrow(pRc, pBuf, 4) ) return;
  sqlite3Fts5Put32(&pBuf->p[pBuf->n], iVal);
  pBuf->n += 4;
}

/*
** Append buffer nData/pData to buffer pBuf. If an OOM error occurs, set 
** the error code in p. If an error has already occurred when this function
** is called, it is a no-op.
*/
void sqlite3Fts5BufferAppendBlob(
  int *pRc,
  Fts5Buffer *pBuf, 
  int nData, 
  const u8 *pData
){
  assert( *pRc || nData>=0 );
  if( sqlite3Fts5BufferGrow(pRc, pBuf, nData) ) return;
  memcpy(&pBuf->p[pBuf->n], pData, nData);
  pBuf->n += nData;
}

/*
** Append the nul-terminated string zStr to the buffer pBuf. This function
** ensures that the byte following the buffer data is set to 0x00, even 

int sqlite3Fts5PoslistWriterAppend(
  Fts5Buffer *pBuf, 
  Fts5PoslistWriter *pWriter,
  i64 iPos
){
  static const i64 colmask = ((i64)(0x7FFFFFFF)) << 32;
  int rc = SQLITE_OK;
  if( 0==sqlite3Fts5BufferGrow(&rc, pBuf, 5+5+5) ){
    if( (iPos & colmask) != (pWriter->iPrev & colmask) ){
      pBuf->p[pBuf->n++] = 1;
      pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], (iPos>>32));
      pWriter->iPrev = (iPos & colmask);
    }
    pBuf->n += sqlite3Fts5PutVarint(&pBuf->p[pBuf->n], (iPos-pWriter->iPrev)+2);
    pWriter->iPrev = iPos;

  Fts5Buffer *pBuf
){
  if( p->rc==SQLITE_OK ){
    Fts5SegIter *pSeg = &pMulti->aSeg[ pMulti->aFirst[1].iFirst ];
    assert( fts5MultiIterEof(p, pMulti)==0 );
    assert( pSeg->nPos>0 );
    if( 0==fts5BufferGrow(&p->rc, pBuf, pSeg->nPos+9+9) ){
      int iSv1;
      int iSv2;
      int iData;

      if( pSeg->iLeafOffset+pSeg->nPos<=pSeg->pLeaf->szLeaf 
       && (pColset==0 || pColset->nCol==1)
      ){
        const u8 *pPos = &pSeg->pLeaf->p[pSeg->iLeafOffset];
        int nPos;
        if( pColset ){
          nPos = fts5IndexExtractCol(&pPos, pSeg->nPos, pColset->aiCol[0]);
          if( nPos==0 ) return 1;
        }else{
          nPos = pSeg->nPos;
        }
        assert( nPos>0 );
        fts5BufferSafeAppendVarint(pBuf, iDelta);
        fts5BufferSafeAppendVarint(pBuf, nPos*2);
        fts5BufferSafeAppendBlob(pBuf, pPos, nPos);
      }else{




        /* Append iDelta */
        iSv1 = pBuf->n;
        fts5BufferSafeAppendVarint(pBuf, iDelta);

        /* WRITEPOSLISTSIZE */
        iSv2 = pBuf->n;
        fts5BufferSafeAppendVarint(pBuf, pSeg->nPos*2);

              int nReq = sqlite3Fts5GetVarintLen((u32)(nActual*2));
              while( iSv2<(iData-nReq) ){ pBuf->p[iSv2++] = 0x80; }
              sqlite3Fts5PutVarint(&pBuf->p[iSv2], nActual*2);
            }
          }
        }
      }

    }
  }

  return 0;
}

static void fts5DoclistIterNext(Fts5DoclistIter *pIter){

    Fts5DoclistIter i1;
    Fts5DoclistIter i2;
    Fts5Buffer out;
    Fts5Buffer tmp;
    memset(&out, 0, sizeof(out));
    memset(&tmp, 0, sizeof(tmp));

    sqlite3Fts5BufferGrow(&p->rc, &out, p1->n + p2->n);
    fts5DoclistIterInit(p1, &i1);
    fts5DoclistIterInit(p2, &i2);
    while( p->rc==SQLITE_OK && (i1.aPoslist!=0 || i2.aPoslist!=0) ){
      if( i2.aPoslist==0 || (i1.aPoslist && i1.iRowid<i2.iRowid) ){
        /* Copy entry from i1 */
        fts5MergeAppendDocid(&out, iLastRowid, i1.iRowid);
        fts5BufferSafeAppendBlob(&out, i1.aPoslist, i1.nPoslist+i1.nSize);

  Fts5IndexIter *pRet = 0;
  int iIdx = 0;
  Fts5Buffer buf = {0, 0, 0};

  /* If the QUERY_SCAN flag is set, all other flags must be clear. */
  assert( (flags & FTS5INDEX_QUERY_SCAN)==0 || flags==FTS5INDEX_QUERY_SCAN );

  if( sqlite3Fts5BufferGrow(&p->rc, &buf, nToken+1)==0 ){
    memcpy(&buf.p[1], pToken, nToken);

#ifdef SQLITE_DEBUG
    /* If the QUERY_TEST_NOIDX flag was specified, then this must be a
    ** prefix-query. Instead of using a prefix-index (if one exists), 
    ** evaluate the prefix query using the main FTS index. This is used
    ** for internal sanity checking by the integrity-check in debug