From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/unistd/nice.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 src/unistd/nice.c

(limited to 'src/unistd/nice.c')

diff --git a/src/unistd/nice.c b/src/unistd/nice.c
new file mode 100644
index 0000000..1c2295f
--- /dev/null
+++ b/src/unistd/nice.c
@@ -0,0 +1,23 @@
+#include <unistd.h>
+#include <errno.h>
+#include <sys/resource.h>
+#include <limits.h>
+#include "syscall.h"
+
+int nice(int inc)
+{
+	int prio = inc;
+	// Only query old priority if it can affect the result.
+	// This also avoids issues with integer overflow.
+	if (inc > -2*NZERO && inc < 2*NZERO)
+		prio += getpriority(PRIO_PROCESS, 0);
+	if (prio > NZERO-1) prio = NZERO-1;
+	if (prio < -NZERO) prio = -NZERO;
+	if (setpriority(PRIO_PROCESS, 0, prio)) {
+		if (errno == EACCES)
+			errno = EPERM;
+		return -1;
+	} else {
+		return prio;
+	}
+}
-- 
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