begin work on making safe wrappers

src/btree.rs

@@ -2,20 +2,33 @@ use alloc::string::{String, ToString};
 use alloc::vec;
 use alloc::vec::Vec;
 use ondisk_btree::{BTree, FromBytes, SizeOf, ToBytes};
-use vapfs::{BlockDevice, Index};
+use vapfs::{Index};
 use crate::crc32;
-use crate::structs::Superblock;
 
-/// # BTd
+/// # BTD
 /// min-degree of all BTrees
-pub const BTd: u32 = 3;
+pub const BTD: u32 = 3;
+
+/// # EntryType
+/// the type of an entry in a directory listing
+#[derive(Debug, Clone)]
+pub enum EntryType {
+    /// a file or directory, stored in an inode
+    Inode(Index),
+    /// a hard link (i.e. pointer to inode, cannot be directory)
+    HardLink(Index),
+    /// a soft link (i.e. path string, can be directory)
+    SoftLink(String),
+    /// this entry is corrupt
+    Corrupt,
+}
 
 /// # DirectoryListing
 /// an entry in a list of all files and directories sharing a common crc32 hash collision (unlikely to happen but just in case!)
 #[derive(Debug, Clone)]
 pub struct DirectoryListing {
     pub name: String,
-    pub inode: Index,
+    pub data: EntryType,
 }
 
 /// # BTreeEntry
@@ -38,7 +51,20 @@ pub struct Directory {
     pub btree: BTree<BTreeEntry>,
 }
 
+impl Default for Directory {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl Directory {
+    /// creates a new, empty directory
+    pub fn new() -> Self {
+        let mut new = Self { backup_entries: Vec::new(), crc32: 0, btree: BTree::new(BTD) };
+        // calculate crc32 hash of empty b-tree
+        new.crc32 = crc32::crc32(&new.btree.to_bytes());
+        new
+    }
     /// Reads the directory into memory from the given bytes
     pub fn open(bytes: &[u8]) -> Self {
         Self::from_bytes(bytes)
@@ -50,29 +76,29 @@ impl Directory {
     }
 
     /// Adds a new entry to the directory listing
-    pub fn new_entry(&mut self, name: &str, inode: Index) {
+    pub fn new_entry(&mut self, name: &str, data: EntryType) {
         let crc32 = crc32::crc32(name.as_bytes());
         // check if this crc32 hash already exists
         let index = self.btree.search(crc32);
         if let Some(node) = index {
             if let Some(key) = node.keys.iter_mut().find(|key| key.0 == crc32) {
                 // if it does, add the new entry to the existing list
-                key.1.entries.push(DirectoryListing { name: name.to_string(), inode });
+                key.1.entries.push(DirectoryListing { name: name.to_string(), data });
             }
         } else {
             // if it doesn't, create a new list
-            let entries = vec![DirectoryListing { name: name.to_string(), inode }];
+            let entries = vec![DirectoryListing { name: name.to_string(), data }];
             self.btree.insert(crc32, BTreeEntry { crc32, entries });
         }
     }
 
     /// Returns an inode for the given entry name
-    pub fn find(&mut self, name: &str) -> Option<Index> {
+    pub fn find(&mut self, name: &str) -> Option<EntryType> {
         let crc32 = crc32::crc32(name.as_bytes());
         let index = self.btree.search(crc32);
         if let Some(node) = index {
             if let Some(key) = node.keys.iter().find(|key| key.0 == crc32) {
-                return Some(key.1.entries.iter().find(|entry| entry.name == name).unwrap().inode);
+                return Some(key.1.entries.iter().find(|entry| entry.name == name).unwrap().data.clone());
             }
         }
         None
@@ -86,6 +112,7 @@ impl Directory {
             if let Some(key) = node.keys.iter_mut().find(|key| key.0 == crc32) {
                 key.1.entries.retain(|entry| entry.name != name);
                 if key.1.entries.is_empty() {
+                    self.btree.remove(crc32);
                 }
             }
         }
@@ -104,7 +131,7 @@ impl Directory {
 
     /// Rebuilds the b-tree from the backup entries
     pub fn rebuild(&mut self) {
-        self.btree = BTree::new(BTd);
+        self.btree = BTree::new(BTD);
         for entry in &self.backup_entries {
             let crc32 = crc32::crc32(entry.name.as_bytes());
             let index = self.btree.search(crc32);
@@ -156,7 +183,29 @@ impl ToBytes for DirectoryListing {
         let name_len: u32 = self.name.len() as u32;
         bytes.extend_from_slice(&name_len.to_be_bytes());
         bytes.extend_from_slice(self.name.as_bytes());
-        bytes.extend_from_slice(&self.inode.to_be_bytes());
+        match &self.data {
+            EntryType::Inode(index) => {
+                // 0 for inode
+                bytes.push(0);
+                bytes.extend_from_slice(&index.to_be_bytes());
+            }
+            EntryType::HardLink(index) => {
+                // 1 for hard link
+                bytes.push(1);
+                bytes.extend_from_slice(&index.to_be_bytes());
+            }
+            EntryType::SoftLink(str) => {
+                // 2 for soft link
+                bytes.push(2);
+                let str_len: u32 = str.len() as u32;
+                bytes.extend_from_slice(&str_len.to_be_bytes());
+                bytes.extend_from_slice(str.as_bytes());
+            }
+            EntryType::Corrupt => {
+                // 3 for corrupt
+                bytes.push(3);
+            }
+        }
         bytes
     }
 }
@@ -165,8 +214,24 @@ impl FromBytes for DirectoryListing {
     fn from_bytes(bytes: &[u8]) -> Self {
         let name_len = u32::from_be_bytes(bytes[0..4].try_into().unwrap()) as usize;
         let name = String::from_utf8(bytes[4..4 + name_len].to_vec()).unwrap();
-        let inode = Index::from_be_bytes(bytes[4 + name_len..12 + name_len].try_into().unwrap());
-        Self { name, inode }
+        match bytes[4 + name_len] {
+            0 => {
+                let index = u64::from_be_bytes(bytes[5 + name_len..13 + name_len].try_into().unwrap());
+                Self { name, data: EntryType::Inode(index) }
+            }
+            1 => {
+                let index = u64::from_be_bytes(bytes[5 + name_len..13 + name_len].try_into().unwrap());
+                Self { name, data: EntryType::HardLink(index) }
+            }
+            2 => {
+                let str_len = u32::from_be_bytes(bytes[5 + name_len..9 + name_len].try_into().unwrap()) as usize;
+                let str = String::from_utf8(bytes[9 + name_len..9 + name_len + str_len].to_vec()).unwrap();
+                Self { name, data: EntryType::SoftLink(str) }
+            }
+            _ => {
+                Self { name, data: EntryType::Corrupt }
+            }
+        }
     }
 }
 

src/journal/mod.rs

@@ -0,0 +1 @@
+pub mod file_create;

src/lib.rs

@@ -13,6 +13,8 @@ pub mod structs;
 pub mod bitmap;
 pub mod crc32;
 pub mod safe;
+pub mod listblock;
+pub mod journal;
 
 /// Reads the superblock (located at byte offset 1024 of the block device) and returns it.
 /// Returns None if the block device is too small to contain a superblock.
@@ -32,10 +34,11 @@ pub fn get_superblock(bd: &mut dyn BlockDevice) -> Option<Superblock> {
 /// # Safety
 /// unsafe because it does not journal the write, and does not update any other metadata.
 pub unsafe fn write_superblock(mut sb: Superblock, bd: &mut dyn BlockDevice) -> bool {
+    let block_size = sb.block_size;
     sb.convert_native_to_big_endian();
     let mut buf: [u8; core::mem::size_of::<Superblock>()] = [0; core::mem::size_of::<Superblock>()];
     core::ptr::write(buf.as_mut_ptr() as *mut Superblock, sb);
-    bd.seek(1024);
+    bd.seek(block_size as u64);
     let write_count = bd.write_blocks(&buf);
     write_count == core::mem::size_of::<Superblock>()
 }
@@ -444,10 +447,6 @@ pub fn get_indirect_datablock(sb: &Superblock, bd: &mut dyn BlockDevice, list: L
     }
 }
 
-/// Resizes an inode to the given size.
-/// # Safety
-/// unsafe because it does not journal the write, and does not update any other metadata.
-
 /// Creates a journal entry for a single block write operation.
 /// Should be safe to call at anytime, and shouldn't corrupt anything if the system crashes.
 /// Returns None if the journal is full, or if the block device cannot be written to.
@@ -1314,7 +1313,7 @@ pub fn flush_multi_block_write(sb: &Superblock, bd: &mut dyn BlockDevice, entry_
 
         // enclosed to make collapsable
         // todo! we should refactor this code eventually so that we don't have
-        // multi-hundred line long things cluttering everything like this
+        // todo! multi-hundred line long things cluttering everything like this
         {
             fn pushunused1(
                 sb: &Superblock, bd: &mut dyn BlockDevice, list_block: &[Index], old_count: usize,
@@ -1840,19 +1839,11 @@ pub fn journaled_write_data(sb: &Superblock, bd: &mut dyn BlockDevice, inode: In
             }
 
             // try again
-            journal_entry = if data.len() > sb.block_size as _ {
-                schedule_multi_block_write(
-                    sb, bd, inode,
-                    from_block, (data.len() as Index + sb.block_size as Index - 1) / sb.block_size as Index,
-                    data,
-                )
-            } else {
-                schedule_single_block_write(
+            journal_entry = schedule_single_block_write(
                     sb, bd, inode,
                     JBRTargetType::DataBlock, Some(from_block),
                     data,
-                )
-            };
+                );
 
             if journal_entry.is_none() {
                 return JournaledWriteResult::UnderlyingBlockDeviceError;

src/listblock.rs

@@ -0,0 +1,267 @@
+use alloc::vec;
+use alloc::vec::Vec;
+use vapfs::{BlockDevice, Index};
+use crate::read_datablock;
+use crate::structs::{ListBlock, Superblock};
+
+pub struct ListblockIter<'a> {
+    listblock: &'a ListBlock,
+    index: usize,
+    buf1: (Index, Vec<u8>),
+    buf2: (Index, Vec<u8>),
+    buf3: (Index, Vec<u8>),
+    buf4: (Index, Vec<u8>),
+    buf5: (Index, Vec<u8>),
+    buf6: (Index, Vec<u8>),
+}
+
+impl<'a> ListblockIter<'a> {
+    pub fn new(listblock: &'a ListBlock) -> Self {
+        Self { listblock, index: 0, buf1: (0, vec![]), buf2: (0, vec![]), buf3: (0, vec![]), buf4: (0, vec![]), buf5: (0, vec![]), buf6: (0, vec![]) }
+    }
+
+    pub fn next(&mut self, sb: &Superblock, bd: &mut dyn BlockDevice) -> Option<Index> {
+        if self.index as Index >= self.listblock.count {
+            return None;
+        }
+
+        if self.index < 32 {
+            let index = self.listblock.direct_block_addresses[self.index];
+            self.index += 1;
+            return Some(index);
+        } else {
+            // copy pasted from structs.rs
+            // if greater than 32, see the following:
+            // let N = (maximum number of pointers in an indirect block) * 32
+            // (beginning...count)
+            // 32..N: single indirect block
+            // 32+N..N^2: double indirect block
+            // 32+N^2..N^3: triple indirect block
+            // 32+N^3..N^4: quadruple indirect block
+            // 32+N^4..N^5: quintuple indirect block
+            // 32+N^5..N^6: sextuple indirect block
+
+            // block index is address / (max_per_block ^ (1 if single, 2 if double, etc))
+            // after getting your layer's address, repeat the previous layer's process
+
+            let max_per_block = sb.block_size as u64 / 8;
+            let N = max_per_block * 32;
+            let N2 = N * N;
+            let N3 = N2 * N;
+            let N4 = N3 * N;
+            let N5 = N4 * N;
+            let N6 = N5 * N;
+
+            let mut address = self.index as u64 - 32;
+
+            // todo: you could probably rewrite this using like recursion or smth
+
+            match address {
+                _ if address < N => {
+                    let block_index = address / max_per_block;
+                    let address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != self.listblock.single_indirect_block_address[block_index as usize] {
+                        self.buf1.1 = read_datablock(self.listblock.single_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf1.0 = self.listblock.single_indirect_block_address[block_index as usize];
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(address * 8) as usize..(address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ if address < N2 => {
+                    let address = address - N;
+                    let block_index = (address) / (max_per_block ^ 2);
+                    if self.buf2.1.len() == 0 || self.buf2.0 != self.listblock.double_indirect_block_address[block_index as usize] {
+                        self.buf2.1 = read_datablock(self.listblock.double_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf2.0 = self.listblock.double_indirect_block_address[block_index as usize];
+                    }
+                    let layer2_address = address / max_per_block;
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf2.1[(layer2_address * 8) as usize..(layer2_address * 8 + 8) as usize]);
+                    let layer1_block = u64::from_be_bytes(buf);
+                    let layer1_address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != layer1_block {
+                        self.buf1.1 = read_datablock(layer1_block, sb, bd);
+                        self.buf1.0 = layer1_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(layer1_address * 8) as usize..(layer1_address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ if address < N3 => {
+                    let address = address - N2;
+                    let block_index = (address) / (max_per_block ^ 3);
+                    if self.buf3.1.len() == 0 || self.buf3.0 != self.listblock.triple_indirect_block_address[block_index as usize] {
+                        self.buf3.1 = read_datablock(self.listblock.triple_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf3.0 = self.listblock.triple_indirect_block_address[block_index as usize];
+                    }
+                    let layer3_address = address / (max_per_block ^ 2);
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf3.1[(layer3_address * 8) as usize..(layer3_address * 8 + 8) as usize]);
+                    let layer2_block = u64::from_be_bytes(buf);
+                    let layer2_address = (address % (max_per_block ^ 2)) / max_per_block;
+                    if self.buf2.1.len() == 0 || self.buf2.0 != layer2_block {
+                        self.buf2.1 = read_datablock(layer2_block, sb, bd);
+                        self.buf2.0 = layer2_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf2.1[(layer2_address * 8) as usize..(layer2_address * 8 + 8) as usize]);
+                    let layer1_block = u64::from_be_bytes(buf);
+                    let layer1_address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != layer1_block {
+                        self.buf1.1 = read_datablock(layer1_block, sb, bd);
+                        self.buf1.0 = layer1_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(layer1_address * 8) as usize..(layer1_address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ if address < N4 => {
+                    let address = address - N3;
+                    let block_index = (address) / (max_per_block ^ 4);
+                    if self.buf4.1.len() == 0 || self.buf4.0 != self.listblock.quadruple_indirect_block_address[block_index as usize] {
+                        self.buf4.1 = read_datablock(self.listblock.quadruple_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf4.0 = self.listblock.quadruple_indirect_block_address[block_index as usize];
+                    }
+                    let layer4_address = address / (max_per_block ^ 3);
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf4.1[(layer4_address * 8) as usize..(layer4_address * 8 + 8) as usize]);
+                    let layer3_block = u64::from_be_bytes(buf);
+                    let layer3_address = (address % (max_per_block ^ 3)) / (max_per_block ^ 2);
+                    if self.buf3.1.len() == 0 || self.buf3.0 != layer3_block {
+                        self.buf3.1 = read_datablock(layer3_block, sb, bd);
+                        self.buf3.0 = layer3_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf3.1[(layer3_address * 8) as usize..(layer3_address * 8 + 8) as usize]);
+                    let layer2_block = u64::from_be_bytes(buf);
+                    let layer2_address = (address % (max_per_block ^ 2)) / max_per_block;
+                    if self.buf2.1.len() == 0 || self.buf2.0 != layer2_block {
+                        self.buf2.1 = read_datablock(layer2_block, sb, bd);
+                        self.buf2.0 = layer2_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf2.1[(layer2_address * 8) as usize..(layer2_address * 8 + 8) as usize]);
+                    let layer1_block = u64::from_be_bytes(buf);
+                    let layer1_address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != layer1_block {
+                        self.buf1.1 = read_datablock(layer1_block, sb, bd);
+                        self.buf1.0 = layer1_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(layer1_address * 8) as usize..(layer1_address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ if address < N5 => {
+                    let address = address - N4;
+                    let block_index = (address) / (max_per_block ^ 5);
+                    if self.buf5.1.len() == 0 || self.buf5.0 != self.listblock.quintuple_indirect_block_address[block_index as usize] {
+                        self.buf5.1 = read_datablock(self.listblock.quintuple_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf5.0 = self.listblock.quintuple_indirect_block_address[block_index as usize];
+                    }
+                    let layer5_address = address / (max_per_block ^ 4);
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf5.1[(layer5_address * 8) as usize..(layer5_address * 8 + 8) as usize]);
+                    let layer4_block = u64::from_be_bytes(buf);
+                    let layer4_address = (address % (max_per_block ^ 4)) / (max_per_block ^ 3);
+                    if self.buf4.1.len() == 0 || self.buf4.0 != layer4_block {
+                        self.buf4.1 = read_datablock(layer4_block, sb, bd);
+                        self.buf4.0 = layer4_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf4.1[(layer4_address * 8) as usize..(layer4_address * 8 + 8) as usize]);
+                    let layer3_block = u64::from_be_bytes(buf);
+                    let layer3_address = (address % (max_per_block ^ 3)) / (max_per_block ^ 2);
+                    if self.buf3.1.len() == 0 || self.buf3.0 != layer3_block {
+                        self.buf3.1 = read_datablock(layer3_block, sb, bd);
+                        self.buf3.0 = layer3_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf3.1[(layer3_address * 8) as usize..(layer3_address * 8 + 8) as usize]);
+                    let layer2_block = u64::from_be_bytes(buf);
+                    let layer2_address = (address % (max_per_block ^ 2)) / max_per_block;
+                    if self.buf2.1.len() == 0 || self.buf2.0 != layer2_block {
+                        self.buf2.1 = read_datablock(layer2_block, sb, bd);
+                        self.buf2.0 = layer2_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf2.1[(layer2_address * 8) as usize..(layer2_address * 8 + 8) as usize]);
+                    let layer1_block = u64::from_be_bytes(buf);
+                    let layer1_address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != layer1_block {
+                        self.buf1.1 = read_datablock(layer1_block, sb, bd);
+                        self.buf1.0 = layer1_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(layer1_address * 8) as usize..(layer1_address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ if address < N6 => {
+                    let address = address - N5;
+                    let block_index = (address) / (max_per_block ^ 6);
+                    if self.buf6.1.len() == 0 || self.buf6.0 != self.listblock.sextuple_indirect_block_address[block_index as usize] {
+                        self.buf6.1 = read_datablock(self.listblock.sextuple_indirect_block_address[block_index as usize], sb, bd);
+                        self.buf6.0 = self.listblock.sextuple_indirect_block_address[block_index as usize];
+                    }
+                    let layer6_address = address / (max_per_block ^ 5);
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf6.1[(layer6_address * 8) as usize..(layer6_address * 8 + 8) as usize]);
+                    let layer5_block = u64::from_be_bytes(buf);
+                    let layer5_address = (address % (max_per_block ^ 5)) / (max_per_block ^ 4);
+                    if self.buf5.1.len() == 0 || self.buf5.0 != layer5_block {
+                        self.buf5.1 = read_datablock(layer5_block, sb, bd);
+                        self.buf5.0 = layer5_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf5.1[(layer5_address * 8) as usize..(layer5_address * 8 + 8) as usize]);
+                    let layer4_block = u64::from_be_bytes(buf);
+                    let layer4_address = (address % (max_per_block ^ 4)) / (max_per_block ^ 3);
+                    if self.buf4.1.len() == 0 || self.buf4.0 != layer4_block {
+                        self.buf4.1 = read_datablock(layer4_block, sb, bd);
+                        self.buf4.0 = layer4_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf4.1[(layer4_address * 8) as usize..(layer4_address * 8 + 8) as usize]);
+                    let layer3_block = u64::from_be_bytes(buf);
+                    let layer3_address = (address % (max_per_block ^ 3)) / (max_per_block ^ 2);
+                    if self.buf3.1.len() == 0 || self.buf3.0 != layer3_block {
+                        self.buf3.1 = read_datablock(layer3_block, sb, bd);
+                        self.buf3.0 = layer3_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf3.1[(layer3_address * 8) as usize..(layer3_address * 8 + 8) as usize]);
+                    let layer2_block = u64::from_be_bytes(buf);
+                    let layer2_address = (address % (max_per_block ^ 2)) / max_per_block;
+                    if self.buf2.1.len() == 0 || self.buf2.0 != layer2_block {
+                        self.buf2.1 = read_datablock(layer2_block, sb, bd);
+                        self.buf2.0 = layer2_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf2.1[(layer2_address * 8) as usize..(layer2_address * 8 + 8) as usize]);
+                    let layer1_block = u64::from_be_bytes(buf);
+                    let layer1_address = address % max_per_block;
+                    if self.buf1.1.len() == 0 || self.buf1.0 != layer1_block {
+                        self.buf1.1 = read_datablock(layer1_block, sb, bd);
+                        self.buf1.0 = layer1_block;
+                    }
+                    let mut buf: [u8; 8] = [0; 8];
+                    buf.copy_from_slice(&self.buf1.1[(layer1_address * 8) as usize..(layer1_address * 8 + 8) as usize]);
+                    let block = u64::from_be_bytes(buf);
+                    self.index += 1;
+                    Some(block)
+                }
+                _ => None,
+            }
+        }
+    }
+}

src/safe.rs

@@ -0,0 +1,219 @@
+use alloc::vec;
+use ondisk_btree::ToBytes;
+use vapfs::{BlockDevice, Timestamp};
+use crate::btree::Directory;
+use crate::{bitmap, structs, write_datablock, write_inode, write_journal_entry, write_superblock};
+use crate::structs::{Filetype, Inode, JournalBlockWrite, JournalEntry, JournalEntryContents, ListBlock, Superblock, UNIXMode};
+
+pub enum FilesystemError {
+    /// Returned when an error relating to a lack of storage space occurs
+    NotEnoughStorageSpace,
+    /// Returned during filesystem initialisation if the block size is too small
+    BlockSizeTooSmall,
+    /// Returned when an error occurs that was not expected
+    UnexpectedError,
+}
+
+/// initialises a filesystem with the given details
+/// block_size is in bytes, and must be at least 2048 bytes
+/// bd_size is in blocks, and should not exceed the size of the device that `bd` represents
+/// current_time is the current time, in seconds since the unix epoch
+/// inode_count is the number of inodes to create, or None to use the default (1/8 of the blocks available)
+/// journal_count is the number of journal blocks to create, or None to use the default (128 blocks)
+pub fn init_filesystem(bd: &mut dyn BlockDevice, block_size: u32, bd_size: u64, current_time: Timestamp, inode_count: Option<u64>, journal_count: Option<u64>) -> Result<(), FilesystemError> {
+    if block_size < 2048 {
+        return Err(FilesystemError::BlockSizeTooSmall);
+    }
+    let mut blocks_available = bd_size as i64;
+    // if we have less than 5 blocks (probably around the minimum size), return not enough storage space
+    if blocks_available < 5 {
+        return Err(FilesystemError::NotEnoughStorageSpace);
+    }
+    // minus one for the superblock
+    blocks_available -= 1;
+    // subtract journal count from blocks available
+    blocks_available -= journal_count.unwrap_or(128) as i64;
+    if blocks_available < 0 {
+        return Err(FilesystemError::NotEnoughStorageSpace);
+    }
+    // inode count is the number of blocks available divided by 8
+    let inode_count = inode_count.unwrap_or(blocks_available as u64 / 8);
+    // each inode takes up one block, subtract that from the blocks available
+    blocks_available -= inode_count as i64;
+    if blocks_available < 0 {
+        return Err(FilesystemError::NotEnoughStorageSpace);
+    }
+    // divide inode count by 8 (rounded up) to get the size of the inode bitmap
+    let inode_bitmap_size = (inode_count + 7) / 8;
+    // divide the bitmap size by the block size to get the number of blocks needed for the inode bitmap
+    let inode_bitmap_blocks = (inode_bitmap_size + (block_size as u64 - 1)) / block_size as u64;
+    // subtract the number of blocks needed for the inode bitmap from the blocks available
+    blocks_available -= inode_bitmap_blocks as i64;
+    if blocks_available < 0 {
+        return Err(FilesystemError::NotEnoughStorageSpace);
+    }
+    // divide the number of blocks available by 8 to get size of the data bitmap
+    let data_bitmap_blocks = (blocks_available as u64 + 7) / 8;
+    // divide the data bitmap size by the block size to get the number of blocks needed for the data bitmap
+    let data_bitmap_blocks = (data_bitmap_blocks + (block_size as u64 - 1)) / block_size as u64;
+    // subtract the number of blocks needed for the data bitmap from the blocks available
+    blocks_available -= data_bitmap_blocks as i64;
+    if blocks_available < 0 {
+        return Err(FilesystemError::NotEnoughStorageSpace);
+    }
+
+    // layout of disk is roughly
+    // superblock
+    // data block bitmap
+    // inode block bitmap
+    // inode blocks
+    // journal blocks
+    // data blocks
+    let sb_block = 1;
+    let data_bitmap_block = sb_block + 1;
+    let inode_bitmap_block = data_bitmap_block + data_bitmap_blocks;
+    let inode_blocks = inode_bitmap_block + inode_bitmap_blocks;
+    let journal_blocks = inode_blocks + inode_count;
+    let data_blocks = journal_blocks + journal_count.unwrap_or(128);
+
+    // create the superblock
+    let mut sb = Superblock {
+        magic: structs::MAGIC,
+        block_size,
+        first_data_block: data_blocks,
+        first_inode_block: inode_blocks,
+        first_journal_block: journal_blocks,
+        inode_count,
+        data_block_count: blocks_available as u64,
+        journal_block_count: journal_count.unwrap_or(128),
+        creation_time: current_time,
+        last_modification_time: current_time,
+        checksum: 0,
+        journal_position: 0,
+        reserved: [0; 7],
+    };
+
+    // calculate the checksum
+    sb.convert_native_to_big_endian();
+    sb.recalculate_checksum();
+    sb.convert_big_endian_to_native();
+
+    // create the first inode, which is the root directory
+    let root_perms = UNIXMode::ReadOwner as u16 | UNIXMode::WriteOwner as u16 |
+        UNIXMode::ExecuteOwner as u16 | UNIXMode::ReadGroup as u16 |
+        UNIXMode::ExecuteGroup as u16 | UNIXMode::Read as u16 | UNIXMode::Execute as u16 |
+        Filetype::Directory as u16;
+    let mut root_inode = Inode {
+        mode: root_perms,
+        link_count: 0,
+        uid: 0,
+        gid: 0,
+        size: 0,
+        block_count: 0,
+        creation_time: current_time,
+        last_access_time: current_time,
+        last_modification_time: current_time,
+        last_inode_modification_time: current_time,
+        deletion_time: 0,
+        flags: 0,
+        listblock: ListBlock {
+            count: 0,
+            direct_block_addresses: [0; 32],
+            single_indirect_block_address: [0; 32],
+            double_indirect_block_address: [0; 32],
+            triple_indirect_block_address: [0; 32],
+            quadruple_indirect_block_address: [0; 32],
+            quintuple_indirect_block_address: [0; 32],
+            sextuple_indirect_block_address: [0; 32],
+        },
+        checksum: 0,
+    };
+
+    let root_data = Directory::new();
+    let root_bytes = root_data.to_bytes();
+    // how many blocks are needed to store the root directory
+    let root_block_count = (root_bytes.len() + (block_size as usize - 1)) / block_size as usize;
+    // if its over 32 blocks, return unexpected error
+    // (unless my b-tree implementation is awful, an empty directory should not take up 64KB)
+    if root_block_count > 32 {
+        return Err(FilesystemError::UnexpectedError);
+    }
+    let mut left = root_block_count;
+    let mut buffer = vec![0; block_size as usize];
+    let mut blocki = 0;
+    let mut bufi = 0;
+    let mut datai = 0;
+    while left > 0 {
+        buffer.clear();
+        while bufi < block_size && datai < root_bytes.len() {
+            buffer.push(root_bytes[datai]);
+            bufi += 1;
+            datai += 1;
+        }
+        unsafe { write_datablock(blocki, &sb, bd, &buffer) };
+        blocki += 1;
+        bufi = 0;
+        left -= 1;
+    }
+    root_inode.size = root_bytes.len() as u64;
+    root_inode.block_count = root_block_count as u64;
+    for i in 0..root_block_count {
+        root_inode.listblock.direct_block_addresses[i] = i as u64;
+    }
+    root_inode.listblock.count = root_block_count as u64;
+
+    // recalculate the inode checksum
+    root_inode.convert_native_to_big_endian();
+    root_inode.recalculate_checksum();
+    root_inode.convert_big_endian_to_native();
+
+    // write the root inode to the first inode block
+    unsafe {
+        write_inode(0, &sb, bd, root_inode);
+    }
+
+    // create the inode bitmap
+    let mut inode_bitmap = vec![0u8; inode_bitmap_size as usize];
+    // set the first bit to 1, as the root inode is allocated
+    inode_bitmap[0] |= 1;
+    // write the inode bitmap to the inode bitmap block
+    bd.seek(inode_bitmap_block * block_size as u64);
+    bd.write_blocks(&inode_bitmap);
+
+    // create the data bitmap
+    let mut data_bitmap = vec![0u8; data_bitmap_blocks as usize];
+    for i in 0..root_block_count {
+        bitmap::set_bit(&mut data_bitmap, i, true);
+    }
+    // write the data bitmap to the data bitmap block
+    bd.seek(data_bitmap_block * block_size as u64);
+    bd.write_blocks(&data_bitmap);
+
+    // zero out the journal blocks
+    for i in 0..journal_blocks {
+        unsafe {
+            write_journal_entry(i, &sb, bd, JournalEntry {
+                operation: 0,
+                zeroed_content_crc32: 0,
+                content: JournalEntryContents {
+                    block_write: JournalBlockWrite {
+                        flags: 0,
+                        target_type: 0,
+                        target_inode: 0,
+                        target_block: 0,
+                        real_target_block: 0,
+                        source_block: 0,
+                        source_block_crc32: 0,
+                    },
+                },
+            });
+        }
+    }
+
+    // write the superblock to the superblock block
+    unsafe {
+        write_superblock(sb, bd);
+    }
+
+    Ok(())
+}

src/structs.rs

@@ -7,7 +7,7 @@ pub const MAGIC: u64 = 0x766170554653;
 
 /// # Superblock
 /// The primary struct of a VapUFS filesystem, contains metadata about the filesystem.
-/// Located at byte offset 2048 of the block device.
+/// Located at block 1 of the block device.
 /// All values are big-endian unless otherwise specified.
 /// Directly after (i.e. the next block after) the Superblock are the free data blocks bitmap and the free inodes bitmap.
 /// Free data blocks bitmap is data_block_count / 8 bytes long (rounded up).
@@ -31,10 +31,6 @@ pub struct Superblock {
     pub data_block_count: Index,
     /// total count of blocks dedicated to journal
     pub journal_block_count: Index,
-    /// total count of inodes in use
-    pub allocated_inode_count: Index,
-    /// total count of data blocks in use
-    pub allocated_data_block_count: Index,
     /// timestamp of creation
     pub creation_time: Timestamp,
     /// timestamp of last modification
@@ -63,8 +59,6 @@ impl Superblock {
             self.inode_count = u64::from_be(self.inode_count);
             self.data_block_count = u64::from_be(self.data_block_count);
             self.journal_block_count = u64::from_be(self.journal_block_count);
-            self.allocated_inode_count = u64::from_be(self.allocated_inode_count);
-            self.allocated_data_block_count = u64::from_be(self.allocated_data_block_count);
             self.creation_time = u64::from_be(self.creation_time);
             self.last_modification_time = u64::from_be(self.last_modification_time);
             for i in 0..8 {
@@ -85,8 +79,6 @@ impl Superblock {
             self.inode_count = u64::to_be(self.inode_count);
             self.data_block_count = u64::to_be(self.data_block_count);
             self.journal_block_count = u64::to_be(self.journal_block_count);
-            self.allocated_inode_count = u64::to_be(self.allocated_inode_count);
-            self.allocated_data_block_count = u64::to_be(self.allocated_data_block_count);
             self.creation_time = u64::to_be(self.creation_time);
             self.last_modification_time = u64::to_be(self.last_modification_time);
             for i in 0..8 {
@@ -350,6 +342,12 @@ pub enum JournalOperation {
     SingleBlockWrite = 0,
     /// A multi-block write, described by a `JournalMultiblockWrite`
     MultiblockWrite = 1,
+    /// A file creation, described by a `JournalFileCreate`
+    FileCreate = 2,
+    /// A file deletion, described by a `JournalFileDelete`
+    FileDelete = 3,
+    /// A file truncation, described by a `JournalFileTruncate`
+    FileTruncate = 4,
 }
 
 /// # JournalBlockWrite