use `options.fd` if provided for `fs.Read/WriteStream` (#4378)

* use `options.fd` over path

* tests

* fix `@clack/prompts`

* == null

2 files changed, 38 insertions, 34 deletions

diff --git a/src/js/node/fs.js b/src/js/node/fs.js
index 9cc0748cb..a6b1adb88 100644
--- a/src/js/node/fs.js
+++ b/src/js/node/fs.js
@@ -345,7 +345,7 @@ var kIoDone = Symbol.for("kIoDone");
 
 var defaultReadStreamOptions = {
   file: undefined,
-  fd: undefined,
+  fd: null,
   flags: "r",
   encoding: undefined,
   mode: 0o666,
@@ -408,6 +408,7 @@ ReadStream = (function (InternalReadStream) {
         autoDestroy = defaultReadStreamOptions.autoClose,
         fs = defaultReadStreamOptions.fs,
         highWaterMark = defaultReadStreamOptions.highWaterMark,
+        fd = defaultReadStreamOptions.fd,
       } = options;
 
       if (pathOrFd?.constructor?.name === "URL") {
@@ -416,7 +417,13 @@ ReadStream = (function (InternalReadStream) {
 
       // This is kinda hacky but we create a temporary object to assign props that we will later pull into the `this` context after we call super
       var tempThis = {};
-      if (typeof pathOrFd === "string") {
+      if (fd != null) {
+        if (typeof fd !== "number") {
+          throw new TypeError("Expected options.fd to be a number");
+        }
+        tempThis.fd = tempThis[readStreamPathOrFdSymbol] = fd;
+        tempThis.autoClose = false;
+      } else if (typeof pathOrFd === "string") {
         if (pathOrFd.startsWith("file://")) {
           pathOrFd = Bun.fileURLToPath(pathOrFd);
         }
@@ -437,7 +444,7 @@ ReadStream = (function (InternalReadStream) {
       }
 
       // If fd not open for this file, open it
-      if (!tempThis.fd) {
+      if (tempThis.fd === undefined) {
         // NOTE: this fs is local to constructor, from options
         tempThis.fd = fs.openSync(pathOrFd, flags, mode);
       }
@@ -756,7 +763,13 @@ WriteStream = (function (InternalWriteStream) {
       } = options;
 
       var tempThis = {};
-      if (typeof path === "string") {
+      if (fd != null) {
+        if (typeof fd !== "number") {
+          throw new Error("Expected options.fd to be a number");
+        }
+        tempThis.fd = fd;
+        tempThis[writeStreamPathFastPathSymbol] = false;
+      } else if (typeof path === "string") {
         if (path.length === 0) {
           throw new TypeError("Expected a non-empty path");
         }
@@ -772,12 +785,9 @@ WriteStream = (function (InternalWriteStream) {
           (start === undefined || start === 0) &&
           fs.write === defaultWriteStreamOptions.fs.write &&
           fs.close === defaultWriteStreamOptions.fs.close;
-      } else {
-        tempThis.fd = fd;
-        tempThis[writeStreamPathFastPathSymbol] = false;
       }
 
-      if (!tempThis.fd) {
+      if (tempThis.fd == null) {
         tempThis.fd = fs.openSync(path, flags, mode);
       }
 
@@ -960,30 +970,20 @@ WriteStream = (function (InternalWriteStream) {
 
       // TODO: Replace this when something like lseek is available
       var native = this.pos === undefined;
+      const callback = native
+        ? (err, bytes) => {
+            this[kIoDone] = false;
+            this.#handleWrite(err, bytes);
+            this.emit(kIoDone);
+            if (cb) !err ? cb() : cb(err);
+          }
+        : () => {};
       this[kIoDone] = true;
-      return super.write(
-        chunk,
-        encoding,
-        native
-          ? (err, bytes) => {
-              this[kIoDone] = false;
-              this.#handleWrite(err, bytes);
-              this.emit(kIoDone);
-              if (cb) !err ? cb() : cb(err);
-            }
-          : () => {},
-        native,
-      );
-    }
-
-    #internalWriteSlow(chunk, encoding, cb) {
-      this.#fs.write(this.fd, chunk, 0, chunk.length, this.pos, (err, bytes) => {
-        this[kIoDone] = false;
-        this.#handleWrite(err, bytes);
-        this.emit(kIoDone);
-
-        !err ? cb() : cb(err);
-      });
+      if (this._write) {
+        return this._write(chunk, encoding, callback);
+      } else {
+        return super.write(chunk, encoding, callback, native);
+      }
     }
 
     end(chunk, encoding, cb) {
@@ -991,7 +991,7 @@ WriteStream = (function (InternalWriteStream) {
       return super.end(chunk, encoding, cb, native);
     }
 
-    _write = this.#internalWriteSlow;
+    _write = undefined;
     _writev = undefined;
 
     get pending() {
diff --git a/src/js/node/tty.js b/src/js/node/tty.js
index 09010e8fc..d5645c6da 100644
--- a/src/js/node/tty.js
+++ b/src/js/node/tty.js
@@ -4,7 +4,9 @@ function ReadStream(fd) {
   if (!(this instanceof ReadStream)) return new ReadStream(fd);
   if (fd >> 0 !== fd || fd < 0) throw new RangeError("fd must be a positive integer");
 
-  const stream = require("node:fs").ReadStream.call(this, `/dev/fd/${fd}`);
+  const stream = require("node:fs").ReadStream.call(this, "", {
+    fd,
+  });
 
   stream.isRaw = false;
   stream.isTTY = isatty(stream.fd);
@@ -93,7 +95,9 @@ function WriteStream(fd) {
   if (!(this instanceof WriteStream)) return new WriteStream(fd);
   if (fd >> 0 !== fd || fd < 0) throw new RangeError("fd must be a positive integer");
 
-  const stream = require("node:fs").WriteStream.call(this, `/dev/fd/${fd}`);
+  const stream = require("node:fs").WriteStream.call(this, "", {
+    fd,
+  });
 
   stream.columns = undefined;
   stream.rows = undefined;