docs

src/extent.rs

@@ -21,7 +21,7 @@ impl Iterator<> for BlockIter {
     }
 }
 
-/// A disk extent
+/// A disk extent, [wikipedia](https://en.wikipedia.org/wiki/Extent_(file_systems))
 #[derive(Copy, Clone, Debug, Default)]
 #[repr(packed)]
 pub struct Extent {

src/filesystem.rs

@@ -43,6 +43,7 @@ impl<D: Disk> FileSystem<D> {
 
     /// Create a file system on a disk, with reserved data at the beginning
     /// Reserved data will be zero padded up to the nearest block
+    /// We need to pass ctime and ctime_nsec in order to initialize the unix timestamps
     pub fn create_reserved(mut disk: D, reserved: &[u8], ctime: u64, ctime_nsec: u32) -> Result<Self> {
         let size = disk.size()?;
         let block_offset = (reserved.len() as u64 + BLOCK_SIZE - 1)/BLOCK_SIZE;
@@ -80,6 +81,7 @@ impl<D: Disk> FileSystem<D> {
         }
     }
 
+    /// Read at a certain spot in the disk, returning data into buffer
     pub fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
         self.disk.read_at(self.block + block, buffer)
     }

src/node.rs

@@ -110,19 +110,26 @@ impl Node {
         self.mode & Node::MODE_TYPE == Node::MODE_SYMLINK
     }
 
+    /// Tests if UID is the owner of that file, only true when uid=0 or when the UID stored in metadata is equal to the UID you supply
     pub fn owner(&self, uid: u32) -> bool {
         uid == 0 || self.uid == uid
     }
 
+    /// Tests if the current user has enough permissions to view the file, op is the operation,
+    /// like read and write, these modes are MODE_EXEC, MODE_READ, and MODE_WRITE
     pub fn permission(&self, uid: u32, gid: u32, op: u16) -> bool {
         let mut perm = self.mode & 0o7;
         if self.uid == uid {
+            // If self.mode is 101100110, >> 6 would be 000000101
+            // 0o7 is octal for 111, or, when expanded to 9 digits is 000000111
             perm |= (self.mode >> 6) & 0o7;
+            // Since we erased the GID and OTHER bits when >>6'ing, |= will keep those bits in place. 
         }
         if self.gid == gid || gid == 0 {
             perm |= (self.mode >> 3) & 0o7;
         }
         if uid == 0 {
+            //set the `other` bits to 111
             perm |= 0o7;
         }
         perm & op == op