Implement basic functional kill command with some tests

Signed-off-by: Malhar Vora <mlvora.2010@gmail.com>

Author: vbmade2000

src/uu/kill/src/kill.rs

@@ -5,17 +5,25 @@
 
 // Remove this if the tool is ported to Non-UNIX platforms.
 
-use clap::{Command, crate_version};
+use clap::{Arg, ArgAction, Command, crate_version, value_parser};
+use uucore::libc;
 #[cfg(target_os = "linux")]
 #[cfg(target_os = "linux")]
 use uucore::{error::UResult, format_usage, help_about, help_usage};
 
 const ABOUT: &str = help_about!("kill.md");
 const USAGE: &str = help_usage!("kill.md");
 
+
 #[uucore::main]
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
-    let _matches = uu_app().try_get_matches_from(args)?;
+    let matches = uu_app().try_get_matches_from(args)?;
+
+    if let Some(pids) = matches.get_many::<i32>("pid") {
+        for pid in pids {
+            unsafe { libc::kill(*pid, libc::SIGTERM) };
+        }
+    }
 
     Ok(())
 }
@@ -26,4 +34,12 @@ pub fn uu_app() -> Command {
         .about(ABOUT)
         .override_usage(format_usage(USAGE))
         .infer_long_args(true)
+        .arg(
+            Arg::new("pid")
+                .help("PID of the process to kill")
+                .required(false)
+                .action(ArgAction::Append)
+                .value_name("PID")
+                .value_parser(value_parser!(i32)),
+        )
 }

tests/by-util/test_kill.rs

@@ -0,0 +1,23 @@
+// 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 uutests::new_ucmd;
+
+#[test]
+fn test_invalid_arg() {
+    new_ucmd!().arg("--definitely-invalid").fails().code_is(1);
+}
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_non_number_pid() {
+    let res = new_ucmd!().arg("xyz").run();
+
+    let stdout = res.stdout_str();
+    let stderr = res.stderr_str();
+
+    assert!(stdout.trim().len() == 0);
+    assert!(stderr.contains("invalid value 'xyz'"));
+}

tests/tests.rs

@@ -15,6 +15,11 @@ fn init() {
         std::env::set_var("UUTESTS_BINARY_PATH", TESTS_BINARY);
     }
 }
+
+#[cfg(feature = "kill")]
+#[path = "by-util/test_kill.rs"]
+mod test_kill;
+
 #[cfg(feature = "lscpu")]
 #[path = "by-util/test_lscpu.rs"]
 mod test_lscpu;