SQLite

** The first argument, pCur, is a cursor opened on some b-tree. Count the
** number of entries in the b-tree and write the result to *pnEntry.
**
** SQLITE_OK is returned if the operation is successfully executed. 
** Otherwise, if an error is encountered (i.e. an IO error or database
** corruption) an SQLite error code is returned.
*/
int sqlite3BtreeCount(sqlite3 *db, BtCursor *pCur, i64 *pnEntry){
  i64 nEntry = 0;                      /* Value to return in *pnEntry */
  int rc;                              /* Return code */

  rc = moveToRoot(pCur);
  if( rc==SQLITE_EMPTY ){
    *pnEntry = 0;
    return SQLITE_OK;
  }

  /* Unless an error occurs, the following loop runs one iteration for each
  ** page in the B-Tree structure (not including overflow pages). 
  */
  while( rc==SQLITE_OK && !db->u1.isInterrupted ){
    int iIdx;                          /* Index of child node in parent */
    MemPage *pPage;                    /* Current page of the b-tree */

    /* If this is a leaf page or the tree is not an int-key tree, then 
    ** this page contains countable entries. Increment the entry counter
    ** accordingly.
    */

    checkAppendMsg(pCheck, "invalid page number %d", iPage);
    return 1;
  }
  if( getPageReferenced(pCheck, iPage) ){
    checkAppendMsg(pCheck, "2nd reference to page %d", iPage);
    return 1;
  }
  if( pCheck->db->u1.isInterrupted ) return 1;
  setPageReferenced(pCheck, iPage);
  return 0;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Check that the entry in the pointer-map for page iChild maps to 

**
** Write the number of error seen in *pnErr.  Except for some memory
** allocation errors,  an error message held in memory obtained from
** malloc is returned if *pnErr is non-zero.  If *pnErr==0 then NULL is
** returned.  If a memory allocation error occurs, NULL is returned.
*/
char *sqlite3BtreeIntegrityCheck(
  sqlite3 *db,  /* Database connection that is running the check */
  Btree *p,     /* The btree to be checked */
  int *aRoot,   /* An array of root pages numbers for individual trees */
  int nRoot,    /* Number of entries in aRoot[] */
  int mxErr,    /* Stop reporting errors after this many */
  int *pnErr    /* Write number of errors seen to this variable */
){
  Pgno i;
  IntegrityCk sCheck;
  BtShared *pBt = p->pBt;
  u64 savedDbFlags = pBt->db->flags;
  char zErr[100];
  VVA_ONLY( int nRef );

  sqlite3BtreeEnter(p);
  assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
  VVA_ONLY( nRef = sqlite3PagerRefcount(pBt->pPager) );
  assert( nRef>=0 );
  sCheck.db = db;
  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = btreePagecount(sCheck.pBt);
  sCheck.mxErr = mxErr;
  sCheck.nErr = 0;
  sCheck.mallocFailed = 0;
  sCheck.zPfx = 0;

i64 sqlite3BtreeOffset(BtCursor*);
#endif
int sqlite3BtreePayload(BtCursor*, u32 offset, u32 amt, void*);
const void *sqlite3BtreePayloadFetch(BtCursor*, u32 *pAmt);
u32 sqlite3BtreePayloadSize(BtCursor*);
sqlite3_int64 sqlite3BtreeMaxRecordSize(BtCursor*);

char *sqlite3BtreeIntegrityCheck(sqlite3*,Btree*,int*aRoot,int nRoot,int,int*);
struct Pager *sqlite3BtreePager(Btree*);
i64 sqlite3BtreeRowCountEst(BtCursor*);

#ifndef SQLITE_OMIT_INCRBLOB
int sqlite3BtreePayloadChecked(BtCursor*, u32 offset, u32 amt, void*);
int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
void sqlite3BtreeIncrblobCursor(BtCursor *);
#endif
void sqlite3BtreeClearCursor(BtCursor *);
int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
int sqlite3BtreeCursorHasHint(BtCursor*, unsigned int mask);
int sqlite3BtreeIsReadonly(Btree *pBt);
int sqlite3HeaderSizeBtree(void);

#ifndef NDEBUG
int sqlite3BtreeCursorIsValid(BtCursor*);
#endif
int sqlite3BtreeCursorIsValidNN(BtCursor*);

#ifndef SQLITE_OMIT_BTREECOUNT
int sqlite3BtreeCount(sqlite3*, BtCursor*, i64*);
#endif

#ifdef SQLITE_TEST
int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
void sqlite3BtreeCursorList(Btree*);
#endif

  int mxErr;        /* Stop accumulating errors when this reaches zero */
  int nErr;         /* Number of messages written to zErrMsg so far */
  int mallocFailed; /* A memory allocation error has occurred */
  const char *zPfx; /* Error message prefix */
  int v1, v2;       /* Values for up to two %d fields in zPfx */
  StrAccum errMsg;  /* Accumulate the error message text here */
  u32 *heap;        /* Min-heap used for analyzing cell coverage */
  sqlite3 *db;      /* Database connection running the check */
};

/*
** Routines to read or write a two- and four-byte big-endian integer values.
*/
#define get2byte(x)   ((x)[0]<<8 | (x)[1])
#define put2byte(p,v) ((p)[0] = (u8)((v)>>8), (p)[1] = (u8)(v))

  i64 nEntry;
  BtCursor *pCrsr;

  assert( p->apCsr[pOp->p1]->eCurType==CURTYPE_BTREE );
  pCrsr = p->apCsr[pOp->p1]->uc.pCursor;
  assert( pCrsr );
  nEntry = 0;  /* Not needed.  Only used to silence a warning. */
  rc = sqlite3BtreeCount(db, pCrsr, &nEntry);
  if( rc ) goto abort_due_to_error;
  pOut = out2Prerelease(p, pOp);
  pOut->u.i = nEntry;
  goto check_for_interrupt;
}
#endif

/* Opcode: Savepoint P1 * * P4 *
**
** Open, release or rollback the savepoint named by parameter P4, depending
** on the value of P1. To open a new savepoint set P1==0 (SAVEPOINT_BEGIN).

  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
  pnErr = &aMem[pOp->p3];
  assert( (pnErr->flags & MEM_Int)!=0 );
  assert( (pnErr->flags & (MEM_Str|MEM_Blob))==0 );
  pIn1 = &aMem[pOp->p1];
  assert( pOp->p5<db->nDb );
  assert( DbMaskTest(p->btreeMask, pOp->p5) );
  z = sqlite3BtreeIntegrityCheck(db, db->aDb[pOp->p5].pBt, &aRoot[1], nRoot,
                                 (int)pnErr->u.i+1, &nErr);
  sqlite3VdbeMemSetNull(pIn1);
  if( nErr==0 ){
    assert( z==0 );
  }else if( z==0 ){
    goto no_mem;
  }else{
    pnErr->u.i -= nErr-1;
    sqlite3VdbeMemSetStr(pIn1, z, -1, SQLITE_UTF8, sqlite3_free);
  }
  UPDATE_MAX_BLOBSIZE(pIn1);
  sqlite3VdbeChangeEncoding(pIn1, encoding);
  goto check_for_interrupt;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/* Opcode: RowSetAdd P1 P2 * * *
** Synopsis: rowset(P1)=r[P2]
**
** Insert the integer value held by register P2 into a RowSet object