Add '-x' flag to not cross filesystems

Fixes #3

9 files changed, 51 insertions, 10 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0033c3d..8043cb5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 #### v2.6.0
 
 * Use `x` to only mark entries for deletion, instead of toggling them.
+* Add `-x` | `--stay-on-filesystem` flag to force staying on the file system the root is on, similar to `-x` in the venerable `du` tool.
 
 #### v2.5.0 Much more nuanced percentage bars for a more precise visualization of space consumption
 
diff --git a/src/aggregate.rs b/src/aggregate.rs
index b04fa83..b7ef995 100644
--- a/src/aggregate.rs
+++ b/src/aggregate.rs
@@ -1,4 +1,4 @@
-use crate::{InodeFilter, WalkOptions, WalkResult};
+use crate::{crossdev, InodeFilter, WalkOptions, WalkResult};
 use failure::Error;
 use filesize::PathExt;
 use std::borrow::Cow;
@@ -10,7 +10,7 @@ use termion::color;
 /// If `sort_by_size_in_bytes` is set, we will sort all sizes (ascending) before outputting them.
 pub fn aggregate(
     mut out: impl io::Write,
-    options: WalkOptions,
+    walk_options: WalkOptions,
     compute_total: bool,
     sort_by_size_in_bytes: bool,
     paths: impl IntoIterator<Item = impl AsRef<Path>>,
@@ -27,15 +27,19 @@ pub fn aggregate(
         num_roots += 1;
         let mut num_bytes = 0u64;
         let mut num_errors = 0u64;
-        for entry in options.iter_from_path(path.as_ref()) {
+        let device_id = crossdev::init(path.as_ref())?;
+        for entry in walk_options.iter_from_path(path.as_ref()) {
             stats.entries_traversed += 1;
             match entry {
                 Ok(entry) => {
                     let file_size = match entry.client_state {
                         Some(Ok(ref m))
-                            if !m.is_dir() && (options.count_hard_links || inodes.add(m)) =>
+                            if !m.is_dir()
+                                && (walk_options.count_hard_links || inodes.add(m))
+                                && (walk_options.cross_filesystems
+                                    || crossdev::is_same_device(device_id, m)) =>
                         {
-                            if options.apparent_size {
+                            if walk_options.apparent_size {
                                 m.len()
                             } else {
                                 entry.path().size_on_disk_fast(m).unwrap_or_else(|_| {
@@ -64,7 +68,7 @@ pub fn aggregate(
         } else {
             write_path(
                 &mut out,
-                &options,
+                &walk_options,
                 &path,
                 num_bytes,
                 num_errors,
@@ -84,7 +88,7 @@ pub fn aggregate(
         for (path, num_bytes, num_errors) in aggregates.into_iter() {
             write_path(
                 &mut out,
-                &options,
+                &walk_options,
                 &path,
                 num_bytes,
                 num_errors,
@@ -96,7 +100,7 @@ pub fn aggregate(
     if num_roots > 1 && compute_total {
         write_path(
             &mut out,
-            &options,
+            &walk_options,
             Path::new("total"),
             total,
             res.num_errors,
diff --git a/src/common.rs b/src/common.rs
index f88c491..e5cf697 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -155,6 +155,7 @@ pub struct WalkOptions {
     pub apparent_size: bool,
     pub color: Color,
     pub sorting: TraversalSorting,
+    pub cross_filesystems: bool,
 }
 
 type WalkDir = jwalk::WalkDirGeneric<((), Option<Result<std::fs::Metadata, jwalk::Error>>)>;
diff --git a/src/crossdev.rs b/src/crossdev.rs
new file mode 100644
index 0000000..94c5c67
--- /dev/null
+++ b/src/crossdev.rs
@@ -0,0 +1,25 @@
+use std::{io, path::Path};
+
+#[cfg(unix)]
+pub fn init(path: &Path) -> io::Result<u64> {
+    use std::os::unix::fs::MetadataExt;
+
+    path.metadata().map(|m| m.dev())
+}
+
+#[cfg(unix)]
+pub fn is_same_device(device_id: u64, meta: &std::fs::Metadata) -> bool {
+    use std::os::unix::fs::MetadataExt;
+
+    meta.dev() == device_id
+}
+
+#[cfg(not(any(unix, windows)))]
+pub fn is_same_device(device_id: u64, meta: &std::fs::Metadata) -> bool {
+    true
+}
+
+#[cfg(not(any(unix, windows)))]
+pub fn init(path: &Path) -> io::Result<u64> {
+    Ok(0)
+}
diff --git a/src/interactive/app_test/utils.rs b/src/interactive/app_test/utils.rs
index 8fde29f..57854d9 100644
--- a/src/interactive/app_test/utils.rs
+++ b/src/interactive/app_test/utils.rs
@@ -175,6 +175,7 @@ pub fn initialized_app_and_terminal_with_closure<P: AsRef<Path>>(
             count_hard_links: false,
             color: Color::None,
             sorting: TraversalSorting::AlphabeticalByFileName,
+            cross_filesystems: false,
         },
         input,
         Interaction::None,
diff --git a/src/lib.rs b/src/lib.rs
index ae6f953..f1f4f5c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,7 @@ extern crate jwalk;
 
 mod aggregate;
 mod common;
+mod crossdev;
 mod inodefilter;
 
 pub mod traverse;
diff --git a/src/main.rs b/src/main.rs
index e9ea37e..7f505d9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -32,6 +32,7 @@ fn run() -> Result<(), Error> {
         apparent_size: opt.apparent_size,
         count_hard_links: opt.count_hard_links,
         sorting: TraversalSorting::None,
+        cross_filesystems: !opt.stay_on_filesystem,
     };
     let res = match opt.command {
         Some(Interactive { input }) => {
diff --git a/src/options.rs b/src/options.rs
index 1a06e45..5b9d604 100644
--- a/src/options.rs
+++ b/src/options.rs
@@ -60,6 +60,10 @@ pub struct Args {
     #[structopt(short = "l", long)]
     pub count_hard_links: bool,
 
+    /// If set, we will not cross filesystems or traverse mount points
+    #[structopt(short = "x", long)]
+    pub stay_on_filesystem: bool,
+
     /// One or more input files or directories. If unset, we will use all entries in the current working directory.
     #[structopt(parse(from_os_str))]
     pub input: Vec<PathBuf>,
diff --git a/src/traverse.rs b/src/traverse.rs
index d78041f..5027b69 100644
--- a/src/traverse.rs
+++ b/src/traverse.rs
@@ -1,4 +1,4 @@
-use crate::{get_size_or_panic, InodeFilter, WalkOptions};
+use crate::{crossdev, get_size_or_panic, InodeFilter, WalkOptions};
 use failure::Error;
 use filesize::PathExt;
 use petgraph::{graph::NodeIndex, stable_graph::StableGraph, Directed, Direction};
@@ -80,6 +80,7 @@ impl Traversal {
         }
         for path in input.into_iter() {
             let mut last_seen_eid = 0;
+            let device_id = crossdev::init(path.as_ref())?;
             for (eid, entry) in walk_options
                 .iter_from_path(path.as_ref())
                 .into_iter()
@@ -97,7 +98,9 @@ impl Traversal {
                         let file_size = match entry.client_state {
                             Some(Ok(ref m))
                                 if !m.is_dir()
-                                    && (walk_options.count_hard_links || inodes.add(m)) =>
+                                    && (walk_options.count_hard_links || inodes.add(m))
+                                    && (walk_options.cross_filesystems
+                                        || crossdev::is_same_device(device_id, m)) =>
                             {
                                 if walk_options.apparent_size {
                                     m.len()