impl sys_getppid. fix checking pointer for process syscalls

crate/thread/src/thread_pool.rs

@@ -198,6 +198,9 @@ impl ThreadPool {
     pub fn get_children(&self, tid: Tid) -> Vec<Tid> {
         self.threads[tid].lock().as_ref().expect("process not exist").children.clone()
     }
+    pub fn get_parent(&self, tid: Tid) -> Tid {
+        self.threads[tid].lock().as_ref().expect("process not exist").parent
+    }
 
     pub fn exit(&self, tid: Tid, code: ExitCode) {
         // NOTE: if `tid` is running, status change will be deferred.

kernel/src/syscall/mod.rs

@@ -50,7 +50,6 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
 //        034 => sys_pause(),
         035 => sys_sleep(args[0]), // TODO: nanosleep
         039 => sys_getpid(),
-//        040 => sys_getppid(),
         041 => sys_socket(args[0], args[1], args[2]),
         042 => sys_connect(args[0], args[1] as *const u8, args[2]),
 //        043 => sys_accept(),
@@ -82,6 +81,7 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
         096 => sys_get_time(), // TODO: sys_gettimeofday
 //        097 => sys_getrlimit(),
 //        098 => sys_getrusage(),
+        110 => sys_getppid(),
 //        133 => sys_mknod(),
         141 => sys_set_priority(args[0]),
 //        160 => sys_setrlimit(),

kernel/src/syscall/proc.rs

@@ -13,7 +13,9 @@ pub fn sys_fork(tf: &TrapFrame) -> SysResult {
 /// Wait the process exit.
 /// Return the PID. Store exit code to `code` if it's not null.
 pub fn sys_wait(pid: usize, code: *mut i32) -> SysResult {
-    // TODO: check ptr
+    if !process().memory_set.check_mut_ptr(code) {
+        return Err(SysError::EFAULT);
+    }
     loop {
         use alloc::vec;
         let wait_procs = match pid {
@@ -49,19 +51,25 @@ pub fn sys_wait(pid: usize, code: *mut i32) -> SysResult {
 }
 
 pub fn sys_exec(name: *const u8, argc: usize, argv: *const *const u8, tf: &mut TrapFrame) -> SysResult {
-    // TODO: check ptr
+    let proc = process();
-    let name = if name.is_null() { "" } else { unsafe { util::from_cstr(name) } };
+    let name = if name.is_null() { String::from("") } else {
-    info!("exec: {:?}, argc: {}, argv: {:?}", name, argc, argv);
+        unsafe { proc.memory_set.check_and_clone_cstr(name) }
-    // Copy args to kernel
+            .ok_or(SysError::EFAULT)?
-    let args: Vec<String> = unsafe {
-        slice::from_raw_parts(argv, argc).iter()
-            .map(|&arg| String::from(util::from_cstr(arg)))
-            .collect()
     };
-
+    if argc <= 0 {
-    if args.len() <= 0 {
         return Err(SysError::EINVAL);
     }
+    // Check and copy args to kernel
+    let mut args = Vec::new();
+    unsafe {
+        for &ptr in slice::from_raw_parts(argv, argc) {
+            let arg = proc.memory_set.check_and_clone_cstr(ptr)
+                .ok_or(SysError::EFAULT)?;
+            args.push(arg);
+        }
+    }
+    info!("exec: name: {:?}, args: {:?}", name, args);
+
     // Read program file
     let path = args[0].as_str();
     let inode = crate::fs::ROOT_INODE.lookup(path)?;
@@ -107,6 +115,13 @@ pub fn sys_getpid() -> SysResult {
     Ok(thread::current().id() as isize)
 }
 
+/// Get the parent process id
+pub fn sys_getppid() -> SysResult {
+    let pid = thread::current().id();
+    let ppid = processor().manager().get_parent(pid);
+    Ok(ppid as isize)
+}
+
 /// Exit the current process
 pub fn sys_exit(exit_code: isize) -> ! {
     let pid = thread::current().id();