From efd64d55e1c684279ea1d96fe0da2ee659280d66 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Wed, 19 Apr 2017 21:56:09 -0600
Subject: [PATCH] Bug fixes for fcntl and o_cloexec Add fcntl to schemes Fix
 debug: hang

---
 src/context/context.rs       |  2 +-
 src/context/file.rs          |  2 +-
 src/scheme/debug.rs          | 93 ++++++++++++++++++++++++++++++------
 src/scheme/env.rs            | 10 ++++
 src/scheme/event.rs          |  6 +++
 src/scheme/initfs.rs         | 13 ++++-
 src/scheme/irq.rs            |  4 ++
 src/scheme/live.rs           |  7 +++
 src/scheme/memory.rs         |  6 ++-
 src/scheme/null.rs           |  4 ++
 src/scheme/pipe.rs           |  2 +-
 src/scheme/sys/iostat.rs     |  2 +-
 src/scheme/sys/mod.rs        |  2 +
 src/scheme/sys/scheme.rs     |  2 +-
 src/scheme/sys/scheme_num.rs | 25 ++++++++++
 src/scheme/time.rs           |  4 ++
 src/scheme/zero.rs           |  4 ++
 src/syscall/fs.rs            | 49 +++++++++++++------
 src/syscall/process.rs       | 10 ++--
 19 files changed, 204 insertions(+), 43 deletions(-)
 create mode 100644 src/scheme/sys/scheme_num.rs

diff --git a/src/context/context.rs b/src/context/context.rs
index 51921216..b50773d4 100644
--- a/src/context/context.rs
+++ b/src/context/context.rs
@@ -239,7 +239,7 @@ impl Context {
     pub fn get_file(&self, i: FileHandle) -> Option<File> {
         let files = self.files.lock();
         if i.into() < files.len() {
-            files[i.into()]
+            files[i.into()].clone()
         } else {
             None
         }
diff --git a/src/context/file.rs b/src/context/file.rs
index e7519b63..4fea00fb 100644
--- a/src/context/file.rs
+++ b/src/context/file.rs
@@ -4,7 +4,7 @@ use scheme::SchemeId;
 
 /// A file
 //TODO: Close on exec
-#[derive(Copy, Clone, Debug)]
+#[derive(Clone, Debug)]
 pub struct File {
     /// The scheme that this file refers to
     pub scheme: SchemeId,
diff --git a/src/scheme/debug.rs b/src/scheme/debug.rs
index a699aa8a..23eb0490 100644
--- a/src/scheme/debug.rs
+++ b/src/scheme/debug.rs
@@ -5,7 +5,7 @@ use context;
 use device::serial::COM1;
 use scheme::*;
 use sync::WaitQueue;
-use syscall::flag::EVENT_READ;
+use syscall::flag::{EVENT_READ, F_GETFL, F_SETFL, O_ACCMODE, O_NONBLOCK};
 use syscall::scheme::Scheme;
 
 pub static DEBUG_SCHEME_ID: AtomicSchemeId = ATOMIC_SCHEMEID_INIT;
@@ -24,62 +24,127 @@ pub fn debug_input(b: u8) {
     context::event::trigger(DEBUG_SCHEME_ID.load(Ordering::SeqCst), 0, EVENT_READ, len);
 }
 
-pub struct DebugScheme;
+pub struct DebugScheme {
+    next_id: AtomicUsize,
+    handles: RwLock<BTreeMap<usize, usize>>
+}
 
 impl DebugScheme {
     pub fn new(scheme_id: SchemeId) -> DebugScheme {
         DEBUG_SCHEME_ID.store(scheme_id, Ordering::SeqCst);
-        DebugScheme
+        DebugScheme {
+            next_id: AtomicUsize::new(0),
+            handles: RwLock::new(BTreeMap::new())
+        }
     }
 }
 
 impl Scheme for DebugScheme {
-    fn open(&self, _path: &[u8], _flags: usize, _uid: u32, _gid: u32) -> Result<usize> {
-        Ok(0)
+    fn open(&self, _path: &[u8], flags: usize, _uid: u32, _gid: u32) -> Result<usize> {
+        let id = self.next_id.fetch_add(1, Ordering::SeqCst);
+        self.handles.write().insert(id, flags & ! O_ACCMODE);
+
+        Ok(id)
     }
 
-    fn dup(&self, _file: usize, _buf: &[u8]) -> Result<usize> {
-        Ok(0)
+    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+        let flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
+        let new_id = self.next_id.fetch_add(1, Ordering::SeqCst);
+        self.handles.write().insert(new_id, flags);
+
+        Ok(new_id)
     }
 
     /// Read the file `number` into the `buffer`
     ///
     /// Returns the number of bytes read
-    fn read(&self, _file: usize, buf: &mut [u8]) -> Result<usize> {
-        Ok(INPUT.call_once(init_input).receive_into(buf, true))
+    fn read(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
+        let flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
+        Ok(INPUT.call_once(init_input).receive_into(buf, flags & O_NONBLOCK != O_NONBLOCK))
     }
 
     /// Write the `buffer` to the `file`
     ///
     /// Returns the number of bytes written
-    fn write(&self, _file: usize, buffer: &[u8]) -> Result<usize> {
+    fn write(&self, id: usize, buffer: &[u8]) -> Result<usize> {
+        let _flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
         let mut com = COM1.lock();
         for &byte in buffer.iter() {
             com.send(byte);
         }
+
         Ok(buffer.len())
     }
 
-    fn fevent(&self, _file: usize, _flags: usize) -> Result<usize> {
+    fn fcntl(&self, id: usize, cmd: usize, arg: usize) -> Result<usize> {
+        let mut handles = self.handles.write();
+        if let Some(flags) = handles.get_mut(&id) {
+            match cmd {
+                F_GETFL => Ok(*flags),
+                F_SETFL => {
+                    *flags = arg & ! O_ACCMODE;
+                    Ok(0)
+                },
+                _ => Err(Error::new(EINVAL))
+            }
+        } else {
+            Err(Error::new(EBADF))
+        }
+    }
+
+    fn fevent(&self, id: usize, _flags: usize) -> Result<usize> {
+        let _flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
         Ok(0)
     }
 
-    fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
+    fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
+        let _flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
         let mut i = 0;
         let scheme_path = b"debug:";
         while i < buf.len() && i < scheme_path.len() {
             buf[i] = scheme_path[i];
             i += 1;
         }
+
         Ok(i)
     }
 
-    fn fsync(&self, _file: usize) -> Result<usize> {
+    fn fsync(&self, id: usize) -> Result<usize> {
+        let _flags = {
+            let handles = self.handles.read();
+            *handles.get(&id).ok_or(Error::new(EBADF))?
+        };
+
         Ok(0)
     }
 
     /// Close the file `number`
-    fn close(&self, _file: usize) -> Result<usize> {
+    fn close(&self, id: usize) -> Result<usize> {
+        let _flags = {
+            let mut handles = self.handles.write();
+            handles.remove(&id).ok_or(Error::new(EBADF))?
+        };
+
         Ok(0)
     }
 }
diff --git a/src/scheme/env.rs b/src/scheme/env.rs
index 2e03be28..d4a2973a 100644
--- a/src/scheme/env.rs
+++ b/src/scheme/env.rs
@@ -154,7 +154,17 @@ impl Scheme for EnvScheme {
         Ok(handle.seek)
     }
 
+    fn fcntl(&self, id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        let handles = self.handles.read();
+        let _handle = handles.get(&id).ok_or(Error::new(EBADF))?;
+
+        Ok(0)
+    }
+
     fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
+        let handles = self.handles.read();
+        let _handle = handles.get(&id).ok_or(Error::new(EBADF))?;
+
         let mut i = 0;
         //TODO: Get env name
         let scheme_path = b"env:";
diff --git a/src/scheme/event.rs b/src/scheme/event.rs
index 861a0d4e..f68c2a3d 100644
--- a/src/scheme/event.rs
+++ b/src/scheme/event.rs
@@ -62,6 +62,12 @@ impl Scheme for EventScheme {
         Ok(handle.receive_into(event_buf, true) * mem::size_of::<Event>())
     }
 
+    fn fcntl(&self, id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        let handles = self.handles.read();
+        let handle_weak = handles.get(&id).ok_or(Error::new(EBADF))?;
+        handle_weak.upgrade().ok_or(Error::new(EBADF)).and(Ok(0))
+    }
+
     fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
         let mut i = 0;
         let scheme_path = b"event:";
diff --git a/src/scheme/initfs.rs b/src/scheme/initfs.rs
index 827b0f99..7c099aaf 100644
--- a/src/scheme/initfs.rs
+++ b/src/scheme/initfs.rs
@@ -5,7 +5,7 @@ use spin::RwLock;
 
 use syscall::data::Stat;
 use syscall::error::*;
-use syscall::flag::{O_CLOEXEC, MODE_DIR, MODE_FILE, SEEK_SET, SEEK_CUR, SEEK_END};
+use syscall::flag::{MODE_DIR, MODE_FILE, SEEK_SET, SEEK_CUR, SEEK_END};
 use syscall::scheme::Scheme;
 
 #[cfg(test)]
@@ -112,6 +112,13 @@ impl Scheme for InitFsScheme {
         Ok(handle.seek)
     }
 
+    fn fcntl(&self, id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        let handles = self.handles.read();
+        let _handle = handles.get(&id).ok_or(Error::new(EBADF))?;
+
+        Ok(0)
+    }
+
     fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
         let handles = self.handles.read();
         let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
@@ -146,7 +153,9 @@ impl Scheme for InitFsScheme {
         Ok(0)
     }
 
-    fn fsync(&self, _id: usize) -> Result<usize> {
+    fn fsync(&self, id: usize) -> Result<usize> {
+        let handles = self.handles.read();
+        let _handle = handles.get(&id).ok_or(Error::new(EBADF))?;
         Ok(0)
     }
 
diff --git a/src/scheme/irq.rs b/src/scheme/irq.rs
index a65367a4..a5c0333c 100644
--- a/src/scheme/irq.rs
+++ b/src/scheme/irq.rs
@@ -87,6 +87,10 @@ impl Scheme for IrqScheme {
         }
     }
 
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
     fn fevent(&self, file: usize, _flags: usize) -> Result<usize> {
         Ok(file)
     }
diff --git a/src/scheme/live.rs b/src/scheme/live.rs
index c3f77ff2..e027564a 100644
--- a/src/scheme/live.rs
+++ b/src/scheme/live.rs
@@ -112,6 +112,13 @@ impl Scheme for DiskScheme {
         Ok(handle.seek)
     }
 
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        let handles = self.handles.read();
+        let _handle = handles.get(&id).ok_or(Error::new(EBADF))?;
+
+        Ok(0)
+    }
+
     fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
         let handles = self.handles.read();
         let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/memory.rs b/src/scheme/memory.rs
index 0934b10e..6d525c56 100644
--- a/src/scheme/memory.rs
+++ b/src/scheme/memory.rs
@@ -23,7 +23,11 @@ impl Scheme for MemoryScheme {
         Ok(0)
     }
 
-    fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
+    fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
         let mut i = 0;
         let scheme_path = b"memory:";
         while i < buf.len() && i < scheme_path.len() {
diff --git a/src/scheme/null.rs b/src/scheme/null.rs
index c33377e8..81b64549 100644
--- a/src/scheme/null.rs
+++ b/src/scheme/null.rs
@@ -26,6 +26,10 @@ impl Scheme for NullScheme {
         Ok(buffer.len())
     }
 
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
     fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
         let mut i = 0;
         let scheme_path = b"null:";
diff --git a/src/scheme/pipe.rs b/src/scheme/pipe.rs
index 7de8636b..802b748d 100644
--- a/src/scheme/pipe.rs
+++ b/src/scheme/pipe.rs
@@ -112,7 +112,7 @@ impl Scheme for PipeScheme {
         Err(Error::new(EBADF))
     }
 
-    fn fpath(&self, id: usize, buf: &mut [u8]) -> Result<usize> {
+    fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
         let mut i = 0;
         let scheme_path = b"pipe:";
         while i < buf.len() && i < scheme_path.len() {
diff --git a/src/scheme/sys/iostat.rs b/src/scheme/sys/iostat.rs
index 9bb34e6c..1f2610b1 100644
--- a/src/scheme/sys/iostat.rs
+++ b/src/scheme/sys/iostat.rs
@@ -28,7 +28,7 @@ pub fn resource() -> Result<Vec<u8>> {
             for (fd, f) in row.2.iter().enumerate() {
                 let file = match *f {
                     None => continue,
-                    Some(file) => file
+                    Some(ref file) => file.clone()
                 };
 
                 let scheme = {
diff --git a/src/scheme/sys/mod.rs b/src/scheme/sys/mod.rs
index ed09117d..39b8953d 100644
--- a/src/scheme/sys/mod.rs
+++ b/src/scheme/sys/mod.rs
@@ -14,6 +14,7 @@ mod cpu;
 mod exe;
 mod iostat;
 mod scheme;
+mod scheme_num;
 //mod interrupt;
 //mod log;
 //mod test;
@@ -43,6 +44,7 @@ impl SysScheme {
         files.insert(b"exe", Box::new(move || exe::resource()));
         files.insert(b"iostat", Box::new(move || iostat::resource()));
         files.insert(b"scheme", Box::new(move || scheme::resource()));
+        files.insert(b"scheme_num", Box::new(move || scheme_num::resource()));
         //files.insert(b"interrupt", Box::new(move || interrupt::resource()));
         //files.insert(b"log", Box::new(move || log::resource()));
         //files.insert(b"test", Box::new(move || test::resource()));
diff --git a/src/scheme/sys/scheme.rs b/src/scheme/sys/scheme.rs
index b0f0c7d0..92f68833 100644
--- a/src/scheme/sys/scheme.rs
+++ b/src/scheme/sys/scheme.rs
@@ -15,7 +15,7 @@ pub fn resource() -> Result<Vec<u8>> {
     let mut data = Vec::new();
 
     let schemes = scheme::schemes();
-    for (name, _scheme_lock) in schemes.iter_name(scheme_ns) {
+    for (name, _scheme_id) in schemes.iter_name(scheme_ns) {
         data.extend_from_slice(name);
         data.push(b'\n');
     }
diff --git a/src/scheme/sys/scheme_num.rs b/src/scheme/sys/scheme_num.rs
new file mode 100644
index 00000000..e3ae184b
--- /dev/null
+++ b/src/scheme/sys/scheme_num.rs
@@ -0,0 +1,25 @@
+use collections::Vec;
+
+use context;
+use scheme;
+use syscall::error::{Error, ESRCH, Result};
+
+pub fn resource() -> Result<Vec<u8>> {
+    let scheme_ns = {
+        let contexts = context::contexts();
+        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+        let context = context_lock.read();
+        context.ens
+    };
+
+    let mut data = Vec::new();
+
+    let schemes = scheme::schemes();
+    for (name, &scheme_id) in schemes.iter_name(scheme_ns) {
+        data.extend_from_slice(format!("{:>4}: ", scheme_id.into()).as_bytes());
+        data.extend_from_slice(name);
+        data.push(b'\n');
+    }
+
+    Ok(data)
+}
diff --git a/src/scheme/time.rs b/src/scheme/time.rs
index 0ff04952..faef3608 100644
--- a/src/scheme/time.rs
+++ b/src/scheme/time.rs
@@ -97,6 +97,10 @@ impl Scheme for TimeScheme {
         Ok(i * mem::size_of::<TimeSpec>())
     }
 
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
     fn fevent(&self, id: usize, _flags: usize) ->  Result<usize> {
         let handles = self.handles.read();
         handles.get(&id).ok_or(Error::new(EBADF)).and(Ok(id))
diff --git a/src/scheme/zero.rs b/src/scheme/zero.rs
index 213cdbc1..194f2ecb 100644
--- a/src/scheme/zero.rs
+++ b/src/scheme/zero.rs
@@ -31,6 +31,10 @@ impl Scheme for ZeroScheme {
         Ok(buffer.len())
     }
 
+    fn fcntl(&self, _id: usize, _cmd: usize, _arg: usize) -> Result<usize> {
+        Ok(0)
+    }
+
     fn fpath(&self, _id: usize, buf: &mut [u8]) -> Result<usize> {
         let mut i = 0;
         let scheme_path = b"zero:";
diff --git a/src/syscall/fs.rs b/src/syscall/fs.rs
index 2b80c41d..f1f0e170 100644
--- a/src/syscall/fs.rs
+++ b/src/syscall/fs.rs
@@ -6,7 +6,7 @@ use scheme::{self, FileHandle};
 use syscall;
 use syscall::data::{Packet, Stat};
 use syscall::error::*;
-use syscall::flag::{F_SETFL, O_ACCMODE, O_RDONLY, O_WRONLY, MODE_DIR, MODE_FILE};
+use syscall::flag::{F_GETFL, F_SETFL, O_ACCMODE, O_RDONLY, O_WRONLY, MODE_DIR, MODE_FILE};
 
 pub fn file_op(a: usize, fd: FileHandle, c: usize, d: usize) -> Result<usize> {
     let (file, pid, uid, gid) = {
@@ -303,7 +303,7 @@ pub fn dup2(fd: FileHandle, new_fd: FileHandle, buf: &[u8]) -> Result<FileHandle
     }
 }
 
-// File descriptor controls
+/// File descriptor controls
 pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize) -> Result<usize> {
     let file = {
         let contexts = context::contexts();
@@ -313,6 +313,7 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize) -> Result<usize> {
         file
     };
 
+    // Communicate fcntl with scheme
     let res = {
         let scheme = {
             let schemes = scheme::schemes();
@@ -322,17 +323,29 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize) -> Result<usize> {
         scheme.fcntl(file.number, cmd, arg)?
     };
 
-    if cmd == F_SETFL {
+    // Perform kernel operation if scheme agrees
+    {
         let contexts = context::contexts();
         let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
         let context = context_lock.read();
         let mut files = context.files.lock();
-        let mut file = files.get_mut(fd.into()).ok_or(Error::new(EBADF))?.ok_or(Error::new(EBADF))?;
-        let accmode = file.flags & O_ACCMODE;
-        file.flags = accmode | arg & !O_ACCMODE;
+        match *files.get_mut(fd.into()).ok_or(Error::new(EBADF))? {
+            Some(ref mut file) => match cmd {
+                F_GETFL => {
+                    Ok(file.flags)
+                },
+                F_SETFL => {
+                    let new_flags = (file.flags & O_ACCMODE) | (arg & ! O_ACCMODE);
+                    file.flags = new_flags;
+                    Ok(0)
+                },
+                _ => {
+                    Err(Error::new(EINVAL))
+                }
+            },
+            None => Err(Error::new(EBADF))
+        }
     }
-
-    Ok(res)
 }
 
 /// Register events for file
@@ -342,12 +355,16 @@ pub fn fevent(fd: FileHandle, flags: usize) -> Result<usize> {
         let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
         let context = context_lock.read();
         let mut files = context.files.lock();
-        let mut file = files.get_mut(fd.into()).ok_or(Error::new(EBADF))?.ok_or(Error::new(EBADF))?;
-        if let Some(event_id) = file.event.take() {
-            println!("{:?}: {:?}:{}: events already registered: {}", fd, file.scheme, file.number, event_id);
-            context::event::unregister(fd, file.scheme, event_id);
+        match *files.get_mut(fd.into()).ok_or(Error::new(EBADF))? {
+            Some(ref mut file) => {
+                if let Some(event_id) = file.event.take() {
+                    println!("{:?}: {:?}:{}: events already registered: {}", fd, file.scheme, file.number, event_id);
+                    context::event::unregister(fd, file.scheme, event_id);
+                }
+                file.clone()
+            },
+            None => return Err(Error::new(EBADF))
         }
-        file.clone()
     };
 
     let scheme = {
@@ -361,8 +378,10 @@ pub fn fevent(fd: FileHandle, flags: usize) -> Result<usize> {
         let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
         let context = context_lock.read();
         let mut files = context.files.lock();
-        let mut file = files.get_mut(fd.into()).ok_or(Error::new(EBADF))?.ok_or(Error::new(EBADF))?;
-        file.event = Some(event_id);
+        match *files.get_mut(fd.into()).ok_or(Error::new(EBADF))? {
+            Some(ref mut file) => file.event = Some(event_id),
+            None => return Err(Error::new(EBADF)),
+        }
     }
     context::event::register(fd, file.scheme, event_id);
     Ok(0)
diff --git a/src/syscall/process.rs b/src/syscall/process.rs
index a3028612..d202d46b 100644
--- a/src/syscall/process.rs
+++ b/src/syscall/process.rs
@@ -253,15 +253,14 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<ContextId> {
         // This has to be done outside the context lock to prevent deadlocks
         if flags & CLONE_FILES == 0 {
             for (_fd, mut file_option) in files.lock().iter_mut().enumerate() {
-                let new_file_option = if let Some(file) = *file_option {
+                let new_file_option = if let Some(ref file) = *file_option {
                     let result = {
                         let scheme = {
                             let schemes = scheme::schemes();
                             let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
                             scheme.clone()
                         };
-                        let result = scheme.dup(file.number, b"clone");
-                        result
+                        scheme.dup(file.number, b"clone")
                     };
                     match result {
                         Ok(new_number) => {
@@ -731,7 +730,7 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
 
                 // Duplicate current files using b"exec", close previous
                 for (fd, mut file_option) in files.lock().iter_mut().enumerate() {
-                    let new_file_option = if let Some(file) = *file_option {
+                    let new_file_option = if let Some(ref file) = *file_option {
                         // Duplicate
                         let result = {
                             if file.flags & O_CLOEXEC == O_CLOEXEC {
@@ -742,8 +741,7 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
                                     schemes.get(file.scheme).map(|scheme| scheme.clone())
                                 };
                                 if let Some(scheme) = scheme_option {
-                                    let result = scheme.dup(file.number, b"exec");
-                                    result
+                                    scheme.dup(file.number, b"exec")
                                 } else {
                                     Err(Error::new(EBADF))
                                 }
-- 
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