1 files changed, 103 insertions, 0 deletions
diff --git a/std/node/_fs/_fs_open.ts b/std/node/_fs/_fs_open.ts
new file mode 100644
index 000000000..bf53115de
--- /dev/null
+++ b/std/node/_fs/_fs_open.ts
@@ -0,0 +1,103 @@
+import { existsSync } from "../../fs/mod.ts";
+import { fromFileUrl } from "../path.ts";
+import { getOpenOptions } from "./_fs_common.ts";
+
+type openFlags =
+  | "a"
+  | "ax"
+  | "a+"
+  | "ax+"
+  | "as"
+  | "as+"
+  | "r"
+  | "r+"
+  | "rs+"
+  | "w"
+  | "wx"
+  | "w+"
+  | "wx+";
+
+type openCallback = (err: Error | undefined, fd: number) => void;
+
+function convertFlagAndModeToOptions(
+  flag?: openFlags,
+  mode?: number,
+): Deno.OpenOptions | undefined {
+  if (!flag && !mode) return undefined;
+  if (!flag && mode) return { mode };
+  return { ...getOpenOptions(flag), mode };
+}
+
+export function open(path: string | URL, callback: openCallback): void;
+export function open(
+  path: string | URL,
+  flags: openFlags,
+  callback: openCallback,
+): void;
+export function open(
+  path: string | URL,
+  flags: openFlags,
+  mode: number,
+  callback: openCallback,
+): void;
+export function open(
+  path: string | URL,
+  flagsOrCallback: openCallback | openFlags,
+  callbackOrMode?: openCallback | number,
+  maybeCallback?: openCallback,
+) {
+  const flags = typeof flagsOrCallback === "string"
+    ? flagsOrCallback
+    : undefined;
+  const callback = typeof flagsOrCallback === "function"
+    ? flagsOrCallback
+    : typeof callbackOrMode === "function"
+    ? callbackOrMode
+    : maybeCallback;
+  const mode = typeof callbackOrMode === "number" ? callbackOrMode : undefined;
+  path = path instanceof URL ? fromFileUrl(path) : path;
+
+  if (!callback) throw new Error("No callback function supplied");
+
+  if (["ax", "ax+", "wx", "wx+"].includes(flags || "") && existsSync(path)) {
+    const err = new Error(`EEXIST: file already exists, open '${path}'`);
+    callback(err, 0);
+  } else {
+    if (flags === "as" || flags === "as+") {
+      try {
+        const res = openSync(path, flags, mode);
+        callback(undefined, res);
+      } catch (error) {
+        callback(error, error);
+      }
+      return;
+    }
+    Deno.open(path, convertFlagAndModeToOptions(flags, mode))
+      .then((file) => callback(undefined, file.rid))
+      .catch((err) => callback(err, err));
+  }
+}
+
+export function openSync(path: string | URL): number;
+export function openSync(path: string | URL, flags?: openFlags): number;
+export function openSync(path: string | URL, mode?: number): number;
+export function openSync(
+  path: string | URL,
+  flags?: openFlags,
+  mode?: number,
+): number;
+export function openSync(
+  path: string | URL,
+  flagsOrMode?: openFlags | number,
+  maybeMode?: number,
+) {
+  const flags = typeof flagsOrMode === "string" ? flagsOrMode : undefined;
+  const mode = typeof flagsOrMode === "number" ? flagsOrMode : maybeMode;
+  path = path instanceof URL ? fromFileUrl(path) : path;
+
+  if (["ax", "ax+", "wx", "wx+"].includes(flags || "") && existsSync(path)) {
+    throw new Error(`EEXIST: file already exists, open '${path}'`);
+  }
+
+  return Deno.openSync(path, convertFlagAndModeToOptions(flags, mode)).rid;
+}