contrib/pageinspect/fsmfuncs.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * fsmfuncs.c
   4  *        Functions to investigate FSM pages
   5  *
   6  * These functions are restricted to superusers for the fear of introducing
   7  * security holes if the input checking isn't as water-tight as it should.
   8  * You'd need to be superuser to obtain a raw page image anyway, so
   9  * there's hardly any use case for using these without superuser-rights
  10  * anyway.
  11  *
  12  * Copyright (c) 2007-2023, PostgreSQL Global Development Group
  13  *
  14  * IDENTIFICATION
  15  *        contrib/pageinspect/fsmfuncs.c
  16  *
  17  *-------------------------------------------------------------------------
  18  */
  19
  20 #include "postgres.h"
  21
  22 #include "funcapi.h"
  23 #include "lib/stringinfo.h"
  24 #include "miscadmin.h"
  25 #include "pageinspect.h"
  26 #include "storage/fsm_internals.h"
  27 #include "utils/builtins.h"
  28
  29 /*
  30  * Dumps the contents of a FSM page.
  31  */
  32 PG_FUNCTION_INFO_V1(fsm_page_contents);
  33
  34 Datum
  35 fsm_page_contents(PG_FUNCTION_ARGS)
  36 {
  37         bytea      *raw_page = PG_GETARG_BYTEA_P(0);
  38         StringInfoData sinfo;
  39         Page            page;
  40         FSMPage         fsmpage;
  41         int                     i;
  42
  43         if (!superuser())
  44                 ereport(ERROR,
  45                                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  46                                  errmsg("must be superuser to use raw page functions")));
  47
  48         page = get_page_from_raw(raw_page);
  49
  50         if (PageIsNew(page))
  51                 PG_RETURN_NULL();
  52
  53         fsmpage = (FSMPage) PageGetContents(page);
  54
  55         initStringInfo(&sinfo);
  56
  57         for (i = 0; i < NodesPerPage; i++)
  58         {
  59                 if (fsmpage->fp_nodes[i] != 0)
  60                         appendStringInfo(&sinfo, "%d: %d\n", i, fsmpage->fp_nodes[i]);
  61         }
  62         appendStringInfo(&sinfo, "fp_next_slot: %d\n", fsmpage->fp_next_slot);
  63
  64         PG_RETURN_TEXT_P(cstring_to_text_with_len(sinfo.data, sinfo.len));
  65 }