0001-test_compression-Test-module-for-compression-methods.patch

From 39eb787808d77d3cad30dc3d5ce2d02503326cba Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 13 Apr 2026 09:33:30 +0900
Subject: [PATCH] test_compression: Test module for compression methods

The goal of this module is to provide tests for low-level APIs of
compression methods.  pglz is covered in this commit.

This module includes also tests for the cases detected by fuzzing
related to corrupted data, as fixed in 2b5ba2a0a141:
- Control byte with match tag bit set, where no data follows.
- Control byte with match tag bit set, where 1 byte follows.
- Extension byte needed (len=18), where no data follows.

As bonus points, tests are added for compress/decompress roundtrips, and
for check_complete=false/true.

Backpatch-through: 14
---
 src/test/modules/Makefile                     |  1 +
 src/test/modules/meson.build                  |  1 +
 src/test/modules/test_compression/.gitignore  |  4 +
 src/test/modules/test_compression/Makefile    | 23 +++++
 .../expected/test_compression.out             | 51 +++++++++++
 src/test/modules/test_compression/meson.build | 33 +++++++
 .../test_compression/sql/test_compression.sql | 36 ++++++++
 .../test_compression--1.0.sql                 | 12 +++
 .../test_compression/test_compression.c       | 85 +++++++++++++++++++
 .../test_compression/test_compression.control |  4 +
 10 files changed, 250 insertions(+)
 create mode 100644 src/test/modules/test_compression/.gitignore
 create mode 100644 src/test/modules/test_compression/Makefile
 create mode 100644 src/test/modules/test_compression/expected/test_compression.out
 create mode 100644 src/test/modules/test_compression/meson.build
 create mode 100644 src/test/modules/test_compression/sql/test_compression.sql
 create mode 100644 src/test/modules/test_compression/test_compression--1.0.sql
 create mode 100644 src/test/modules/test_compression/test_compression.c
 create mode 100644 src/test/modules/test_compression/test_compression.control

diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 0a74ab5c86f5..dbcd432f8c86 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -22,6 +22,7 @@ SUBDIRS = \
 		  test_bloomfilter \
 		  test_cloexec \
 		  test_checksums \
+		  test_compression \
 		  test_copy_callbacks \
 		  test_custom_rmgrs \
 		  test_custom_stats \
diff --git a/src/test/modules/meson.build b/src/test/modules/meson.build
index 4bca42bb3706..7cb26400d435 100644
--- a/src/test/modules/meson.build
+++ b/src/test/modules/meson.build
@@ -22,6 +22,7 @@ subdir('test_bitmapset')
 subdir('test_bloomfilter')
 subdir('test_cloexec')
 subdir('test_checksums')
+subdir('test_compression')
 subdir('test_copy_callbacks')
 subdir('test_cplusplusext')
 subdir('test_custom_rmgrs')
diff --git a/src/test/modules/test_compression/.gitignore b/src/test/modules/test_compression/.gitignore
new file mode 100644
index 000000000000..5dcb3ff97235
--- /dev/null
+++ b/src/test/modules/test_compression/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/test_compression/Makefile b/src/test/modules/test_compression/Makefile
new file mode 100644
index 000000000000..82c6ace4dc8a
--- /dev/null
+++ b/src/test/modules/test_compression/Makefile
@@ -0,0 +1,23 @@
+# src/test/modules/test_compression/Makefile
+
+MODULE_big = test_compression
+OBJS = \
+	$(WIN32RES) \
+	test_compression.o
+PGFILEDESC = "test_compression - test code for compression methods"
+
+EXTENSION = test_compression
+DATA = test_compression--1.0.sql
+
+REGRESS = test_compression
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/test_compression
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/test_compression/expected/test_compression.out b/src/test/modules/test_compression/expected/test_compression.out
new file mode 100644
index 000000000000..837acc85dd49
--- /dev/null
+++ b/src/test/modules/test_compression/expected/test_compression.out
@@ -0,0 +1,51 @@
+CREATE EXTENSION test_compression;
+-- Round-trip with pglz: compress then decompress.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 400, false) =
+    decode(repeat('abcd', 100), 'escape') AS roundtrip_ok;
+ roundtrip_ok 
+--------------
+ t
+(1 row)
+
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 400, true) =
+    decode(repeat('abcd', 100), 'escape') AS roundtrip_ok;
+ roundtrip_ok 
+--------------
+ t
+(1 row)
+
+-- Decompression with rawsize too large, fails to fill the destination
+-- buffer.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 500, true);
+ERROR:  pglz_decompress failed
+-- Decompression with rawsize too small, fails with source not fully
+-- consumed.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 100, true);
+ERROR:  pglz_decompress failed
+-- Corrupted compressed data.  The control byte is set with match tag bit,
+-- but only 1 byte follows.
+SELECT test_pglz_decompress('\x01ff'::bytea, 1024, false);
+ERROR:  pglz_decompress failed
+SELECT test_pglz_decompress('\x01ff'::bytea, 1024, true);
+ERROR:  pglz_decompress failed
+-- Corrupted compressed data.  Control byte with match tag bit set, where
+-- no data follows.
+SELECT length(test_pglz_decompress('\x01'::bytea, 1024, false)) AS ctrl_only_len;
+ ctrl_only_len 
+---------------
+             0
+(1 row)
+
+SELECT test_pglz_decompress('\x01'::bytea, 1024, true);
+ERROR:  pglz_decompress failed
+-- Corrupted compressed data.  The match tag encodes len=18 (aka the
+-- extension byte is needed) but there is no data.
+SELECT test_pglz_decompress('\x010f01'::bytea, 1024, false);
+ERROR:  pglz_decompress failed
+SELECT test_pglz_decompress('\x010f01'::bytea, 1024, true);
+ERROR:  pglz_decompress failed
+DROP EXTENSION test_compression;
diff --git a/src/test/modules/test_compression/meson.build b/src/test/modules/test_compression/meson.build
new file mode 100644
index 000000000000..b25144ce71cd
--- /dev/null
+++ b/src/test/modules/test_compression/meson.build
@@ -0,0 +1,33 @@
+# Copyright (c) 2026, PostgreSQL Global Development Group
+
+test_compression_sources = files(
+  'test_compression.c',
+)
+
+if host_system == 'windows'
+  test_compression_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'test_compression',
+    '--FILEDESC', 'test_compression - test code for compression methods',])
+endif
+
+test_compression = shared_module('test_compression',
+  test_compression_sources,
+  kwargs: pg_test_mod_args,
+)
+test_install_libs += test_compression
+
+test_install_data += files(
+  'test_compression.control',
+  'test_compression--1.0.sql',
+)
+
+tests += {
+  'name': 'test_compression',
+  'sd': meson.current_source_dir(),
+  'bd': meson.current_build_dir(),
+  'regress': {
+    'sql': [
+      'test_compression',
+    ],
+  },
+}
diff --git a/src/test/modules/test_compression/sql/test_compression.sql b/src/test/modules/test_compression/sql/test_compression.sql
new file mode 100644
index 000000000000..4775b5ab582e
--- /dev/null
+++ b/src/test/modules/test_compression/sql/test_compression.sql
@@ -0,0 +1,36 @@
+CREATE EXTENSION test_compression;
+
+-- Round-trip with pglz: compress then decompress.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 400, false) =
+    decode(repeat('abcd', 100), 'escape') AS roundtrip_ok;
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 400, true) =
+    decode(repeat('abcd', 100), 'escape') AS roundtrip_ok;
+
+-- Decompression with rawsize too large, fails to fill the destination
+-- buffer.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 500, true);
+
+-- Decompression with rawsize too small, fails with source not fully
+-- consumed.
+SELECT test_pglz_decompress(test_pglz_compress(
+    decode(repeat('abcd', 100), 'escape')), 100, true);
+
+-- Corrupted compressed data.  The control byte is set with match tag bit,
+-- but only 1 byte follows.
+SELECT test_pglz_decompress('\x01ff'::bytea, 1024, false);
+SELECT test_pglz_decompress('\x01ff'::bytea, 1024, true);
+
+-- Corrupted compressed data.  Control byte with match tag bit set, where
+-- no data follows.
+SELECT length(test_pglz_decompress('\x01'::bytea, 1024, false)) AS ctrl_only_len;
+SELECT test_pglz_decompress('\x01'::bytea, 1024, true);
+
+-- Corrupted compressed data.  The match tag encodes len=18 (aka the
+-- extension byte is needed) but there is no data.
+SELECT test_pglz_decompress('\x010f01'::bytea, 1024, false);
+SELECT test_pglz_decompress('\x010f01'::bytea, 1024, true);
+
+DROP EXTENSION test_compression;
diff --git a/src/test/modules/test_compression/test_compression--1.0.sql b/src/test/modules/test_compression/test_compression--1.0.sql
new file mode 100644
index 000000000000..cc789df87340
--- /dev/null
+++ b/src/test/modules/test_compression/test_compression--1.0.sql
@@ -0,0 +1,12 @@
+/* src/test/modules/test_compression/test_compression--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_compression" to load this file. \quit
+
+CREATE FUNCTION test_pglz_compress(bytea)
+RETURNS bytea
+AS 'MODULE_PATHNAME' LANGUAGE C STRICT;
+
+CREATE FUNCTION test_pglz_decompress(bytea, int4, bool)
+RETURNS bytea
+AS 'MODULE_PATHNAME' LANGUAGE C STRICT;
diff --git a/src/test/modules/test_compression/test_compression.c b/src/test/modules/test_compression/test_compression.c
new file mode 100644
index 000000000000..2a1d27999395
--- /dev/null
+++ b/src/test/modules/test_compression/test_compression.c
@@ -0,0 +1,85 @@
+/*--------------------------------------------------------------------------
+ *
+ * test_compression.c
+ *		Test harness for compression methods.
+ *
+ * Copyright (c) 2026, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/test/modules/test_compression/test_compression.c
+ *
+ * -------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "common/pg_lzcompress.h"
+#include "fmgr.h"
+#include "varatt.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(test_pglz_compress);
+PG_FUNCTION_INFO_V1(test_pglz_decompress);
+
+/*
+ * test_pglz_compress
+ *
+ * Compress the input using pglz_compress().  Only the "always" strategy is
+ * currently supported.
+ *
+ * Returns the compressed data, or NULL if compression fails.
+ */
+Datum
+test_pglz_compress(PG_FUNCTION_ARGS)
+{
+	bytea	   *input = PG_GETARG_BYTEA_PP(0);
+	char	   *source = VARDATA_ANY(input);
+	int32		slen = VARSIZE_ANY_EXHDR(input);
+	int32		maxout = PGLZ_MAX_OUTPUT(slen);
+	bytea	   *result;
+	int32		clen;
+
+	result = (bytea *) palloc(maxout + VARHDRSZ);
+	clen = pglz_compress(source, slen, VARDATA(result),
+						 PGLZ_strategy_always);
+	if (clen < 0)
+		PG_RETURN_NULL();
+
+	SET_VARSIZE(result, clen + VARHDRSZ);
+	PG_RETURN_BYTEA_P(result);
+}
+
+/*
+ * test_pglz_decompress
+ *
+ * Decompress the input using pglz_decompress().
+ *
+ * The second argument is the expected uncompressed data size.  The third
+ * argument is here for the check_complete flag.
+ *
+ * Returns the decompressed data, or raises an error if decompression fails.
+ */
+Datum
+test_pglz_decompress(PG_FUNCTION_ARGS)
+{
+	bytea	   *input = PG_GETARG_BYTEA_PP(0);
+	int32		rawsize = PG_GETARG_INT32(1);
+	bool		check_complete = PG_GETARG_BOOL(2);
+	char	   *source = VARDATA_ANY(input);
+	int32		slen = VARSIZE_ANY_EXHDR(input);
+	bytea	   *result;
+	int32		dlen;
+
+	if (rawsize < 0)
+		elog(ERROR, "rawsize must not be negative");
+
+	result = (bytea *) palloc(rawsize + VARHDRSZ);
+
+	dlen = pglz_decompress(source, slen, VARDATA(result),
+						   rawsize, check_complete);
+	if (dlen < 0)
+		elog(ERROR, "pglz_decompress failed");
+
+	SET_VARSIZE(result, dlen + VARHDRSZ);
+	PG_RETURN_BYTEA_P(result);
+}
diff --git a/src/test/modules/test_compression/test_compression.control b/src/test/modules/test_compression/test_compression.control
new file mode 100644
index 000000000000..f707d4dfcf51
--- /dev/null
+++ b/src/test/modules/test_compression/test_compression.control
@@ -0,0 +1,4 @@
+comment = 'Test code for compression methods'
+default_version = '1.0'
+module_pathname = '$libdir/test_compression'
+relocatable = true
-- 
2.53.0