feat: With a single path provided as root, pretend it's the current w…

…orking dir (#110)

This makes it seem like the user started the directory walk directly in the given directory,
which is more intuitive than the previous approach only showed the given directory as
top-level directory.

Note that this change only affects invocations like `dua <dir>` or `dua i <dir>`.

src/main.rs

@@ -49,7 +49,7 @@ fn main() -> Result<()> {
             let res = TerminalApp::initialize(
                 &mut terminal,
                 walk_options,
-                paths_from(input, !opt.stay_on_filesystem)?,
+                extract_paths_maybe_set_cwd(input, !opt.stay_on_filesystem)?,
                 Interaction::Full,
             )?
             .map(|(keys_rx, mut app)| {
@@ -101,7 +101,7 @@ fn main() -> Result<()> {
                 walk_options,
                 !no_total,
                 !no_sort,
-                paths_from(input, !opt.stay_on_filesystem)?,
+                extract_paths_maybe_set_cwd(input, !opt.stay_on_filesystem)?,
             )?;
             if statistics {
                 writeln!(io::stderr(), "{:?}", stats).ok();
@@ -117,7 +117,7 @@ fn main() -> Result<()> {
                 walk_options,
                 true,
                 true,
-                paths_from(opt.input, !opt.stay_on_filesystem)?,
+                extract_paths_maybe_set_cwd(opt.input, !opt.stay_on_filesystem)?,
             )?
             .0
         }
@@ -126,7 +126,14 @@ fn main() -> Result<()> {
     process::exit(res.to_exit_code());
 }
 
-fn paths_from(paths: Vec<PathBuf>, cross_filesystems: bool) -> Result<Vec<PathBuf>, io::Error> {
+fn extract_paths_maybe_set_cwd(
+    mut paths: Vec<PathBuf>,
+    cross_filesystems: bool,
+) -> Result<Vec<PathBuf>, io::Error> {
+    if paths.len() == 1 {
+        std::env::set_current_dir(&paths[0])?;
+        paths.clear();
+    }
     let device_id = std::env::current_dir()
         .ok()
         .and_then(|cwd| crossdev::init(&cwd).ok());