Add fcntl

src/libos/src/fs/file_table.rs

@@ -11,12 +11,6 @@ pub struct FileTable {
     num_fds: usize,
 }
 
-#[derive(Debug, Clone)]
-struct FileTableEntry {
-    file: FileRef,
-    close_on_spawn: bool,
-}
-
 impl FileTable {
     pub fn new() -> FileTable {
         FileTable {
@@ -25,12 +19,38 @@ impl FileTable {
         }
     }
 
+    pub fn dup(&mut self, fd: FileDesc, min_fd: FileDesc, close_on_spawn: bool) -> Result<FileDesc, Error> {
+        let file_ref = self.get(fd)?;
+
+        let min_fd = min_fd as usize;
+        let min_free_fd = {
+            let mut table = &mut self.table;
+
+            // Make sure that min_fd does not exceed the capacity of the table
+            if min_fd >= table.len() {
+                let expand_size = min_fd - table.len() + 1;
+                for _ in 0..expand_size {
+                    table.push(None)
+                }
+            }
+
+            table.iter()
+                .enumerate()
+                .skip(min_fd as usize)
+                .find(|&(idx, opt)| opt.is_none())
+                .unwrap().0
+        } as FileDesc;
+
+        self.put_at(min_free_fd, file_ref, close_on_spawn);
+
+        Ok(min_free_fd)
+    }
+
     pub fn put(&mut self, file: FileRef, close_on_spawn: bool) -> FileDesc {
         let mut table = &mut self.table;
 
         let min_free_fd = if self.num_fds < table.len() {
-            table
-                .iter()
+            table.iter()
                 .enumerate()
                 .find(|&(idx, opt)| opt.is_none())
                 .unwrap()
@@ -59,13 +79,30 @@ impl FileTable {
     }
 
     pub fn get(&self, fd: FileDesc) -> Result<FileRef, Error> {
+        let entry = self.get_entry(fd)?;
+        Ok(entry.file.clone())
+    }
+
+    pub fn get_entry(&self, fd: FileDesc) -> Result<&FileTableEntry, Error> {
         if fd as usize >= self.table.len() {
             return errno!(EBADF, "Invalid file descriptor");
         }
 
         let table = &self.table;
         match table[fd as usize].as_ref() {
-            Some(table_entry) => Ok(table_entry.file.clone()),
+            Some(table_entry) => Ok(table_entry),
+            None => errno!(EBADF, "Invalid file descriptor"),
+        }
+    }
+
+    pub fn get_entry_mut(&mut self, fd: FileDesc) -> Result<&mut FileTableEntry, Error> {
+        if fd as usize >= self.table.len() {
+            return errno!(EBADF, "Invalid file descriptor");
+        }
+
+        let table = &mut self.table;
+        match table[fd as usize].as_mut() {
+            Some(table_entry) => Ok(table_entry),
             None => errno!(EBADF, "Invalid file descriptor"),
         }
     }
@@ -114,11 +151,33 @@ impl Clone for FileTable {
     }
 }
 
+#[derive(Debug, Clone)]
+pub struct FileTableEntry {
+    file: FileRef,
+    close_on_spawn: bool,
+}
+
 impl FileTableEntry {
-    fn new(file: FileRef, close_on_spawn: bool) -> FileTableEntry {
+    pub fn new(file: FileRef, close_on_spawn: bool) -> FileTableEntry {
         FileTableEntry {
             file,
             close_on_spawn,
         }
     }
+
+    pub fn get_file(&self) -> &FileRef {
+        &self.file
+    }
+
+    pub fn is_close_on_spawn(&self) -> bool {
+        self.close_on_spawn
+    }
+
+    pub fn get_file_mut(&mut self) -> &mut FileRef {
+        &mut self.file
+    }
+
+    pub fn set_close_on_spawn(&mut self, close_on_spawn: bool) {
+        self.close_on_spawn = close_on_spawn;
+    }
 }

src/libos/src/fs/mod.rs

@@ -390,7 +390,7 @@ fn split_path(path: &str) -> (&str, &str) {
 }
 
 bitflags! {
-    struct OpenFlags: u32 {
+    pub struct OpenFlags: u32 {
         /// read only
         const RDONLY = 0;
         /// write only
@@ -614,3 +614,84 @@ pub unsafe fn write_cstr(ptr: *mut u8, s: &str) {
     ptr.copy_from(s.as_ptr(), s.len());
     ptr.add(s.len()).write(0);
 }
+
+
+#[derive(Debug)]
+pub enum FcntlCmd {
+    /// Duplicate the file descriptor fd using the lowest-numbered available
+    /// file descriptor greater than or equal to arg.
+    DupFd(FileDesc),
+    /// As for `DupFd`, but additionally set the close-on-exec flag for the
+    /// duplicate file descriptor.
+    DupFdCloexec(FileDesc),
+    /// Return (as the function result) the file descriptor flags
+    GetFd(),
+    /// Set the file descriptor to be close-on-exec or not
+    SetFd(u32),
+    /// Get the file status flags
+    GetFl(),
+    /// Set the file status flags
+    SetFl(OpenFlags),
+}
+
+pub const F_DUPFD : u32             = 0;
+pub const F_GETFD : u32             = 1;
+pub const F_SETFD : u32             = 2;
+pub const F_GETFL : u32             = 3;
+pub const F_SETFL : u32             = 4;
+pub const F_DUPFD_CLOEXEC : u32     = 1030;
+
+pub const FD_CLOEXEC : u32          = 1;
+
+impl FcntlCmd {
+    #[deny(unreachable_patterns)]
+    pub fn from_raw(cmd: u32, arg: u64) -> Result<FcntlCmd, Error> {
+        Ok(match cmd {
+            F_DUPFD => FcntlCmd::DupFd(arg as FileDesc),
+            F_DUPFD_CLOEXEC => FcntlCmd::DupFdCloexec(arg as FileDesc),
+            F_GETFD => FcntlCmd::GetFd(),
+            F_SETFD => FcntlCmd::SetFd(arg as u32),
+            F_GETFL => FcntlCmd::GetFl(),
+            F_SETFL => FcntlCmd::SetFl(OpenFlags::from_bits_truncate(arg as u32)),
+            _ => return errno!(EINVAL, "invalid command"),
+        })
+    }
+}
+
+pub fn do_fcntl(fd: FileDesc, cmd: &FcntlCmd) -> Result<isize, Error> {
+    info!("do_fcntl: {:?}, {:?}", &fd, cmd);
+    let current_ref = process::get_current();
+    let mut current = current_ref.lock().unwrap();
+    let files_ref = current.get_files();
+    let mut files = files_ref.lock().unwrap();
+    Ok(match cmd {
+        FcntlCmd::DupFd(min_fd) => {
+            let dup_fd = files.dup(fd, *min_fd, false)?;
+            dup_fd as isize
+        },
+        FcntlCmd::DupFdCloexec(min_fd) => {
+            let dup_fd = files.dup(fd, *min_fd, true)?;
+            dup_fd as isize
+        },
+        FcntlCmd::GetFd() => {
+            let entry = files.get_entry(fd)?;
+            let fd_flags = if entry.is_close_on_spawn() {
+                FD_CLOEXEC
+            } else {
+                0
+            };
+            fd_flags as isize
+        },
+        FcntlCmd::SetFd(fd_flags) => {
+            let entry = files.get_entry_mut(fd)?;
+            entry.set_close_on_spawn((fd_flags & FD_CLOEXEC) != 0);
+            0
+        },
+        FcntlCmd::GetFl() => {
+            unimplemented!();
+        },
+        FcntlCmd::SetFl(flags) => {
+            unimplemented!();
+        },
+    })
+}

src/libos/src/syscall/mod.rs

@@ -1,5 +1,5 @@
 use {fs, process, std, vm};
-use fs::{File, FileDesc, off_t, AccessModes, AccessFlags, AT_FDCWD};
+use fs::{File, FileDesc, off_t, AccessModes, AccessFlags, AT_FDCWD, FcntlCmd};
 use prelude::*;
 use process::{ChildProcessFilter, FileAction, pid_t, CloneFlags, FutexFlags, FutexOp};
 use std::ffi::{CStr, CString};
@@ -72,6 +72,7 @@ pub extern "C" fn dispatch_syscall(
         SYS_RMDIR => do_rmdir(arg0 as *const i8),
         SYS_LINK => do_link(arg0 as *const i8, arg1 as *const i8),
         SYS_UNLINK => do_unlink(arg0 as *const i8),
+        SYS_FCNTL => do_fcntl(arg0 as FileDesc, arg1 as u32, arg2 as u64),
 
         SYS_EXIT => do_exit(arg0 as i32),
         SYS_SPAWN => do_spawn(
@@ -726,6 +727,11 @@ fn do_unlink(path: *const i8) -> Result<isize, Error> {
     Ok(0)
 }
 
+fn do_fcntl(fd: FileDesc, cmd: u32, arg: u64) -> Result<isize, Error> {
+    let cmd = FcntlCmd::from_raw(cmd, arg)?;
+    fs::do_fcntl(fd, &cmd)
+}
+
 fn do_arch_prctl(code: u32, addr: *mut usize) -> Result<isize, Error> {
     let code = process::ArchPrctlCode::from_u32(code)?;
     check_mut_ptr(addr)?;