feat: add FuseFs

crates/core/Cargo.toml

@@ -39,6 +39,7 @@ default = []
 cli = ["merge", "clap"]
 merge = ["dep:merge"]
 clap = ["dep:clap"]
+fuse = ["dep:fuse_mt"]
 webdav = ["dep:dav-server", "dep:futures"]
 
 [package.metadata.docs.rs]
@@ -97,6 +98,7 @@ merge = { version = "0.1.0", optional = true }
 
 # vfs support
 dav-server = { version = "0.5.8", default-features = false, optional = true }
+fuse_mt = { version = "0.6", optional = true }
 futures = { version = "0.3", optional = true }
 runtime-format = "0.1.3"
 

crates/core/src/vfs.rs

@@ -1,4 +1,6 @@
 mod format;
+#[cfg(feature = "fuse")]
+mod fusefs;
 #[cfg(feature = "webdav")]
 mod webdavfs;
 
@@ -12,6 +14,8 @@ use bytes::{Bytes, BytesMut};
 use runtime_format::FormatArgs;
 use strum::EnumString;
 
+#[cfg(feature = "fuse")]
+pub use crate::vfs::fusefs::FuseFS;
 #[cfg(feature = "webdav")]
 /// A struct which enables `WebDAV` access to a [`Vfs`] using [`dav-server`]
 pub use crate::vfs::webdavfs::WebDavFS;
@@ -390,6 +394,11 @@ impl Vfs {
         Ok(result)
     }
 
+    #[cfg(feature = "fuse")]
+    pub fn into_fuse_fs<P, S: IndexedFull>(self, repo: Repository<P, S>) -> FuseFS<P, S> {
+        FuseFS::new(repo, self)
+    }
+
     #[cfg(feature = "webdav")]
     /// Turn the [`Vfs`] into a [`WebDavFS`]
     ///

crates/core/src/vfs/fusefs.rs

@@ -0,0 +1,239 @@
+use super::Vfs;
+
+#[cfg(not(windows))]
+use std::os::unix::prelude::OsStrExt;
+use std::{
+    collections::BTreeMap,
+    ffi::{CString, OsStr},
+    path::Path,
+    sync::RwLock,
+    time::{Duration, SystemTime},
+};
+
+use crate::{
+    repofile::{Node, NodeType},
+    IndexedFull, Repository,
+};
+
+use fuse_mt::{
+    CallbackResult, DirectoryEntry, FileAttr, FileType, FilesystemMT, RequestInfo, ResultData,
+    ResultEmpty, ResultEntry, ResultOpen, ResultReaddir, ResultSlice, ResultXattr, Xattr,
+};
+use itertools::Itertools;
+use nix::libc;
+
+use super::OpenFile;
+
+pub struct FuseFS<P, S> {
+    repo: Repository<P, S>,
+    vfs: Vfs,
+    open_files: RwLock<BTreeMap<u64, OpenFile>>,
+    now: SystemTime,
+}
+
+impl<P, S: IndexedFull> FuseFS<P, S> {
+    pub(crate) fn new(repo: Repository<P, S>, vfs: Vfs) -> Self {
+        let open_files = RwLock::new(BTreeMap::new());
+
+        Self {
+            repo,
+            vfs,
+            open_files,
+            now: SystemTime::now(),
+        }
+    }
+
+    fn node_from_path(&self, path: &Path) -> Result<Node, i32> {
+        self.vfs
+            .node_from_path(&self.repo, path)
+            .map_err(|_| libc::ENOENT)
+    }
+
+    fn dir_entries_from_path(&self, path: &Path) -> Result<Vec<Node>, i32> {
+        self.vfs
+            .dir_entries_from_path(&self.repo, path)
+            .map_err(|_| libc::ENOENT)
+    }
+}
+
+fn node_to_filetype(node: &Node) -> FileType {
+    match node.node_type {
+        NodeType::File => FileType::RegularFile,
+        NodeType::Dir => FileType::Directory,
+        NodeType::Symlink { .. } => FileType::Symlink,
+        NodeType::Chardev { .. } => FileType::CharDevice,
+        NodeType::Dev { .. } => FileType::BlockDevice,
+        NodeType::Fifo => FileType::NamedPipe,
+        NodeType::Socket => FileType::Socket,
+    }
+}
+
+fn node_type_to_rdev(tpe: &NodeType) -> u32 {
+    u32::try_from(match tpe {
+        NodeType::Dev { device } | NodeType::Chardev { device } => *device,
+        _ => 0,
+    })
+    .unwrap()
+}
+
+fn node_to_linktarget(node: &Node) -> Option<&OsStr> {
+    if node.is_symlink() {
+        Some(node.node_type.to_link().as_os_str())
+    } else {
+        None
+    }
+}
+
+fn node_to_file_attr(node: &Node, now: SystemTime) -> FileAttr {
+    FileAttr {
+        /// Size in bytes
+        size: node.meta.size,
+        /// Size in blocks
+        blocks: 0,
+        // Time of last access
+        atime: node.meta.atime.map(SystemTime::from).unwrap_or(now),
+        /// Time of last modification
+        mtime: node.meta.mtime.map(SystemTime::from).unwrap_or(now),
+        /// Time of last metadata change
+        ctime: node.meta.ctime.map(SystemTime::from).unwrap_or(now),
+        /// Time of creation (macOS only)
+        crtime: now,
+        /// Kind of file (directory, file, pipe, etc.)
+        kind: node_to_filetype(node),
+        /// Permissions
+        perm: node.meta.mode.unwrap_or(0o755) as u16,
+        /// Number of hard links
+        nlink: node.meta.links.try_into().unwrap_or(1),
+        /// User ID
+        uid: node.meta.uid.unwrap_or(0),
+        /// Group ID
+        gid: node.meta.gid.unwrap_or(0),
+        /// Device ID (if special file)
+        rdev: node_type_to_rdev(&node.node_type),
+        /// Flags (macOS only; see chflags(2))
+        flags: 0,
+    }
+}
+
+impl<P, S: IndexedFull> FilesystemMT for FuseFS<P, S> {
+    fn getattr(&self, _req: RequestInfo, path: &Path, _fh: Option<u64>) -> ResultEntry {
+        let node = self.node_from_path(path)?;
+        Ok((Duration::from_secs(1), node_to_file_attr(&node, self.now)))
+    }
+
+    #[cfg(not(windows))]
+    fn readlink(&self, _req: RequestInfo, path: &Path) -> ResultData {
+        let target = node_to_linktarget(&self.node_from_path(path)?)
+            .ok_or(libc::ENOSYS)?
+            .as_bytes()
+            .to_vec();
+
+        Ok(target)
+    }
+
+    fn open(&self, _req: RequestInfo, path: &Path, _flags: u32) -> ResultOpen {
+        let node = self.node_from_path(path)?;
+        let open = self.repo.open_file(&node).map_err(|_| libc::ENOSYS)?;
+        let fh = {
+            let mut open_files = self.open_files.write().unwrap();
+            let fh = open_files
+                .last_key_value()
+                .map(|(fh, _)| *fh + 1)
+                .unwrap_or(0);
+            _ = open_files.insert(fh, open);
+            fh
+        };
+        Ok((fh, 0))
+    }
+
+    fn release(
+        &self,
+        _req: RequestInfo,
+        _path: &Path,
+        fh: u64,
+        _flags: u32,
+        _lock_owner: u64,
+        _flush: bool,
+    ) -> ResultEmpty {
+        _ = self.open_files.write().unwrap().remove(&fh);
+        Ok(())
+    }
+
+    fn read(
+        &self,
+        _req: RequestInfo,
+        _path: &Path,
+        fh: u64,
+        offset: u64,
+        size: u32,
+
+        callback: impl FnOnce(ResultSlice<'_>) -> CallbackResult,
+    ) -> CallbackResult {
+        if let Some(open_file) = self.open_files.read().unwrap().get(&fh) {
+            if let Ok(data) =
+                self.repo
+                    .read_file_at(open_file, offset.try_into().unwrap(), size as usize)
+            {
+                return callback(Ok(&data));
+            }
+        }
+        callback(Err(libc::ENOSYS))
+    }
+
+    fn opendir(&self, _req: RequestInfo, _path: &Path, _flags: u32) -> ResultOpen {
+        Ok((0, 0))
+    }
+
+    fn readdir(&self, _req: RequestInfo, path: &Path, _fh: u64) -> ResultReaddir {
+        let nodes = self.dir_entries_from_path(path)?;
+
+        let result = nodes
+            .into_iter()
+            .map(|node| DirectoryEntry {
+                name: node.name(),
+                kind: node_to_filetype(&node),
+            })
+            .collect();
+        Ok(result)
+    }
+
+    fn releasedir(&self, _req: RequestInfo, _path: &Path, _fh: u64, _flags: u32) -> ResultEmpty {
+        Ok(())
+    }
+
+    fn listxattr(&self, _req: RequestInfo, path: &Path, size: u32) -> ResultXattr {
+        let node = self.node_from_path(path)?;
+        let xattrs = node
+            .meta
+            .extended_attributes
+            .into_iter()
+            // convert into null-terminated [u8]
+            .map(|a| CString::new(a.name).unwrap().into_bytes_with_nul())
+            .concat();
+
+        if size == 0 {
+            Ok(Xattr::Size(u32::try_from(xattrs.len()).unwrap()))
+        } else {
+            Ok(Xattr::Data(xattrs))
+        }
+    }
+
+    fn getxattr(&self, _req: RequestInfo, path: &Path, name: &OsStr, size: u32) -> ResultXattr {
+        let node = self.node_from_path(path)?;
+        match node
+            .meta
+            .extended_attributes
+            .into_iter()
+            .find(|a| name == OsStr::new(&a.name))
+        {
+            None => Err(libc::ENOSYS),
+            Some(attr) => {
+                if size == 0 {
+                    Ok(Xattr::Size(u32::try_from(attr.value.len()).unwrap()))
+                } else {
+                    Ok(Xattr::Data(attr.value))
+                }
+            }
+        }
+    }
+}