fix wasi-fyi tests (#4708)

lib/virtual-fs/src/arc_fs.rs

@@ -18,6 +18,10 @@ impl ArcFileSystem {
 }
 
 impl FileSystem for ArcFileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        self.fs.readlink(path)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         self.fs.read_dir(path)
     }

lib/virtual-fs/src/empty_fs.rs

@@ -12,6 +12,10 @@ pub struct EmptyFileSystem {}
 
 #[allow(unused_variables)]
 impl FileSystem for EmptyFileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        Err(FsError::EntryNotFound)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         // Special-case the root path by returning an empty iterator.
         // An empty file system should still be readable, just not contain

lib/virtual-fs/src/host_fs.rs

@@ -52,6 +52,10 @@ impl FileSystem {
 }
 
 impl crate::FileSystem for FileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        fs::read_link(path).map_err(Into::into)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         let read_dir = fs::read_dir(path)?;
         let mut data = read_dir
@@ -153,6 +157,12 @@ impl crate::FileSystem for FileSystem {
             .and_then(TryInto::try_into)
             .map_err(Into::into)
     }
+
+    fn symlink_metadata(&self, path: &Path) -> Result<Metadata> {
+        fs::symlink_metadata(path)
+            .and_then(TryInto::try_into)
+            .map_err(Into::into)
+    }
 }
 
 impl TryInto<Metadata> for std::fs::Metadata {

lib/virtual-fs/src/lib.rs

@@ -91,6 +91,7 @@ pub trait ClonableVirtualFile: VirtualFile + Clone {}
 pub use ops::{copy_reference, copy_reference_ext};
 
 pub trait FileSystem: fmt::Debug + Send + Sync + 'static + Upcastable {
+    fn readlink(&self, path: &Path) -> Result<PathBuf>;
     fn read_dir(&self, path: &Path) -> Result<ReadDir>;
     fn create_dir(&self, path: &Path) -> Result<()>;
     fn remove_dir(&self, path: &Path) -> Result<()>;
@@ -99,9 +100,7 @@ pub trait FileSystem: fmt::Debug + Send + Sync + 'static + Upcastable {
     /// This method gets metadata without following symlinks in the path.
     /// Currently identical to `metadata` because symlinks aren't implemented
     /// yet.
-    fn symlink_metadata(&self, path: &Path) -> Result<Metadata> {
-        self.metadata(path)
-    }
+    fn symlink_metadata(&self, path: &Path) -> Result<Metadata>;
     fn remove_file(&self, path: &Path) -> Result<()>;
 
     fn new_open_options(&self) -> OpenOptions;
@@ -128,6 +127,10 @@ where
         (**self).read_dir(path)
     }
 
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        (**self).readlink(path)
+    }
+
     fn create_dir(&self, path: &Path) -> Result<()> {
         (**self).create_dir(path)
     }
@@ -144,6 +147,10 @@ where
         (**self).metadata(path)
     }
 
+    fn symlink_metadata(&self, path: &Path) -> Result<Metadata> {
+        (**self).symlink_metadata(path)
+    }
+
     fn remove_file(&self, path: &Path) -> Result<()> {
         (**self).remove_file(path)
     }

lib/virtual-fs/src/mem_fs/filesystem.rs

@@ -257,6 +257,18 @@ impl FileSystem {
 }
 
 impl crate::FileSystem for FileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        // Read lock.
+        let guard = self.inner.read().map_err(|_| FsError::Lock)?;
+
+        // Canonicalize the path.
+        let (_, inode_of_directory) = guard.canonicalize(path)?;
+        match inode_of_directory {
+            InodeResolution::Found(_) => Err(FsError::InvalidInput),
+            InodeResolution::Redirect(fs, path) => fs.readlink(path.as_path()),
+        }
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         // Read lock.
         let guard = self.inner.read().map_err(|_| FsError::Lock)?;
@@ -591,6 +603,23 @@ impl crate::FileSystem for FileSystem {
         }
     }
 
+    fn symlink_metadata(&self, path: &Path) -> Result<Metadata> {
+        // Read lock.
+        let guard = self.inner.read().map_err(|_| FsError::Lock)?;
+        match guard.inode_of(path)? {
+            InodeResolution::Found(inode) => Ok(guard
+                .storage
+                .get(inode)
+                .ok_or(FsError::UnknownError)?
+                .metadata()
+                .clone()),
+            InodeResolution::Redirect(fs, path) => {
+                drop(guard);
+                fs.symlink_metadata(path.as_path())
+            }
+        }
+    }
+
     fn remove_file(&self, path: &Path) -> Result<()> {
         let (inode_of_parent, position, inode_of_file) = {
             // Read lock.

lib/virtual-fs/src/overlay_fs.rs

@@ -113,6 +113,35 @@ where
     S: for<'a> FileSystems<'a> + Send + Sync + 'static,
     for<'a> <<S as FileSystems<'a>>::Iter as IntoIterator>::IntoIter: Send,
 {
+    fn readlink(&self, path: &Path) -> crate::Result<PathBuf> {
+        // Whiteout files can not be read, they are just markers
+        if ops::is_white_out(path).is_some() {
+            return Err(FsError::EntryNotFound);
+        }
+
+        // Check if the file is in the primary
+        match self.primary.readlink(path) {
+            Ok(meta) => return Ok(meta),
+            Err(e) if should_continue(e) => {}
+            Err(e) => return Err(e),
+        }
+
+        // There might be a whiteout, search for this
+        if ops::has_white_out(&self.primary, path) {
+            return Err(FsError::EntryNotFound);
+        }
+
+        // Otherwise scan the secondaries
+        for fs in self.secondaries.filesystems() {
+            match fs.readlink(path) {
+                Err(e) if should_continue(e) => continue,
+                other => return other,
+            }
+        }
+
+        Err(FsError::EntryNotFound)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir, FsError> {
         let mut entries = Vec::new();
         let mut had_at_least_one_success = false;
@@ -328,6 +357,35 @@ where
         Err(FsError::EntryNotFound)
     }
 
+    fn symlink_metadata(&self, path: &Path) -> crate::Result<Metadata> {
+        // Whiteout files can not be read, they are just markers
+        if ops::is_white_out(path).is_some() {
+            return Err(FsError::EntryNotFound);
+        }
+
+        // Check if the file is in the primary
+        match self.primary.symlink_metadata(path) {
+            Ok(meta) => return Ok(meta),
+            Err(e) if should_continue(e) => {}
+            Err(e) => return Err(e),
+        }
+
+        // There might be a whiteout, search for this
+        if ops::has_white_out(&self.primary, path) {
+            return Err(FsError::EntryNotFound);
+        }
+
+        // Otherwise scan the secondaries
+        for fs in self.secondaries.filesystems() {
+            match fs.symlink_metadata(path) {
+                Err(e) if should_continue(e) => continue,
+                other => return other,
+            }
+        }
+
+        Err(FsError::EntryNotFound)
+    }
+
     fn remove_file(&self, path: &Path) -> Result<(), FsError> {
         // It is not possible to delete whiteout files directly, instead
         // one must delete the original file

lib/virtual-fs/src/passthru_fs.rs

@@ -18,6 +18,10 @@ impl PassthruFileSystem {
 }
 
 impl FileSystem for PassthruFileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        self.fs.readlink(path)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         self.fs.read_dir(path)
     }

lib/virtual-fs/src/scoped_directory_fs.rs

@@ -51,6 +51,11 @@ impl ScopedDirectoryFileSystem {
 }
 
 impl FileSystem for ScopedDirectoryFileSystem {
+    fn readlink(&self, path: &Path) -> crate::Result<PathBuf> {
+        let path = self.prepare_path(path);
+        self.inner.readlink(&path)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir, FsError> {
         let path = self.prepare_path(path);
 
@@ -94,6 +99,11 @@ impl FileSystem for ScopedDirectoryFileSystem {
         self.inner.metadata(&path)
     }
 
+    fn symlink_metadata(&self, path: &Path) -> crate::Result<Metadata> {
+        let path = self.prepare_path(path);
+        self.inner.symlink_metadata(&path)
+    }
+
     fn remove_file(&self, path: &Path) -> Result<(), FsError> {
         let path = self.prepare_path(path);
         self.inner.remove_file(&path)

lib/virtual-fs/src/static_fs.rs

@@ -238,6 +238,20 @@ fn transform_into_read_dir(path: &Path, fs_entries: &[FsEntry<'_>]) -> crate::Re
 }
 
 impl FileSystem for StaticFileSystem {
+    fn readlink(&self, path: &Path) -> crate::Result<PathBuf> {
+        let path = normalizes_path(path);
+        if self
+            .volumes
+            .values()
+            .find_map(|v| v.get_file_entry(&path).ok())
+            .is_some()
+        {
+            Err(FsError::InvalidInput)
+        } else {
+            self.memory.readlink(Path::new(&path))
+        }
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir, FsError> {
         let path = normalizes_path(path);
         for volume in self.volumes.values() {

lib/virtual-fs/src/tmp_fs.rs

@@ -61,6 +61,10 @@ impl TmpFileSystem {
 }
 
 impl FileSystem for TmpFileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        self.fs.readlink(path)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         self.fs.read_dir(path)
     }

lib/virtual-fs/src/trace_fs.rs

@@ -39,6 +39,11 @@ impl<F> FileSystem for TraceFileSystem<F>
 where
     F: FileSystem,
 {
+    #[tracing::instrument(level = "trace", skip(self), err)]
+    fn readlink(&self, path: &std::path::Path) -> crate::Result<PathBuf> {
+        self.0.readlink(path)
+    }
+
     #[tracing::instrument(level = "trace", skip(self), err)]
     fn read_dir(&self, path: &std::path::Path) -> crate::Result<crate::ReadDir> {
         self.0.read_dir(path)
@@ -68,6 +73,11 @@ where
         self.0.metadata(path)
     }
 
+    #[tracing::instrument(level = "trace", skip(self), err)]
+    fn symlink_metadata(&self, path: &std::path::Path) -> crate::Result<crate::Metadata> {
+        self.0.symlink_metadata(path)
+    }
+
     #[tracing::instrument(level = "trace", skip(self), err)]
     fn remove_file(&self, path: &std::path::Path) -> crate::Result<()> {
         self.0.remove_file(path)

lib/virtual-fs/src/union_fs.rs

@@ -206,6 +206,32 @@ impl UnionFileSystem {
 }
 
 impl FileSystem for UnionFileSystem {
+    fn readlink(&self, path: &Path) -> Result<PathBuf> {
+        debug!("readlink: path={}", path.display());
+        let mut ret_error = FsError::EntryNotFound;
+        let path = path.to_string_lossy();
+        for (path_inner, mount) in filter_mounts(&self.mounts, path.as_ref()) {
+            match mount.fs.readlink(Path::new(path_inner.as_str())) {
+                Ok(ret) => {
+                    return Ok(ret);
+                }
+                Err(err) => {
+                    // This fixes a bug when attempting to create the directory /usr when it does not exist
+                    // on the x86 version of memfs
+                    // TODO: patch virtual-fs and remove
+                    if let FsError::NotAFile = &err {
+                        ret_error = FsError::EntryNotFound;
+                    } else {
+                        debug!("readlink failed: (path={}) - {}", path, err);
+                        ret_error = err;
+                    }
+                }
+            }
+        }
+        debug!("readlink: failed={}", ret_error);
+        Err(ret_error)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir> {
         debug!("read_dir: path={}", path.display());
         self.read_dir_internal(path)

lib/virtual-fs/src/webc_fs.rs

@@ -304,6 +304,10 @@ where
     T: std::fmt::Debug + Send + Sync + 'static,
     T: Deref<Target = WebC<'static>>,
 {
+    fn readlink(&self, _path: &Path) -> crate::Result<PathBuf> {
+        Err(FsError::InvalidInput)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<ReadDir, FsError> {
         let path = normalizes_path(path);
         let read_dir_result = self

lib/virtual-fs/src/webc_volume_fs.rs

@@ -49,6 +49,10 @@ impl WebcVolumeFileSystem {
 }
 
 impl FileSystem for WebcVolumeFileSystem {
+    fn readlink(&self, _path: &Path) -> crate::Result<PathBuf> {
+        Err(FsError::InvalidInput)
+    }
+
     fn read_dir(&self, path: &Path) -> Result<crate::ReadDir, FsError> {
         let meta = self.metadata(path)?;
 
@@ -134,6 +138,10 @@ impl FileSystem for WebcVolumeFileSystem {
             .ok_or(FsError::EntryNotFound)
     }
 
+    fn symlink_metadata(&self, path: &Path) -> crate::Result<Metadata> {
+        self.metadata(path)
+    }
+
     fn remove_file(&self, path: &Path) -> Result<(), FsError> {
         let meta = self.metadata(path)?;
 

lib/wasix/src/fs/mod.rs

@@ -308,6 +308,13 @@ impl WasiFsRoot {
 }
 
 impl FileSystem for WasiFsRoot {
+    fn readlink(&self, path: &Path) -> virtual_fs::Result<PathBuf> {
+        match self {
+            WasiFsRoot::Sandbox(fs) => fs.readlink(path),
+            WasiFsRoot::Backing(fs) => fs.readlink(path),
+        }
+    }
+
     fn read_dir(&self, path: &Path) -> virtual_fs::Result<virtual_fs::ReadDir> {
         match self {
             WasiFsRoot::Sandbox(fs) => fs.read_dir(path),
@@ -992,7 +999,8 @@ impl WasiFs {
                                 }
                             } else if file_type.is_symlink() {
                                 should_insert = false;
-                                let link_value = file.read_link().map_err(map_io_err)?;
+                                let link_value =
+                                    self.root_fs.readlink(&file).ok().ok_or(Errno::Noent)?;
                                 debug!("attempting to decompose path {:?}", link_value);
 
                                 let (pre_open_dir_fd, relative_path) = if link_value.is_relative() {
@@ -2026,6 +2034,9 @@ impl FallbackFileSystem {
 }
 
 impl FileSystem for FallbackFileSystem {
+    fn readlink(&self, _path: &Path) -> virtual_fs::Result<PathBuf> {
+        Self::fail()
+    }
     fn read_dir(&self, _path: &Path) -> Result<virtual_fs::ReadDir, FsError> {
         Self::fail();
     }