Merge pull request #1003 from Arcterus/fix-preserve-root

chgrp: fix more --preserve-root problems

src/chgrp/chgrp.rs

@@ -217,6 +217,22 @@ impl Chgrper {
         }
     }
 
+    #[cfg(windows)]
+    fn is_bind_root<P: AsRef<Path>>(&self, root: P) -> bool {
+        // TODO: is there an equivalent on Windows?
+        false
+    }
+
+    #[cfg(unix)]
+    fn is_bind_root<P: AsRef<Path>>(&self, path: P) -> bool {
+        if let (Ok(given), Ok(root)) = (fs::metadata(path), fs::metadata("/")) {
+            given.dev() == root.dev() && given.ino() == root.ino()
+        } else {
+            // FIXME: not totally sure if it's okay to just ignore an error here
+            false
+        }
+    }
+
     fn traverse<P: AsRef<Path>>(&self, root: P) -> i32 {
         let follow_arg = self.dereference || self.bit_flag != FTS_PHYSICAL;
         let path = root.as_ref();
@@ -244,7 +260,7 @@ impl Chgrper {
             };
 
             if let Some(p) = may_exist {
-                if p.parent().is_none() {
+                if p.parent().is_none() || self.is_bind_root(p) {
                     show_info!("it is dangerous to operate recursively on '/'");
                     show_info!("use --no-preserve-root to override this failsafe");
                     return 1;

src/uucore/fs.rs

@@ -14,7 +14,6 @@ use std::fs;
 use std::io::{Error, ErrorKind};
 use std::io::Result as IOResult;
 use std::path::{Component, Path, PathBuf};
-#[cfg(unix)]
 use std::borrow::Cow;
 
 pub fn resolve_relative_path<'a>(path: &'a Path) -> Cow<'a, Path> {
@@ -26,6 +25,9 @@ pub fn resolve_relative_path<'a>(path: &'a Path) -> Cow<'a, Path> {
     for comp in path.components() {
         match comp {
             Component::ParentDir => {
+                if let Ok(p) = result.read_link() {
+                    result = p;
+                }
                 result.pop();
             }
             Component::CurDir => (),