1 files changed, 78 insertions, 0 deletions
diff --git a/std/node/_fs/_fs_readlink.ts b/std/node/_fs/_fs_readlink.ts
new file mode 100644
index 000000000..d1cb69f51
--- /dev/null
+++ b/std/node/_fs/_fs_readlink.ts
@@ -0,0 +1,78 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import {
+  intoCallbackAPIWithIntercept,
+  MaybeEmpty,
+  notImplemented
+} from "../_utils.ts";
+
+const { readlink: denoReadlink, readlinkSync: denoReadlinkSync } = Deno;
+
+type ReadlinkCallback = (
+  err: MaybeEmpty<Error>,
+  linkString: MaybeEmpty<string | Uint8Array>
+) => void;
+
+interface ReadlinkOptions {
+  encoding?: string | null;
+}
+
+function maybeEncode(
+  data: string,
+  encoding: string | null
+): string | Uint8Array {
+  if (encoding === "buffer") {
+    return new TextEncoder().encode(data);
+  }
+  return data;
+}
+
+function getEncoding(
+  optOrCallback?: ReadlinkOptions | ReadlinkCallback
+): string | null {
+  if (!optOrCallback || typeof optOrCallback === "function") {
+    return null;
+  } else {
+    if (optOrCallback.encoding) {
+      if (
+        optOrCallback.encoding === "utf8" ||
+        optOrCallback.encoding === "utf-8"
+      ) {
+        return "utf8";
+      } else if (optOrCallback.encoding === "buffer") {
+        return "buffer";
+      } else {
+        notImplemented();
+      }
+    }
+    return null;
+  }
+}
+
+export function readlink(
+  path: string,
+  optOrCallback: ReadlinkCallback | ReadlinkOptions,
+  callback?: ReadlinkCallback
+): void {
+  let cb: ReadlinkCallback | undefined;
+  if (typeof optOrCallback === "function") {
+    cb = optOrCallback;
+  } else {
+    cb = callback;
+  }
+
+  const encoding = getEncoding(optOrCallback);
+
+  intoCallbackAPIWithIntercept<string, Uint8Array | string>(
+    denoReadlink,
+    (data: string): string | Uint8Array => maybeEncode(data, encoding),
+    cb,
+    path
+  );
+}
+
+export function readlinkSync(
+  path: string,
+  opt?: ReadlinkOptions
+): string | Uint8Array {
+  return maybeEncode(denoReadlinkSync(path), getEncoding(opt));
+}