SQLite

** testing and debugging only.
*/
Pager *sqlite3BtreePager(Btree *p){
  return p->pBt->pPager;
}

#ifndef SQLITE_OMIT_INTEGRITY_CHECK
/*
** Record an OOM error during integrity_check
*/
static void checkOom(IntegrityCk *pCheck){
  pCheck->rc = SQLITE_NOMEM;
  pCheck->mxErr = 0;  /* Causes integrity_check processing to stop */
  if( pCheck->nErr==0 ) pCheck->nErr++;
}

/*
** Invoke the progress handler, if appropriate.  Also check for an
** interrupt.
*/
static void checkProgress(IntegrityCk *pCheck){
  sqlite3 *db = pCheck->db;
  if( AtomicLoad(&db->u1.isInterrupted) ){
    pCheck->rc = SQLITE_INTERRUPT;
    pCheck->nErr++;
    pCheck->mxErr = 0;
  }
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  if( db->xProgress ){
    assert( db->nProgressOps>0 );
    pCheck->nStep++;
    if( (pCheck->nStep % db->nProgressOps)==0
     && db->xProgress(db->pProgressArg)
    ){
      pCheck->rc = SQLITE_INTERRUPT;
      pCheck->nErr++;
      pCheck->mxErr = 0;
    }
  }
#endif
}

/*
** Append a message to the error message string.
*/
static void checkAppendMsg(
  IntegrityCk *pCheck,
  const char *zFormat,
  ...
){
  va_list ap;
  checkProgress(pCheck);
  if( !pCheck->mxErr ) return;
  pCheck->mxErr--;
  pCheck->nErr++;
  va_start(ap, zFormat);
  if( pCheck->errMsg.nChar ){
    sqlite3_str_append(&pCheck->errMsg, "\n", 1);
  }
  if( pCheck->zPfx ){
    sqlite3_str_appendf(&pCheck->errMsg, pCheck->zPfx, pCheck->v1, pCheck->v2);
  }
  sqlite3_str_vappendf(&pCheck->errMsg, zFormat, ap);
  va_end(ap);
  if( pCheck->errMsg.accError==SQLITE_NOMEM ){
    checkOom(pCheck);
  }
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

#ifndef SQLITE_OMIT_INTEGRITY_CHECK

/*

    checkAppendMsg(pCheck, "invalid page number %d", iPage);
    return 1;
  }
  if( getPageReferenced(pCheck, iPage) ){
    checkAppendMsg(pCheck, "2nd reference to page %d", iPage);
    return 1;
  }

  setPageReferenced(pCheck, iPage);
  return 0;
}

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

){
  int rc;
  u8 ePtrmapType;
  Pgno iPtrmapParent;

  rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ) checkOom(pCheck);
    checkAppendMsg(pCheck, "Failed to read ptrmap key=%d", iChild);
    return;
  }

  if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
    checkAppendMsg(pCheck,
      "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)", 

  const char *saved_zPfx = pCheck->zPfx;
  int saved_v1 = pCheck->v1;
  int saved_v2 = pCheck->v2;
  u8 savedIsInit = 0;

  /* Check that the page exists
  */
  checkProgress(pCheck);
  if( pCheck->mxErr==0 ) goto end_of_check;
  pBt = pCheck->pBt;
  usableSize = pBt->usableSize;
  if( iPage==0 ) return 0;
  if( checkRef(pCheck, iPage) ) return 0;
  pCheck->zPfx = "Page %u: ";
  pCheck->v1 = iPage;
  if( (rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0 ){

** happens when performing an integrity check on a single table.  The
** zero is skipped, of course.  But in addition, the freelist checks
** and the checks to make sure every page is referenced are also skipped,
** since obviously it is not possible to know which pages are covered by
** the unverified btrees.  Except, if aRoot[1] is 1, then the freelist
** checks are still performed.
*/
int sqlite3BtreeIntegrityCheck(
  sqlite3 *db,  /* Database connection that is running the check */
  Btree *p,     /* The btree to be checked */
  Pgno *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,   /* OUT: Write number of errors seen to this variable */
  char **pzOut  /* OUT: Write the error message string here */
){
  Pgno i;
  IntegrityCk sCheck;
  BtShared *pBt = p->pBt;
  u64 savedDbFlags = pBt->db->flags;
  char zErr[100];
  int bPartial = 0;            /* True if not checking all btrees */

    if( aRoot[1]!=1 ) bCkFreelist = 0;
  }

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







  sqlite3StrAccumInit(&sCheck.errMsg, 0, zErr, sizeof(zErr), SQLITE_MAX_LENGTH);
  sCheck.errMsg.printfFlags = SQLITE_PRINTF_INTERNAL;
  if( sCheck.nPage==0 ){
    goto integrity_ck_cleanup;
  }

  sCheck.aPgRef = sqlite3MallocZero((sCheck.nPage / 8)+ 1);
  if( !sCheck.aPgRef ){
    checkOom(&sCheck);
    goto integrity_ck_cleanup;
  }
  sCheck.heap = (u32*)sqlite3PageMalloc( pBt->pageSize );
  if( sCheck.heap==0 ){
    checkOom(&sCheck);
    goto integrity_ck_cleanup;
  }

  i = PENDING_BYTE_PAGE(pBt);
  if( i<=sCheck.nPage ) setPageReferenced(&sCheck, i);

  /* Check the integrity of the freelist

  }

  /* Clean  up and report errors.
  */
integrity_ck_cleanup:
  sqlite3PageFree(sCheck.heap);
  sqlite3_free(sCheck.aPgRef);
  *pnErr = sCheck.nErr;
  if( sCheck.nErr==0 ){
    sqlite3_str_reset(&sCheck.errMsg);
    *pzOut = 0;
  }else{
    *pzOut = sqlite3StrAccumFinish(&sCheck.errMsg);
  }


  /* Make sure this analysis did not leave any unref() pages. */
  assert( nRef==sqlite3PagerRefcount(pBt->pPager) );
  sqlite3BtreeLeave(p);
  return sCheck.rc;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/*
** Return the full pathname of the underlying database file.  Return
** an empty string if the database is in-memory or a TEMP database.
**

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*);

int sqlite3BtreeIntegrityCheck(
  sqlite3 *db,  /* Database connection that is running the check */
  Btree *p,     /* The btree to be checked */
  Pgno *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,   /* OUT: Write number of errors seen to this variable */
  char **pzOut  /* OUT: Write the error message string here */
);
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 *);

#define ISAUTOVACUUM(pBt) (pBt->autoVacuum)
#else
#define ISAUTOVACUUM(pBt) 0
#endif


/*
** This structure is passed around through all the PRAGMA integrity_check
** checking routines in order to keep track of some global state information.
**
** The aRef[] array is allocated so that there is 1 bit for each page in
** the database. As the integrity-check proceeds, for each page used in
** the database the corresponding bit is set. This allows integrity-check to 
** detect pages that are used twice and orphaned pages (both of which 
** indicate corruption).
*/
typedef struct IntegrityCk IntegrityCk;
struct IntegrityCk {
  BtShared *pBt;    /* The tree being checked out */
  Pager *pPager;    /* The associated pager.  Also accessible by pBt->pPager */
  u8 *aPgRef;       /* 1 bit per page in the db (see above) */
  Pgno nPage;       /* Number of pages in the database */
  int mxErr;        /* Stop accumulating errors when this reaches zero */
  int nErr;         /* Number of messages written to zErrMsg so far */
  int rc;;          /* SQLITE_OK, SQLITE_NOMEM, or SQLITE_INTERRUPT */
  u32 nStep;        /* Number of steps into the integrity_check process */
  const char *zPfx; /* Error message prefix */
  Pgno v1;          /* Value for first %u substitution in zPfx */
  int v2;           /* Value for second %d substitution 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 */
};

  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) );
  rc = sqlite3BtreeIntegrityCheck(db, db->aDb[pOp->p5].pBt, &aRoot[1], nRoot,
                                 (int)pnErr->u.i+1, &nErr, &z);
  sqlite3VdbeMemSetNull(pIn1);
  if( nErr==0 ){
    assert( z==0 );
  }else if( rc ){
    sqlite3_free(z);
    goto abort_due_to_error;
  }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;