Add support for FLOCK

src/libos/src/fs/file_ops/flock.rs

@@ -0,0 +1,19 @@
+use super::*;
+
+pub fn do_flock(fd: FileDesc, ops: FlockOps) -> Result<()> {
+    debug!("flock: fd: {}, ops: {:?}", fd, ops);
+
+    let file_ref = current!().file(fd)?;
+    let inode_file = file_ref.as_inode_file()?;
+    if ops.contains(FlockOps::LOCK_UN) {
+        inode_file.unlock_flock();
+    } else {
+        let is_nonblocking = ops.contains(FlockOps::LOCK_NB);
+        let flock = {
+            let type_ = FlockType::from(ops);
+            Flock::new(&file_ref, type_)
+        };
+        inode_file.set_flock(flock, is_nonblocking)?;
+    }
+    Ok(())
+}

src/libos/src/fs/file_ops/mod.rs

@@ -9,6 +9,7 @@ pub use self::dup::{do_dup, do_dup2, do_dup3};
 pub use self::fallocate::{do_fallocate, FallocateFlags};
 pub use self::fcntl::{do_fcntl, FcntlCmd};
 pub use self::file_flags::{AccessMode, CreationFlags, StatusFlags};
+pub use self::flock::do_flock;
 pub use self::fspath::{get_abs_path_by_fd, FsPath, AT_FDCWD};
 pub use self::fsync::{do_fdatasync, do_fsync};
 pub use self::getdents::{do_getdents, do_getdents64};
@@ -38,6 +39,7 @@ mod dup;
 mod fallocate;
 mod fcntl;
 mod file_flags;
+mod flock;
 mod fspath;
 mod fsync;
 mod getdents;

src/libos/src/fs/inode_file.rs

@@ -338,6 +338,46 @@ impl INodeFile {
 
         range_lock_list.unlock(lock)
     }
+
+    pub fn set_flock(&self, lock: Flock, is_nonblocking: bool) -> Result<()> {
+        let ext = match self.inode.ext() {
+            Some(ext) => ext,
+            None => {
+                warn!("Inode extension is not supported, let the lock could be acquired");
+                // TODO: Implement inode extension for FS
+                return Ok(());
+            }
+        };
+        let flock_list = match ext.get::<FlockList>() {
+            Some(list) => list,
+            None => ext.get_or_put_default::<FlockList>(),
+        };
+
+        flock_list.set_lock(lock, is_nonblocking)
+    }
+
+    pub fn unlock_flock(&self) {
+        let ext = match self.inode.ext() {
+            Some(ext) => ext,
+            None => {
+                return;
+            }
+        };
+        let flock_list = match ext.get::<FlockList>() {
+            Some(list) => list,
+            None => {
+                return;
+            }
+        };
+
+        flock_list.unlock(self);
+    }
+}
+
+impl Drop for INodeFile {
+    fn drop(&mut self) {
+        self.unlock_flock()
+    }
 }
 
 impl Debug for INodeFile {

src/libos/src/fs/locks/flock.rs

@@ -0,0 +1,199 @@
+/// Non-POSIX file advisory lock (FLOCK)
+use super::*;
+use crate::events::{Waiter, WaiterQueue};
+use rcore_fs::vfs::AnyExt;
+use std::ptr;
+use std::sync::Weak;
+
+/// Kernel representation of FLOCK
+pub struct Flock {
+    /// Owner of FLOCK, an opened file descriptor holding the lock
+    owner: Weak<dyn File>,
+    /// Type of lock, SH_LOCK or EX_LOCK
+    type_: FlockType,
+    /// Optional waiters that are blocking by the lock
+    waiters: Option<WaiterQueue>,
+}
+
+impl Flock {
+    pub fn new(owner: &Arc<dyn File>, type_: FlockType) -> Self {
+        Self {
+            owner: Arc::downgrade(owner),
+            type_,
+            waiters: None,
+        }
+    }
+
+    pub fn owner(&self) -> Option<Arc<dyn File>> {
+        Weak::upgrade(&self.owner)
+    }
+
+    pub fn same_owner_with(&self, other: &Self) -> bool {
+        self.owner.ptr_eq(&other.owner)
+    }
+
+    pub fn conflict_with(&self, other: &Self) -> bool {
+        if self.same_owner_with(other) {
+            return false;
+        }
+        if self.type_ == FlockType::EX_LOCK || other.type_ == FlockType::EX_LOCK {
+            return true;
+        }
+        false
+    }
+
+    pub fn enqueue_waiter(&mut self, waiter: &Waiter) {
+        if self.waiters.is_none() {
+            self.waiters = Some(WaiterQueue::new());
+        }
+        self.waiters.as_ref().unwrap().reset_and_enqueue(waiter)
+    }
+
+    pub fn dequeue_and_wake_all_waiters(&mut self) -> usize {
+        if self.waiters.is_some() {
+            return self.waiters.as_ref().unwrap().dequeue_and_wake_all();
+        }
+        0
+    }
+}
+
+impl Drop for Flock {
+    fn drop(&mut self) {
+        self.dequeue_and_wake_all_waiters();
+    }
+}
+
+impl Debug for Flock {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Flock")
+            .field("owner", &self.owner.as_ptr())
+            .field("type_", &self.type_)
+            .finish()
+    }
+}
+
+/// List of Non-POSIX file advisory lock (FLOCK)
+pub struct FlockList {
+    inner: RwLock<VecDeque<Flock>>,
+}
+
+impl FlockList {
+    pub fn new() -> Self {
+        Self {
+            inner: RwLock::new(VecDeque::new()),
+        }
+    }
+
+    pub fn set_lock(&self, mut req_lock: Flock, is_nonblocking: bool) -> Result<()> {
+        debug!(
+            "set_lock with Flock: {:?}, is_nonblocking: {}",
+            req_lock, is_nonblocking
+        );
+
+        loop {
+            let mut list = self.inner.write().unwrap();
+            if let Some(mut conflict_lock) = list.iter_mut().find(|l| req_lock.conflict_with(&l)) {
+                if is_nonblocking {
+                    return_errno!(EAGAIN, "The file is locked");
+                }
+                // Start to wait
+                let waiter = Waiter::new();
+                // FLOCK do not support deadlock detection
+                conflict_lock.enqueue_waiter(&waiter);
+                // Ensure that we drop any locks before wait
+                drop(list);
+                waiter.wait(None)?;
+                // Wake up, let's try to set lock again
+                continue;
+            }
+            match list.iter().position(|l| req_lock.same_owner_with(&l)) {
+                Some(idx) => {
+                    std::mem::swap(&mut req_lock, &mut list[idx]);
+                }
+                None => {
+                    list.push_front(req_lock);
+                }
+            }
+            break;
+        }
+        Ok(())
+    }
+
+    pub fn unlock(&self, req_owner: &INodeFile) {
+        debug!("unlock with owner: {:?}", req_owner as *const INodeFile);
+
+        let mut list = self.inner.write().unwrap();
+        list.retain(|lock| {
+            if let Some(owner) = lock.owner() {
+                !ptr::eq(
+                    Arc::as_ptr(&owner) as *const INodeFile,
+                    req_owner as *const INodeFile,
+                )
+            } else {
+                false
+            }
+        });
+    }
+}
+
+impl Default for FlockList {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl AnyExt for FlockList {}
+
+#[allow(non_camel_case_types)]
+#[derive(Debug, Copy, Clone, PartialEq)]
+#[repr(u16)]
+pub enum FlockType {
+    /// Shared lock
+    SH_LOCK = 0,
+    /// Exclusive lock
+    EX_LOCK = 1,
+}
+
+impl From<FlockOps> for FlockType {
+    fn from(ops: FlockOps) -> Self {
+        if ops.contains(FlockOps::LOCK_EX) {
+            Self::EX_LOCK
+        } else if ops.contains(FlockOps::LOCK_SH) {
+            Self::SH_LOCK
+        } else {
+            panic!("invalid flockops");
+        }
+    }
+}
+
+bitflags! {
+    pub struct FlockOps: i32 {
+        /// Shared lock
+        const LOCK_SH = 1;
+        /// Exclusive lock
+        const LOCK_EX = 2;
+        // Or'd with one of the above to prevent blocking
+        const LOCK_NB = 4;
+        // Remove lock
+        const LOCK_UN = 8;
+    }
+}
+
+impl FlockOps {
+    pub fn from_i32(bits: i32) -> Result<Self> {
+        let ops = Self::from_bits(bits).ok_or_else(|| errno!(EINVAL, "invalid operation"))?;
+        if ops.contains(Self::LOCK_SH) {
+            if ops.contains(Self::LOCK_EX) || ops.contains(Self::LOCK_UN) {
+                return_errno!(EINVAL, "invalid operation");
+            }
+        } else if ops.contains(Self::LOCK_EX) {
+            if ops.contains(Self::LOCK_UN) {
+                return_errno!(EINVAL, "invalid operation");
+            }
+        } else if !ops.contains(Self::LOCK_UN) {
+            return_errno!(EINVAL, "invalid operation");
+        }
+
+        Ok(ops)
+    }
+}

src/libos/src/fs/locks/mod.rs

@@ -1,3 +1,4 @@
 use super::*;
 
+pub mod flock;
 pub mod range_lock;

src/libos/src/fs/mod.rs

@@ -23,13 +23,14 @@ pub use self::file_ops::{
     IfConf, IoctlCmd, Stat, StatusFlags, StructuredIoctlArgType, StructuredIoctlNum,
 };
 pub use self::file_table::{FileDesc, FileTable, FileTableEvent, FileTableNotifier};
-pub use self::locks::range_lock::{
-    FileRange, RangeLock, RangeLockBuilder, RangeLockList, RangeLockType, OFFSET_MAX,
-};
 pub use self::fs_ops::Statfs;
 pub use self::fs_view::FsView;
 pub use self::host_fd::HostFd;
 pub use self::inode_file::{AsINodeFile, INodeExt, INodeFile};
+pub use self::locks::flock::{Flock, FlockList, FlockOps, FlockType};
+pub use self::locks::range_lock::{
+    FileRange, RangeLock, RangeLockBuilder, RangeLockList, RangeLockType, OFFSET_MAX,
+};
 pub use self::pipe::PipeType;
 pub use self::rootfs::ROOT_FS;
 pub use self::stdio::{HostStdioFds, StdinFile, StdoutFile};
@@ -43,12 +44,12 @@ mod events;
 mod file;
 mod file_ops;
 mod file_table;
-mod locks;
 mod fs_ops;
 mod fs_view;
 mod host_fd;
 mod hostfs;
 mod inode_file;
+mod locks;
 mod pipe;
 mod procfs;
 mod rootfs;

src/libos/src/fs/syscalls.rs

@@ -693,3 +693,10 @@ pub fn do_umount(target: *const i8, flags: u32) -> Result<isize> {
     fs_ops::do_umount(&target, flags)?;
     Ok(0)
 }
+
+pub fn do_flock(fd: FileDesc, operation: i32) -> Result<isize> {
+    let flock_ops = FlockOps::from_i32(operation)?;
+
+    file_ops::do_flock(fd, flock_ops)?;
+    Ok(0)
+}

src/libos/src/syscall/mod.rs

@@ -24,14 +24,14 @@ use crate::exception::do_handle_exception;
 use crate::fs::{
     do_access, do_chdir, do_chmod, do_chown, do_close, do_creat, do_dup, do_dup2, do_dup3,
     do_eventfd, do_eventfd2, do_faccessat, do_fallocate, do_fchdir, do_fchmod, do_fchmodat,
-    do_fchown, do_fchownat, do_fcntl, do_fdatasync, do_fstat, do_fstatat, do_fstatfs, do_fsync,
-    do_ftruncate, do_getcwd, do_getdents, do_getdents64, do_ioctl, do_lchown, do_link, do_linkat,
-    do_lseek, do_lstat, do_mkdir, do_mkdirat, do_mount, do_mount_rootfs, do_open, do_openat,
-    do_pipe, do_pipe2, do_pread, do_pwrite, do_read, do_readlink, do_readlinkat, do_readv,
-    do_rename, do_renameat, do_rmdir, do_sendfile, do_stat, do_statfs, do_symlink, do_symlinkat,
-    do_sync, do_timerfd_create, do_timerfd_gettime, do_timerfd_settime, do_truncate, do_umask,
-    do_umount, do_unlink, do_unlinkat, do_write, do_writev, iovec_t, AsTimer, File, FileDesc,
-    FileRef, HostStdioFds, Stat, Statfs,
+    do_fchown, do_fchownat, do_fcntl, do_fdatasync, do_flock, do_fstat, do_fstatat, do_fstatfs,
+    do_fsync, do_ftruncate, do_getcwd, do_getdents, do_getdents64, do_ioctl, do_lchown, do_link,
+    do_linkat, do_lseek, do_lstat, do_mkdir, do_mkdirat, do_mount, do_mount_rootfs, do_open,
+    do_openat, do_pipe, do_pipe2, do_pread, do_pwrite, do_read, do_readlink, do_readlinkat,
+    do_readv, do_rename, do_renameat, do_rmdir, do_sendfile, do_stat, do_statfs, do_symlink,
+    do_symlinkat, do_sync, do_timerfd_create, do_timerfd_gettime, do_timerfd_settime, do_truncate,
+    do_umask, do_umount, do_unlink, do_unlinkat, do_write, do_writev, iovec_t, AsTimer, File,
+    FileDesc, FileRef, HostStdioFds, Stat, Statfs,
 };
 use crate::interrupt::{do_handle_interrupt, sgx_interrupt_info_t};
 use crate::misc::{resource_t, rlimit_t, sysinfo_t, utsname_t, RandFlags};
@@ -161,7 +161,7 @@ macro_rules! process_syscall_table_with_callback {
             (Msgrcv = 70) => handle_unsupported(),
             (Msgctl = 71) => handle_unsupported(),
             (Fcntl = 72) => do_fcntl(fd: FileDesc, cmd: u32, arg: u64),
-            (Flock = 73) => handle_unsupported(),
+            (Flock = 73) => do_flock(fd: FileDesc, operation: i32),
             (Fsync = 74) => do_fsync(fd: FileDesc),
             (Fdatasync = 75) => do_fdatasync(fd: FileDesc),
             (Truncate = 76) => do_truncate(path: *const i8, len: usize),