SQLite

**
** This file contains an implementation of the "dbstat" virtual table.
**
** The dbstat virtual table is used to extract low-level formatting
** information from an SQLite database in order to implement the
** "sqlite3_analyzer" utility.  See the ../tool/spaceanal.tcl script
** for an example implementation.
**
** Additional information is available on the "dbstat.html" page of the
** official SQLite documentation.
*/

#include "sqliteInt.h"   /* Requires access to internal data structures */
#if (defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)) \
    && !defined(SQLITE_OMIT_VIRTUALTABLE)

/*

  "  pageno     INTEGER,          /* Page number */"                        \
  "  pagetype   STRING,           /* 'internal', 'leaf' or 'overflow' */"   \
  "  ncell      INTEGER,          /* Cells on page (0 for overflow) */"     \
  "  payload    INTEGER,          /* Bytes of payload on this page */"      \
  "  unused     INTEGER,          /* Bytes of unused space on this page */" \
  "  mx_payload INTEGER,          /* Largest payload size of all cells */"  \
  "  pgoffset   INTEGER,          /* Offset of page in file */"             \
  "  pgsize     INTEGER,          /* Size of the page */"                   \
  "  schema     TEXT HIDDEN       /* Database schema being analyzed */"     \
  ");"


typedef struct StatTable StatTable;
typedef struct StatCursor StatCursor;
typedef struct StatPage StatPage;
typedef struct StatCell StatCell;

  int nMxPayload;                 /* Largest payload of any cell on this page */
};

struct StatCursor {
  sqlite3_vtab_cursor base;
  sqlite3_stmt *pStmt;            /* Iterates through set of root pages */
  int isEof;                      /* After pStmt has returned SQLITE_DONE */
  int iDb;                        /* Schema used for this query */

  StatPage aPage[32];
  int iPage;                      /* Current entry in aPage[] */

  /* Values to return. */
  char *zName;                    /* Value of 'name' column */
  char *zPath;                    /* Value of 'path' column */

static int statDisconnect(sqlite3_vtab *pVtab){
  sqlite3_free(pVtab);
  return SQLITE_OK;
}

/*
** There is no "best-index". This virtual table always does a linear
** scan.  However, a schema=? constraint should cause this table to
** operate on a different database schema, so check for it.
**
** idxNum is normally 0, but will be 1 if a schema=? constraint exists.
*/
static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  int i;

  pIdxInfo->estimatedCost = 1.0e6;  /* Initial cost estimate */

  /* Look for a valid schema=? constraint.  If found, change the idxNum to
  ** 1 and request the value of that constraint be sent to xFilter.  And
  ** lower the cost estimate to encourage the constrained version to be
  ** used.
  */
  for(i=0; i<pIdxInfo->nConstraint; i++){
    if( pIdxInfo->aConstraint[i].usable==0 ) continue;
    if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    if( pIdxInfo->aConstraint[i].iColumn!=10 ) continue;
    pIdxInfo->idxNum = 1;
    pIdxInfo->estimatedCost = 1.0;
    pIdxInfo->aConstraintUsage[i].argvIndex = 1;
    pIdxInfo->aConstraintUsage[i].omit = 1;
    break;
  }


  /* Records are always returned in ascending order of (name, path). 
  ** If this will satisfy the client, set the orderByConsumed flag so that 
  ** SQLite does not do an external sort.
  */
  if( ( pIdxInfo->nOrderBy==1
     && pIdxInfo->aOrderBy[0].iColumn==0
     && pIdxInfo->aOrderBy[0].desc==0
     ) ||
      ( pIdxInfo->nOrderBy==2
     && pIdxInfo->aOrderBy[0].iColumn==0
     && pIdxInfo->aOrderBy[0].desc==0
     && pIdxInfo->aOrderBy[1].iColumn==1
     && pIdxInfo->aOrderBy[1].desc==0
     )
  ){
    pIdxInfo->orderByConsumed = 1;
  }


  return SQLITE_OK;
}

/*
** Open a new statvfs cursor.
*/
static int statOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
  StatTable *pTab = (StatTable *)pVTab;
  StatCursor *pCsr;


  pCsr = (StatCursor *)sqlite3_malloc64(sizeof(StatCursor));
  if( pCsr==0 ){
    return SQLITE_NOMEM;
  }else{

    memset(pCsr, 0, sizeof(StatCursor));
    pCsr->base.pVtab = pVTab;
    pCsr->iDb = pTab->iDb;
















  }

  *ppCursor = (sqlite3_vtab_cursor *)pCsr;
  return SQLITE_OK;
}

static void statClearPage(StatPage *p){
  int i;
  if( p->aCell ){
    for(i=0; i<p->nCell; i++){
      sqlite3_free(p->aCell[i].aOvfl);

  sqlite3_reset(pCsr->pStmt);
  for(i=0; i<ArraySize(pCsr->aPage); i++){
    statClearPage(&pCsr->aPage[i]);
  }
  pCsr->iPage = 0;
  sqlite3_free(pCsr->zPath);
  pCsr->zPath = 0;
  pCsr->isEof = 0;
}

/*
** Close a statvfs cursor.
*/
static int statClose(sqlite3_vtab_cursor *pCursor){
  StatCursor *pCsr = (StatCursor *)pCursor;

*/
static int statNext(sqlite3_vtab_cursor *pCursor){
  int rc;
  int nPayload;
  char *z;
  StatCursor *pCsr = (StatCursor *)pCursor;
  StatTable *pTab = (StatTable *)pCursor->pVtab;
  Btree *pBt = pTab->db->aDb[pCsr->iDb].pBt;
  Pager *pPager = sqlite3BtreePager(pBt);

  sqlite3_free(pCsr->zPath);
  pCsr->zPath = 0;

statNextRestart:
  if( pCsr->aPage[0].pPg==0 ){

static int statFilter(
  sqlite3_vtab_cursor *pCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  StatCursor *pCsr = (StatCursor *)pCursor;
  StatTable *pTab = (StatTable*)(pCursor->pVtab);
  char *zSql;
  int rc = SQLITE_OK;
  char *zMaster;

  if( idxNum==1 ){
    const char *zDbase = (const char*)sqlite3_value_text(argv[0]);
    pCsr->iDb = sqlite3FindDbName(pTab->db, zDbase);
    if( pCsr->iDb<0 ){
      sqlite3_free(pCursor->pVtab->zErrMsg);
      pCursor->pVtab->zErrMsg = sqlite3_mprintf("no such schema: %s", zDbase);
      return pCursor->pVtab->zErrMsg ? SQLITE_ERROR : SQLITE_NOMEM;
    }
  }else{
    pCsr->iDb = pTab->iDb;
  }
  statResetCsr(pCsr);
  sqlite3_finalize(pCsr->pStmt);
  pCsr->pStmt = 0;
  zMaster = pCsr->iDb==1 ? "sqlite_temp_master" : "sqlite_master";
  zSql = sqlite3_mprintf(
      "SELECT 'sqlite_master' AS name, 1 AS rootpage, 'table' AS type"
      "  UNION ALL  "
      "SELECT name, rootpage, type"
      "  FROM \"%w\".%s WHERE rootpage!=0"
      "  ORDER BY name", pTab->db->aDb[pCsr->iDb].zName, zMaster);
  if( zSql==0 ){
    return SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }

  if( rc==SQLITE_OK ){
    rc = statNext(pCursor);
  }
  return rc;
}

static int statColumn(
  sqlite3_vtab_cursor *pCursor, 
  sqlite3_context *ctx, 
  int i
){

      break;
    case 7:            /* mx_payload */
      sqlite3_result_int(ctx, pCsr->nMxPayload);
      break;
    case 8:            /* pgoffset */
      sqlite3_result_int64(ctx, pCsr->iOffset);
      break;
    case 9:            /* pgsize */

      sqlite3_result_int(ctx, pCsr->szPage);
      break;
    default: {          /* schema */
      sqlite3 *db = sqlite3_context_db_handle(ctx);
      int iDb = pCsr->iDb;
      sqlite3_result_text(ctx, db->aDb[iDb].zName, -1, SQLITE_STATIC);
      break;
    }
  }
  return SQLITE_OK;
}

static int statRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  StatCursor *pCsr = (StatCursor *)pCursor;
  *pRowid = pCsr->iPageno;

** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
** returns a copy of the pointer to the database connection (the 1st
** parameter) of the sqlite3_create_function() and
** sqlite3_create_function16() routines that originally registered the
** application defined function.
*/
sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
  assert( p && p->pOut );
  return p->pOut->db;
}

/*
** Return the current time for a statement.  If the current time
** is requested more than once within the same run of a single prepared
** statement, the exact same time is returned for each invocation regardless