From 554c402de71f7a11196ddc37b598283fb8264d1e Mon Sep 17 00:00:00 2001
From: "Chao Li (Evan)" <lic@highgo.com>
Date: Mon, 12 Oct 2026 09:30:17 +0800
Subject: [PATCH v1] Avoid further compression and writes after LZ4 close
 failures

LZ4Stream_close() continued to call LZ4F_compressEnd() after a failed
buffer flush, and attempted the final write even if compression
finalization failed.

Skip these operations after a failure, while still freeing resources
and closing the file. The function already returned failure in these
cases, so this is a cleanup rather than a correctness fix.

Author: Chao Li <lic@highgo.com>
---
 src/bin/pg_dump/compress_lz4.c | 36 ++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/bin/pg_dump/compress_lz4.c b/src/bin/pg_dump/compress_lz4.c
index a4ae1a4272f..bf8b28ceb16 100644
--- a/src/bin/pg_dump/compress_lz4.c
+++ b/src/bin/pg_dump/compress_lz4.c
@@ -673,25 +673,31 @@ LZ4Stream_close(CompressFileHandle *CFH)
 				state->bufdata = 0;
 			}
 
-			status = LZ4F_compressEnd(state->ctx,
-									  state->buffer + state->bufdata,
-									  state->buflen - state->bufdata,
-									  NULL);
-			if (LZ4F_isError(status))
+			if (success)
 			{
-				pg_log_error("could not end compression: %s",
-							 LZ4F_getErrorName(status));
-				success = false;
+				status = LZ4F_compressEnd(state->ctx,
+										  state->buffer + state->bufdata,
+										  state->buflen - state->bufdata,
+										  NULL);
+				if (LZ4F_isError(status))
+				{
+					pg_log_error("could not end compression: %s",
+								 LZ4F_getErrorName(status));
+					success = false;
+				}
+				else
+					state->bufdata += status;
 			}
-			else
-				state->bufdata += status;
 
-			errno = 0;
-			if (fwrite(state->buffer, 1, state->bufdata, state->fp) != state->bufdata)
+			if (success)
 			{
-				errno = (errno) ? errno : ENOSPC;
-				pg_log_error("could not write to output file: %m");
-				success = false;
+				errno = 0;
+				if (fwrite(state->buffer, 1, state->bufdata, state->fp) != state->bufdata)
+				{
+					errno = (errno) ? errno : ENOSPC;
+					pg_log_error("could not write to output file: %m");
+					success = false;
+				}
 			}
 
 			status = LZ4F_freeCompressionContext(state->ctx);
-- 
2.50.1 (Apple Git-155)