implemented FUSE lookup function

Cargo.lock

@@ -41,6 +41,15 @@ version = "3.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
 
+[[package]]
+name = "castaway"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dec551ab6e7578819132c713a93c022a05d60159dc86e7a7050223577484c55a"
+dependencies = [
+ "rustversion",
+]
+
 [[package]]
 name = "cc"
 version = "1.2.30"
@@ -74,6 +83,20 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "compact_str"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fdb1325a1cece981e8a296ab8f0f9b63ae357bd0784a9faaf548cc7b480707a"
+dependencies = [
+ "castaway",
+ "cfg-if",
+ "itoa",
+ "rustversion",
+ "ryu",
+ "static_assertions",
+]
+
 [[package]]
 name = "core-foundation-sys"
 version = "0.8.7"
@@ -99,6 +122,7 @@ dependencies = [
  "anyhow",
  "bitflags",
  "chrono",
+ "compact_str",
  "enum_dispatch",
  "static_assertions",
  "thiserror",
@@ -126,6 +150,10 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "fat-mount"
+version = "0.1.0"
+
 [[package]]
 name = "fuser"
 version = "0.15.1"
@@ -178,6 +206,12 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
+
 [[package]]
 name = "js-sys"
 version = "0.3.77"
@@ -297,6 +331,12 @@ version = "1.0.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a0d197bd2c9dc6e53b84da9556a69ba4cdfab8619eb41a8bd1cc2027a0f6b1d"
 
+[[package]]
+name = "ryu"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
+
 [[package]]
 name = "shlex"
 version = "1.3.0"

fat-bits/Cargo.toml

@@ -10,6 +10,7 @@ chrono = { version = "0.4.41", default-features = false, features = [
     "alloc",
     "std",
 ] }
+compact_str = "0.9.0"
 enum_dispatch = "0.3.13"
 static_assertions = "1.1.0"
 thiserror = "2.0.12"

fat-bits/src/dir.rs

@@ -3,6 +3,7 @@ use std::io::Read;
 
 use bitflags::bitflags;
 use chrono::{NaiveDate, NaiveDateTime, TimeDelta};
+use compact_str::CompactString;
 
 use crate::datetime::{Date, Time};
 use crate::utils::{load_u16_le, load_u32_le};
@@ -48,7 +49,7 @@ impl Display for Attr {
 /// represents an entry in a diectory
 #[derive(Debug)]
 pub struct DirEntry {
-    name: [u8; 11],
+    name: [u8; 13],
     attr: Attr,
 
     create_time_tenths: u8,
@@ -64,12 +65,13 @@ pub struct DirEntry {
 
     file_size: u32,
 
-    long_name: Option<String>,
+    checksum: u8,
+    long_name: Option<CompactString>,
 }
 
 impl Display for DirEntry {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let mut name = self.name_string().unwrap_or_else(|| "<unknown>".to_owned());
+        let mut name = self.name_string().unwrap_or_else(|| "<unknown>".into());
 
         if self.attr.contains(Attr::Directory) {
             name.push('/');
@@ -89,12 +91,63 @@ impl Display for DirEntry {
 }
 
 impl DirEntry {
+    fn load_name(bytes: [u8; 11], attr: &Attr) -> [u8; 13] {
+        let mut name = [0; 13];
+
+        let mut iter = name.iter_mut();
+
+        if attr.contains(Attr::Hidden) && !attr.contains(Attr::VolumeId) {
+            // hidden file or folder
+            *iter.next().unwrap() = b'.';
+        }
+
+        fn truncate_trailing_spaces(mut bytes: &[u8]) -> &[u8] {
+            while bytes.last() == Some(&0x20) {
+                bytes = &bytes[..bytes.len() - 1];
+            }
+
+            bytes
+        }
+
+        let stem_bytes = truncate_trailing_spaces(&bytes[..8]);
+        let ext_bytes = truncate_trailing_spaces(&bytes[8..]);
+
+        for &c in stem_bytes {
+            let c = match c {
+                // reject non-ascii
+                // TODO: implement code pages? probably not...
+                c if c >= 128 => b'?',
+                c => c,
+            };
+
+            *iter.next().unwrap() = c;
+        }
+
+        if !ext_bytes.is_empty() {
+            *iter.next().unwrap() = b'.';
+
+            for &c in ext_bytes {
+                let c = match c {
+                    // reject non-ascii
+                    // TODO: implement code pages? probably not...
+                    c if c >= 128 => b'?',
+                    c => c,
+                };
+
+                *iter.next().unwrap() = c;
+            }
+        }
+
+        name
+    }
+
     pub fn load(bytes: &[u8]) -> anyhow::Result<DirEntry> {
         assert_eq!(bytes.len(), 32);
 
-        let name = bytes[..11].try_into().unwrap();
         let attr = Attr::from_bits_truncate(bytes[11]);
 
+        let name = Self::load_name(bytes[..11].try_into().unwrap(), &attr);
+
         let create_time_tenths = bytes[13];
         anyhow::ensure!(
             create_time_tenths <= 199,
@@ -142,6 +195,7 @@ impl DirEntry {
             write_date,
             file_size,
             long_name: None,
+            checksum: Self::checksum(&bytes[..11]),
         })
     }
 
@@ -173,8 +227,6 @@ impl DirEntry {
             return false;
         }
 
-        // &self.name[..2] == &[b'.', b' ']
-
         self.name[0] == b'.' && &self.name[1..] == &[b' '; 10]
     }
 
@@ -183,8 +235,6 @@ impl DirEntry {
             return false;
         }
 
-        // &self.name[..3] == &[b'.', b'.', b' ']
-
         &self.name[..2] == &[b'.', b'.'] && &self.name[2..] == &[b' '; 9]
     }
 
@@ -216,15 +266,18 @@ impl DirEntry {
         std::str::from_utf8(self.extension()).ok()
     }
 
-    pub fn name_string(&self) -> Option<String> {
+    pub fn name_string(&self) -> Option<CompactString> {
+        // use a CompactString here to allow inlining of short names
+        // maybe switch to a Cow instead? has disadvantage that we need to alloc for short names
+
         if let Some(long_filename) = self.long_name() {
-            return Some(long_filename.to_owned());
+            return Some(long_filename.into());
         }
 
         let name = std::str::from_utf8(&self.name[..8]).ok()?.trim_ascii_end();
         let ext = std::str::from_utf8(&self.name[8..]).ok()?.trim_ascii_end();
 
-        let mut s = String::new();
+        let mut s = CompactString::const_new("");
 
         if self.attr.contains(Attr::Hidden) {
             s.push('.');
@@ -245,7 +298,7 @@ impl DirEntry {
         self.long_name.as_deref()
     }
 
-    pub fn set_long_name(&mut self, long_name: String) {
+    pub fn set_long_name(&mut self, long_name: CompactString) {
         self.long_name = Some(long_name);
     }
 
@@ -283,10 +336,10 @@ impl DirEntry {
         self.file_size
     }
 
-    pub fn checksum(&self) -> u8 {
+    pub fn checksum(name: &[u8]) -> u8 {
         let mut checksum: u8 = 0;
 
-        for &x in self.name() {
+        for &x in name {
             checksum = checksum.rotate_right(1).wrapping_add(x);
         }
 
@@ -482,9 +535,6 @@ impl LongFilenameBuf {
 pub struct DirIter<R: Read> {
     reader: R,
 
-    // long_filename_rev_buf: Vec<u16>,
-    // long_filename_checksum: Option<u8>,
-    // long_filename_last_ordinal: Option<u8>,
     long_filename_buf: LongFilenameBuf,
 }
 
@@ -492,9 +542,6 @@ impl<R: Read> DirIter<R> {
     pub fn new(reader: R) -> DirIter<R> {
         DirIter {
             reader,
-            // long_filename_rev_buf: Vec::new(),
-            // long_filename_checksum: None,
-            // long_filename_last_ordinal: None,
             long_filename_buf: Default::default(),
         }
     }
@@ -503,14 +550,10 @@ impl<R: Read> DirIter<R> {
     fn next_impl(&mut self) -> anyhow::Result<Option<DirEntry>> {
         let mut chunk = [0; 32];
         if self.reader.read_exact(&mut chunk).is_err() {
-            // reading failed; nothing we can do here
+            // nothing we can do here since we might be in an invalid state after a partial read
             return Ok(None);
         }
 
-        // let Ok(dir_entry) = DirEntry::load(&chunk) else {
-        //     return self.next();
-        // };
-
         let dir_entry = DirEntryWrapper::load(&chunk)
             .map_err(|e| anyhow::anyhow!("failed to load dir entry: {e}"))?;
 
@@ -534,25 +577,23 @@ impl<R: Read> DirIter<R> {
             return self.next_impl();
         }
 
-        match self
+        if let Some(iter) = self
             .long_filename_buf
-            .get_buf(dir_entry.checksum())
+            .get_buf(dir_entry.checksum)
             .map_err(|e| {
                 anyhow::anyhow!(
                     "failed to get long filename for {}: {}",
                     dir_entry.name_string().as_deref().unwrap_or("<invalid>"),
                     e
                 )
-            })? {
+            })?
-            Some(iter) => {
+        {
-                // attach long filename to dir_entry
+            // attach long filename to dir_entry
 
-                let long_filename: String =
+            let long_filename: CompactString =
-                    char::decode_utf16(iter).filter_map(|x| x.ok()).collect();
+                char::decode_utf16(iter).filter_map(|x| x.ok()).collect();
 
-                dir_entry.set_long_name(long_filename);
+            dir_entry.set_long_name(long_filename);
-            }
-            None => {} // no long filename -> do nothing
         }
 
         self.long_filename_buf.reset();
@@ -568,6 +609,7 @@ impl<R: Read> Iterator for DirIter<R> {
         match self.next_impl() {
             Ok(x) => x,
             Err(e) => {
+                // print error message, try next
                 eprintln!("{}", e);
 
                 self.next()

fat-dump/src/main.rs

@@ -2,7 +2,7 @@ use std::cell::RefCell;
 use std::rc::Rc;
 
 use fat_bits::FatFs;
-use fat_bits::dir::{DirEntry, DirIter};
+use fat_bits::dir::DirEntry;
 use fat_bits::fat::Fatty as _;
 
 pub fn main() -> anyhow::Result<()> {

fat-fuse/src/fuse.rs

@@ -1,11 +1,13 @@
 use std::ffi::c_int;
 use std::time::Duration;
 
+use fat_bits::dir::DirEntry;
 use fuser::Filesystem;
-use libc::{EIO, ENOENT, ENOSYS, ENOTDIR, EPERM};
+use libc::{EIO, ENOENT, ENOSYS, EPERM};
 use log::{debug, warn};
 
 use crate::FatFuse;
+use crate::inode::Inode;
 
 impl Filesystem for FatFuse {
     fn init(
@@ -28,35 +30,91 @@ impl Filesystem for FatFuse {
         // warn!("[Not Implemented] lookup(parent: {:#x?}, name {:?})", parent, name);
         // reply.error(ENOSYS);
 
-        let parent_inode = if let Some(inode) = self.get_inode(parent) {
+        let Some(name) = name.to_str() else {
-            inode
+            // TODO: add proper handling of non-utf8 strings
-        } else {
+            reply.error(ENOSYS);
+            return;
+        };
+
+        let Some(parent_inode) = self.get_inode(parent) else {
             // parent inode does not exist
-            // TODO: how can we make sure this does not exist?
+            // TODO: how can we make sure this does not happed?
-            // panic?
+            // TODO: panic?
             reply.error(EIO);
 
             return;
         };
 
-        let Ok(dir_iter) = parent_inode.dir_iter(&self.fat_fs) else {
+        // let Ok(mut dir_iter) = parent_inode.dir_iter(&self.fat_fs) else {
-            reply.error(ENOTDIR);
+        //     reply.error(ENOTDIR);
-            return;
+        //     return;
+        // };
+
+        // let Some(dir_entry) =
+        //     dir_iter.find(|dir_entry| dir_entry.name_string().as_deref() == Some(name))
+        // else {
+        //     reply.error(ENOENT);
+        //     return;
+        // };
+
+        let dir_entry: DirEntry = match parent_inode
+            .dir_iter(&self.fat_fs)
+            // .map_err(|_| ENOTDIR)
+            .and_then(|mut dir_iter| {
+                dir_iter
+                    .find(|dir_entry| dir_entry.name_string().as_deref() == Some(name))
+                    .ok_or(ENOENT)
+            }) {
+            Ok(dir_entry) => dir_entry,
+            Err(err) => {
+                reply.error(err);
+
+                return;
+            }
         };
 
-        let Some(dir_entry) =
+        let inode = match self.get_inode_by_first_cluster(dir_entry.first_cluster()) {
-            dir_iter.find(|dir_entry| dir_entry.name_str().as_deref() == Some(""))
+            Some(inode) => inode,
-        else {
+            None => {
-            reply.error(ENOENT);
+                // no inode found, make a new one
-            return;
+
+                let ino = self.next_ino();
+
+                let inode = Inode::new(&self.fat_fs, dir_entry, ino, self.uid, self.gid);
+
+                self.insert_inode(inode)
+            }
         };
 
-        reply.entry(&Duration::from_secs(1), attr, generation);
+        let attr = inode.file_attr();
+        let generation = inode.generation();
 
-        todo!();
+        reply.entry(&Duration::from_secs(1), &attr, generation as u64);
     }
 
-    fn forget(&mut self, _req: &fuser::Request<'_>, _ino: u64, _nlookup: u64) {}
+    fn forget(&mut self, _req: &fuser::Request<'_>, ino: u64, nlookup: u64) {
+        let Some(inode) = self.get_inode_mut(ino) else {
+            debug!("tried to forget {} refs of inode {}, but was not found", ino, nlookup);
+
+            return;
+        };
+
+        let ref_count = inode.ref_count_mut();
+
+        if *ref_count < nlookup {
+            debug!(
+                "tried to forget {} refs of inode {}, but ref_count is only {}",
+                nlookup, ino, *ref_count
+            );
+        }
+
+        *ref_count = ref_count.saturating_sub(nlookup);
+
+        if *ref_count == 0 {
+            // no more references, drop inode
+            self.drop_inode(ino);
+        }
+    }
 
     fn getattr(
         &mut self,

fat-fuse/src/inode.rs

@@ -3,8 +3,9 @@ use std::time::SystemTime;
 
 use chrono::{NaiveDateTime, NaiveTime};
 use fat_bits::FatFs;
-use fat_bits::dir::{DirEntry, DirIter};
+use fat_bits::dir::DirEntry;
 use fuser::FileAttr;
+use libc::ENOTDIR;
 use rand::{Rng, SeedableRng as _};
 
 thread_local! {
@@ -19,7 +20,10 @@ thread_local! {
 static RNG: LazyCell<RefCell<rand::rngs::SmallRng>> = LazyCell::new(|| RefCell::new(rand::rngs::SmallRng::from_os_rng()));
 }
 
-fn get_random_u32() -> u32 {
+fn get_random<T>() -> T
+where
+    rand::distr::StandardUniform: rand::distr::Distribution<T>,
+{
     // RNG.with(|x| unsafe {
     //     let rng = &mut (*x.get());
 
@@ -50,8 +54,12 @@ const ROOT_INO: u64 = 1;
 #[allow(dead_code)]
 pub struct Inode {
     ino: u64,
+    // FUSE uses a u64 for generation, but the Linux kernel only handles u32s anyway, truncating
+    // the high bits, so using more is pretty pointless and possibly even detrimental
     generation: u32,
 
+    ref_count: u64,
+
     size: u64,
     block_size: u32,
 
@@ -72,10 +80,21 @@ pub struct Inode {
 
 #[allow(dead_code)]
 impl Inode {
-    pub fn new(fat_fs: &FatFs, dir_entry: DirEntry, uid: u32, gid: u32) -> Inode {
+    fn new_generation() -> u32 {
+        let rand: u16 = get_random();
+
+        let secs = SystemTime::UNIX_EPOCH
+            .elapsed()
+            .map(|dur| dur.as_secs() as u16)
+            .unwrap_or(0);
+
+        ((secs as u32) << 16) | rand as u32
+    }
+
+    pub fn new(fat_fs: &FatFs, dir_entry: DirEntry, ino: u64, uid: u32, gid: u32) -> Inode {
         assert!(dir_entry.is_file() || dir_entry.is_dir());
 
-        let generation = get_random_u32();
+        let generation = Self::new_generation();
 
         let kind = if dir_entry.is_dir() {
             Kind::Dir
@@ -96,8 +115,9 @@ impl Inode {
         let crtime = datetime_to_system(dir_entry.create_time());
 
         Inode {
-            ino: dir_entry.first_cluster() as u64,
+            ino,
             generation,
+            ref_count: 0,
             size: dir_entry.file_size() as u64,
             block_size: fat_fs.bpb().bytes_per_sector() as u32,
             kind,
@@ -111,6 +131,26 @@ impl Inode {
         }
     }
 
+    pub fn ino(&self) -> u64 {
+        self.ino
+    }
+
+    pub fn generation(&self) -> u32 {
+        self.generation
+    }
+
+    pub fn ref_count(&self) -> u64 {
+        self.ref_count
+    }
+
+    pub fn ref_count_mut(&mut self) -> &mut u64 {
+        &mut self.ref_count
+    }
+
+    pub fn first_cluster(&self) -> u32 {
+        self.first_cluster
+    }
+
     pub fn file_attr(&self) -> FileAttr {
         let perm = if self.read_only { 0o555 } else { 0o777 };
 
@@ -133,11 +173,12 @@ impl Inode {
         }
     }
 
-    pub fn dir_iter(&self, fat_fs: &FatFs) -> anyhow::Result<impl Iterator<Item = DirEntry>> {
+    pub fn dir_iter(&self, fat_fs: &FatFs) -> Result<impl Iterator<Item = DirEntry>, i32> {
-        anyhow::ensure!(self.kind == Kind::Dir, "cannot dir_iter on a file");
+        // anyhow::ensure!(self.kind == Kind::Dir, "cannot dir_iter on a file");
 
-        // TODO: the boxing here is not particularly pretty, but neccessary, since the DirIter for
+        if self.kind != Kind::Dir {
-        // the root holds a
+            return Err(ENOTDIR);
+        }
 
         if self.ino == ROOT_INO {
             // root dir
@@ -145,9 +186,6 @@ impl Inode {
             return Ok(fat_fs.root_dir_iter());
         }
 
-        let chain_reader = fat_fs.chain_reader(self.first_cluster);
+        Ok(fat_fs.dir_iter(self.first_cluster))
-
-        // TODO: get rid of this Box if the boxing is removed from root_dir_iter
-        Ok(DirIter::new(Box::new(chain_reader)))
     }
 }

fat-fuse/src/lib.rs

@@ -6,6 +6,7 @@ use std::collections::BTreeMap;
 use std::rc::Rc;
 
 use fat_bits::{FatFs, SliceLike};
+use log::debug;
 
 use crate::inode::Inode;
 
@@ -16,9 +17,12 @@ pub struct FatFuse {
     uid: u32,
     gid: u32,
 
+    next_ino: u64,
     next_fd: u32,
 
     inode_table: BTreeMap<u64, Inode>,
+
+    ino_by_first_cluster: BTreeMap<u32, u64>,
 }
 
 impl FatFuse {
@@ -28,15 +32,105 @@ impl FatFuse {
 
         let fat_fs = FatFs::load(data)?;
 
+        // TODO: build and insert root dir inode
+
         Ok(FatFuse {
             fat_fs,
             uid,
             gid,
+            next_ino: 2, // 0 is reserved and 1 is root
             next_fd: 0,
             inode_table: BTreeMap::new(),
+            ino_by_first_cluster: BTreeMap::new(),
         })
     }
 
+    fn next_ino(&mut self) -> u64 {
+        let ino = self.next_ino;
+
+        assert!(!self.inode_table.contains_key(&ino));
+
+        self.next_ino += 1;
+
+        ino
+    }
+
+    fn insert_inode(&mut self, inode: Inode) -> &mut Inode {
+        let ino = inode.ino();
+        let generation = inode.generation();
+        let first_cluster = inode.first_cluster();
+
+        // let old_inode = self.inode_table.insert(ino, inode);
+
+        let entry = self.inode_table.entry(ino);
+
+        let (new_inode, old_inode): (&mut Inode, Option<Inode>) = match entry {
+            std::collections::btree_map::Entry::Vacant(vacant_entry) => {
+                let new_inode = vacant_entry.insert(inode);
+                (new_inode, None)
+            }
+            std::collections::btree_map::Entry::Occupied(occupied_entry) => {
+                let entry_ref = occupied_entry.into_mut();
+
+                let old_inode = std::mem::replace(entry_ref, inode);
+
+                (entry_ref, Some(old_inode))
+            }
+        };
+
+        let old_ino = self.ino_by_first_cluster.insert(first_cluster, ino);
+
+        debug!(
+            "inserted new inode with ino {} and generation {} (first cluster: {})",
+            ino, generation, first_cluster
+        );
+
+        if let Some(old_inode) = old_inode {
+            debug!("ejected inode {} {}", old_inode.ino(), old_inode.generation());
+        }
+
+        if let Some(old_ino) = old_ino {
+            debug!("ejected old {} -> {} cluster to ino mapping", first_cluster, old_ino);
+        }
+
+        new_inode
+    }
+
+    fn drop_inode(&mut self, ino: u64) {
+        let Some(inode) = self.inode_table.remove(&ino) else {
+            debug!("tried to drop inode with ino {}, but was not in table", ino);
+
+            return;
+        };
+
+        let first_cluster = inode.first_cluster();
+
+        let entry = self.ino_by_first_cluster.entry(first_cluster);
+
+        match entry {
+            std::collections::btree_map::Entry::Vacant(_) => debug!(
+                "removed inode with ino {} from table, but it's first cluster did not point to any ino",
+                ino
+            ),
+            std::collections::btree_map::Entry::Occupied(occupied_entry) => {
+                let found_ino = *occupied_entry.get();
+
+                if found_ino == ino {
+                    // matches our inode, remove it
+                    occupied_entry.remove();
+                } else {
+                    // does not match removed inode, leave it as is
+                    debug!(
+                        "removed inode with ino {} from table, but it's first cluster pointer to ino {} instead",
+                        ino, found_ino
+                    );
+                }
+            }
+        }
+
+        todo!()
+    }
+
     fn get_inode(&self, ino: u64) -> Option<&Inode> {
         self.inode_table.get(&ino)
     }
@@ -44,4 +138,34 @@ impl FatFuse {
     fn get_inode_mut(&mut self, ino: u64) -> Option<&mut Inode> {
         self.inode_table.get_mut(&ino)
     }
+
+    pub fn get_inode_by_first_cluster(&self, first_cluster: u32) -> Option<&Inode> {
+        let ino = self.ino_by_first_cluster.get(&first_cluster)?;
+
+        if let Some(inode) = self.inode_table.get(ino) {
+            Some(inode)
+        } else {
+            debug!(
+                "first cluster {} is mapped to ino {}, but inode is not in table",
+                first_cluster, ino
+            );
+
+            None
+        }
+    }
+
+    pub fn get_inode_by_first_cluster_mut(&mut self, first_cluster: u32) -> Option<&mut Inode> {
+        let ino = self.ino_by_first_cluster.get(&first_cluster)?;
+
+        if let Some(inode) = self.inode_table.get_mut(ino) {
+            Some(inode)
+        } else {
+            debug!(
+                "first cluster {} is mapped to ino {}, but inode is not in table",
+                first_cluster, ino
+            );
+
+            None
+        }
+    }
 }