No "Fixes:" in comment because the current behavior emulates old Linux
behavior which is possibly not a bug.
SUS 1997 to POSIX 2024 require to return the new nice value.
https://pubs.opengroup.org/onlinepubs/007908799/xsh/nice.html
https://pubs.opengroup.org/onlinepubs/9799919799/functions/nice.html
https://man7.org/linux/man-pages/man2/nice.2.html
FreeBSD still returns 0:
https://man.freebsd.org/cgi/man.cgi?query=nice&sektion=3
Ancient Unix returned nothing :-)
http://man.cat-v.org/unix_10th/2/nice
--
Regards,
Christian
From 40d17d32e4c0a7dc69f39e57f3d0f9f07fca5c75 Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.fra...@t-online.de>
Date: Wed, 27 Nov 2024 18:54:37 +0100
Subject: [PATCH] Cygwin: nice: align return value and errno with POSIX and
Linux
Return new nice value instead of 0 on success.
Set errno to EPERM instead of EACCES on failure.
Signed-off-by: Christian Franke <christian.fra...@t-online.de>
---
winsup/cygwin/release/3.6.0 | 4 ++++
winsup/cygwin/syscalls.cc | 11 ++++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/release/3.6.0 b/winsup/cygwin/release/3.6.0
index ef7e4018f..1b2f00ad8 100644
--- a/winsup/cygwin/release/3.6.0
+++ b/winsup/cygwin/release/3.6.0
@@ -48,3 +48,7 @@ What changed:
or EPERM if Windows would silently set a lower priority
(HIGH_PRIORITY_CLASS instead of REALTIME_PRIORITY_CLASS) due to
missing administrator privileges.
+
+- nice(2) now returns the new nice value instead of 0 on success
+ and sets errno to EPERM instead of EACCES on failure. This confirms
+ to POSIX and Linux (glibc >= 2.2.4) behavior.
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 72537bc5a..60350b690 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -3959,7 +3959,16 @@ out:
extern "C" int
nice (int incr)
{
- return setpriority (PRIO_PROCESS, myself->pid, myself->nice + incr);
+ if (setpriority (PRIO_PROCESS, myself->pid, myself->nice + incr))
+ {
+ /* POSIX: EPERM instead of EACCES. */
+ set_errno (EPERM);
+ return -1;
+ }
+
+ /* POSIX: return the new nice value. Linux glibc >= 2.2.4 provides
+ conformance with POSIX (FreeBSD returns 0). */
+ return myself->nice;
}
static void
--
2.45.1
