written idea for storage of "infinite" indirects

src/structs.rs

@@ -198,8 +198,29 @@ pub struct Inode {
     /// Flags field, see `InodeFlags`
     pub flags: u32,
     /// Direct-Block-Addresses, last three are indirect if `InodeFlags::INDIRECT` is set
-    /// Indirect blocks are Indexes to other blocks, their contents are a u64 count "N" followed by N u64 indexes
-    /// both are pointers to data blocks, starting from data block 0
+    /// Indirect blocks are Indexes to other blocks, their contents are a u64 count "N" followed by
+    /// for each entry...
+    ///     is_data: bool (true if data block, false if another indirect block)
+    ///     depth: u56 (in total, how many indirect blocks are pointed to if this isn't data, and how many indirect blocks do they point to if they have indirect blocks)
+    ///     ptr: u64 (if is_data, then this is a data block, otherwise it is an indirect block)
+    /// both direct and indirect are pointers to data blocks, starting from data block 0
+    /// ====
+    /// these pointers can be addressed via a u64 in the following way:
+    /// if i < 12, then it refers to a direct block in this array (undefined behaviour if indirect is set and i > 9)
+    /// if i == 12, then it refers to the first index found by going to the first indirect block, and recursing through each found indirect block until the first data block is found.
+    /// if i == 13, then it refers to the second index found by going to the first indirect block, and recursing through each found indirect block until the second data block is found.
+    /// ==
+    /// the algorithm for finding the nth data block is as follows:
+    /// if n < 12, then it is the nth direct block
+    /// if n >= 12...
+    ///    let mut n = n - 12;
+    ///    let mut block_i = n / (block_size - 8);
+    ///    // block_i is how many indirect blocks we need to traverse to get to the indirect block that contains the nth data block
+    ///    let mut current_block = self.direct_block_addresses[12];
+    ///    while not found...
+    ///         // read block, if not data then check depth,
+    ///         // if depth implies that this indirect block could contain the nth data block, then recurse
+    ///         // otherwise, subtract the depth from n, and continue
     pub direct_block_addresses: [Index; 12],
     /// CRC32 checksum of this inode
     pub checksum: u32,