feat: enhance --mounts: display mount root path

src/fs/mounts/linux.rs

@@ -6,9 +6,18 @@
 // SPDX-License-Identifier: MIT
 use crate::fs::mounts::{Error, MountedFs};
 use proc_mounts::MountList;
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::path::PathBuf;
 
 /// Get a list of all mounted filesystems
 pub fn mounts() -> Result<Vec<MountedFs>, Error> {
+    // Try to read from `/proc/self/mountinfo` first
+    if let Ok(mounts) = read_mountinfo() {
+        return Ok(mounts);
+    }
+
+    // Fall back to `/proc/mounts` if `/proc/self/mountinfo` doesn't exist
     Ok(MountList::new()
         .map_err(Error::IOError)?
         .0
@@ -17,6 +26,54 @@ pub fn mounts() -> Result<Vec<MountedFs>, Error> {
             dest: mount.dest.clone(),
             fstype: mount.fstype.clone(),
             source: mount.source.to_string_lossy().into(),
+            root: None,
         })
         .collect())
 }
+
+/// Read and parse the /proc/self/mountinfo file
+fn read_mountinfo() -> Result<Vec<MountedFs>, Error> {
+    let file = File::open("/proc/self/mountinfo").map_err(Error::IOError)?;
+    let reader = BufReader::new(file);
+    let mut mounts = Vec::new();
+
+    for line in reader.lines() {
+        let line = line.map_err(Error::IOError)?;
+        if let Some(mount) = parse_mountinfo_line(&line) {
+            mounts.push(mount);
+        }
+    }
+
+    Ok(mounts)
+}
+
+/// Parse a line from the /proc/self/mountinfo file
+fn parse_mountinfo_line(line: &str) -> Option<MountedFs> {
+    // https://man7.org/linux/man-pages/man5/proc_pid_mountinfo.5.html
+    // Format: 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
+    // Fields: (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
+    // We need: (4) root, (5) mount point, (9) fstype, (10) source
+
+    let parts: Vec<&str> = line.split_whitespace().collect();
+    if parts.len() < 10 {
+        return None;
+    }
+
+    // Find the separator "-" which marks the end of optional fields
+    let separator_pos = parts.iter().position(|&p| p == "-")?;
+    if separator_pos + 3 > parts.len() {
+        return None;
+    }
+
+    let root = parts[3].to_string();
+    let dest = PathBuf::from(parts[4]);
+    let fstype = parts[separator_pos + 1].to_string();
+    let source = parts[separator_pos + 2].to_string();
+
+    Some(MountedFs {
+        dest,
+        fstype,
+        source,
+        root: Some(root),
+    })
+}

src/fs/mounts/macos.rs

@@ -57,6 +57,7 @@ pub fn mounts() -> Result<Vec<MountedFs>, Error> {
             dest,
             fstype,
             source,
+            root: None,
         });
     }
 

src/fs/mounts/mod.rs

@@ -24,6 +24,7 @@ pub struct MountedFs {
     pub dest: PathBuf,
     pub fstype: String,
     pub source: String,
+    pub root: Option<String>,
 }
 
 #[derive(Debug)]

src/output/file_name.rs

@@ -326,6 +326,16 @@ impl<'a, 'dir, C: Colours> FileName<'a, 'dir, C> {
                 // This is a filesystem mounted on the directory, output its details
                 bits.push(Style::default().paint(" ["));
                 bits.push(Style::default().paint(mount_details.source.clone()));
+
+                match &mount_details.root {
+                    Some(root) if root != "/" => {
+                        bits.push(Style::default().paint("["));
+                        bits.push(Style::default().paint(root.clone()));
+                        bits.push(Style::default().paint("]"));
+                    }
+                    _ => {}
+                }
+
                 bits.push(Style::default().paint(" ("));
                 bits.push(Style::default().paint(mount_details.fstype.clone()));
                 bits.push(Style::default().paint(")]"));