Function recoverGetPage

modules/dasSQLITE/sqlite/shell.c:14144–14188

** The implementation of a user-defined SQL function invoked by the ** sqlite_dbdata and sqlite_dbptr virtual table modules to access pages ** of the database being recovered. ** ** This function always takes a single integer argument. If the argument ** is zero, then the value returned is the number of pages in the db being ** recovered. If the argument is greater than zero, it is a page number.

**     SELECT getpage(4);       -- return page 4 of db as a blob of data 
*/
static void recoverGetPage(
  sqlite3_context *pCtx,
  int nArg,
  sqlite3_value **apArg
){
  sqlite3_recover *p = (sqlite3_recover*)sqlite3_user_data(pCtx);
  i64 pgno = sqlite3_value_int64(apArg[0]);
  sqlite3_stmt *pStmt = 0;

  assert( nArg==1 );
  if( pgno==0 ){
    i64 nPg = recoverPageCount(p);
    sqlite3_result_int64(pCtx, nPg);
    return;
  }else{
    if( p->pGetPage==0 ){
      pStmt = p->pGetPage = recoverPreparePrintf(
          p, p->dbIn, "SELECT data FROM sqlite_dbpage(%Q) WHERE pgno=?", p->zDb
      );
    }else if( p->errCode==SQLITE_OK ){
      pStmt = p->pGetPage;
    }

    if( pStmt ){
      sqlite3_bind_int64(pStmt, 1, pgno);
      if( SQLITE_ROW==sqlite3_step(pStmt) ){
        const u8 *aPg;
        int nPg;
        assert( p->errCode==SQLITE_OK );
        aPg = sqlite3_column_blob(pStmt, 0);
        nPg = sqlite3_column_bytes(pStmt, 0);
        if( pgno==1 && nPg==p->pgsz && 0==memcmp(p->pPage1Cache, aPg, nPg) ){
          aPg = p->pPage1Disk;
        }
        sqlite3_result_blob(pCtx, aPg, nPg-p->nReserve, SQLITE_TRANSIENT);
      }
      recoverReset(p, pStmt);
    }
  }

  if( p->errCode ){
    if( p->zErrMsg ) sqlite3_result_error(pCtx, p->zErrMsg, -1);
    sqlite3_result_error_code(pCtx, p->errCode);
  }
}

/*
** Find a string that is not found anywhere in z[].  Return a pointer