Implement init hook

4 files changed, 99 insertions, 70 deletions

diff --git a/src/fuse/mod.rs b/src/fuse/mod.rs
index 5fe6f46..a4c9f06 100644
--- a/src/fuse/mod.rs
+++ b/src/fuse/mod.rs
@@ -14,7 +14,7 @@ pub mod session;
 mod private_trait {
     pub trait Operation<'o> {
         type RequestBody: crate::proto::Structured<'o>;
-        type ReplyTail: Default;
+        type ReplyTail;
     }
 }
 
diff --git a/src/fuse/ops.rs b/src/fuse/ops.rs
index 9bca233..60e5815 100644
--- a/src/fuse/ops.rs
+++ b/src/fuse/ops.rs
@@ -5,7 +5,11 @@ use std::{
     os::unix::ffi::OsStrExt,
 };
 
-use crate::{proto, util::OutputChain, Errno, Ino, TimeToLive};
+use crate::{
+    proto,
+    util::{page_size, OutputChain},
+    Errno, Ino, TimeToLive,
+};
 
 use super::{
     io::{AccessFlags, Entry, FsInfo, Interruptible, Known},
@@ -124,7 +128,7 @@ op! {
 op! {
     Open {
         type RequestBody = &'o proto::OpenIn;
-        type ReplyTail = private::OpenFlags;
+        type ReplyTail = state::OpenFlags;
     }
 
     impl Reply {
@@ -166,12 +170,42 @@ op! {
 op! {
     Init {
         type RequestBody = &'o proto::InitIn;
-        type ReplyTail = ();
+        type ReplyTail = state::Init;
     }
 
     impl Reply {
         pub fn ok(self) -> Done<'o> {
-            self.nop()
+            let state::Init { kernel_flags, buffer_pages } = self.tail;
+
+            let flags = {
+                use proto::InitFlags;
+
+                let supported = InitFlags::PARALLEL_DIROPS
+                    | InitFlags::ABORT_ERROR
+                    | InitFlags::MAX_PAGES
+                    | InitFlags::CACHE_SYMLINKS;
+
+                kernel_flags & supported
+            };
+
+            let buffer_size = page_size() * buffer_pages;
+
+            // See fs/fuse/dev.c in the kernel source tree for details about max_write
+            let max_write = buffer_size - std::mem::size_of::<(proto::InHeader, proto::WriteIn)>();
+
+            self.single(&proto::InitOut {
+                major: proto::MAJOR_VERSION,
+                minor: proto::TARGET_MINOR_VERSION,
+                max_readahead: 0, //TODO
+                flags: flags.bits(),
+                max_background: 0,       //TODO
+                congestion_threshold: 0, //TODO
+                max_write: max_write.try_into().unwrap(),
+                time_gran: 1, //TODO
+                max_pages: buffer_pages.try_into().unwrap(),
+                padding: Default::default(),
+                unused: Default::default(),
+            })
         }
     }
 }
@@ -255,9 +289,14 @@ op! {
     }
 }
 
-mod private {
+pub(crate) mod state {
     use crate::proto;
 
+    pub struct Init {
+        pub kernel_flags: proto::InitFlags,
+        pub buffer_pages: usize,
+    }
+
     #[derive(Copy, Clone)]
     pub struct OpenFlags(pub proto::OpenOutFlags);
 
@@ -269,10 +308,6 @@ mod private {
 }
 
 impl<'o, O: Operation<'o>> Reply<'o, O> {
-    fn nop(self) -> Done<'o> {
-        Done::done()
-    }
-
     fn empty(self) -> Done<'o> {
         self.chain(OutputChain::empty())
     }
diff --git a/src/fuse/session.rs b/src/fuse/session.rs
index 5045099..e947bef 100644
--- a/src/fuse/session.rs
+++ b/src/fuse/session.rs
@@ -1,5 +1,4 @@
 use std::{
-    convert::TryInto,
     future::Future,
     io,
     marker::PhantomData,
@@ -10,7 +9,7 @@ use std::{
 use nix::{
     fcntl::{fcntl, FcntlArg, OFlag},
     sys::uio::{writev, IoVec},
-    unistd::{read, sysconf, SysconfVar},
+    unistd::read,
 };
 
 use tokio::{
@@ -23,7 +22,7 @@ use smallvec::SmallVec;
 
 use crate::{
     proto::{self, InHeader, Structured},
-    util::{DumbFd, OutputChain},
+    util::{page_size, DumbFd, OutputChain},
     Errno, FuseError, FuseResult,
 };
 
@@ -104,12 +103,15 @@ impl Session {
         self.interrupt_tx.subscribe()
     }
 
-    async fn handshake(&mut self, buffer: &mut Buffer) -> FuseResult<Handshake> {
+    async fn handshake<F>(&mut self, buffer: &mut Buffer, init: F) -> FuseResult<Handshake<F>>
+    where
+        F: FnOnce(Op<'_, ops::Init>) -> Done<'_>,
+    {
         self.session_fd.readable().await?.retain_ready();
         let bytes = read(*self.session_fd.get_ref(), &mut buffer.0).map_err(io::Error::from)?;
 
         let (header, opcode) = InHeader::from_bytes(&buffer.0[..bytes])?;
-        let init = match opcode {
+        let body = match opcode {
             proto::Opcode::Init => <&proto::InitIn>::toplevel_from(&buffer.0[HEADER_END..bytes])?,
 
             _ => {
@@ -119,11 +121,11 @@ impl Session {
         };
 
         use std::cmp::Ordering;
-        let supported = match init.major.cmp(&proto::MAJOR_VERSION) {
+        let supported = match body.major.cmp(&proto::MAJOR_VERSION) {
             Ordering::Less => false,
 
             Ordering::Equal => {
-                self.proto_minor = init.minor;
+                self.proto_minor = body.minor;
                 self.proto_minor >= proto::REQUIRED_MINOR_VERSION
             }
 
@@ -131,7 +133,7 @@ impl Session {
                 let tail = [bytes_of(&proto::MAJOR_VERSION)];
                 self.ok(header.unique, OutputChain::tail(&tail))?;
 
-                return Ok(Handshake::Restart);
+                return Ok(Handshake::Restart(init));
             }
         };
 
@@ -141,8 +143,8 @@ impl Session {
                 "Unsupported protocol {}.{}; this build requires \
                  {major}.{}..={major}.{} (or a greater version \
                  through compatibility)",
-                init.major,
-                init.minor,
+                body.major,
+                body.minor,
                 proto::REQUIRED_MINOR_VERSION,
                 proto::TARGET_MINOR_VERSION,
                 major = proto::MAJOR_VERSION
@@ -152,40 +154,17 @@ impl Session {
             return Err(FuseError::ProtocolInit);
         }
 
-        let flags = {
-            use proto::InitFlags;
-
-            let kernel = InitFlags::from_bits_truncate(init.flags);
-            let supported = InitFlags::PARALLEL_DIROPS
-                | InitFlags::ABORT_ERROR
-                | InitFlags::MAX_PAGES
-                | InitFlags::CACHE_SYMLINKS;
-
-            kernel & supported
-        };
-
-        let buffer_size = page_size() * self.buffer_pages;
-
-        // See fs/fuse/dev.c in the kernel source tree for details about max_write
-        let max_write = buffer_size - std::mem::size_of::<(InHeader, proto::WriteIn)>();
-
-        let init_out = proto::InitOut {
-            major: proto::MAJOR_VERSION,
-            minor: proto::TARGET_MINOR_VERSION,
-            max_readahead: 0, //TODO
-            flags: flags.bits(),
-            max_background: 0,       //TODO
-            congestion_threshold: 0, //TODO
-            max_write: max_write.try_into().unwrap(),
-            time_gran: 1, //TODO
-            max_pages: self.buffer_pages.try_into().unwrap(),
-            padding: Default::default(),
-            unused: Default::default(),
+        let request = Request { header, body };
+        let reply = Reply {
+            session: self,
+            unique: header.unique,
+            tail: ops::state::Init {
+                kernel_flags: proto::InitFlags::from_bits_truncate(body.flags),
+                buffer_pages: self.buffer_pages,
+            },
         };
 
-        let tail = [bytes_of(&init_out)];
-        self.ok(header.unique, OutputChain::tail(&tail))?;
-
+        let _ = init((request, reply));
         Ok(Handshake::Done)
     }
 
@@ -270,7 +249,7 @@ impl Endpoint<'_> {
             }
         };
 
-        let (header, opcode) = proto::InHeader::from_bytes(&buffer[..bytes?])?;
+        let (header, opcode) = InHeader::from_bytes(&buffer[..bytes?])?;
         let common = IncomingCommon {
             session: self.session,
             buffer: &mut self.local_buffer,
@@ -317,7 +296,10 @@ impl Endpoint<'_> {
 }
 
 impl Start {
-    pub async fn start(self) -> FuseResult<Arc<Session>> {
+    pub async fn start<F>(self, mut init: F) -> FuseResult<Arc<Session>>
+    where
+        F: FnOnce(Op<'_, ops::Init>) -> Done<'_>,
+    {
         let session_fd = self.session_fd.into_raw_fd();
 
         let flags = OFlag::O_NONBLOCK | OFlag::O_LARGEFILE;
@@ -344,10 +326,13 @@ impl Start {
         let mut init_buffer = session.buffers.get_mut().unwrap().pop().unwrap();
 
         loop {
-            if let Handshake::Done = session.handshake(&mut init_buffer).await? {
-                session.buffers.get_mut().unwrap().push(init_buffer);
-                break Ok(Arc::new(session));
-            }
+            init = match session.handshake(&mut init_buffer, init).await? {
+                Handshake::Restart(init) => init,
+                Handshake::Done => {
+                    session.buffers.get_mut().unwrap().push(init_buffer);
+                    break Ok(Arc::new(session));
+                }
+            };
         }
     }
 
@@ -359,7 +344,10 @@ impl Start {
     }
 }
 
-impl<'o, O: Operation<'o>> Incoming<'o, O> {
+impl<'o, O: Operation<'o>> Incoming<'o, O>
+where
+    O::ReplyTail: Default,
+{
     pub fn op(self) -> Result<Op<'o, O>, Done<'o>> {
         try_op(
             self.common.session,
@@ -397,7 +385,10 @@ impl<O: for<'o> Operation<'o>> Incoming<'_, O> {
     }
 }
 
-impl<O: for<'o> Operation<'o>> Owned<O> {
+impl<O: for<'o> Operation<'o>> Owned<O>
+where
+    for<'o> <O as Operation<'o>>::ReplyTail: Default,
+{
     pub fn op(&self) -> Result<Op<'_, O>, Done<'_>> {
         try_op(&self.session, &self.buffer.0, self.header)
     }
@@ -419,12 +410,12 @@ const HEADER_END: usize = std::mem::size_of::<InHeader>();
 struct IncomingCommon<'o> {
     session: &'o Arc<Session>,
     buffer: &'o mut Buffer,
-    header: proto::InHeader,
+    header: InHeader,
 }
 
-enum Handshake {
+enum Handshake<F> {
     Done,
-    Restart,
+    Restart(F),
 }
 
 struct Buffer(Box<[u8]>);
@@ -455,8 +446,11 @@ impl Buffer {
 fn try_op<'o, O: Operation<'o>>(
     session: &'o Session,
     bytes: &'o [u8],
-    header: proto::InHeader,
-) -> Result<Op<'o, O>, Done<'o>> {
+    header: InHeader,
+) -> Result<Op<'o, O>, Done<'o>>
+where
+    O::ReplyTail: Default,
+{
     let body = match Structured::toplevel_from(&bytes[HEADER_END..header.len as usize]) {
         Ok(body) => body,
         Err(error) => {
@@ -480,7 +474,3 @@ fn try_op<'o, O: Operation<'o>>(
 
     Ok((request, reply))
 }
-
-fn page_size() -> usize {
-    sysconf(SysconfVar::PAGE_SIZE).unwrap().unwrap() as usize
-}
diff --git a/src/util.rs b/src/util.rs
index 2ad8c00..c21442f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -3,7 +3,7 @@ use std::{
     os::unix::io::{IntoRawFd, RawFd},
 };
 
-use nix::unistd::close;
+use nix::unistd::{close, sysconf, SysconfVar};
 use quick_error::quick_error;
 
 quick_error! {
@@ -98,3 +98,7 @@ pub fn display_or<'a, T: fmt::Display + 'a>(
 
     Params(maybe, default)
 }
+
+pub fn page_size() -> usize {
+    sysconf(SysconfVar::PAGE_SIZE).unwrap().unwrap() as usize
+}