Add FileSystem.lstat support

.changeset/tiny-cats-listen.md

@@ -0,0 +1,6 @@
+---
+"@effect/platform-node-shared": patch
+"effect": patch
+---
+
+Add `FileSystem.lstat` for inspecting symbolic links without following them.

packages/effect/src/FileSystem.ts

@@ -289,6 +289,12 @@ export interface FileSystem {
       readonly mode?: number | undefined
     }
   ) => Sink.Sink<void, Uint8Array, never, PlatformError>
+  /**
+   * Get information about a file at `path` without following symbolic links.
+   */
+  readonly lstat: (
+    path: string
+  ) => Effect.Effect<File.Info, PlatformError>
   /**
    * Get information about a file at `path`.
    */
@@ -978,6 +984,9 @@ export const makeNoop = (fileSystem: Partial<FileSystem>): FileSystem =>
     sink(path) {
       return Sink.fail(notFound("sink", path))
     },
+    lstat(path) {
+      return Effect.fail(notFound("lstat", path))
+    },
     stat(path) {
       return Effect.fail(notFound("stat", path))
     },

packages/platform-node-shared/src/NodeFileSystem.ts

@@ -505,6 +505,14 @@ const makeFileInfo = (stat: NFS.Stats): FileSystem.File.Info => ({
   blksize: stat.blksize !== undefined ? Option.some(FileSystem.Size(stat.blksize)) : Option.none(),
   blocks: Option.fromNullishOr(stat.blocks)
 })
+const lstat = (() => {
+  const nodeLstat = effectify(
+    NFS.lstat,
+    handleErrnoException("FileSystem", "lstat"),
+    handleBadArgument("lstat")
+  )
+  return (path: string) => Effect.map(nodeLstat(path), makeFileInfo)
+})()
 const stat = (() => {
   const nodeStat = effectify(
     NFS.stat,
@@ -636,6 +644,7 @@ const makeFileSystem = Effect.map(Effect.serviceOption(FileSystem.WatchBackend),
     copyFile,
     glob,
     link,
+    lstat,
     makeDirectory,
     makeTempDirectory,
     makeTempDirectoryScoped,

packages/platform-node-shared/test/NodeFileSystem.test.ts

@@ -47,6 +47,23 @@ describe("FileSystem", () => {
       assert(error.reason._tag === "NotFound")
     })))
 
+  it("lstat does not follow symbolic links", () =>
+    runPromise(Effect.scoped(Effect.gen(function*() {
+      const fs = yield* Fs.FileSystem
+      const dir = yield* fs.makeTempDirectoryScoped()
+      const target = `${dir}/target.txt`
+      const link = `${dir}/link.txt`
+
+      yield* fs.writeFileString(target, "target")
+      yield* fs.symlink(target, link)
+
+      const followed = yield* fs.stat(link)
+      const notFollowed = yield* fs.lstat(link)
+
+      assert.strictEqual(followed.type, "File")
+      assert.strictEqual(notFollowed.type, "SymbolicLink")
+    }))))
+
   it("truncate", () =>
     runPromise(Effect.gen(function*() {
       const fs = yield* Fs.FileSystem