get_filesystem returns Result instead of option

Removes unwrap and returns a Result instead of panicing if an invalid
path is given.
Previously if the flag: '-x' was provided with an argument of an
invalid directory the code would crash here

src/utils/mod.rs

@@ -100,7 +100,7 @@ pub fn get_dir_tree(
 fn get_allowed_filesystems(top_level_names: &HashSet<String>) -> Option<HashSet<u64>> {
     let mut limit_filesystems: HashSet<u64> = HashSet::new();
     for file_name in top_level_names.iter() {
-        if let Some(a) = get_filesystem(file_name) {
+        if let Ok(a) = get_filesystem(file_name) {
             limit_filesystems.insert(a);
         }
     }

src/utils/platform.rs

@@ -1,5 +1,6 @@
 use jwalk::DirEntry;
 use std::fs;
+use std::io;
 
 #[cfg(target_family = "unix")]
 fn get_block_size() -> u64 {
@@ -41,20 +42,20 @@ pub fn get_metadata(d: &DirEntry, _apparent: bool) -> Option<(u64, Option<(u64,
 }
 
 #[cfg(target_family = "unix")]
-pub fn get_filesystem(file_path: &str) -> Option<u64> {
+pub fn get_filesystem(file_path: &str) -> Result<u64, io::Error> {
     use std::os::unix::fs::MetadataExt;
-    let metadata = fs::metadata(file_path).unwrap();
+    let metadata = fs::metadata(file_path)?;
-    Some(metadata.dev())
+    Ok(metadata.dev())
 }
 
 #[cfg(target_family = "windows")]
-pub fn get_device(file_path: &str) -> Option<u64> {
+pub fn get_device(file_path: &str) -> Result<u64, io::Error> {
     use std::os::windows::fs::MetadataExt;
-    let metadata = fs::metadata(file_path).unwrap();
+    let metadata = fs::metadata(file_path)?;
-    Some(metadata.volume_serial_number())
+    Ok(metadata.volume_serial_number())
 }
 
 #[cfg(all(not(target_family = "windows"), not(target_family = "unix")))]
-pub fn get_device(file_path: &str) -> Option<u64> {
+pub fn get_device(file_path: &str) -> Result<u64, io::Error> {
     None
 }