MFC r279154,r279397:

r279154 (by jilles):

nice(): Correct return value and [EPERM] error.

PR:		189821
Obtained from:	NetBSD
Relnotes:	yes

r279397 (by jilles):

nice(): Put back old return value, keeping [EPERM] error.

Commit r279154 changed the API and ABI significantly, and {NZERO} is still
wrong.

Also, preserve errno on success instead of setting it to 0.

PR:		189821
Relnotes:	yes

1 files changed, 11 insertions, 5 deletions

diff --git a/lib/libc/gen/nice.c b/lib/libc/gen/nice.c
index e8375e8..ba9524b 100644
--- a/lib/libc/gen/nice.c
+++ b/lib/libc/gen/nice.c
@@ -43,14 +43,20 @@ __FBSDID("$FreeBSD$");
  * Backwards compatible nice.
  */
 int
-nice(incr)
-	int incr;
+nice(int incr)
 {
-	int prio;
+	int saverrno, prio;
 
+	saverrno = errno;
 	errno = 0;
 	prio = getpriority(PRIO_PROCESS, 0);
-	if (prio == -1 && errno)
+	if (prio == -1 && errno != 0)
 		return (-1);
-	return (setpriority(PRIO_PROCESS, 0, prio + incr));
+	if (setpriority(PRIO_PROCESS, 0, prio + incr) == -1) {
+		if (errno == EACCES)
+			errno = EPERM;
+		return (-1);
+	}
+	errno = saverrno;
+	return (0);
 }