diff --git a/crate/thread/src/thread_pool.rs b/crate/thread/src/thread_pool.rs
index 715ad35..8a8e5b0 100644
--- a/crate/thread/src/thread_pool.rs
+++ b/crate/thread/src/thread_pool.rs
@@ -154,7 +154,11 @@ impl ThreadPool {
     }
 
     pub fn get_status(&self, tid: Tid) -> Option<Status> {
-        self.threads[tid].lock().as_ref().map(|p| p.status.clone())
+        if tid < self.threads.len() {
+            self.threads[tid].lock().as_ref().map(|p| p.status.clone())
+        } else {
+            None
+        }
     }
 
     /// Remove an exited proc `tid`.
diff --git a/kernel/src/syscall/fs.rs b/kernel/src/syscall/fs.rs
index 40eca94..d413c03 100644
--- a/kernel/src/syscall/fs.rs
+++ b/kernel/src/syscall/fs.rs
@@ -1,6 +1,7 @@
 //! Syscalls for file system
 
 use core::mem::size_of;
+use core::cmp::min;
 use rcore_fs::vfs::Timespec;
 use smoltcp::socket::*;
 
@@ -252,12 +253,16 @@ pub fn sys_readv(fd: usize, iov_ptr: *const IoVec, iov_count: usize) -> SysResul
 pub fn sys_writev(fd: usize, iov_ptr: *const IoVec, iov_count: usize) -> SysResult {
     info!("writev: fd: {}, iov: {:?}, count: {}", fd, iov_ptr, iov_count);
     let mut proc = process();
-    let iovs = IoVecs::check_and_new(iov_ptr, iov_count, &proc.memory_set,  false)?;
+    let iovs = IoVecs::check_and_new(iov_ptr, iov_count, &proc.memory_set, false)?;
 
-    let file = proc.get_file(fd)?;
     let buf = iovs.read_all_to_vec();
-    let len = file.write(buf.as_slice())?;
-    Ok(len as isize)
+    let len = buf.len();
+
+    match proc.files.get(&fd) {
+        Some(FileLike::File(_)) => sys_write_file(&mut proc, fd, buf.as_ptr(), len),
+        Some(FileLike::Socket(_)) => sys_write_socket(&mut proc, fd, buf.as_ptr(), len),
+        None => Err(SysError::EINVAL)
+    }
 }
 
 pub fn sys_open(path: *const u8, flags: usize, mode: usize) -> SysResult {
@@ -527,7 +532,7 @@ pub fn sys_pipe(fds: *mut u32) -> SysResult {
     info!("pipe: fds: {:?}", fds);
 
     let mut proc = process();
-    proc.memory_set.check_mut_array(fds, 2);
+    proc.memory_set.check_mut_array(fds, 2)?;
     let (read, write) = Pipe::create_pair();
     let read_fd = proc.get_free_inode();
 
@@ -550,6 +555,7 @@ impl Process {
         })
     }
     fn lookup_inode(&self, path: &str) -> Result<Arc<INode>, SysError> {
+        debug!("lookup_inode: cwd {} path {}", self.cwd, path);
         if path.len() > 0 && path.as_bytes()[0] == b'/' {
             // absolute path
             let abs_path = path.split_at(1).1; // skip start '/'
@@ -832,10 +838,13 @@ impl IoVecs {
         let iovs = unsafe { slice::from_raw_parts(iov_ptr, iov_count) }.to_vec();
         // check all bufs in iov
         for iov in iovs.iter() {
-            if readv {
-                vm.check_mut_array(iov.base, iov.len as usize)?;
-            } else {
-                vm.check_array(iov.base, iov.len as usize)?;
+            if iov.len > 0 {
+                // skip empty iov
+                if readv {
+                    vm.check_mut_array(iov.base, iov.len as usize)?;
+                } else {
+                    vm.check_array(iov.base, iov.len as usize)?;
+                }
             }
         }
         let slices = iovs.iter().map(|iov| unsafe { slice::from_raw_parts_mut(iov.base, iov.len as usize) }).collect();
@@ -852,9 +861,16 @@ impl IoVecs {
 
     fn write_all_from_slice(&mut self, buf: &[u8]) {
         let mut copied_len = 0;
+        debug!("copy {:?}", buf);
         for slice in self.0.iter_mut() {
-            slice.copy_from_slice(&buf[copied_len..copied_len + slice.len()]);
-            copied_len += slice.len();
+            let copy_len = min(slice.len(), buf.len() - copied_len);
+            if copy_len == 0 {
+                continue;
+            }
+
+            slice[..copy_len].copy_from_slice(&buf[copied_len..copied_len + copy_len]);
+            debug!("copy to {:?}", slice);
+            copied_len += copy_len;
         }
     }
 
diff --git a/kernel/src/syscall/mem.rs b/kernel/src/syscall/mem.rs
index 6a3bb59..a77cbc9 100644
--- a/kernel/src/syscall/mem.rs
+++ b/kernel/src/syscall/mem.rs
@@ -66,6 +66,5 @@ fn prot_to_attr(prot: MmapProt) -> MemoryAttr {
     let mut attr = MemoryAttr::default().user();
     if prot.contains(MmapProt::EXEC) { attr = attr.execute(); }
     if !prot.contains(MmapProt::WRITE) { attr = attr.readonly(); }
-    assert!(prot.contains(MmapProt::READ));
     attr
 }
\ No newline at end of file
diff --git a/kernel/src/syscall/mod.rs b/kernel/src/syscall/mod.rs
index b2fa883..66afeba 100644
--- a/kernel/src/syscall/mod.rs
+++ b/kernel/src/syscall/mod.rs
@@ -100,6 +100,7 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
 //        160 => sys_setrlimit(),
 //        162 => sys_sync(),
 //        169 => sys_reboot(),
+        186 => sys_gettid(),
         201 => sys_time(args[0] as *mut u64),
         217 => sys_getdents64(args[0], args[1] as *mut LinuxDirent64, args[2]),
 //        293 => sys_pipe(),
diff --git a/kernel/src/syscall/proc.rs b/kernel/src/syscall/proc.rs
index e8bd400..0e776df 100644
--- a/kernel/src/syscall/proc.rs
+++ b/kernel/src/syscall/proc.rs
@@ -117,6 +117,12 @@ pub fn sys_getpid() -> SysResult {
     Ok(thread::current().id() as isize)
 }
 
+/// Get the current thread id
+pub fn sys_gettid() -> SysResult {
+    // use pid as tid for now
+    Ok(thread::current().id() as isize)
+}
+
 /// Get the parent process id
 pub fn sys_getppid() -> SysResult {
     let pid = thread::current().id();