From a7f6b4420a4a28148657c437aed13dda798176bd Mon Sep 17 00:00:00 2001
From: Michael Debertol <michael.debertol@gmail.com>
Date: Thu, 2 Sep 2021 22:31:49 +0200
Subject: [PATCH] uucore/perms: take traverse_symlinks into account

---
 src/uucore/src/lib/features/perms.rs | 15 ++++++-
 tests/by-util/test_chgrp.rs          | 65 ++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 2 deletions(-)

diff --git a/src/uucore/src/lib/features/perms.rs b/src/uucore/src/lib/features/perms.rs
index b605c0cdf..a4a01c499 100644
--- a/src/uucore/src/lib/features/perms.rs
+++ b/src/uucore/src/lib/features/perms.rs
@@ -265,10 +265,21 @@ impl ChownExecutor {
     }
 
     fn dive_into<P: AsRef<Path>>(&self, root: P) -> i32 {
-        let mut ret = 0;
         let root = root.as_ref();
+
+        // walkdir always dereferences the root directory, so we have to check it ourselves
+        // TODO: replace with `root.is_symlink()` once it is stable
+        if self.traverse_symlinks == TraverseSymlinks::None
+            && std::fs::symlink_metadata(root)
+                .map(|m| m.file_type().is_symlink())
+                .unwrap_or(false)
+        {
+            return 0;
+        }
+
+        let mut ret = 0;
         let mut iterator = WalkDir::new(root)
-            .follow_links(self.dereference)
+            .follow_links(self.traverse_symlinks == TraverseSymlinks::All)
             .min_depth(1)
             .into_iter();
         // We can't use a for loop because we need to manipulate the iterator inside the loop.
diff --git a/tests/by-util/test_chgrp.rs b/tests/by-util/test_chgrp.rs
index 0fc73520e..1d047cfe2 100644
--- a/tests/by-util/test_chgrp.rs
+++ b/tests/by-util/test_chgrp.rs
@@ -288,3 +288,68 @@ fn test_subdir_permission_denied() {
             .stderr_only("chgrp: cannot access 'dir/subdir': Permission denied");
     }
 }
+
+#[test]
+#[cfg(not(target_vendor = "apple"))]
+fn test_traverse_symlinks() {
+    use std::os::unix::prelude::MetadataExt;
+    let groups = nix::unistd::getgroups().unwrap();
+    if groups.len() < 2 {
+        return;
+    }
+    let (first_group, second_group) = (groups[0], groups[1]);
+
+    for &(args, traverse_first, traverse_second) in &[
+        (&[][..] as &[&str], false, false),
+        (&["-H"][..], true, false),
+        (&["-P"][..], false, false),
+        (&["-L"][..], true, true),
+    ] {
+        let scenario = TestScenario::new("chgrp");
+
+        let (at, mut ucmd) = (scenario.fixtures.clone(), scenario.ucmd());
+
+        at.mkdir("dir");
+        at.mkdir("dir2");
+        at.touch("dir2/file");
+        at.mkdir("dir3");
+        at.touch("dir3/file");
+        at.symlink_dir("dir2", "dir/dir2_ln");
+        at.symlink_dir("dir3", "dir3_ln");
+
+        scenario
+            .ccmd("chgrp")
+            .arg(first_group.to_string())
+            .arg("dir2/file")
+            .arg("dir3/file")
+            .succeeds();
+
+        assert!(at.plus("dir2/file").metadata().unwrap().gid() == first_group.as_raw());
+        assert!(at.plus("dir3/file").metadata().unwrap().gid() == first_group.as_raw());
+
+        ucmd.arg("-R")
+            .args(args)
+            .arg(second_group.to_string())
+            .arg("dir")
+            .arg("dir3_ln")
+            .succeeds()
+            .no_stderr();
+
+        assert_eq!(
+            at.plus("dir2/file").metadata().unwrap().gid(),
+            if traverse_second {
+                second_group.as_raw()
+            } else {
+                first_group.as_raw()
+            }
+        );
+        assert_eq!(
+            at.plus("dir3/file").metadata().unwrap().gid(),
+            if traverse_first {
+                second_group.as_raw()
+            } else {
+                first_group.as_raw()
+            }
+        );
+    }
+}