Add sys/resource.h implementation and nice(3)

1 files changed, 24 insertions, 4 deletions

diff --git a/lib/libc/unistd/nice.c b/lib/libc/unistd/nice.c
index 78dccbb0..29ac8487 100644
--- a/lib/libc/unistd/nice.c
+++ b/lib/libc/unistd/nice.c
@@ -1,8 +1,28 @@
-#include <unistd.h> // for nice
+#include <errno.h>
+#include <limits.h>
+#include <sys/resource.h>
+#include <unistd.h>
 
 int nice(int incr)
 {
-	(void)incr;
-	// TODO: needs getpriority and setpriority from sys/resouce.h
-	return 0;
+	int priority = incr;
+
+	if (incr > NZERO * -2 && incr < NZERO * 2) {
+		priority += getpriority(PRIO_PROCESS, 0);
+	}
+
+	if (priority > NZERO - 1)
+		priority = NZERO - 1;
+
+	if (priority < -NZERO)
+		priority = -NZERO;
+
+	if (setpriority(PRIO_PROCESS, 0, priority)) {
+		if (errno == EACCES)
+			errno = EPERM;
+
+		return -1;
+	}
+
+	return priority;
 }