2008-09-30 12:52:14 +02:00
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/*-------------------------------------------------------------------------
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*
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* fsmfuncs.c
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* Functions to investigate FSM pages
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*
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* These functions are restricted to superusers for the fear of introducing
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* security holes if the input checking isn't as water-tight as it should.
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* You'd need to be superuser to obtain a raw page image anyway, so
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* there's hardly any use case for using these without superuser-rights
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* anyway.
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*
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2024-01-04 02:49:05 +01:00
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* Copyright (c) 2007-2024, PostgreSQL Global Development Group
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2008-09-30 12:52:14 +02:00
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*
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* IDENTIFICATION
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2010-09-20 22:08:53 +02:00
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* contrib/pageinspect/fsmfuncs.c
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2008-09-30 12:52:14 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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2012-08-29 05:43:09 +02:00
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#include "funcapi.h"
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#include "lib/stringinfo.h"
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#include "miscadmin.h"
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2019-10-23 05:56:22 +02:00
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#include "pageinspect.h"
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2008-09-30 12:52:14 +02:00
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#include "storage/fsm_internals.h"
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#include "utils/builtins.h"
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/*
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* Dumps the contents of a FSM page.
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*/
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PG_FUNCTION_INFO_V1(fsm_page_contents);
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Datum
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fsm_page_contents(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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StringInfoData sinfo;
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pageinspect: Fix handling of page sizes and AM types
This commit fixes a set of issues related to the use of the SQL
functions in this module when the caller is able to pass down raw page
data as input argument:
- The page size check was fuzzy in a couple of places, sometimes
looking after only a sub-range, but what we are looking for is an exact
match on BLCKSZ. After considering a few options here, I have settled
down to do a generalization of get_page_from_raw(). Most of the SQL
functions already used that, and this is not strictly required if not
accessing an 8-byte-wide value from a raw page, but this feels safer in
the long run for alignment-picky environment, particularly if a code
path begins to access such values. This also reduces the number of
strings that need to be translated.
- The BRIN function brin_page_items() uses a Relation but it did not
check the access method of the opened index, potentially leading to
crashes. All the other functions in need of a Relation already did
that.
- Some code paths could fail on elog(), but we should to use ereport()
for failures that can be triggered by the user.
Tests are added to stress all the cases that are fixed as of this
commit, with some junk raw pages (\set VERBOSITY ensures that this works
across all page sizes) and unexpected index types when functions open
relations.
Author: Michael Paquier, Justin Prysby
Discussion: https://postgr.es/m/20220218030020.GA1137@telsasoft.com
Backpatch-through: 10
2022-03-16 03:19:39 +01:00
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Page page;
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2008-09-30 12:52:14 +02:00
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FSMPage fsmpage;
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int i;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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2020-01-30 17:32:04 +01:00
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errmsg("must be superuser to use raw page functions")));
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2008-09-30 12:52:14 +02:00
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pageinspect: Fix handling of page sizes and AM types
This commit fixes a set of issues related to the use of the SQL
functions in this module when the caller is able to pass down raw page
data as input argument:
- The page size check was fuzzy in a couple of places, sometimes
looking after only a sub-range, but what we are looking for is an exact
match on BLCKSZ. After considering a few options here, I have settled
down to do a generalization of get_page_from_raw(). Most of the SQL
functions already used that, and this is not strictly required if not
accessing an 8-byte-wide value from a raw page, but this feels safer in
the long run for alignment-picky environment, particularly if a code
path begins to access such values. This also reduces the number of
strings that need to be translated.
- The BRIN function brin_page_items() uses a Relation but it did not
check the access method of the opened index, potentially leading to
crashes. All the other functions in need of a Relation already did
that.
- Some code paths could fail on elog(), but we should to use ereport()
for failures that can be triggered by the user.
Tests are added to stress all the cases that are fixed as of this
commit, with some junk raw pages (\set VERBOSITY ensures that this works
across all page sizes) and unexpected index types when functions open
relations.
Author: Michael Paquier, Justin Prysby
Discussion: https://postgr.es/m/20220218030020.GA1137@telsasoft.com
Backpatch-through: 10
2022-03-16 03:19:39 +01:00
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page = get_page_from_raw(raw_page);
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pageinspect: Fix handling of all-zero pages
Getting from get_raw_page() an all-zero page is considered as a valid
case by the buffer manager and it can happen for example when finding a
corrupted page with zero_damaged_pages enabled (using zero_damaged_pages
to look at corrupted pages happens), or after a crash when a relation
file is extended before any WAL for its new data is generated (before a
vacuum or autovacuum job comes in to do some cleanup).
However, all the functions of pageinspect, as of the index AMs (except
hash that has its own idea of new pages), heap, the FSM or the page
header have never worked with all-zero pages, causing various crashes
when going through the page internals.
This commit changes all the pageinspect functions to be compliant with
all-zero pages, where the choice is made to return NULL or no rows for
SRFs when finding a new page. get_raw_page() still works the same way,
returning a batch of zeros in the bytea of the page retrieved. A hard
error could be used but NULL, while more invasive, is useful when
scanning relation files in full to get a batch of results for a single
relation in one query. Tests are added for all the code paths
impacted.
Reported-by: Daria Lepikhova
Author: Michael Paquier
Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru
Backpatch-through: 10
2022-04-14 08:08:03 +02:00
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if (PageIsNew(page))
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PG_RETURN_NULL();
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pageinspect: Fix handling of page sizes and AM types
This commit fixes a set of issues related to the use of the SQL
functions in this module when the caller is able to pass down raw page
data as input argument:
- The page size check was fuzzy in a couple of places, sometimes
looking after only a sub-range, but what we are looking for is an exact
match on BLCKSZ. After considering a few options here, I have settled
down to do a generalization of get_page_from_raw(). Most of the SQL
functions already used that, and this is not strictly required if not
accessing an 8-byte-wide value from a raw page, but this feels safer in
the long run for alignment-picky environment, particularly if a code
path begins to access such values. This also reduces the number of
strings that need to be translated.
- The BRIN function brin_page_items() uses a Relation but it did not
check the access method of the opened index, potentially leading to
crashes. All the other functions in need of a Relation already did
that.
- Some code paths could fail on elog(), but we should to use ereport()
for failures that can be triggered by the user.
Tests are added to stress all the cases that are fixed as of this
commit, with some junk raw pages (\set VERBOSITY ensures that this works
across all page sizes) and unexpected index types when functions open
relations.
Author: Michael Paquier, Justin Prysby
Discussion: https://postgr.es/m/20220218030020.GA1137@telsasoft.com
Backpatch-through: 10
2022-03-16 03:19:39 +01:00
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fsmpage = (FSMPage) PageGetContents(page);
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2008-09-30 12:52:14 +02:00
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initStringInfo(&sinfo);
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2009-06-11 16:49:15 +02:00
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for (i = 0; i < NodesPerPage; i++)
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2008-09-30 12:52:14 +02:00
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{
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if (fsmpage->fp_nodes[i] != 0)
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appendStringInfo(&sinfo, "%d: %d\n", i, fsmpage->fp_nodes[i]);
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}
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appendStringInfo(&sinfo, "fp_next_slot: %d\n", fsmpage->fp_next_slot);
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2013-11-18 16:17:07 +01:00
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PG_RETURN_TEXT_P(cstring_to_text_with_len(sinfo.data, sinfo.len));
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2008-09-30 12:52:14 +02:00
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}
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