From b3d55d9194e7a98ef0abcc2b4e26436654be8646 Mon Sep 17 00:00:00 2001
From: Will Fancher <elvishjerricco@gmail.com>
Date: Thu, 2 Aug 2018 01:14:23 -0400
Subject: [PATCH] Use async / await, like civilized people.

---
 example/src/index.ts | 18 ++++++++-------
 kernel/src/index.ts  | 55 ++++++++++++++++++++++++++------------------
 2 files changed, 42 insertions(+), 31 deletions(-)

diff --git a/example/src/index.ts b/example/src/index.ts
index d67fc5c..71d38dc 100644
--- a/example/src/index.ts
+++ b/example/src/index.ts
@@ -1,4 +1,4 @@
-import { Device, configureFileSystem, BFSCallback, Stats, File, FileFlag } from "webabi-kernel";
+import { Device, configureFileSystem, BFSCallback, Stats, File, FileFlag, FS, asyncRead, asyncWrite } from "webabi-kernel";
 
 class JSaddleDevice implements Device {
   open(flag: FileFlag, cb: BFSCallback<File>): void {
@@ -7,12 +7,14 @@ class JSaddleDevice implements Device {
   }
 }
 
-configureFileSystem({ "/jsaddle": new JSaddleDevice() }, (err, fs) => {
-  console.log(err);
+async function main() {
+  let fs = await configureFileSystem({ "/jsaddle": new JSaddleDevice() });
   let buf = Buffer.from("foo\n");
-  fs.write(1, buf, 0, buf.length, null, () => {
-    fs.read(0, buf, 0, 4, null, (err, n, buf) => {
-      console.log({ err: err, n: n, buf: buf && buf.toString() });
-    });
-  });
+  await asyncWrite(fs, 1, buf, 0, buf.length, null);
+  const { byteLength } = await asyncRead(fs, 0, buf, 0, buf.length, null);
+  console.log({ byteLength: byteLength, buffer: buf.toString() });
+}
+
+main().catch(e => {
+  console.error("Error: ", e);
 });
diff --git a/kernel/src/index.ts b/kernel/src/index.ts
index 0500894..ecc5092 100644
--- a/kernel/src/index.ts
+++ b/kernel/src/index.ts
@@ -67,32 +67,41 @@ export class DeviceFileSystem extends BaseFileSystem implements FileSystem {
   }
 }
 
-export function configureFileSystem(devices: { [name: string]: Device }, cb: BFSCallback<FS>): void {
-  DeviceFileSystem.Create({ devices: devices }, (e, dfs) => {
-    if (e) {
-      cb(e);
-      return;
-    }
+export async function configureFileSystem(devices: { [name: string]: Device }): Promise<FS> {
+  const dfs = await new Promise<DeviceFileSystem>((resolve, reject) => {
+    DeviceFileSystem.Create({ devices: devices }, (e, dfs) => e ? reject(e) : resolve(dfs))
+  });
+  const mfs = await new Promise<MountableFileSystem>((resolve, reject) => {
     MountableFileSystem.Create({
       "/dev": dfs
-    }, (e, mfs) => {
-      if (e) {
-        cb(e);
-        return
-      }
-
-      const fs = new FS();
-      fs.initialize(mfs);
-
-      const fdMap: {[id: number]: File} = (fs as any).fdMap;
-      fdMap[0] = handles.stdin;
-      fdMap[1] = handles.stdout;
-      fdMap[2] = handles.stderr;
-
-      cb(undefined, fs);
-    });
+    }, (e, mfs) => e ? reject(e) : resolve(mfs));
+  });
+
+  const fs = new FS();
+  fs.initialize(mfs);
+
+  const fdMap: {[id: number]: File} = (fs as any).fdMap;
+  fdMap[0] = handles.stdin;
+  fdMap[1] = handles.stdout;
+  fdMap[2] = handles.stderr;
+
+  return fs;
+}
+
+export async function asyncRead(fs: FS, fd: number, buffer: Buffer, offset: number, length: number, position: number | null)
+: Promise<{ byteLength: number, buffer: Buffer }> {
+  return new Promise<{ byteLength: number, buffer: Buffer }>((resolve, reject) => {
+    fs.read(fd, buffer, offset, length, position,
+            (err, n, buf) => err ? reject(err) : resolve({ byteLength: n, buffer: buf }));
+  });
+}
+
+export async function asyncWrite(fs: FS, fd: number, buffer: Buffer, offset: number, length: number, position: number | null)
+: Promise<void> {
+  return new Promise<void>((resolve, reject) => {
+    fs.write(fd, buffer, offset, length, position, e => e ? reject(e) : resolve())
   });
 }
 
 // Re-export for device implementors
-export { BFSCallback, Stats, File, FileFlag };
+export { BFSCallback, Stats, File, FileFlag, FS };