Dir::hard_link: dont support symlink following

if we're asked to follow symlinks, give ERRNO_INVAL instead.

crates/wasi-c2/cap-std-sync/src/dir.rs

@@ -200,7 +200,6 @@ impl WasiDir for Dir {
     fn hard_link(
         &self,
         src_path: &str,
-        symlink_follow: bool, // XXX not in cap-std yet
         target_dir: &dyn WasiDir,
         target_path: &str,
     ) -> Result<(), Error> {

crates/wasi-c2/src/dir.rs

@@ -32,7 +32,6 @@ pub trait WasiDir {
     fn hard_link(
         &self,
         path: &str,
-        symlink_follow: bool,
         target_dir: &dyn WasiDir,
         target_path: &str,
     ) -> Result<(), Error>;

crates/wasi-c2/src/snapshots/preview_1.rs

@@ -749,10 +749,13 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
             .get_dir(u32::from(target_fd))?
             .get_cap(DirCaps::LINK_TARGET)?;
         let symlink_follow = src_flags.contains(types::Lookupflags::SYMLINK_FOLLOW);
+        if symlink_follow {
+            return Err(Error::invalid_argument()
+                .context("symlink following on path_link is not supported"));
+        }
 
         src_dir.hard_link(
             src_path.as_str()?.deref(),
-            symlink_follow,
             target_dir.deref(),
             target_path.as_str()?.deref(),
         )