postgres/contrib
Michael Paquier 732061150b xml2: Improve error handling of libxml2 calls
The contrib module xml2/ has always been fuzzy with the cleanup of the
memory allocated by the calls internal to libxml2, even if there are
APIs in place giving a lot of control over the error behavior, all
located in the backend's xml.c.

The code paths fixed in the commit address multiple defects, while
sanitizing the code:
- In xpath.c, several allocations are done by libxml2 for
xpath_workspace, whose memory cleanup could go out of sight as it relied
on a single TRY/CATCH block done in pgxml_xpath().  workspace->res is
allocated by libxml2, and may finish by not being freed at all upon a
failure outside of a TRY area.  This code is refactored so as the
TRY/CATCH block of pgxml_xpath() is moved one level higher to its
callers, which are responsible for cleaning up the contents of a
workspace on failure.  cleanup_workspace() now requires a volatile
workspace, forcing as a rule that a TRY/CATCH block should be used.
- Several calls, like xmlStrdup(), xmlXPathNewContext(),
xmlXPathCtxtCompile(), etc. can return NULL on failures (for most of
them allocation failures.  These forgot to check for failures, or missed
that pg_xml_error_occurred() should be called, to check if an error is
already on the stack.
- Some memory allocated by libxml2 calls was freed in an incorrect way,
"resstr" in xslt_process() being one example.

The class of errors fixed here are for problems that are unlikely going
to happen in practice, so no backpatch is done.  The changes have
finished by being rather invasive, so it is perhaps not a bad thing to
be conservative and to keep these changes only on HEAD anyway.

Author: Michael Paquier <michael@paquier.xyz>
Reported-by: Karavaev Alexey <maralist86@mail.ru>
Reviewed-by: Jim Jones <jim.jones@uni-muenster.de>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18943-2f2a04ab03904598@postgresql.org
2025-07-01 15:48:32 +09:00
..
amcheck Run pgperltidy 2025-06-29 21:14:21 -04:00
auth_delay Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
auto_explain Revert "Don't lock partitions pruned by initial pruning" 2025-05-22 17:02:35 +09:00
basebackup_to_shell Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
basic_archive Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
bloom Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
bool_plperl Fix erroneous construction of functions' dependencies on transforms. 2025-04-07 13:31:37 -04:00
btree_gin Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
btree_gist Rename gist stratnum support function 2025-06-02 08:41:27 +02:00
citext Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
cube Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
dblink Avoid resource leaks when a dblink connection fails. 2025-05-29 10:39:55 -04:00
dict_int Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
dict_xsyn Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
earthdistance Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
file_fdw Disallow "=" in names of reloptions and foreign-data options. 2025-06-02 15:22:44 -04:00
fuzzystrmatch Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
hstore Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
hstore_plperl Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
hstore_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
intagg Update copyright for 2025 2025-01-01 11:21:55 -05:00
intarray Fix GIN's shimTriConsistentFn to not corrupt its input. 2025-04-12 12:28:02 -04:00
isn Revert a few small patches that were intended for version 19. 2025-06-11 15:10:12 -07:00
jsonb_plperl Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
jsonb_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
lo Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
ltree Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
ltree_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
oid2name Update copyright for 2025 2025-01-01 11:21:55 -05:00
pageinspect Be more wary of corrupt data in pageinspect's heap_page_items(). 2025-04-19 16:37:42 -04:00
passwordcheck Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_buffercache Fix a few duplicate words in comments 2025-04-21 10:41:18 +12:00
pg_freespacemap Prevent assertion failure in contrib/pg_freespacemap. 2025-03-27 13:20:23 -04:00
pg_logicalinspect Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_overexplain Revert support for improved tracking of nested queries 2025-06-12 10:08:55 +09:00
pg_prewarm pg_prewarm: Allow autoprewarm to use more than 1GB to dump blocks. 2025-06-06 08:18:27 -04:00
pg_stat_statements Fix typo in comment 2025-06-26 18:33:48 +02:00
pg_surgery Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_trgm Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_visibility read_stream: Introduce and use optional batchmode support 2025-03-30 18:36:41 -04:00
pg_walinspect Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pgcrypto Fix incorrect format placeholder 2025-04-08 19:12:03 +02:00
pgrowlocks Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pgstattuple Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
postgres_fdw Add new OID alias type regdatabase. 2025-06-30 15:38:54 -05:00
seg Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
sepgsql Fix incorrect year in some copyright notices 2025-05-19 09:46:52 +09:00
spi Revert a few small patches that were intended for version 19. 2025-06-11 15:10:12 -07:00
sslinfo Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
start-scripts Remove gratuitous references to postmaster program 2023-01-26 10:48:32 +01:00
tablefunc Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
tcn Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
test_decoding Fix re-distributing previously distributed invalidation messages during logical decoding. 2025-06-16 17:36:01 -07:00
tsm_system_rows Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
tsm_system_time Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
unaccent Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
uuid-ossp Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
vacuumlo Update copyright for 2025 2025-01-01 11:21:55 -05:00
xml2 xml2: Improve error handling of libxml2 calls 2025-07-01 15:48:32 +09:00
contrib-global.mk
Makefile pg_overexplain: Additional EXPLAIN options for debugging. 2025-03-26 13:52:21 -04:00
meson.build pg_overexplain: Additional EXPLAIN options for debugging. 2025-03-26 13:52:21 -04:00
README

The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.