v1-0015-Add-assertion-about-ssize_t-narrowing-in-AIO-code.patch

From cba8024ab07162e4474501fe9523db478ea1aa0c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 29 Jun 2026 13:37:54 +0200
Subject: [PATCH v1 15/15] Add assertion about ssize_t narrowing in AIO code

The result from pg_preadv() or pg_pwritev(), which is of type ssize_t,
is assigned to PgAioHandle.result, which is of type int.  This should
be ok because the maximum result is limited by PG_IOV_MAX times
BLCKSZ.  Add an assertion and a code comment to explain and check
this.
---
 src/backend/storage/aio/aio_io.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/backend/storage/aio/aio_io.c b/src/backend/storage/aio/aio_io.c
index 72b4c9feb3a..132868130e7 100644
--- a/src/backend/storage/aio/aio_io.c
+++ b/src/backend/storage/aio/aio_io.c
@@ -141,6 +141,11 @@ pgaio_io_perform_synchronously(PgAioHandle *ioh)
 			elog(ERROR, "trying to execute invalid IO operation");
 	}
 
+	/*
+	 * ssize_t to int conversion should be ok because result should be no more
+	 * than PG_IOV_MAX times BLCKSZ.
+	 */
+	Assert(result <= INT_MAX);
 	ioh->result = result < 0 ? -errno : result;
 
 	pgaio_io_process_completion(ioh, ioh->result);
-- 
2.54.0