/* 
** Argument is a pointer to an Fts5Data structure that contains a leaf
** page. This macro evaluates to true if the leaf contains no terms, or
** false if it contains at least one term.
*/
#define fts5LeafIsTermless(x) ((x)->szLeaf >= (x)->nn)

#define fts5LeafFirstTermOff(x) (fts5GetU16(&x->p[(x)->szLeaf]))


/*
** poslist:
**   Used by sqlite3Fts5IterPoslist() when the poslist needs to be buffered.
**   There is no way to tell if this is populated or not.
*/
struct Fts5IndexIter {
................................................................................
    pIter->pSeg = pSeg;
    pIter->iLeafPgno = pSeg->pgnoFirst-1;
    fts5SegIterNextPage(p, pIter);
  }

  if( p->rc==SQLITE_OK ){
    u8 *a = pIter->pLeaf->p;
    pIter->iLeafOffset = fts5GetU16(&a[pIter->pLeaf->szLeaf]);
    assert( pIter->iLeafOffset==4 );
    fts5SegIterLoadTerm(p, pIter, 0);
    fts5SegIterLoadNPos(p, pIter);
  }
}

/*
** This function is only ever called on iterators created by calls to
................................................................................
        iOff = 0;
        /* Next entry is not on the current page */
        while( iOff==0 ){
          fts5SegIterNextPage(p, pIter);
          pLeaf = pIter->pLeaf;
          if( pLeaf==0 ) break;
          ASSERT_SZLEAF_OK(pLeaf);
          if( (iOff = fts5GetU16(&pLeaf->p[0])) && iOff<pLeaf->szLeaf ){
            iOff += sqlite3Fts5GetVarint(&pLeaf->p[iOff], (u64*)&pIter->iRowid);
            pIter->iLeafOffset = iOff;
          }
          else if( pLeaf->nn>pLeaf->szLeaf ){
            iOff = fts5GetU16(&pLeaf->p[pLeaf->szLeaf]);
            pIter->iLeafOffset = iOff;
            bNewTerm = 1;
          }
          if( iOff>=pLeaf->szLeaf ){
            p->rc = FTS5_CORRUPT;
            return;
          }
................................................................................
      /* The last rowid in the doclist may not be on the current page. Search
      ** forward to find the page containing the last rowid.  */
      for(pgno=pIter->iLeafPgno+1; !p->rc && pgno<=pSeg->pgnoLast; pgno++){
        i64 iAbs = FTS5_SEGMENT_ROWID(pSeg->iSegid, 0, pgno);
        Fts5Data *pNew = fts5DataRead(p, iAbs);
        if( pNew ){
          int iRowid, bTermless;
          iRowid = fts5GetU16(pNew->p);
          bTermless = fts5LeafIsTermless(pNew);
          if( iRowid ){
            SWAPVAL(Fts5Data*, pNew, pLast);
            pgnoLast = pgno;
          }
          fts5DataRelease(pNew);
          if( bTermless==0 ) break;
................................................................................
  int nNew = 0;
  int iTerm = 0;
  int nPgTerm = (pIter->pLeaf->nn - pIter->pLeaf->szLeaf) >> 1;

  assert( p->rc==SQLITE_OK );
  assert( pIter->pLeaf );

  iOff = fts5GetU16(&a[n]);
  if( iOff<4 || iOff>=n ){
    p->rc = FTS5_CORRUPT;
    return;
  }

  while( 1 ){
    int i;
................................................................................
    assert( p->rc!=SQLITE_OK || pIter->iLeafPgno==iLeafPgno );

    if( p->rc==SQLITE_OK ){
      int iOff;
      u8 *a = pIter->pLeaf->p;
      int n = pIter->pLeaf->szLeaf;

      iOff = fts5GetU16(&a[0]);
      if( iOff<4 || iOff>=n ){
        p->rc = FTS5_CORRUPT;
      }else{
        iOff += fts5GetVarint(&a[iOff], (u64*)&pIter->iRowid);
        pIter->iLeafOffset = iOff;
        fts5SegIterLoadNPos(p, pIter);
      }
................................................................................

  /* Now check that the iter.nEmpty leaves following the current leaf
  ** (a) exist and (b) contain no terms. */
  for(i=iFirst; p->rc==SQLITE_OK && i<=iLast; i++){
    Fts5Data *pLeaf = fts5DataRead(p, FTS5_SEGMENT_ROWID(pSeg->iSegid, 0, i));
    if( pLeaf ){
      if( !fts5LeafIsTermless(pLeaf) ) p->rc = FTS5_CORRUPT;
      if( i>=iNoRowid && 0!=fts5GetU16(&pLeaf->p[0]) ) p->rc = FTS5_CORRUPT;
    }
    fts5DataRelease(pLeaf);
    if( p->rc ) break;
  }
}

static void fts5IndexIntegrityCheckSegment(
................................................................................
    }else{
      int iOff;                   /* Offset of first term on leaf */
      int iRowidOff;              /* Offset of first rowid on leaf */
      int nTerm;                  /* Size of term on leaf in bytes */
      int res;                    /* Comparison of term and split-key */

      iOff = fts5LeafFirstTermOff(pLeaf);
      iRowidOff = fts5GetU16(&pLeaf->p[0]);
      if( iRowidOff>=iOff ){
        p->rc = FTS5_CORRUPT;
      }else{
        iOff += fts5GetVarint32(&pLeaf->p[iOff], nTerm);
        res = memcmp(&pLeaf->p[iOff], zIdxTerm, MIN(nTerm, nIdxTerm));
        if( res==0 ) res = nTerm - nIdxTerm;
        if( res<0 ) p->rc = FTS5_CORRUPT;
................................................................................
      ){

        /* Check any rowid-less pages that occur before the current leaf. */
        for(iPg=iPrevLeaf+1; iPg<fts5DlidxIterPgno(pDlidx); iPg++){
          iKey = FTS5_SEGMENT_ROWID(iSegid, 0, iPg);
          pLeaf = fts5DataRead(p, iKey);
          if( pLeaf ){
            if( fts5GetU16(&pLeaf->p[0])!=0 ) p->rc = FTS5_CORRUPT;
            fts5DataRelease(pLeaf);
          }
        }
        iPrevLeaf = fts5DlidxIterPgno(pDlidx);

        /* Check that the leaf page indicated by the iterator really does
        ** contain the rowid suggested by the same. */
        iKey = FTS5_SEGMENT_ROWID(iSegid, 0, iPrevLeaf);
        pLeaf = fts5DataRead(p, iKey);
        if( pLeaf ){
          i64 iRowid;
          int iRowidOff = fts5GetU16(&pLeaf->p[0]);
          ASSERT_SZLEAF_OK(pLeaf);
          if( iRowidOff>=pLeaf->szLeaf ){
            p->rc = FTS5_CORRUPT;
          }else{
            fts5GetVarint(&pLeaf->p[iRowidOff], (u64*)&iRowid);
            if( iRowid!=fts5DlidxIterRowid(pDlidx) ) p->rc = FTS5_CORRUPT;
          }

/* 
** Argument is a pointer to an Fts5Data structure that contains a leaf
** page. This macro evaluates to true if the leaf contains no terms, or
** false if it contains at least one term.
*/
#define fts5LeafIsTermless(x) ((x)->szLeaf >= (x)->nn)

#define fts5LeafFirstTermOff(x) (fts5GetU16(&(x)->p[(x)->szLeaf]))
#define fts5LeafFirstRowidOff(x) (fts5GetU16((x)->p))

/*
** poslist:
**   Used by sqlite3Fts5IterPoslist() when the poslist needs to be buffered.
**   There is no way to tell if this is populated or not.
*/
struct Fts5IndexIter {
................................................................................
    pIter->pSeg = pSeg;
    pIter->iLeafPgno = pSeg->pgnoFirst-1;
    fts5SegIterNextPage(p, pIter);
  }

  if( p->rc==SQLITE_OK ){
    u8 *a = pIter->pLeaf->p;
    pIter->iLeafOffset = 4;
    assert( fts5LeafFirstTermOff(pIter->pLeaf)==4 );
    fts5SegIterLoadTerm(p, pIter, 0);
    fts5SegIterLoadNPos(p, pIter);
  }
}

/*
** This function is only ever called on iterators created by calls to
................................................................................
        iOff = 0;
        /* Next entry is not on the current page */
        while( iOff==0 ){
          fts5SegIterNextPage(p, pIter);
          pLeaf = pIter->pLeaf;
          if( pLeaf==0 ) break;
          ASSERT_SZLEAF_OK(pLeaf);
          if( (iOff = fts5LeafFirstRowidOff(pLeaf)) && iOff<pLeaf->szLeaf ){
            iOff += sqlite3Fts5GetVarint(&pLeaf->p[iOff], (u64*)&pIter->iRowid);
            pIter->iLeafOffset = iOff;
          }
          else if( pLeaf->nn>pLeaf->szLeaf ){
            iOff = fts5LeafFirstTermOff(pLeaf);
            pIter->iLeafOffset = iOff;
            bNewTerm = 1;
          }
          if( iOff>=pLeaf->szLeaf ){
            p->rc = FTS5_CORRUPT;
            return;
          }
................................................................................
      /* The last rowid in the doclist may not be on the current page. Search
      ** forward to find the page containing the last rowid.  */
      for(pgno=pIter->iLeafPgno+1; !p->rc && pgno<=pSeg->pgnoLast; pgno++){
        i64 iAbs = FTS5_SEGMENT_ROWID(pSeg->iSegid, 0, pgno);
        Fts5Data *pNew = fts5DataRead(p, iAbs);
        if( pNew ){
          int iRowid, bTermless;
          iRowid = fts5LeafFirstRowidOff(pNew);
          bTermless = fts5LeafIsTermless(pNew);
          if( iRowid ){
            SWAPVAL(Fts5Data*, pNew, pLast);
            pgnoLast = pgno;
          }
          fts5DataRelease(pNew);
          if( bTermless==0 ) break;
................................................................................
  int nNew = 0;
  int iTerm = 0;
  int nPgTerm = (pIter->pLeaf->nn - pIter->pLeaf->szLeaf) >> 1;

  assert( p->rc==SQLITE_OK );
  assert( pIter->pLeaf );

  iOff = fts5LeafFirstTermOff(pIter->pLeaf);
  if( iOff<4 || iOff>=n ){
    p->rc = FTS5_CORRUPT;
    return;
  }

  while( 1 ){
    int i;
................................................................................
    assert( p->rc!=SQLITE_OK || pIter->iLeafPgno==iLeafPgno );

    if( p->rc==SQLITE_OK ){
      int iOff;
      u8 *a = pIter->pLeaf->p;
      int n = pIter->pLeaf->szLeaf;

      iOff = fts5LeafFirstRowidOff(pIter->pLeaf);
      if( iOff<4 || iOff>=n ){
        p->rc = FTS5_CORRUPT;
      }else{
        iOff += fts5GetVarint(&a[iOff], (u64*)&pIter->iRowid);
        pIter->iLeafOffset = iOff;
        fts5SegIterLoadNPos(p, pIter);
      }
................................................................................

  /* Now check that the iter.nEmpty leaves following the current leaf
  ** (a) exist and (b) contain no terms. */
  for(i=iFirst; p->rc==SQLITE_OK && i<=iLast; i++){
    Fts5Data *pLeaf = fts5DataRead(p, FTS5_SEGMENT_ROWID(pSeg->iSegid, 0, i));
    if( pLeaf ){
      if( !fts5LeafIsTermless(pLeaf) ) p->rc = FTS5_CORRUPT;
      if( i>=iNoRowid && 0!=fts5LeafFirstRowidOff(pLeaf) ) p->rc = FTS5_CORRUPT;
    }
    fts5DataRelease(pLeaf);
    if( p->rc ) break;
  }
}

static void fts5IndexIntegrityCheckSegment(
................................................................................
    }else{
      int iOff;                   /* Offset of first term on leaf */
      int iRowidOff;              /* Offset of first rowid on leaf */
      int nTerm;                  /* Size of term on leaf in bytes */
      int res;                    /* Comparison of term and split-key */

      iOff = fts5LeafFirstTermOff(pLeaf);
      iRowidOff = fts5LeafFirstRowidOff(pLeaf);
      if( iRowidOff>=iOff ){
        p->rc = FTS5_CORRUPT;
      }else{
        iOff += fts5GetVarint32(&pLeaf->p[iOff], nTerm);
        res = memcmp(&pLeaf->p[iOff], zIdxTerm, MIN(nTerm, nIdxTerm));
        if( res==0 ) res = nTerm - nIdxTerm;
        if( res<0 ) p->rc = FTS5_CORRUPT;
................................................................................
      ){

        /* Check any rowid-less pages that occur before the current leaf. */
        for(iPg=iPrevLeaf+1; iPg<fts5DlidxIterPgno(pDlidx); iPg++){
          iKey = FTS5_SEGMENT_ROWID(iSegid, 0, iPg);
          pLeaf = fts5DataRead(p, iKey);
          if( pLeaf ){
            if( fts5LeafFirstRowidOff(pLeaf)!=0 ) p->rc = FTS5_CORRUPT;
            fts5DataRelease(pLeaf);
          }
        }
        iPrevLeaf = fts5DlidxIterPgno(pDlidx);

        /* Check that the leaf page indicated by the iterator really does
        ** contain the rowid suggested by the same. */
        iKey = FTS5_SEGMENT_ROWID(iSegid, 0, iPrevLeaf);
        pLeaf = fts5DataRead(p, iKey);
        if( pLeaf ){
          i64 iRowid;
          int iRowidOff = fts5LeafFirstRowidOff(pLeaf);
          ASSERT_SZLEAF_OK(pLeaf);
          if( iRowidOff>=pLeaf->szLeaf ){
            p->rc = FTS5_CORRUPT;
          }else{
            fts5GetVarint(&pLeaf->p[iRowidOff], (u64*)&iRowid);
            if( iRowid!=fts5DlidxIterRowid(pDlidx) ) p->rc = FTS5_CORRUPT;
          }