du: add --no-dereference

src/uu/du/src/du.rs

@@ -68,6 +68,7 @@ mod options {
     pub const ONE_FILE_SYSTEM: &str = "one-file-system";
     pub const DEREFERENCE: &str = "dereference";
     pub const DEREFERENCE_ARGS: &str = "dereference-args";
+    pub const NO_DEREFERENCE: &str = "no-dereference";
     pub const INODES: &str = "inodes";
     pub const EXCLUDE: &str = "exclude";
     pub const EXCLUDE_FROM: &str = "exclude-from";
@@ -824,13 +825,14 @@ pub fn uu_app() -> Command {
                 .help("follow only symlinks that are listed on the command line")
                 .action(ArgAction::SetTrue)
         )
-        // .arg(
-        //     Arg::new("no-dereference")
-        //         .short('P')
-        //         .long("no-dereference")
-        //         .help("don't follow any symbolic links (this is the default)")
-        //         .action(ArgAction::SetTrue),
-        // )
+         .arg(
+             Arg::new(options::NO_DEREFERENCE)
+                 .short('P')
+                 .long(options::NO_DEREFERENCE)
+                 .help("don't follow any symbolic links (this is the default)")
+                 .overrides_with(options::DEREFERENCE)
+                 .action(ArgAction::SetTrue),
+         )
         .arg(
             Arg::new(options::BLOCK_SIZE_1M)
                 .short('m')

tests/by-util/test_du.rs

@@ -336,6 +336,42 @@ fn _du_dereference(s: &str) {
     }
 }
 
+#[cfg(not(windows))]
+#[test]
+fn test_du_no_dereference() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let dir = "a_dir";
+    let symlink = "symlink";
+
+    at.mkdir(dir);
+    at.symlink_dir(dir, symlink);
+
+    for arg in ["-P", "--no-dereference"] {
+        ts.ucmd()
+            .arg(arg)
+            .succeeds()
+            .stdout_contains(dir)
+            .stdout_does_not_contain(symlink);
+
+        // ensure no-dereference "wins"
+        ts.ucmd()
+            .arg("--dereference")
+            .arg(arg)
+            .succeeds()
+            .stdout_contains(dir)
+            .stdout_does_not_contain(symlink);
+
+        // ensure dereference "wins"
+        ts.ucmd()
+            .arg(arg)
+            .arg("--dereference")
+            .succeeds()
+            .stdout_contains(symlink)
+            .stdout_does_not_contain(dir);
+    }
+}
+
 #[test]
 fn test_du_inodes_basic() {
     let ts = TestScenario::new(util_name!());