From 89e7066d6c3c6a7eeb147c3f2d345c3046a4d155 Mon Sep 17 00:00:00 2001
From: Georgios Kokolatos <gkokolatos@pm.me>
Date: Mon, 8 May 2023 19:48:03 +0000
Subject: [PATCH v2] Advance input pointer when LZ4 compressing data

LZ4File_write() did not advance the input pointer on subsequent invocations of
LZ4F_compressUpdate(). As a result the generated compressed output would be a
compressed version of the same input chunk.

WriteDataToArchiveLZ4() which is also using LZ4F_compressUpdate() did not suffer
from this omission. Tests failed to catch this error because all of their input
would comfortably fit within the same input chunk. Tests have been added to
provide adequate coverage.
---
 src/bin/pg_dump/compress_io.h    |  7 ++++-
 src/bin/pg_dump/compress_lz4.c   |  2 ++
 src/bin/pg_dump/t/002_pg_dump.pl | 46 ++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/src/bin/pg_dump/compress_io.h b/src/bin/pg_dump/compress_io.h
index fd8752db0d..e8efc57f1a 100644
--- a/src/bin/pg_dump/compress_io.h
+++ b/src/bin/pg_dump/compress_io.h
@@ -17,7 +17,12 @@
 
 #include "pg_backup_archiver.h"
 
-/* Default size used for IO buffers */
+/*
+ * Default size used for IO buffers
+ *
+ * When altering this value it might be useful to verify that the relevant tests
+ * cases are meaningfully updated to provide coverage.
+ */
 #define DEFAULT_IO_BUFFER_SIZE	4096
 
 extern char *supports_compression(const pg_compress_specification compression_spec);
diff --git a/src/bin/pg_dump/compress_lz4.c b/src/bin/pg_dump/compress_lz4.c
index f97b7550d1..b869780c0b 100644
--- a/src/bin/pg_dump/compress_lz4.c
+++ b/src/bin/pg_dump/compress_lz4.c
@@ -588,6 +588,8 @@ LZ4Stream_write(const void *ptr, size_t size, CompressFileHandle *CFH)
 			errno = (errno) ? errno : ENOSPC;
 			return false;
 		}
+
+		ptr = ((const char *) ptr) + chunk;
 	}
 
 	return true;
diff --git a/src/bin/pg_dump/t/002_pg_dump.pl b/src/bin/pg_dump/t/002_pg_dump.pl
index 93e24d5145..d66f3b42ea 100644
--- a/src/bin/pg_dump/t/002_pg_dump.pl
+++ b/src/bin/pg_dump/t/002_pg_dump.pl
@@ -3108,6 +3108,52 @@ my %tests = (
 		},
 	},
 
+	'CREATE TABLE test_compression_method' => {
+		create_order => 110,
+		create_sql   => 'CREATE TABLE dump_test.test_compression_method (
+						   col1 text
+					   );',
+		regexp => qr/^
+			\QCREATE TABLE dump_test.test_compression_method (\E\n
+			\s+\Qcol1 text\E\n
+			\Q);\E
+			/xm,
+		like => {
+			%full_runs,
+			%dump_test_schema_runs,
+			section_pre_data     => 1,
+		},
+		unlike => {
+			exclude_dump_test_schema => 1,
+			only_dump_measurement    => 1,
+		},
+	},
+
+	# Insert enough data to surpass DEFAULT_IO_BUFFER_SIZE during
+	# (de)compression operations
+	'COPY test_compression_method' => {
+		create_order => 111,
+		create_sql   => 'INSERT INTO dump_test.test_compression_method (col1) '
+		  . 'SELECT string_agg(a::text, \'\') FROM generate_series(1,4096) a;',
+		regexp => qr/^
+			\QCOPY dump_test.test_compression_method (col1) FROM stdin;\E
+			\n(?:\d{15277}\n){1}\\\.\n
+			/xm,
+		like => {
+			%full_runs,
+			data_only                => 1,
+			section_data             => 1,
+			only_dump_test_schema    => 1,
+			test_schema_plus_large_objects    => 1,
+		},
+		unlike => {
+			binary_upgrade           => 1,
+			exclude_dump_test_schema => 1,
+			schema_only              => 1,
+			only_dump_measurement    => 1,
+		},
+	},
+
 	'CREATE TABLE fk_reference_test_table' => {
 		create_order => 21,
 		create_sql   => 'CREATE TABLE dump_test.fk_reference_test_table (
-- 
2.34.1