From 8c6c86c362820e93f066992ede6e5ca23f128807 Mon Sep 17 00:00:00 2001
From: Georgios Kokolatos <gkokolatos@pm.me>
Date: Mon, 8 May 2023 15:25:25 +0000
Subject: [PATCH v1] 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_lz4.c   |  5 +++-
 src/bin/pg_dump/t/002_pg_dump.pl | 44 ++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/src/bin/pg_dump/compress_lz4.c b/src/bin/pg_dump/compress_lz4.c
index f97b7550d1..76211c82f0 100644
--- a/src/bin/pg_dump/compress_lz4.c
+++ b/src/bin/pg_dump/compress_lz4.c
@@ -564,6 +564,7 @@ LZ4Stream_write(const void *ptr, size_t size, CompressFileHandle *CFH)
 	LZ4State   *state = (LZ4State *) CFH->private_data;
 	size_t		status;
 	int			remaining = size;
+	const void *in = ptr;
 
 	/* Lazy init */
 	if (!LZ4Stream_init(state, size, true))
@@ -576,7 +577,7 @@ LZ4Stream_write(const void *ptr, size_t size, CompressFileHandle *CFH)
 		remaining -= chunk;
 
 		status = LZ4F_compressUpdate(state->ctx, state->buffer, state->buflen,
-									 ptr, chunk, NULL);
+									 in, chunk, NULL);
 		if (LZ4F_isError(status))
 		{
 			state->errcode = status;
@@ -588,6 +589,8 @@ LZ4Stream_write(const void *ptr, size_t size, CompressFileHandle *CFH)
 			errno = (errno) ? errno : ENOSPC;
 			return false;
 		}
+
+		in = ((const char *) in) + 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..c6b1225815 100644
--- a/src/bin/pg_dump/t/002_pg_dump.pl
+++ b/src/bin/pg_dump/t/002_pg_dump.pl
@@ -3108,6 +3108,50 @@ 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,
+		},
+	},
+
+	'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