file dropping fix

src/lib.rs

@@ -69,26 +69,32 @@ pub fn run() -> Result<(), Error> {
     let pipes = create_pipes(pipes)?;
 
     // spawn all processes
-    let spawner = Spawner {
+    Spawner {
         spec: &spec,
-        pipes: &pipes,
+        pipes,
         binary,
         trailing: &trailing,
-    };
-
-    spawner.spawn()?;
-
-    // TODO: Fix this dirty hack to prevent files dropping (and closing)
-    // switch to Option<File> and use a mut ref to take, then call
-    // IntoRawFd if used
-    std::thread::sleep(std::time::Duration::from_secs(10));
-
-    Ok(())
+    }
+    .spawn()
 }
 
 pub struct PipePair {
-    read: File,
-    write: File,
+    read: Option<File>,
+    write: Option<File>,
+}
+
+impl PipePair {
+    fn take_read(&mut self) -> File {
+        self.read
+            .take()
+            .expect("read pipes should only be used once")
+    }
+
+    fn take_write(&mut self) -> File {
+        self.write
+            .take()
+            .expect("write pipes should only be used once")
+    }
 }
 
 fn create_pipes(names: Vec<&str>) -> Result<HashMap<String, PipePair>, Error> {
@@ -106,8 +112,8 @@ fn create_pipes(names: Vec<&str>) -> Result<HashMap<String, PipePair>, Error> {
         pipes.insert(
             pipe.to_string(),
             PipePair {
-                read: unsafe { File::from_raw_fd(read) },
-                write: unsafe { File::from_raw_fd(write) },
+                read: Some(unsafe { File::from_raw_fd(read) }),
+                write: Some(unsafe { File::from_raw_fd(write) }),
             },
         );
     }

src/spawner.rs

@@ -9,7 +9,7 @@ use std::collections::HashMap;
 use std::ffi::CString;
 use std::fs::File;
 use std::io::Read;
-use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::io::AsRawFd;
 
 use close_fds::CloseFdsBuilder;
 use nix::unistd::{self, Pid};
@@ -18,13 +18,13 @@ const BUFFER_SIZE: usize = 1024;
 
 pub struct Spawner<'a> {
     pub spec: &'a Specification,
-    pub pipes: &'a HashMap<String, PipePair>,
+    pub pipes: HashMap<String, PipePair>,
     pub binary: &'a str,
     pub trailing: &'a Vec<&'a str>,
 }
 
 impl<'a> Spawner<'a> {
-    pub fn spawn(&self) -> Result<(), Error> {
+    pub fn spawn(&mut self) -> Result<(), Error> {
         for (name, entrypoint) in &self.spec.entrypoints {
             info!("spawning entrypoint `{}`", name.as_str());
 
@@ -50,16 +50,14 @@ impl<'a> Spawner<'a> {
                 }
 
                 Trigger::Pipe(s) => {
-                    // TODO: Consider typing the pipes so CLONE_FILES is only when necessary
-                    if clone3(CloneArgs::new(CloneFlags::CLONE_FILES)).map_err(|e| Error::Nix {
+                    // take the pipe in the initiating thread so the File isn't dropped
+                    let pipe = self.pipes.get_mut(s).unwrap().take_read();
+
+                    if clone3(CloneArgs::new(CloneFlags::empty())).map_err(|e| Error::Nix {
                         msg: "clone3",
                         src: e,
                     })? == Pid::from_raw(0)
                     {
-                        // Rust's ownership is out of the window now we've cloned
-                        // Unsafely move to a new owned pipe
-                        let pipe = unsafe { File::from_raw_fd(self.pipes[s].read.as_raw_fd()) };
-
                         let mut closer = CloseFdsBuilder::new();
                         let keep = [pipe.as_raw_fd()];
                         closer.keep_fds(&keep);
@@ -103,7 +101,7 @@ impl<'a> Spawner<'a> {
             })? == Pid::from_raw(0)
             {
                 let pipe_trigger = std::str::from_utf8(&buf[0..read_bytes]).unwrap();
-                let args = self.prepare_args(name, &spec.args, Some(pipe_trigger));
+                let args = self.prepare_args_ref(name, &spec.args, Some(pipe_trigger));
 
                 unistd::execv(&CString::new(self.binary).unwrap(), &args).map_err(|e| {
                     Error::Nix {
@@ -116,7 +114,7 @@ impl<'a> Spawner<'a> {
     }
 
     fn prepare_args(
-        &self,
+        &mut self,
         entrypoint: &str,
         args: &[Arg],
         pipe_trigger: Option<&str>,
@@ -126,17 +124,22 @@ impl<'a> Spawner<'a> {
             match arg {
                 Arg::BinaryName => out.push(CString::new(self.binary).unwrap()),
                 Arg::Entrypoint => out.push(CString::new(entrypoint).unwrap()),
+
                 Arg::Pipe(p) => out.push(match p {
                     Pipe::Rx(s) => {
-                        CString::new(self.pipes[s].read.as_raw_fd().to_string()).unwrap()
+                        let pipe = self.pipes.get_mut(s).unwrap().take_read();
+                        CString::new(pipe.as_raw_fd().to_string()).unwrap()
                     }
                     Pipe::Tx(s) => {
-                        CString::new(self.pipes[s].write.as_raw_fd().to_string()).unwrap()
+                        let pipe = self.pipes.get_mut(s).unwrap().take_write();
+                        CString::new(pipe.as_raw_fd().to_string()).unwrap()
                     }
                 }),
+
                 Arg::PipeTrigger => {
                     out.push(CString::new(pipe_trigger.as_ref().unwrap().to_string()).unwrap())
                 }
+
                 Arg::TcpListener { port: _port } => unimplemented!(),
 
                 Arg::Trailing => {
@@ -144,6 +147,37 @@ impl<'a> Spawner<'a> {
                 }
             }
         }
+
+        out
+    }
+
+    fn prepare_args_ref(
+        &self,
+        entrypoint: &str,
+        args: &[Arg],
+        pipe_trigger: Option<&str>,
+    ) -> Vec<CString> {
+        let mut out = Vec::new();
+
+        for arg in args {
+            match arg {
+                Arg::BinaryName => out.push(CString::new(self.binary).unwrap()),
+                Arg::Entrypoint => out.push(CString::new(entrypoint).unwrap()),
+
+                Arg::Pipe(_) => panic!("can't use pipes with an immutable reference"),
+
+                Arg::PipeTrigger => {
+                    out.push(CString::new(pipe_trigger.as_ref().unwrap().to_string()).unwrap())
+                }
+
+                Arg::TcpListener { port: _port } => unimplemented!(),
+
+                Arg::Trailing => {
+                    out.extend(self.trailing.iter().map(|s| CString::new(*s).unwrap()))
+                }
+            }
+        }
+
         out
     }