From bcfc147dbca2e1016991738aa18a97a10b9ccaef Mon Sep 17 00:00:00 2001
From: Daniel Hofstetter <daniel.hofstetter@42dh.com>
Date: Fri, 19 Apr 2024 16:10:09 +0200
Subject: [PATCH] slabtop: add -o/--once

---
 src/uu/slabtop/src/slabtop.rs | 62 ++++++++++++++++++++---------------
 tests/by-util/test_slabtop.rs | 59 ++++++++++++++++++++++++++++++++-
 2 files changed, 93 insertions(+), 28 deletions(-)

diff --git a/src/uu/slabtop/src/slabtop.rs b/src/uu/slabtop/src/slabtop.rs
index 7fb0f09..73c77cc 100644
--- a/src/uu/slabtop/src/slabtop.rs
+++ b/src/uu/slabtop/src/slabtop.rs
@@ -4,7 +4,7 @@
 // file that was distributed with this source code.
 
 use crate::parse::SlabInfo;
-use clap::{arg, crate_version, Command};
+use clap::{arg, crate_version, ArgAction, Command};
 use uucore::{error::UResult, format_usage, help_about, help_usage};
 
 const ABOUT: &str = help_about!("slabtop.md");
@@ -24,12 +24,43 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
     let slabinfo = SlabInfo::new()?.sort(*sort_flag, false);
 
+    if matches.get_flag("once") {
+        output_header(&slabinfo);
+        println!();
+        output_list(&slabinfo);
+    } else {
+        // TODO: implement TUI
+        output_header(&slabinfo);
+        println!();
+        output_list(&slabinfo);
+    }
+
+    Ok(())
+}
+
+fn to_kb(byte: u64) -> f64 {
+    byte as f64 / 1024.0
+}
+
+fn percentage(numerator: u64, denominator: u64) -> f64 {
+    if denominator == 0 {
+        return 0.0;
+    }
+
+    let numerator = numerator as f64;
+    let denominator = denominator as f64;
+
+    (numerator / denominator) * 100.0
+}
+
+fn output_header(slabinfo: &SlabInfo) {
     println!(
         r" Active / Total Objects (% used)    : {} / {} ({:.1}%)",
         slabinfo.total_active_objs(),
         slabinfo.total_objs(),
         percentage(slabinfo.total_active_objs(), slabinfo.total_objs())
     );
+
     println!(
         r" Active / Total Slabs (% used)      : {} / {} ({:.1}%)",
         slabinfo.total_active_slabs(),
@@ -58,38 +89,15 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         to_kb(slabinfo.object_avg()),
         to_kb(slabinfo.object_maximum())
     );
+}
 
-    // separate header info and slab list
-    println!();
-
-    // TODO: TUI Implementation
+fn output_list(info: &SlabInfo) {
     let title = format!(
         "{:>6} {:>6} {:>4} {:>8} {:>6} {:>8} {:>10} {:<}",
         "OBJS", "ACTIVE", "USE", "OBJ SIZE", "SLABS", "OBJ/SLAB", "CACHE SIZE", "NAME"
     );
     println!("{}", title);
 
-    output(&slabinfo);
-
-    Ok(())
-}
-
-fn to_kb(byte: u64) -> f64 {
-    byte as f64 / 1024.0
-}
-
-fn percentage(numerator: u64, denominator: u64) -> f64 {
-    if denominator == 0 {
-        return 0.0;
-    }
-
-    let numerator = numerator as f64;
-    let denominator = denominator as f64;
-
-    (numerator / denominator) * 100.0
-}
-
-fn output(info: &SlabInfo) {
     for name in info.names() {
         let objs = info.fetch(name, "num_objs").unwrap_or_default();
         let active = info.fetch(name, "active_objs").unwrap_or_default();
@@ -121,7 +129,7 @@ pub fn uu_app() -> Command {
         .infer_long_args(true)
         .args([
             // arg!(-d --delay <secs>  "delay updates"),
-            // arg!(-o --once          "only display once, then exit"),
+            arg!(-o --once          "only display once, then exit").action(ArgAction::SetTrue),
             arg!(-s --sort  <char>  "specify sort criteria by character (see below)"),
         ])
         .after_help(
diff --git a/tests/by-util/test_slabtop.rs b/tests/by-util/test_slabtop.rs
index 2576bdc..e287375 100644
--- a/tests/by-util/test_slabtop.rs
+++ b/tests/by-util/test_slabtop.rs
@@ -3,6 +3,8 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
+#[cfg(target_os = "linux")]
+use crate::common::util::run_ucmd_as_root;
 use crate::common::util::TestScenario;
 
 #[test]
@@ -11,6 +13,61 @@ fn test_invalid_arg() {
 }
 
 #[test]
-fn test_slabtop() {
+fn test_help() {
     new_ucmd!().arg("--help").succeeds().code_is(0);
 }
+
+#[cfg(target_os = "linux")]
+#[test]
+fn test_without_args_as_non_root() {
+    new_ucmd!()
+        .fails()
+        .code_is(1)
+        .stderr_contains("Permission denied");
+}
+
+// TODO: tests some temporary behavior; in the future a TUI should be used
+// if there are no args
+#[cfg(target_os = "linux")]
+#[test]
+fn test_without_args_as_root() {
+    let ts = TestScenario::new(util_name!());
+
+    if let Ok(result) = run_ucmd_as_root(&ts, &[]) {
+        result
+            .success()
+            .stdout_contains("Active / Total Objects")
+            .stdout_contains("OBJS");
+    } else {
+        print!("Test skipped; requires root user");
+    }
+}
+
+#[cfg(target_os = "linux")]
+#[test]
+fn test_once_as_non_root() {
+    for arg in ["-o", "--once"] {
+        new_ucmd!()
+            .arg(arg)
+            .fails()
+            .code_is(1)
+            .stderr_contains("Permission denied");
+    }
+}
+
+#[cfg(target_os = "linux")]
+#[test]
+fn test_once_as_root() {
+    let ts = TestScenario::new(util_name!());
+
+    for arg in ["-o", "--once"] {
+        if let Ok(result) = run_ucmd_as_root(&ts, &[arg]) {
+            result
+                .success()
+                .stdout_contains("Active / Total Objects")
+                .stdout_contains("OBJS");
+        } else {
+            print!("Test skipped; requires root user");
+        }
+    }
+}