Implement sys_getcwd

kernel/src/process/structs.rs

@@ -51,7 +51,7 @@ impl Thread {
             proc: Arc::new(Mutex::new(Process {
                 memory_set: MemorySet::new(),
                 files: BTreeMap::default(),
-                cwd: String::new(),
+                cwd: String::from("/"),
                 sockets: SocketSet::new(vec![])
             })),
         })
@@ -67,7 +67,7 @@ impl Thread {
             proc: Arc::new(Mutex::new(Process {
                 memory_set,
                 files: BTreeMap::default(),
-                cwd: String::new(),
+                cwd: String::from("/"),
                 sockets: SocketSet::new(vec![])
             })),
         })
@@ -146,7 +146,7 @@ impl Thread {
             proc: Arc::new(Mutex::new(Process {
                 memory_set,
                 files,
-                cwd: String::new(),
+                cwd: String::from("/"),
                 sockets: SocketSet::new(vec![])
             })),
         })
@@ -178,7 +178,7 @@ impl Thread {
             proc: Arc::new(Mutex::new(Process {
                 memory_set,
                 files: self.proc.lock().files.clone(),
-                cwd: String::new(),
+                cwd: self.proc.lock().cwd.clone(),
                 // TODO: duplicate sockets for child process
                 sockets: SocketSet::new(vec![])
             })),

kernel/src/syscall/fs.rs

@@ -115,6 +115,21 @@ pub fn sys_close(fd: usize) -> SysResult {
     }
 }
 
+pub fn sys_getcwd(buf: *mut u8, len: usize) -> SysResult {
+    info!("getcwd: buf: {:?}, len: {:#x}", buf, len);
+    let mut proc = process();
+    if !proc.memory_set.check_mut_array(buf, len) {
+        return Err(SysError::EFAULT);
+    }
+    if proc.cwd.len() + 1 > len {
+        return Err(SysError::ERANGE);
+    }
+    unsafe {
+        util::write_cstr(buf, &proc.cwd)
+    }
+    Ok(0)
+}
+
 pub fn sys_stat(path: *const u8, stat_ptr: *mut Stat) -> SysResult {
     warn!("stat is partial implemented as lstat");
     sys_lstat(path, stat_ptr)

kernel/src/syscall/mod.rs

@@ -73,7 +73,7 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
 //        074 => sys_fsync(),
 //        076 => sys_trunc(),
 //        077 => sys_ftrunc(),
-//        079 => sys_getcwd(),
+        079 => sys_getcwd(args[0] as *mut u8, args[1]),
 //        080 => sys_chdir(),
 //        082 => sys_rename(),
 //        083 => sys_mkdir(),