[node] Allow SharedArrayBuffer in Buffer.from (#27933)

* Move from namespace to static attributes

* Allow SharedArrayBuffer in Buffer.from

* Address comments

* Add SharedArrayBuffer to byteLength

* Fix tests

types/node/index.d.ts

@@ -26,6 +26,7 @@
 //                 Lishude <https://github.com/islishude>
 //                 Andrew Makarov <https://github.com/r3nya>
 //                 Zane Hannan AU <https://github.com/ZaneHannanAU>
+//                 Thomas den Hollander <https://github.com/ThomasdenH>
 //                 Eugene Y. Q. Shen <https://github.com/eyqs>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
@@ -172,6 +173,10 @@ interface SymbolConstructor {
     readonly asyncIterator: symbol;
 }
 declare var Symbol: SymbolConstructor;
+interface SharedArrayBuffer {
+    readonly byteLength: number;
+    slice(begin?: number, end?: number): SharedArrayBuffer;
+}
 
 // Node.js ESNEXT support
 interface String {
@@ -349,13 +354,13 @@ declare var Buffer: {
     new(array: Uint8Array): Buffer;
     /**
      * Produces a Buffer backed by the same allocated memory as
-     * the given {ArrayBuffer}.
+     * the given {ArrayBuffer}/{SharedArrayBuffer}.
      *
      *
      * @param arrayBuffer The ArrayBuffer with which to share memory.
      * @deprecated since v10.0.0 - Use `Buffer.from(arrayBuffer[, byteOffset[, length]])` instead.
      */
-    new(arrayBuffer: ArrayBuffer): Buffer;
+    new(arrayBuffer: ArrayBuffer | SharedArrayBuffer): Buffer;
     /**
      * Allocates a new buffer containing the given {array} of octets.
      *
@@ -379,8 +384,7 @@ declare var Buffer: {
      *
      * @param arrayBuffer The .buffer property of any TypedArray or a new ArrayBuffer()
      */
-    from(arrayBuffer: ArrayBuffer, byteOffset?: number, length?: number): Buffer;
-    // from(arrayBuffer: SharedArrayBuffer, byteOffset?: number, length?: number): Buffer;
+    from(arrayBuffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): Buffer;
     /**
      * Creates a new Buffer using the passed {data}
      * @param data data to create a new Buffer
@@ -418,7 +422,7 @@ declare var Buffer: {
      * @param string string to test.
      * @param encoding encoding used to evaluate (defaults to 'utf8')
      */
-    byteLength(string: string | NodeJS.TypedArray | DataView | ArrayBuffer /*| SharedArrayBuffer */, encoding?: string): number;
+    byteLength(string: string | NodeJS.TypedArray | DataView | ArrayBuffer | SharedArrayBuffer, encoding?: string): number;
     /**
      * Returns a buffer which is the result of concatenating all the buffers in the list together.
      *

types/node/node-tests.ts

@@ -446,6 +446,11 @@ function bufferTests() {
         const arrUint8: Uint8Array = new Uint8Array(2);
         const buf5: Buffer = Buffer.from(arrUint8);
         const buf6: Buffer = Buffer.from(buf1);
+        const sharedArrayBuffer: SharedArrayBuffer = {
+            byteLength: 10,
+            slice: (begin?: number, end?: number) => sharedArrayBuffer
+        };
+        const buf7: Buffer = Buffer.from(sharedArrayBuffer);
     }
 
     // Class Method: Buffer.from(arrayBuffer[, byteOffset[, length]])