Add semaphores syscalls

linux-loader/src/main.rs

@@ -190,4 +190,9 @@ mod tests {
     async fn test_random() {
         assert_eq!(test("/bin/testrandom").await, 0);
     }
+
+    #[async_std::test]
+    async fn test_sem() {
+        assert_eq!(test("/bin/testsem1").await, 0);
+    }
 }

linux-object/src/error.rs

@@ -95,6 +95,8 @@ pub enum LxError {
     ENOTEMPTY = 39,
     /// Too many symbolic links encountered
     ELOOP = 40,
+    /// Identifier removed
+    EIDRM = 43,
     /// Socket operation on non-socket
     ENOTSOCK = 88,
     /// Protocol not available
@@ -158,6 +160,7 @@ impl fmt::Display for LxError {
             ENOSYS => "Function not implemented",
             ENOTEMPTY => "Directory not empty",
             ELOOP => "Too many symbolic links encountered",
+            EIDRM => "Identifier removed",
             ENOTSOCK => "Socket operation on non-socket",
             ENOPROTOOPT => "Protocol not available",
             EPFNOSUPPORT => "Protocol family not supported",

linux-object/src/ipc/mod.rs

@@ -0,0 +1,82 @@
+//! Linux Inter-Process Communication
+#![deny(missing_docs)]
+mod semary;
+
+pub use self::semary::*;
+use alloc::collections::BTreeMap;
+use alloc::sync::Arc;
+
+/// Semaphore table in a process
+#[derive(Default)]
+pub struct SemProc {
+    /// Semaphore arrays
+    arrays: BTreeMap<SemId, Arc<SemArray>>,
+    /// Undo operations when process terminates
+    undos: BTreeMap<(SemId, SemNum), SemOp>,
+}
+
+/// Semaphore set identifier (in a process)
+type SemId = usize;
+
+/// Semaphore number (in an array)
+type SemNum = u16;
+
+/// Semaphore operation value
+type SemOp = i16;
+
+impl SemProc {
+    /// Insert the `array` and return its ID
+    pub fn add(&mut self, array: Arc<SemArray>) -> SemId {
+        let id = self.get_free_id();
+        self.arrays.insert(id, array);
+        id
+    }
+
+    /// Remove an `array` by ID
+    pub fn remove(&mut self, id: SemId) {
+        self.arrays.remove(&id);
+    }
+
+    /// Get a free ID
+    fn get_free_id(&self) -> SemId {
+        (0..).find(|i| self.arrays.get(i).is_none()).unwrap()
+    }
+
+    /// Get an semaphore set by `id`
+    pub fn get(&self, id: SemId) -> Option<Arc<SemArray>> {
+        self.arrays.get(&id).cloned()
+    }
+
+    /// Add an undo operation
+    pub fn add_undo(&mut self, id: SemId, num: SemNum, op: SemOp) {
+        let old_val = *self.undos.get(&(id, num)).unwrap_or(&0);
+        let new_val = old_val - op;
+        self.undos.insert((id, num), new_val);
+    }
+}
+
+/// Fork the semaphore table. Clear undo info.
+impl Clone for SemProc {
+    fn clone(&self) -> Self {
+        SemProc {
+            arrays: self.arrays.clone(),
+            undos: BTreeMap::default(),
+        }
+    }
+}
+
+/// Auto perform semaphores undo on drop
+impl Drop for SemProc {
+    fn drop(&mut self) {
+        for (&(id, num), &op) in self.undos.iter() {
+            debug!("semundo: id: {}, num: {}, op: {}", id, num, op);
+            let sem_array = self.arrays[&id].clone();
+            let sem = &sem_array[num as usize];
+            match op {
+                1 => sem.release(),
+                0 => {}
+                _ => unimplemented!("Semaphore: semundo.(Not 1)"),
+            }
+        }
+    }
+}

linux-object/src/ipc/semary.rs

@@ -0,0 +1,167 @@
+//! Linux semaphore ipc
+use crate::error::LxError;
+use crate::sync::Semaphore;
+use crate::time::*;
+use alloc::{collections::BTreeMap, sync::Arc, sync::Weak, vec::Vec};
+use bitflags::*;
+use core::ops::Index;
+use lazy_static::*;
+use spin::Mutex;
+use spin::RwLock;
+
+bitflags! {
+    struct SemGetFlag: usize {
+        const CREAT = 1 << 9;
+        const EXCLUSIVE = 1 << 10;
+        const NO_WAIT = 1 << 11;
+    }
+}
+
+/// structure specifies the access permissions on the semaphore set
+///
+/// struct ipc_perm
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct IpcPerm {
+    /// Key supplied to semget(2)
+    pub key: u32,
+    /// Effective UID of owner
+    pub uid: u32,
+    /// Effective GID of owner
+    pub gid: u32,
+    /// Effective UID of creator
+    pub cuid: u32,
+    /// Effective GID of creator
+    pub cgid: u32,
+    /// Permissions
+    pub mode: u32,
+    /// Sequence number
+    pub __seq: u32,
+    /// pad1
+    pub __pad1: usize,
+    /// pad2
+    pub __pad2: usize,
+}
+
+/// semid data structure
+///
+/// struct semid_ds
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct SemidDs {
+    /// Ownership and permissions
+    pub perm: IpcPerm,
+    /// Last semop time
+    pub otime: usize,
+    __pad1: usize,
+    /// Last change time
+    pub ctime: usize,
+    __pad2: usize,
+    /// number of semaphores in set
+    pub nsems: usize,
+}
+
+/// A System V semaphore set
+pub struct SemArray {
+    /// semid data structure
+    pub semid_ds: Mutex<SemidDs>,
+    sems: Vec<Semaphore>,
+}
+
+impl Index<usize> for SemArray {
+    type Output = Semaphore;
+    fn index(&self, idx: usize) -> &Semaphore {
+        &self.sems[idx]
+    }
+}
+
+lazy_static! {
+    static ref KEY2SEM: RwLock<BTreeMap<u32, Weak<SemArray>>> = RwLock::new(BTreeMap::new());
+}
+
+impl SemArray {
+    /// remove semaphores
+    pub fn remove(&self) {
+        let mut key2sem = KEY2SEM.write();
+        let key = self.semid_ds.lock().perm.key;
+        key2sem.remove(&key);
+        for sem in self.sems.iter() {
+            sem.remove();
+        }
+    }
+
+    /// set last semop time
+    pub fn otime(&self) {
+        self.semid_ds.lock().otime = TimeSpec::now().sec;
+    }
+
+    /// set last change time
+    pub fn ctime(&self) {
+        self.semid_ds.lock().ctime = TimeSpec::now().sec;
+    }
+
+    /// for IPC_SET
+    /// see man semctl(2)
+    pub fn set(&self, new: &SemidDs) {
+        let mut lock = self.semid_ds.lock();
+        lock.perm.uid = new.perm.uid;
+        lock.perm.gid = new.perm.gid;
+        lock.perm.mode = new.perm.mode & 0x1ff;
+    }
+
+    /// Get the semaphore array with `key`.
+    /// If not exist, create a new one with `nsems` elements.
+    pub fn get_or_create(mut key: u32, nsems: usize, flags: usize) -> Result<Arc<Self>, LxError> {
+        let mut key2sem = KEY2SEM.write();
+        let flag = SemGetFlag::from_bits_truncate(flags);
+
+        if key == 0 {
+            // IPC_PRIVATE
+            // find an empty key slot
+            key = (1u32..).find(|i| key2sem.get(i).is_none()).unwrap();
+        } else {
+            // check existence
+            if let Some(weak_array) = key2sem.get(&key) {
+                if let Some(array) = weak_array.upgrade() {
+                    if flag.contains(SemGetFlag::CREAT) && flag.contains(SemGetFlag::EXCLUSIVE) {
+                        // exclusive
+                        return Err(LxError::EEXIST);
+                    }
+                    return Ok(array);
+                }
+            }
+        }
+
+        // not found, create one
+        let mut semaphores = Vec::new();
+        for _ in 0..nsems {
+            semaphores.push(Semaphore::new(0));
+        }
+
+        // insert to global map
+        let array = Arc::new(SemArray {
+            semid_ds: Mutex::new(SemidDs {
+                perm: IpcPerm {
+                    key,
+                    uid: 0,
+                    gid: 0,
+                    cuid: 0,
+                    cgid: 0,
+                    // least significant 9 bits
+                    mode: (flags as u32) & 0x1ff,
+                    __seq: 0,
+                    __pad1: 0,
+                    __pad2: 0,
+                },
+                otime: 0,
+                ctime: TimeSpec::now().sec,
+                nsems,
+                __pad1: 0,
+                __pad2: 0,
+            }),
+            sems: semaphores,
+        });
+        key2sem.insert(key, Arc::downgrade(&array));
+        Ok(array)
+    }
+}

linux-object/src/lib.rs

@@ -1,7 +1,7 @@
 //! Linux kernel objects
 
 #![no_std]
-#![deny(warnings, unsafe_code)]
+#![deny(warnings, unsafe_code, missing_docs)]
 #![feature(bool_to_option)]
 
 extern crate alloc;
@@ -16,8 +16,10 @@ pub mod error;
 pub mod fs;
 
 // layer 2
+pub mod ipc;
 pub mod loader;
 pub mod process;
 pub mod signal;
 pub mod sync;
 pub mod thread;
+pub mod time;

linux-object/src/process.rs

@@ -2,6 +2,7 @@
 
 use crate::error::*;
 use crate::fs::*;
+use crate::ipc::*;
 use crate::signal::{Signal as LinuxSignal, SignalAction};
 use alloc::vec::Vec;
 use alloc::{
@@ -149,6 +150,8 @@ struct LinuxProcessInner {
     file_limit: RLimit,
     /// Opened files
     files: HashMap<FileDesc, Arc<dyn FileLike>>,
+    /// Semaphore
+    semaphores: SemProc,
     /// Futexes
     futexes: HashMap<VirtAddr, Arc<Futex>>,
     /// Child processes
@@ -361,6 +364,26 @@ impl LinuxProcess {
     pub fn set_signal_action(&self, signal: LinuxSignal, action: SignalAction) {
         self.inner.lock().signal_actions.table[signal as u8 as usize] = action;
     }
+
+    /// Insert a `SemArray` and return its ID
+    pub fn semaphores_add(&self, array: Arc<SemArray>) -> usize {
+        self.inner.lock().semaphores.add(array)
+    }
+
+    /// Get an semaphore set by `id`
+    pub fn semaphores_get(&self, id: usize) -> Option<Arc<SemArray>> {
+        self.inner.lock().semaphores.get(id)
+    }
+
+    /// Add an undo operation
+    pub fn semaphores_add_undo(&self, id: usize, num: u16, op: i16) {
+        self.inner.lock().semaphores.add_undo(id, num, op)
+    }
+
+    /// Remove an `SemArray` by ID
+    pub fn semaphores_remove(&self, id: usize) {
+        self.inner.lock().semaphores.remove(id)
+    }
 }
 
 impl LinuxProcessInner {

linux-object/src/signal/action.rs

@@ -5,9 +5,10 @@ pub const SIG_ERR: usize = usize::max_value() - 1;
 pub const SIG_DFL: usize = 0;
 pub const SIG_IGN: usize = 1;
 
-// yet there's a bug because of mismatching bits: https://sourceware.org/bugzilla/show_bug.cgi?id=25657
-// just support 64bits size sigset
 /// Linux struct sigset_t
+///
+/// yet there's a bug because of mismatching bits: https://sourceware.org/bugzilla/show_bug.cgi?id=25657
+/// just support 64bits size sigset
 #[derive(Default, Clone, Copy, Debug)]
 #[repr(C)]
 pub struct Sigset(u64);

linux-object/src/signal/mod.rs

@@ -1,3 +1,5 @@
+//! Linux signals
+#![allow(missing_docs)]
 use bitflags::*;
 use numeric_enum_macro::numeric_enum;
 
@@ -125,6 +127,7 @@ impl Signal {
 }
 
 /// See musl struct __ucontext
+///
 /// Not exactly the same for now
 #[repr(C)]
 #[derive(Clone)]
@@ -139,10 +142,14 @@ pub struct SignalUserContext {
 #[repr(C)]
 #[derive(Clone)]
 pub struct SignalFrame {
-    pub ret_code_addr: usize, // point to ret_code
+    /// point to ret_code
+    pub ret_code_addr: usize,
+    /// Signal Frame info
     pub info: SigInfo,
-    pub ucontext: SignalUserContext, // adapt interface, a little bit waste
-    pub ret_code: [u8; 7],           // call sys_sigreturn
+    /// adapt interface, a little bit waste
+    pub ucontext: SignalUserContext,
+    /// call sys_sigreturn
+    pub ret_code: [u8; 7],
 }
 
 bitflags! {

linux-object/src/sync/event_bus.rs

@@ -33,7 +33,7 @@ bitflags! {
 
         /// Semaphore: is removed
         const SEMAPHORE_REMOVED             = 1 << 20;
-        /// Semaphore: can acquired
+        /// Semaphore: can acquired a resource of this semaphore
         const SEMAPHORE_CAN_ACQUIRE         = 1 << 21;
     }
 }