fix(util-body-length-node): calculateBodyLength for Readable stream w…

…ith range

A ReadStream created with createReadStream(file, {start: 0, end: 0}) would not be detected by this function, or would falsly just use the size of the original file at body.path. This uses the end and start numbers if present, both are inclusive so 1 is added.

Inclusive according to: https://nodejs.org/api/fs.html#fs_fs_createreadstream_path_options

packages/util-body-length-node/src/index.spec.ts

@@ -1,3 +1,8 @@
+import { promises } from 'fs';
+import { createReadStream, writeFile } from "fs-extra";
+import * as os from "os";
+import * as path from "path";
+
 import { calculateBodyLength } from "./";
 
 const arrayBuffer = new ArrayBuffer(1);
@@ -28,4 +33,28 @@ describe("caclulateBodyLength", () => {
   it("should handle DataView inputs", () => {
     expect(calculateBodyLength(view)).toEqual(1);
   });
+
+  it("should handle a Readable from a file", async () => {
+    const tmpDir = await promises.mkdtemp(path.join(os.tmpdir(), 'test1-'));
+    const filePath = path.join(tmpDir, "foo");
+    await writeFile(filePath, "foo");
+    const handle = await promises.open(filePath, 'r');
+    const readStream = createReadStream(filePath, {fd: handle.fd});
+    expect(calculateBodyLength(readStream)).toEqual(3);
+    readStream.destroy();
+    await promises.unlink(filePath);
+    await promises.rmdir(tmpDir);
+  });
+
+  it("should handle Readable with start end from a file", async () => {
+    const tmpDir = await promises.mkdtemp(path.join(os.tmpdir(), 'test2-'));
+    const filePath = path.join(tmpDir, "foo");
+    await writeFile(filePath, "foo");
+    const handle = await promises.open(filePath, 'r');
+    const readStream = createReadStream(filePath, {fd: handle.fd, start: 1, end: 1});
+    expect(calculateBodyLength(readStream)).toEqual(1);
+    readStream.destroy();
+    await promises.unlink(filePath);
+    await promises.rmdir(tmpDir);
+  });
 });

packages/util-body-length-node/src/index.ts

@@ -11,6 +11,8 @@ export function calculateBodyLength(body: any): number | undefined {
     return body.byteLength;
   } else if (typeof body.size === "number") {
     return body.size;
+  } else if (typeof body.start === "number" && typeof body.end === "number") {
+    return body.end + 1 - body.start;
   } else if (typeof body.path === "string") {
     // handles fs readable streams
     return lstatSync(body.path).size;