Implement getcwd()

kernel/src/syscall/getcwd.rs

@@ -1,14 +1,27 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use super::SyscallReturn;
-use crate::prelude::*;
+use crate::{
+    fs::fs_resolver::{FsPath, AT_FDCWD},
+    prelude::*,
+};
 
 pub fn sys_getcwd(buf: Vaddr, len: usize, ctx: &Context) -> Result<SyscallReturn> {
-    // TODO: getcwd only return a fake result now
-    let fake_cwd = CString::new("/")?;
-    let bytes = fake_cwd.as_bytes_with_nul();
+    let current = ctx.process;
+    let dirent = current
+        .fs()
+        .read()
+        .lookup(&FsPath::new(AT_FDCWD, "").unwrap())
+        .unwrap();
+    let name = dirent.abs_path();
+
+    debug!("getcwd: {:?}", name);
+
+    let cwd = CString::new(name)?;
+    let bytes = cwd.as_bytes_with_nul();
     let write_len = len.min(bytes.len());
     ctx.get_user_space()
         .write_bytes(buf, &mut VmReader::from(&bytes[..write_len]))?;
+
     Ok(SyscallReturn::Return(write_len as _))
 }