mv: support moving folder containing symlinks to different filesystem (#8605)

Co-authored-by: Sylvestre Ledru <sylvestre@debian.org>

src/uu/mv/src/mv.rs

@@ -1099,7 +1099,13 @@ fn copy_dir_contents_recursive(
             }
             #[cfg(not(unix))]
             {
-                fs::copy(&from_path, &to_path)?;
+                if from_path.is_symlink() {
+                    // Copy a symlink file (no-follow).
+                    rename_symlink_fallback(&from_path, &to_path)?;
+                } else {
+                    // Copy a regular file.
+                    fs::copy(&from_path, &to_path)?;
+                }
             }
 
             // Print verbose message for file
@@ -1142,14 +1148,19 @@ 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() {
+        // Copy a symlink file (no-follow).
+        rename_symlink_fallback(from, to)?;
+    } else {
+        // Copy a regular file.
+        #[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

@@ -623,6 +623,58 @@ fn test_mv_symlink_into_target() {
     ucmd.arg("dir-link").arg("dir").succeeds();
 }
 
+#[cfg(all(unix, not(target_os = "android")))]
+#[ignore = "requires sudo"]
+#[test]
+fn test_mv_broken_symlink_to_another_fs() {
+    let scene = TestScenario::new(util_name!());
+
+    scene.fixtures.mkdir("foo");
+
+    let output = scene
+        .cmd("sudo")
+        .env("PATH", env!("PATH"))
+        .args(&["-E", "--non-interactive", "ls"])
+        .run();
+    println!("test output: {output:?}");
+
+    let mount = scene
+        .cmd("sudo")
+        .env("PATH", env!("PATH"))
+        .args(&[
+            "-E",
+            "--non-interactive",
+            "mount",
+            "none",
+            "-t",
+            "tmpfs",
+            "foo",
+        ])
+        .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")
+        .env("PATH", env!("PATH"))
+        .args(&["-E", "--non-interactive", "umount", "foo"])
+        .succeeds();
+}
+
 #[test]
 #[cfg(all(unix, not(target_os = "android")))]
 fn test_mv_hardlink_to_symlink() {