mv: Make mv command fallback to copy only if the src and dst are on different device

Author: hamflx

Cargo.lock

@@ -25,6 +25,12 @@ uucore = { workspace = true, features = [
   "update-control",
 ] }
 
+[target.'cfg(target_os = "windows")'.dependencies]
+winapi = { version="0.3" }
+
+[target.'cfg(target_os = "linux")'.dependencies]
+libc = { workspace = true }
+
 [[bin]]
 name = "mv"
 path = "src/main.rs"

src/uu/mv/Cargo.toml

@@ -591,7 +591,15 @@ fn rename_with_fallback(
     to: &Path,
     multi_progress: Option<&MultiProgress>,
 ) -> io::Result<()> {
-    if fs::rename(from, to).is_err() {
+    if let Err(err) = fs::rename(from, to) {
+        // We will only copy if they're not on the same device, otherwise we'll report an error.
+        #[cfg(windows)]
+        const EXDEV: i32 = winapi::shared::winerror::ERROR_NOT_SAME_DEVICE as _;
+        #[cfg(unix)]
+        const EXDEV: i32 = libc::EXDEV as _;
+        if err.raw_os_error() != Some(EXDEV) {
+            return Err(err);
+        }
         // Get metadata without following symlinks
         let metadata = from.symlink_metadata()?;
         let file_type = metadata.file_type();

src/uu/mv/src/mv.rs

@@ -1610,6 +1610,51 @@ fn test_acl() {
     assert!(compare_xattrs(&file, &file_target));
 }
 
+#[test]
+#[cfg(windows)]
+fn test_move_should_not_fallback_to_copy() {
+    use std::os::windows::fs::OpenOptionsExt;
+
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    let locked_file = "a_file_is_locked";
+    let locked_file_path = at.plus(locked_file);
+    let file = std::fs::OpenOptions::new()
+        .create(true)
+        .write(true)
+        .share_mode(
+            uucore::windows_sys::Win32::Storage::FileSystem::FILE_SHARE_READ
+                | uucore::windows_sys::Win32::Storage::FileSystem::FILE_SHARE_WRITE,
+        )
+        .open(locked_file_path);
+
+    let target_file = "target_file";
+    ucmd.arg(locked_file).arg(target_file).fails();
+
+    assert!(at.file_exists(locked_file));
+    assert!(!at.file_exists(target_file));
+
+    drop(file);
+}
+
+#[test]
+#[cfg(unix)]
+fn test_move_should_not_fallback_to_copy() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    let readonly_dir = "readonly_dir";
+    let locked_file = "readonly_dir/a_file_is_locked";
+    at.mkdir(readonly_dir);
+    at.touch(locked_file);
+    at.set_mode(readonly_dir, 0o555);
+
+    let target_file = "target_file";
+    ucmd.arg(locked_file).arg(target_file).fails();
+
+    assert!(at.file_exists(locked_file));
+    assert!(!at.file_exists(target_file));
+}
+
 // Todo:
 
 // $ at.touch a b