Add renice

Co-authored-by: Sylvestre Ledru <sylvestre@debian.org>

src/uu/renice/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "uu_renice"
+version = "0.0.1"
+edition = "2021"
+description = "renice ~ (uutils) Alter priority of running processes"
+
+[lib]
+path = "src/renice.rs"
+
+[[bin]]
+name = "renice"
+path = "src/main.rs"
+
+[dependencies]
+clap = { workspace = true }
+libc = { workspace = true }
+uucore = { workspace = true }

src/uu/renice/renice.md

@@ -0,0 +1,7 @@
+# renice
+
+```
+renice [--priority|--relative] priority [-g|-p|-u] identifier...
+```
+
+Alter priority of running processes

src/uu/renice/src/main.rs

@@ -0,0 +1 @@
+uucore::bin!(uu_renice);

src/uu/renice/src/renice.rs

@@ -0,0 +1,65 @@
+// This file is part of the uutils util-linux package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use clap::{crate_version, Arg, Command};
+#[cfg(not(windows))]
+use libc::PRIO_PROCESS;
+use std::env;
+#[cfg(not(windows))]
+use std::io::Error;
+use std::process;
+use uucore::{error::UResult, format_usage, help_about, help_usage};
+
+const ABOUT: &str = help_about!("renice.md");
+const USAGE: &str = help_usage!("renice.md");
+
+#[uucore::main]
+pub fn uumain(args: impl uucore::Args) -> UResult<()> {
+    let matches = uu_app().try_get_matches_from(args)?;
+
+    let nice_value_str = matches.get_one::<String>("nice_value").unwrap(); // Retrieve as String
+    let nice_value = nice_value_str.parse::<i32>().unwrap_or_else(|_| {
+        eprintln!("Invalid nice value");
+        process::exit(1);
+    });
+
+    let pid_str = matches.get_one::<String>("pid").unwrap(); // Retrieve as String
+    let pid = pid_str.parse::<i32>().unwrap_or_else(|_| {
+        eprintln!("Invalid PID");
+        process::exit(1);
+    });
+
+    // TODO: implement functionality on windows
+    #[cfg(not(windows))]
+    if unsafe { libc::setpriority(PRIO_PROCESS, pid.try_into().unwrap(), nice_value) } == -1 {
+        eprintln!("Failed to set nice value: {}", Error::last_os_error());
+        process::exit(1);
+    }
+
+    println!("Nice value of process {} set to {}", pid, nice_value);
+    Ok(())
+}
+
+pub fn uu_app() -> Command {
+    Command::new(uucore::util_name())
+        .version(crate_version!())
+        .about(ABOUT)
+        .override_usage(format_usage(USAGE))
+        .infer_long_args(true)
+        .arg(
+            Arg::new("nice_value")
+                .value_name("NICE_VALUE")
+                .help("The new nice value for the process")
+                .required(true)
+                .index(1),
+        )
+        .arg(
+            Arg::new("pid")
+                .value_name("PID")
+                .help("The PID of the process")
+                .required(true)
+                .index(2),
+        )
+}