mikros: Add CWD support

library/std/src/sys/pal/mikros/common.rs

@@ -8,6 +8,7 @@ pub unsafe fn init(_argc: isize, _argv: *const *const u8, _sigpipe: u8) {
     rpc::init();
     super::stdio::init();
     super::args::init();
+    super::os::init_cwd();
 }
 
 // SAFETY: must be called only once during runtime cleanup.

library/std/src/sys/pal/mikros/fs.rs

@@ -1,8 +1,8 @@
 // use super::rmp_serde;
-use serde::{Serialize, Serializer};
+use serde::de::{Unexpected, Visitor};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use crate::ffi::OsString;
-use crate::fmt;
 use crate::hash::{Hash, Hasher};
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, SeekFrom};
 use crate::os::mikros::ipc::rpc;
@@ -10,6 +10,7 @@
 use crate::path::{Path, PathBuf};
 use crate::sys::time::SystemTime;
 use crate::sys::unsupported;
+use crate::{fmt, str};
 
 #[unstable(feature = "rmp", issue = "none")]
 impl Serialize for Path {
@@ -34,6 +35,99 @@ fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     }
 }
 
+#[unstable(feature = "rmp", issue = "none")]
+struct PathVisitor;
+
+#[unstable(feature = "rmp", issue = "none")]
+impl<'a> Visitor<'a> for PathVisitor {
+    type Value = &'a Path;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str("a borrowed path")
+    }
+
+    fn visit_borrowed_str<E>(self, v: &'a str) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(v.as_ref())
+    }
+
+    fn visit_borrowed_bytes<E>(self, v: &'a [u8]) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        str::from_utf8(v)
+            .map(AsRef::as_ref)
+            .map_err(|_| serde::de::Error::invalid_value(Unexpected::Bytes(v), &self))
+    }
+}
+
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+#[unstable(feature = "rmp", issue = "none")]
+impl<'de: 'a, 'a> Deserialize<'de> for &'a Path {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_str(PathVisitor)
+    }
+}
+
+#[unstable(feature = "rmp", issue = "none")]
+struct PathBufVisitor;
+
+#[unstable(feature = "rmp", issue = "none")]
+impl<'de> Visitor<'de> for PathBufVisitor {
+    type Value = PathBuf;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str("path string")
+    }
+
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(From::from(v))
+    }
+
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(From::from(v))
+    }
+
+    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        str::from_utf8(v)
+            .map(From::from)
+            .map_err(|_| serde::de::Error::invalid_value(Unexpected::Bytes(v), &self))
+    }
+
+    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        String::from_utf8(v)
+            .map(From::from)
+            .map_err(|e| serde::de::Error::invalid_value(Unexpected::Bytes(&e.into_bytes()), &self))
+    }
+}
+
+#[unstable(feature = "rmp", issue = "none")]
+impl<'de> Deserialize<'de> for PathBuf {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_string(PathBufVisitor)
+    }
+}
+
 pub struct File {
     pub(crate) fs_pid: u64,
     pub(crate) fd: u64,

library/std/src/sys/pal/mikros/os.rs

@@ -3,9 +3,13 @@
 use crate::ffi::{OsStr, OsString};
 use crate::marker::PhantomData;
 use crate::os::mikros::Errno;
-use crate::path::{self, PathBuf};
+use crate::os::mikros::ipc::rpc;
+use crate::path::{self, Component, Path, PathBuf};
+use crate::sync::Mutex;
 use crate::{fmt, io};
 
+static CWD: Mutex<Option<PathBuf>> = Mutex::new(None);
+
 pub fn errno() -> Errno {
     Errno::EIO
 }
@@ -153,11 +157,48 @@ pub fn error_string(errno: Errno) -> String {
 }
 
 pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
+    Ok(CWD.lock().unwrap().clone().unwrap())
 }
 
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
+fn canonicalize_path(path: &Path) -> PathBuf {
+    path.components().fold(PathBuf::from("/"), |mut buf, component| match component {
+        Component::Prefix(_) => unreachable!(),
+        Component::RootDir | Component::Normal(_) => {
+            buf.push(component);
+            buf
+        }
+        Component::CurDir => buf,
+        Component::ParentDir => {
+            buf.pop();
+            buf
+        }
+    })
+}
+
+pub fn chdir(path: &path::Path) -> io::Result<()> {
+    let cwd = getcwd()?;
+    let abs_path = if path.is_relative() {
+        let mut abs_path = cwd.clone();
+        abs_path.push(path);
+        canonicalize_path(&abs_path)
+    } else {
+        path.to_owned()
+    };
+    // Try to open the given directory, if it fails it's not a valid directory.
+    // Use Metadata instead once it's implemented.
+    crate::fs::read_dir(&abs_path)?;
+    *CWD.lock().unwrap() = Some(abs_path);
+    Ok(())
+}
+
+pub fn init_cwd() {
+    let Some(proc_man_pid) = syscalls::try_get_registered(3) else {
+        *CWD.lock().unwrap() = Some(PathBuf::from("/"));
+        return;
+    };
+    let cwd: PathBuf =
+        postcard::from_bytes(&rpc::send_call(proc_man_pid, 8, 10, &[]).get_return()).unwrap();
+    *CWD.lock().unwrap() = Some(cwd);
 }
 
 pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);

library/std/src/sys/pal/mikros/process.rs

@@ -1,3 +1,4 @@
+use super::os::getcwd;
 use super::stdio::{STDERR_FD, STDIN_FD, STDOUT_FD};
 use super::syscalls;
 pub use crate::ffi::OsString as EnvKey;
@@ -147,6 +148,17 @@ pub fn spawn(
             )
             .unwrap();
             res?;
+            let res: Result<(), Errno> = postcard::from_bytes(
+                &rpc::send_call(
+                    proc_man_pid,
+                    8,
+                    9,
+                    &postcard::to_allocvec(&(pid, getcwd()?)).unwrap(),
+                )
+                .get_return(),
+            )
+            .unwrap();
+            res?;
         };
         syscalls::wake_new(pid).unwrap();
         Ok((Process { pid }, StdioPipes { stdin: None, stdout: None, stderr: None }))