mv: support moving folder containing symlinks to different filesystem

Author: yuankunzhang

src/uu/mv/src/mv.rs

@@ -1044,7 +1044,11 @@ fn copy_dir_contents_recursive(
             }
             #[cfg(not(unix))]
             {
-                fs::copy(&from_path, &to_path)?;
+                if from_path.is_symlink() {
+                    rename_symlink_fallback(&from_path, &to_path)?;
+                } else {
+                    fs::copy(&from_path, &to_path)?;
+                }
             }
         }
 
@@ -1076,14 +1080,19 @@ fn copy_file_with_hardlinks_helper(
         return Ok(());
     }
 
-    // Regular file copy
-    #[cfg(all(unix, not(any(target_os = "macos", target_os = "redox"))))]
-    {
-        fs::copy(from, to).and_then(|_| fsxattr::copy_xattrs(&from, &to))?;
-    }
-    #[cfg(any(target_os = "macos", target_os = "redox"))]
-    {
-        fs::copy(from, to)?;
+    if from.is_symlink() {
+        // Symlink copy
+        rename_symlink_fallback(from, to)?;
+    } else {
+        // Regular file copy
+        #[cfg(all(unix, not(any(target_os = "macos", target_os = "redox"))))]
+        {
+            fs::copy(from, to).and_then(|_| fsxattr::copy_xattrs(&from, &to))?;
+        }
+        #[cfg(any(target_os = "macos", target_os = "redox"))]
+        {
+            fs::copy(from, to)?;
+        }
     }
 
     Ok(())

tests/by-util/test_mv.rs

@@ -621,6 +621,54 @@ fn test_mv_symlink_into_target() {
     ucmd.arg("dir-link").arg("dir").succeeds();
 }
 
+#[test]
+#[cfg(all(unix, not(target_os = "android")))]
+fn test_mv_folder_containing_dangling_symlink_across_fs() {
+    let scene = TestScenario::new(util_name!());
+
+    scene.fixtures.mkdir("foo");
+    let mountpoint = scene.fixtures.plus("foo");
+
+    let mount = scene
+        .cmd("sudo")
+        .args(&[
+            "-E",
+            "--non-interactive",
+            "mount",
+            "none",
+            "-t",
+            "tmpfs",
+            mountpoint.to_str().unwrap(),
+        ])
+        .run();
+
+    if !mount.succeeded() {
+        print!("Test skipped; requires root user");
+        return;
+    }
+
+    scene.fixtures.mkdir("bar");
+    scene.fixtures.symlink_file("nonexistent", "bar/baz");
+
+    scene
+        .ucmd()
+        .arg("bar")
+        .arg("foo")
+        .succeeds()
+        .no_stderr()
+        .no_stdout();
+
+    scene
+        .cmd("sudo")
+        .args(&[
+            "-E",
+            "--non-interactive",
+            "umount",
+            mountpoint.to_str().unwrap(),
+        ])
+        .succeeds();
+}
+
 #[test]
 #[cfg(all(unix, not(target_os = "android")))]
 fn test_mv_hardlink_to_symlink() {