From 46fadf4bf14360be046b9b770ddf205fad96a0a7 Mon Sep 17 00:00:00 2001
From: Kacper <kacper@mail.openlinux.dev>
Date: Mon, 22 Dec 2025 23:49:08 +0100
Subject: Add sys/resource.h implementation and nice(3)

---
 include/sys/resource.h              | 42 +++++++++++++++++++++++++++----------
 lib/libc/sys/resource/getpriority.c | 12 +++++++++++
 lib/libc/sys/resource/getrlimit.c   |  7 +++++++
 lib/libc/sys/resource/getrusage.c   |  7 +++++++
 lib/libc/sys/resource/setpriority.c |  7 +++++++
 lib/libc/sys/resource/setrlimit.c   |  7 +++++++
 lib/libc/unistd/nice.c              | 28 +++++++++++++++++++++----
 7 files changed, 95 insertions(+), 15 deletions(-)
 create mode 100644 lib/libc/sys/resource/getpriority.c
 create mode 100644 lib/libc/sys/resource/getrlimit.c
 create mode 100644 lib/libc/sys/resource/getrusage.c
 create mode 100644 lib/libc/sys/resource/setpriority.c
 create mode 100644 lib/libc/sys/resource/setrlimit.c

diff --git a/include/sys/resource.h b/include/sys/resource.h
index 086d8cd8..eb596700 100644
--- a/include/sys/resource.h
+++ b/include/sys/resource.h
@@ -2,19 +2,39 @@
 #define __SYS_RESOURCE_H
 
 #include <time.h>
+
+#define RUSAGE_SELF	0
+#define RUSAGE_CHILDREN (-1)
+#define RUSAGE_BOTH	(-2)
+#define RUSAGE_THREAD	1
+
+#define PRIO_MIN (-20)
+#define PRIO_MAX 20
+
+#define PRIO_PROCESS 0
+#define PRIO_PGRP    1
+#define PRIO_USER    2
+
+#define RLIMIT_CPU     0
+#define RLIMIT_FSIZE   1
+#define RLIMIT_DATA    2
+#define RLIMIT_STACK   3
+#define RLIMIT_CORE    4
+#define RLIMIT_RSS     5
+#define RLIMIT_NPROC   6
+#define RLIMIT_NOFILE  7
+#define RLIMIT_MEMLOCK 8
+#define RLIMIT_AS      9
+
 typedef __INT64_TYPE__ time_t;
 typedef __INT64_TYPE__ suseconds_t;
+typedef __UINT64_TYPE__ rlim_t;
 
 struct __timeval {
 	time_t tv_sec;
 	suseconds_t tv_usec;
 };
 
-#define RUSAGE_SELF	0
-#define RUSAGE_CHILDREN (-1)
-#define RUSAGE_BOTH	(-2)
-#define RUSAGE_THREAD	1
-
 struct rusage {
 	struct __timeval ru_utime;
 	struct __timeval ru_stime;
@@ -34,14 +54,14 @@ struct rusage {
 	long ru_nivcsw;
 };
 
-#define PRIO_MIN (-20)
-#define PRIO_MAX 20
-
-#define PRIO_PROCESS 0
-#define PRIO_PGRP    1
-#define PRIO_USER    2
+struct rlimit {
+	rlim_t rlim_cur;
+	rlim_t rlim_max;
+};
 
 int getpriority(int, int);
+int getrlimit(int, struct rlimit *);
+int setrlimit(int, const struct rlimit *);
 int setpriority(int, int, int);
 int getrusage(int, struct rusage *);
 
diff --git a/lib/libc/sys/resource/getpriority.c b/lib/libc/sys/resource/getpriority.c
new file mode 100644
index 00000000..3df9eb30
--- /dev/null
+++ b/lib/libc/sys/resource/getpriority.c
@@ -0,0 +1,12 @@
+#include <sys/resource.h>
+#include <syscall.h>
+
+int getpriority(int which, int who)
+{
+	int r = syscall(getpriority, which, who);
+
+	if (r < 0)
+		return r;
+
+	return 20 - r;
+}
diff --git a/lib/libc/sys/resource/getrlimit.c b/lib/libc/sys/resource/getrlimit.c
new file mode 100644
index 00000000..7b7c8269
--- /dev/null
+++ b/lib/libc/sys/resource/getrlimit.c
@@ -0,0 +1,7 @@
+#include <sys/resource.h>
+#include <syscall.h>
+
+int getrlimit(int resource, struct rlimit *rlp)
+{
+	return syscall(getrlimit, resource, rlp);
+}
diff --git a/lib/libc/sys/resource/getrusage.c b/lib/libc/sys/resource/getrusage.c
new file mode 100644
index 00000000..a91ded16
--- /dev/null
+++ b/lib/libc/sys/resource/getrusage.c
@@ -0,0 +1,7 @@
+#include <sys/resource.h>
+#include <syscall.h>
+
+int getrusage(int who, struct rusage *r_usage)
+{
+	return syscall(getrusage, who, r_usage);
+}
diff --git a/lib/libc/sys/resource/setpriority.c b/lib/libc/sys/resource/setpriority.c
new file mode 100644
index 00000000..96bebbf2
--- /dev/null
+++ b/lib/libc/sys/resource/setpriority.c
@@ -0,0 +1,7 @@
+#include <sys/resource.h>
+#include <syscall.h>
+
+int setpriority(int which, int who, int value)
+{
+	return syscall(setpriority, which, who, value);
+}
diff --git a/lib/libc/sys/resource/setrlimit.c b/lib/libc/sys/resource/setrlimit.c
new file mode 100644
index 00000000..39148bc3
--- /dev/null
+++ b/lib/libc/sys/resource/setrlimit.c
@@ -0,0 +1,7 @@
+#include <sys/resource.h>
+#include <syscall.h>
+
+int setrlimit(int resource, const struct rlimit *rlp)
+{
+	return syscall(setrlimit, resource, rlp);
+}
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;
 }
-- 
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