From d25d392e89440f97bfafc0e80dc7737872659d76 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 1 Jul 2025 12:40:35 -0400 Subject: [PATCH] Make sure IOV_MAX is defined. We stopped defining IOV_MAX on non-Windows systems in 75357ab94, on the assumption that every non-Windows system defines it in as required by X/Open. GNU Hurd, however, doesn't follow that standard either. Put back the old logic to assume 16 if it's not defined. Author: Michael Banck Co-authored-by: Christoph Berg Reviewed-by: Tom Lane Discussion: https://postgr.es/m/6862e8d1.050a0220.194b8d.76fa@mx.google.com Discussion: https://postgr.es/m/6846e0c3.df0a0220.39ef9b.c60e@mx.google.com Backpatch-through: 16 --- src/include/port/pg_iovec.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/src/include/port/pg_iovec.h b/src/include/port/pg_iovec.h index 689799c4258..5882c5b20f0 100644 --- a/src/include/port/pg_iovec.h +++ b/src/include/port/pg_iovec.h @@ -20,9 +20,6 @@ #else -/* POSIX requires at least 16 as a maximum iovcnt. */ -#define IOV_MAX 16 - /* Define our own POSIX-compatible iovec struct. */ struct iovec { @@ -32,6 +29,15 @@ struct iovec #endif +/* + * If didn't define IOV_MAX, define our own. X/Open requires at + * least 16. (GNU Hurd apparently feel that they're not bound by X/Open, + * because they don't define this symbol at all.) + */ +#ifndef IOV_MAX +#define IOV_MAX 16 +#endif + /* Define a reasonable maximum that is safe to use on the stack. */ #define PG_IOV_MAX Min(IOV_MAX, 32) -- 2.39.5