SQLite

                     i, pgno);
    }
    free(a);
    parent = pgno;
    pgno = iNext;
  }
}

/*
** Determine pages used as PTRMAP pages
*/
static void page_usage_ptrmap(unsigned char *a){
  if( a[55] ){
    int usable = pagesize - a[20];
    int pgno = 2;
    int perPage = usable/5;
    while( pgno<=mxPage ){
      page_usage_msg(pgno, "PTRMAP page covering %d..%d",
                           pgno+1, pgno+perPage);
      pgno += perPage + 1;
    }
  }
}

/*
** Try to figure out how every page in the database file is being used.
*/
static void page_usage_report(const char *zDbName){
  int i, j;
  int rc;

  zPageUse = sqlite3_malloc( sizeof(zPageUse[0])*(mxPage+1) );
  if( zPageUse==0 ) out_of_memory();
  memset(zPageUse, 0, sizeof(zPageUse[0])*(mxPage+1));

  /* Discover the usage of each page */
  a = getContent(0, 100);
  page_usage_freelist(decodeInt32(a+32));
  page_usage_ptrmap(a);
  free(a);
  page_usage_btree(1, 0, 0, "sqlite_master");
  sqlite3_exec(db, "PRAGMA writable_schema=ON", 0, 0, 0);
  for(j=0; j<2; j++){
    sqlite3_snprintf(sizeof(zQuery), zQuery,
             "SELECT type, name, rootpage FROM SQLITE_MASTER WHERE rootpage"
             " ORDER BY rowid %s", j?"DESC":"");

  for(i=1; i<=mxPage; i++){
    printf("%5d: %s\n", i, zPageUse[i] ? zPageUse[i] : "???");
    sqlite3_free(zPageUse[i]);
  }
  sqlite3_free(zPageUse);
  zPageUse = 0;
}

/*
** Try to figure out how every page in the database file is being used.
*/
static void ptrmap_coverage_report(const char *zDbName){
  unsigned int pgno;
  unsigned char *aHdr;
  unsigned char *a;
  int usable;
  int perPage;
  unsigned int i;

  /* Avoid the pathological case */
  if( mxPage<1 ){
    printf("empty database\n");
    return;
  }

  /* Make sure PTRMAPs are used in this database */
  aHdr = getContent(0, 100);
  if( aHdr[55]==0 ){
    printf("database does not use PTRMAP pages\n");
    return;
  }
  usable = pagesize - aHdr[20];
  perPage = usable/5;
  free(aHdr);
  printf("%5d: root of sqlite_master\n", 1);
  for(pgno=2; pgno<=mxPage; pgno += perPage+1){
    printf("%5d: PTRMAP page covering %d..%d\n", pgno,
           pgno+1, pgno+perPage);
    a = getContent((pgno-1)*pagesize, usable);
    for(i=0; i+5<=usable && pgno+1+i/5<=mxPage; i+=5){
      const char *zType = "???";
      unsigned int iFrom = decodeInt32(&a[i+1]);
      switch( a[i] ){
        case 1:  zType = "b-tree root page";        break;
        case 2:  zType = "freelist page";           break;
        case 3:  zType = "first page of overflow";  break;
        case 4:  zType = "later page of overflow";  break;
        case 5:  zType = "b-tree non-root page";    break;
      }
      printf("%5d: %s, parent=%u\n", pgno+1+i/5, zType, iFrom);
    }
    free(a);
  }
}

/*
** Print a usage comment
*/
static void usage(const char *argv0){
  fprintf(stderr, "Usage %s FILENAME ?args...?\n\n", argv0);
  fprintf(stderr,
    "args:\n"
    "    dbheader        Show database header\n"
    "    pgidx           Index of how each page is used\n"
    "    ptrmap          Show all PTRMAP page content\n"
    "    NNN..MMM        Show hex of pages NNN through MMM\n"
    "    NNN..end        Show hex of pages NNN through end of file\n"
    "    NNNb            Decode btree page NNN\n"
    "    NNNbc           Decode btree page NNN and show content\n"
    "    NNNbm           Decode btree page NNN and show a layout map\n"
    "    NNNt            Decode freelist trunk page NNN\n"
    "    NNNtd           Show leaf freelist pages on the decode\n"

      if( strcmp(argv[i], "dbheader")==0 ){
        print_db_header();
        continue;
      }
      if( strcmp(argv[i], "pgidx")==0 ){
        page_usage_report(argv[1]);
        continue;
      }
      if( strcmp(argv[i], "ptrmap")==0 ){
        ptrmap_coverage_report(argv[1]);
        continue;
      }
      if( strcmp(argv[i], "help")==0 ){
        usage(argv[0]);
        continue;
      }
      if( !isdigit(argv[i][0]) ){
        fprintf(stderr, "%s: unknown option: [%s]\n", argv[0], argv[i]);
        continue;
      }
      iStart = strtol(argv[i], &zLeft, 0);
      if( zLeft && strcmp(zLeft,"..end")==0 ){