From 07a9584a08a23b44ccb95ae60fad8e7345d05e3f Mon Sep 17 00:00:00 2001
From: Pat Hickey <pat@moreproductive.org>
Date: Tue, 5 Jan 2021 12:19:56 -0800
Subject: [PATCH] add hard_link to dir

---
 crates/wasi-c2/TEST_FAILURES              |  6 +++---
 crates/wasi-c2/src/dir.rs                 | 21 +++++++++++++++++++++
 crates/wasi-c2/src/snapshots/preview_1.rs | 18 +++++++++++++++---
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/crates/wasi-c2/TEST_FAILURES b/crates/wasi-c2/TEST_FAILURES
index 866e4a060f..1c45606b01 100644
--- a/crates/wasi-c2/TEST_FAILURES
+++ b/crates/wasi-c2/TEST_FAILURES
@@ -1,17 +1,17 @@
 
 wasi_tests::dangling_symlink
-    - Dir::open_dir nofollow not yet implemented
+    - symlink following behavior not yet implemented
 wasi_tests::directory_seek
     - something weird about directory open rights / fdstat. need debug
       impl of Caps to see about this
 wasi_tests::fd_flags_set
     - set_fdflags is not implemented. test wanted to clear O_APPEND mode
 wasi_tests::nofollow_errors
-    - nofollow not implemented for dirs
+    - symlink following behavior not yet implemented
 wasi_tests::path_filestat
     - fdstat.fs_flags is not populated correctly
 wasi_tests::path_link
-    - path_link is not implemented
+    - symlink following behavior not yet implemented
 wasi_tests::path_rename_trailing_slashes
     - unclear, trailing slash behavior is wrong
 wasi_tests::path_symlink_trailing_slashes
diff --git a/crates/wasi-c2/src/dir.rs b/crates/wasi-c2/src/dir.rs
index d70e3c554c..0e851cd293 100644
--- a/crates/wasi-c2/src/dir.rs
+++ b/crates/wasi-c2/src/dir.rs
@@ -27,6 +27,13 @@ pub trait WasiDir {
     fn read_link(&self, path: &str) -> Result<PathBuf, Error>;
     fn get_filestat(&self) -> Result<Filestat, Error>;
     fn rename(&self, path: &str, dest_dir: &dyn WasiDir, dest_path: &str) -> Result<(), Error>;
+    fn hard_link(
+        &self,
+        path: &str,
+        symlink_follow: bool,
+        target_dir: &dyn WasiDir,
+        target_path: &str,
+    ) -> Result<(), Error>;
 }
 
 pub(crate) struct DirEntry {
@@ -363,4 +370,18 @@ impl WasiDir for cap_std::fs::Dir {
         self.rename(Path::new(src_path), dest_dir, Path::new(dest_path))?;
         Ok(())
     }
+    fn hard_link(
+        &self,
+        src_path: &str,
+        symlink_follow: bool,
+        target_dir: &dyn WasiDir,
+        target_path: &str,
+    ) -> Result<(), Error> {
+        let target_dir = target_dir
+            .as_any()
+            .downcast_ref::<Self>()
+            .ok_or(Error::NotCapable)?;
+        self.hard_link(Path::new(src_path), target_dir, Path::new(target_path))?;
+        Ok(())
+    }
 }
diff --git a/crates/wasi-c2/src/snapshots/preview_1.rs b/crates/wasi-c2/src/snapshots/preview_1.rs
index 9bec5adb6c..04deb9f80b 100644
--- a/crates/wasi-c2/src/snapshots/preview_1.rs
+++ b/crates/wasi-c2/src/snapshots/preview_1.rs
@@ -670,10 +670,22 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
         src_fd: types::Fd,
         src_flags: types::Lookupflags,
         src_path: &GuestPtr<'_, str>,
-        dest_fd: types::Fd,
-        dest_path: &GuestPtr<'_, str>,
+        target_fd: types::Fd,
+        target_path: &GuestPtr<'_, str>,
     ) -> Result<(), Error> {
-        unimplemented!()
+        let table = self.table();
+        let src_entry: Ref<DirEntry> = table.get(u32::from(src_fd))?;
+        let src_dir = src_entry.get_cap(DirCaps::LINK_SOURCE)?;
+        let target_entry: Ref<DirEntry> = table.get(u32::from(target_fd))?;
+        let target_dir = target_entry.get_cap(DirCaps::LINK_TARGET)?;
+        let symlink_follow = src_flags.contains(&types::Lookupflags::SYMLINK_FOLLOW);
+
+        src_dir.hard_link(
+            src_path.as_str()?.deref(),
+            symlink_follow,
+            target_dir.deref(),
+            target_path.as_str()?.deref(),
+        )
     }
 
     fn path_open(