🐛 [Crash] linux_filesystem.dart: int.parse crashes on Btrfs/overlay/network mounts with non-numeric Use% value

[Toqsick]

Summary

LinuxFilesystem.disks() crashes with an unhandled FormatException on systems where df -h returns a non-numeric string in the Use% column. This is a confirmed crash reproducible on Btrfs, overlay filesystems (e.g. Docker, Flatpak sandbox layers), network mounts (NFS, CIFS), and pseudo-filesystems.

Affected File

lib/linux/linux_filesystem.dart — disks() method

Root Cause

// Line ~50 in disks()
devices.add(DeviceInfo(
    values[0],
    values[1],
    values[2],
    values[3],
    int.parse(values[4].substring(0, values[4].length - 1)),  // ← CRASH HERE
    values[5],
    _removableDevices.any((x) => values[5].contains(x))));

int.parse() throws FormatException when values[4] is:

• "-" — emitted by Btrfs and some overlay mounts when usage is indeterminate
• "100%" with trailing space variants
• Empty string when df output is malformed

Additionally, there is no bounds check on values.length. A df line with fewer than 6 columns (e.g. long filesystem names that wrap to the next line) will cause a RangeError on values[4] or values[5].

Reproduction

1. Run linux-assistant on a system with Btrfs root filesystem, or with Docker/Podman running (overlay mounts active)
2. Open the Health Check or any page that calls LinuxFilesystem.disks()
3. App crashes immediately with:

   FormatException: Invalid radix-10 number (at character 1)
   -
   ^
   

Or with a Docker/overlay mount:

RangeError (index): Index out of range: index 5, valid range is 0..4

Affected Systems

• Any distro with Btrfs as root (openSUSE Tumbleweed default, Fedora optional, Arch)
• Any system running Docker, Podman, LXC/LXD (overlay mounts)
• Systems with NFS/Samba mounts that have unusual df output
• Flatpak sandbox overlay layers

Fix

for (var line in lines) {
  var values = line.split(" ");
  values.removeWhere((x) => x == "");
  
  // Guard against short lines (wrapped filesystem names)
  if (values.length < 6) continue;
  
  if (devicesRead.contains(values[0]) || values[1].endsWith("M")) {
    continue;
  }

  // Strip "%" and parse safely — use 0 as fallback for "-" or empty
  final rawPercent = values[4].substring(0, values[4].length - 1);
  final usedPercent = int.tryParse(rawPercent) ?? 0;

  devices.add(DeviceInfo(
      values[0],
      values[1],
      values[2],
      values[3],
      usedPercent,
      values[5],
      _removableDevices.any((x) => values[5].contains(x))));

  devicesRead.add(values[0]);
}

Severity

P1 — App crash on widely-used configurations. openSUSE Tumbleweed ships Btrfs by default, Fedora offers it as an install option. Docker is installed on millions of Linux systems. This crash affects a significant portion of the user base silently.