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

diff --git a/contrib/pageinspect/brinfuncs.c b/contrib/pageinspect/brinfuncs.c
index 2086d8c8bbe758db4b777d1d5fbf278b8f6edb5d..521f7f6121b734fc79765cf34e633a98389375e1 100644 (file)
--- a/contrib/pageinspect/brinfuncs.c
+++ b/contrib/pageinspect/brinfuncs.c
@@ -60,6 +60,9 @@ brin_page_type(PG_FUNCTION_ARGS)
 
    page = get_page_from_raw(raw_page);
 
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    /* verify the special space has the expected size */
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
            ereport(ERROR,
@@ -97,6 +100,9 @@ verify_brin_page(bytea *raw_page, uint16 type, const char *strtype)
 {
    Page        page = get_page_from_raw(raw_page);
 
+   if (PageIsNew(page))
+       return page;
+
    /* verify the special space has the expected size */
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
            ereport(ERROR,
@@ -184,6 +190,13 @@ brin_page_items(PG_FUNCTION_ARGS)
    /* minimally verify the page we got */
    page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
 
+   if (PageIsNew(page))
+   {
+       brin_free_desc(bdesc);
+       index_close(indexRel, AccessShareLock);
+       PG_RETURN_NULL();
+   }
+
    /*
     * Initialize output functions for all indexed datatypes; simplifies
     * calling them later.
@@ -350,6 +363,9 @@ brin_metapage_info(PG_FUNCTION_ARGS)
 
    page = verify_brin_page(raw_page, BRIN_PAGETYPE_META, "metapage");
 
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");
@@ -401,6 +417,12 @@ brin_revmap_data(PG_FUNCTION_ARGS)
        /* minimally verify the page we got */
        page = verify_brin_page(raw_page, BRIN_PAGETYPE_REVMAP, "revmap");
 
+       if (PageIsNew(page))
+       {
+           MemoryContextSwitchTo(mctx);
+           PG_RETURN_NULL();
+       }
+
        state = palloc(sizeof(*state));
        state->tids = ((RevmapContents *) PageGetContents(page))->rm_tids;
        state->idx = 0;

diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index 652dc2fc8c00133f5c57f84b6461f93d9022c4c2..5835549d34c7e96dc5cb5778dc2e6166bdf528c1 100644 (file)
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -447,6 +447,12 @@ bt_page_items_bytea(PG_FUNCTION_ARGS)
 
        uargs->page = get_page_from_raw(raw_page);
 
+       if (PageIsNew(uargs->page))
+       {
+           MemoryContextSwitchTo(mctx);
+           PG_RETURN_NULL();
+       }
+
        uargs->offset = FirstOffsetNumber;
 
        /* verify the special space has the expected size */

diff --git a/contrib/pageinspect/expected/brin.out b/contrib/pageinspect/expected/brin.out
index 62ee783b604d1b08a2ee15392f1a6f6a4c682c9f..d19cdc3b957f8fe1910a3e7e66679331504a17c7 100644 (file)
--- a/contrib/pageinspect/expected/brin.out
+++ b/contrib/pageinspect/expected/brin.out
@@ -62,4 +62,29 @@ ERROR:  input page is not a valid BRIN page
 SELECT * FROM brin_revmap_data(get_raw_page('test1', 0));
 ERROR:  input page is not a valid BRIN page
 \set VERBOSITY default
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT brin_page_type(decode(repeat('00', :block_size), 'hex'));
+ brin_page_type 
+----------------
+ 
+(1 row)
+
+SELECT brin_page_items(decode(repeat('00', :block_size), 'hex'), 'test1_a_idx');
+ brin_page_items 
+-----------------
+(0 rows)
+
+SELECT brin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+ brin_metapage_info 
+--------------------
+ 
+(1 row)
+
+SELECT brin_revmap_data(decode(repeat('00', :block_size), 'hex'));
+ brin_revmap_data 
+------------------
+ 
+(1 row)
+
 DROP TABLE test1;

diff --git a/contrib/pageinspect/expected/btree.out b/contrib/pageinspect/expected/btree.out
index 6e05a58e7aed0385ad7319eb424696a770858d80..241ec000785c5463f3a13eab4c51757374bf451a 100644 (file)
--- a/contrib/pageinspect/expected/btree.out
+++ b/contrib/pageinspect/expected/btree.out
@@ -86,4 +86,10 @@ ERROR:  input page is not a valid btree page
 SELECT bt_page_items(get_raw_page('test1_a_brin', 0));
 ERROR:  input page is not a valid btree page
 \set VERBOSITY default
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT bt_page_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-+-
+bt_page_items | 
+
 DROP TABLE test1;

diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index c1f93ffaa199b7ef6c07ab9b0381504327215e6e..5f49ff577bf8c745f8dd8c761259cc013829cd83 100644 (file)
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -54,3 +54,17 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+

diff --git a/contrib/pageinspect/expected/hash.out b/contrib/pageinspect/expected/hash.out
index 7db8abe0998839386bcc5835081a6cbed61293fb..82f18752882e3a05d694ff9d7222a918fc2a3220 100644 (file)
--- a/contrib/pageinspect/expected/hash.out
+++ b/contrib/pageinspect/expected/hash.out
@@ -186,4 +186,16 @@ ERROR:  input page is not a valid hash page
 SELECT hash_page_type(get_raw_page('test_hash', 0));
 ERROR:  input page is not a valid hash page
 \set VERBOSITY default
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT hash_metapage_info(decode(repeat('00', :block_size), 'hex'));
+ERROR:  page is not a hash meta page
+SELECT hash_page_items(decode(repeat('00', :block_size), 'hex'));
+ERROR:  page is not a hash bucket or overflow page
+SELECT hash_page_stats(decode(repeat('00', :block_size), 'hex'));
+ERROR:  page is not a hash bucket or overflow page
+SELECT hash_page_type(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--+-------
+hash_page_type | unused
+
 DROP TABLE test_hash;

diff --git a/contrib/pageinspect/expected/page.out b/contrib/pageinspect/expected/page.out
index 75d7e8232b460ef28d9407eb07ee3807474dd2ed..bb6b1162f3110546766d23bb40a2a2300373557c 100644 (file)
--- a/contrib/pageinspect/expected/page.out
+++ b/contrib/pageinspect/expected/page.out
@@ -124,3 +124,23 @@ ERROR:  invalid page size
 SELECT page_header('ccc'::bytea);
 ERROR:  invalid page size
 \set VERBOSITY default
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT fsm_page_contents(decode(repeat('00', :block_size), 'hex'));
+ fsm_page_contents 
+-------------------
+ 
+(1 row)
+
+SELECT page_header(decode(repeat('00', :block_size), 'hex'));
+      page_header      
+-----------------------
+ (0/0,0,0,0,0,0,0,0,0)
+(1 row)
+
+SELECT page_checksum(decode(repeat('00', :block_size), 'hex'), 1);
+ page_checksum 
+---------------
+              
+(1 row)
+

diff --git a/contrib/pageinspect/fsmfuncs.c b/contrib/pageinspect/fsmfuncs.c
index 788c6fb397c39945d28edf54ded0020952b8b862..f0cbb7a178151062fd475000880cce7de2ac1bc5 100644 (file)
--- a/contrib/pageinspect/fsmfuncs.c
+++ b/contrib/pageinspect/fsmfuncs.c
@@ -47,6 +47,10 @@ fsm_page_contents(PG_FUNCTION_ARGS)
                 (errmsg("must be superuser to use raw page functions"))));
 
    page = get_page_from_raw(raw_page);
+
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    fsmpage = (FSMPage) PageGetContents(page);
 
    initStringInfo(&sinfo);

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index 4212e229509363aedad94b86551b22a3645218c4..70385e0b720d6fe2f81bf02f09b7e044d078e41f 100644 (file)
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -50,6 +50,9 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
    page = get_page_from_raw(raw_page);
 
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -116,6 +119,9 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
    page = get_page_from_raw(raw_page);
 
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -200,6 +206,12 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
        page = get_page_from_raw(raw_page);
 
+       if (PageIsNew(page))
+       {
+           MemoryContextSwitchTo(mctx);
+           PG_RETURN_NULL();
+       }
+
        if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c
index 072f1efe2216621f9b62c6a5658caffa524d3247..535205da612a267881e33b286e5e96e675ea4fc1 100644 (file)
--- a/contrib/pageinspect/rawpage.c
+++ b/contrib/pageinspect/rawpage.c
@@ -296,5 +296,8 @@ page_checksum(PG_FUNCTION_ARGS)
 
    page = get_page_from_raw(raw_page);
 
+   if (PageIsNew(page))
+       PG_RETURN_NULL();
+
    PG_RETURN_INT16(pg_checksum_page((char *) page, blkno));
 }

diff --git a/contrib/pageinspect/sql/brin.sql b/contrib/pageinspect/sql/brin.sql
index dc5d1661b6d03c3e5ccf4aa17651e03d4df2e981..45098c1ef5e4baa34e5f4e9dc0ad79e59c846dbc 100644 (file)
--- a/contrib/pageinspect/sql/brin.sql
+++ b/contrib/pageinspect/sql/brin.sql
@@ -27,4 +27,11 @@ SELECT * FROM brin_metapage_info(get_raw_page('test1', 0));
 SELECT * FROM brin_revmap_data(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT brin_page_type(decode(repeat('00', :block_size), 'hex'));
+SELECT brin_page_items(decode(repeat('00', :block_size), 'hex'), 'test1_a_idx');
+SELECT brin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+SELECT brin_revmap_data(decode(repeat('00', :block_size), 'hex'));
+
 DROP TABLE test1;

diff --git a/contrib/pageinspect/sql/btree.sql b/contrib/pageinspect/sql/btree.sql
index cde0083586cb523b107209a1f228d975b2ceac29..75587c1aca1f5fa058626a01c4a08abf24fbb462 100644 (file)
--- a/contrib/pageinspect/sql/btree.sql
+++ b/contrib/pageinspect/sql/btree.sql
@@ -41,4 +41,8 @@ SELECT bt_page_items(get_raw_page('test1', 0));
 SELECT bt_page_items(get_raw_page('test1_a_brin', 0));
 \set VERBOSITY default
 
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT bt_page_items(decode(repeat('00', :block_size), 'hex'));
+
 DROP TABLE test1;

diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index 342354a481f780a46e33680f04a88396da8828f1..b0c20c03073990d8ea0b185cb56d7e583f8e02a0 100644 (file)
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -31,3 +31,9 @@ SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
 SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
+
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));

diff --git a/contrib/pageinspect/sql/hash.sql b/contrib/pageinspect/sql/hash.sql
index 8fd209c815b5f030b895dbac8ff988e5a536dab5..3acdc7d9554d79fdacc9ae8c5a1d2bf01780c870 100644 (file)
--- a/contrib/pageinspect/sql/hash.sql
+++ b/contrib/pageinspect/sql/hash.sql
@@ -96,4 +96,11 @@ SELECT hash_page_stats(get_raw_page('test_hash', 0));
 SELECT hash_page_type(get_raw_page('test_hash', 0));
 \set VERBOSITY default
 
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT hash_metapage_info(decode(repeat('00', :block_size), 'hex'));
+SELECT hash_page_items(decode(repeat('00', :block_size), 'hex'));
+SELECT hash_page_stats(decode(repeat('00', :block_size), 'hex'));
+SELECT hash_page_type(decode(repeat('00', :block_size), 'hex'));
+
 DROP TABLE test_hash;

diff --git a/contrib/pageinspect/sql/page.sql b/contrib/pageinspect/sql/page.sql
index dddb80b457c588160e567ed6f08a1a5f6af270a2..71f7679d88c4bdefe820014f0df2d84356f64c78 100644 (file)
--- a/contrib/pageinspect/sql/page.sql
+++ b/contrib/pageinspect/sql/page.sql
@@ -61,3 +61,9 @@ SELECT fsm_page_contents('aaa'::bytea);
 SELECT page_checksum('bbb'::bytea, 0);
 SELECT page_header('ccc'::bytea);
 \set VERBOSITY default
+
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT fsm_page_contents(decode(repeat('00', :block_size), 'hex'));
+SELECT page_header(decode(repeat('00', :block_size), 'hex'));
+SELECT page_checksum(decode(repeat('00', :block_size), 'hex'), 1);