From 33f62789cde407059abba0a7ac18b2145c648ea7 Mon Sep 17 00:00:00 2001
From: Yusuke Sakurai <kerokerokerop@gmail.com>
Date: Mon, 11 Feb 2019 08:49:48 +0900
Subject: [PATCH] feat: multipart, etc.. (denoland/deno_std#180)

Original: https://github.com/denoland/deno_std/commit/fda9c98d055091fa886fa444ebd1adcd2ecd21bc
---
 .gitignore                    |   4 +
 bytes/bytes.ts                |  60 +++++
 bytes/bytes_test.ts           |  36 +++
 io/bufio_test.ts              |   2 +-
 io/ioutil.ts                  |  36 ++-
 io/ioutil_test.ts             |  29 +-
 io/readers.ts                 |  38 +++
 io/readers_test.ts            |  36 +++
 io/util.ts                    |  26 +-
 io/util_test.ts               |  15 +-
 io/writers.ts                 |  38 +++
 io/writers_test.ts            |  14 +
 multipart/fixtures/sample.txt |  27 ++
 multipart/formfile.ts         |  24 ++
 multipart/formfile_test.ts    |  19 ++
 multipart/multipart.ts        | 492 ++++++++++++++++++++++++++++++++++
 multipart/multipart_test.ts   | 208 ++++++++++++++
 strings/strings.ts            |  15 ++
 test.ts                       |   7 +
 19 files changed, 1112 insertions(+), 14 deletions(-)
 create mode 100644 .gitignore
 create mode 100644 bytes/bytes.ts
 create mode 100644 bytes/bytes_test.ts
 create mode 100644 io/readers.ts
 create mode 100644 io/readers_test.ts
 create mode 100644 io/writers.ts
 create mode 100644 io/writers_test.ts
 create mode 100644 multipart/fixtures/sample.txt
 create mode 100644 multipart/formfile.ts
 create mode 100644 multipart/formfile_test.ts
 create mode 100644 multipart/multipart.ts
 create mode 100644 multipart/multipart_test.ts
 create mode 100644 strings/strings.ts

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000..b2941c3c2b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.DS_Store
+.idea
+tsconfig.json
+deno.d.ts
\ No newline at end of file
diff --git a/bytes/bytes.ts b/bytes/bytes.ts
new file mode 100644
index 0000000000..ef333288e7
--- /dev/null
+++ b/bytes/bytes.ts
@@ -0,0 +1,60 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/** Find first index of binary pattern from a. If not found, then return -1 **/
+export function bytesFindIndex(a: Uint8Array, pat: Uint8Array): number {
+  const s = pat[0];
+  for (let i = 0; i < a.length; i++) {
+    if (a[i] !== s) continue;
+    const pin = i;
+    let matched = 1;
+    while (matched < pat.length) {
+      i++;
+      if (a[i] !== pat[i - pin]) {
+        break;
+      }
+      matched++;
+    }
+    if (matched === pat.length) {
+      return pin;
+    }
+  }
+  return -1;
+}
+
+/** Find last index of binary pattern from a. If not found, then return -1 **/
+export function bytesFindLastIndex(a: Uint8Array, pat: Uint8Array) {
+  const e = pat[pat.length - 1];
+  for (let i = a.length - 1; i >= 0; i--) {
+    if (a[i] !== e) continue;
+    const pin = i;
+    let matched = 1;
+    while (matched < pat.length) {
+      i--;
+      if (a[i] !== pat[pat.length - 1 - (pin - i)]) {
+        break;
+      }
+      matched++;
+    }
+    if (matched === pat.length) {
+      return pin - pat.length + 1;
+    }
+  }
+  return -1;
+}
+
+/** Check whether binary arrays are equal to each other **/
+export function bytesEqual(a: Uint8Array, match: Uint8Array): boolean {
+  if (a.length !== match.length) return false;
+  for (let i = 0; i < match.length; i++) {
+    if (a[i] !== match[i]) return false;
+  }
+  return true;
+}
+
+/** Check whether binary array has binary prefix  **/
+export function bytesHasPrefix(a: Uint8Array, prefix: Uint8Array): boolean {
+  for (let i = 0, max = prefix.length; i < max; i++) {
+    if (a[i] !== prefix[i]) return false;
+  }
+  return true;
+}
diff --git a/bytes/bytes_test.ts b/bytes/bytes_test.ts
new file mode 100644
index 0000000000..3d87497fe5
--- /dev/null
+++ b/bytes/bytes_test.ts
@@ -0,0 +1,36 @@
+import {
+  bytesFindIndex,
+  bytesFindLastIndex,
+  bytesEqual,
+  bytesHasPrefix
+} from "./bytes.ts";
+import { assertEqual, test } from "./deps.ts";
+
+test(function bytesBytesFindIndex() {
+  const i = bytesFindIndex(
+    new Uint8Array([1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 3]),
+    new Uint8Array([0, 1, 2])
+  );
+  assertEqual(i, 2);
+});
+
+test(function bytesBytesFindLastIndex1() {
+  const i = bytesFindLastIndex(
+    new Uint8Array([0, 1, 2, 0, 1, 2, 0, 1, 3]),
+    new Uint8Array([0, 1, 2])
+  );
+  assertEqual(i, 3);
+});
+
+test(function bytesBytesBytesEqual() {
+  const v = bytesEqual(
+    new Uint8Array([0, 1, 2, 3]),
+    new Uint8Array([0, 1, 2, 3])
+  );
+  assertEqual(v, true);
+});
+
+test(function bytesBytesHasPrefix() {
+  const v = bytesHasPrefix(new Uint8Array([0, 1, 2]), new Uint8Array([0, 1]));
+  assertEqual(v, true);
+});
diff --git a/io/bufio_test.ts b/io/bufio_test.ts
index fa8f4b73bd..e63f1c5c97 100644
--- a/io/bufio_test.ts
+++ b/io/bufio_test.ts
@@ -30,7 +30,7 @@ test(async function bufioReaderSimple() {
   const data = "hello world";
   const b = new BufReader(stringsReader(data));
   const s = await readBytes(b);
-  assertEqual(s, data);
+  assert.equal(s, data);
 });
 
 type ReadMaker = { name: string; fn: (r: Reader) => Reader };
diff --git a/io/ioutil.ts b/io/ioutil.ts
index 68d6e51905..6590c0f663 100644
--- a/io/ioutil.ts
+++ b/io/ioutil.ts
@@ -1,27 +1,55 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import { BufReader } from "./bufio.ts";
+import { Reader, Writer } from "deno";
+import { assert } from "../testing/mod.ts";
 
-/* Read big endian 16bit short from BufReader */
+/** copy N size at the most. If read size is lesser than N, then returns nread */
+export async function copyN(
+  dest: Writer,
+  r: Reader,
+  size: number
+): Promise<number> {
+  let bytesRead = 0;
+  let buf = new Uint8Array(1024);
+  while (bytesRead < size) {
+    if (size - bytesRead < 1024) {
+      buf = new Uint8Array(size - bytesRead);
+    }
+    const { nread, eof } = await r.read(buf);
+    bytesRead += nread;
+    if (nread > 0) {
+      const n = await dest.write(buf.slice(0, nread));
+      assert.assert(n === nread, "could not write");
+    }
+    if (eof) {
+      break;
+    }
+  }
+  return bytesRead;
+}
+
+/** Read big endian 16bit short from BufReader */
 export async function readShort(buf: BufReader): Promise<number> {
   const [high, low] = [await buf.readByte(), await buf.readByte()];
   return (high << 8) | low;
 }
 
-/* Read big endian 32bit integer from BufReader */
+/** Read big endian 32bit integer from BufReader */
 export async function readInt(buf: BufReader): Promise<number> {
   const [high, low] = [await readShort(buf), await readShort(buf)];
   return (high << 16) | low;
 }
 
 const BIT32 = 0xffffffff;
-/* Read big endian 64bit long from BufReader */
+
+/** Read big endian 64bit long from BufReader */
 export async function readLong(buf: BufReader): Promise<number> {
   const [high, low] = [await readInt(buf), await readInt(buf)];
   // ECMAScript doesn't support 64bit bit ops.
   return high ? high * (BIT32 + 1) + low : low;
 }
 
-/* Slice number into 64bit big endian byte array */
+/** Slice number into 64bit big endian byte array */
 export function sliceLongToBytes(d: number, dest = new Array(8)): number[] {
   let mask = 0xff;
   let low = (d << 32) >>> 32;
diff --git a/io/ioutil_test.ts b/io/ioutil_test.ts
index 4ff69352a7..2c78b25620 100644
--- a/io/ioutil_test.ts
+++ b/io/ioutil_test.ts
@@ -1,8 +1,15 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { Reader, ReadResult } from "deno";
-import { assertEqual, test } from "../testing/mod.ts";
-import { readInt, readLong, readShort, sliceLongToBytes } from "./ioutil.ts";
+import { Buffer, Reader, ReadResult } from "deno";
+import { assert, assertEqual, runTests, test } from "../testing/mod.ts";
+import {
+  copyN,
+  readInt,
+  readLong,
+  readShort,
+  sliceLongToBytes
+} from "./ioutil.ts";
 import { BufReader } from "./bufio.ts";
+import { stringsReader } from "./util.ts";
 
 class BinaryReader implements Reader {
   index = 0;
@@ -61,3 +68,19 @@ test(async function testSliceLongToBytes2() {
   const arr = sliceLongToBytes(0x12345678);
   assertEqual(arr, [0, 0, 0, 0, 0x12, 0x34, 0x56, 0x78]);
 });
+
+test(async function testCopyN1() {
+  const w = new Buffer();
+  const r = stringsReader("abcdefghij");
+  const n = await copyN(w, r, 3);
+  assert.equal(n, 3);
+  assert.equal(w.toString(), "abc");
+});
+
+test(async function testCopyN2() {
+  const w = new Buffer();
+  const r = stringsReader("abcdefghij");
+  const n = await copyN(w, r, 11);
+  assert.equal(n, 10);
+  assert.equal(w.toString(), "abcdefghij");
+});
diff --git a/io/readers.ts b/io/readers.ts
new file mode 100644
index 0000000000..df02993560
--- /dev/null
+++ b/io/readers.ts
@@ -0,0 +1,38 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { Reader, ReadResult } from "deno";
+import { encode } from "../strings/strings.ts";
+
+/** Reader utility for strings */
+export class StringReader implements Reader {
+  private offs = 0;
+  private buf = new Uint8Array(encode(this.s));
+
+  constructor(private readonly s: string) {}
+
+  async read(p: Uint8Array): Promise<ReadResult> {
+    const n = Math.min(p.byteLength, this.buf.byteLength - this.offs);
+    p.set(this.buf.slice(this.offs, this.offs + n));
+    this.offs += n;
+    return { nread: n, eof: this.offs === this.buf.byteLength };
+  }
+}
+
+/** Reader utility for combining multiple readers */
+export class MultiReader implements Reader {
+  private readonly readers: Reader[];
+  private currentIndex = 0;
+
+  constructor(...readers: Reader[]) {
+    this.readers = readers;
+  }
+
+  async read(p: Uint8Array): Promise<ReadResult> {
+    const r = this.readers[this.currentIndex];
+    if (!r) return { nread: 0, eof: true };
+    const { nread, eof } = await r.read(p);
+    if (eof) {
+      this.currentIndex++;
+    }
+    return { nread, eof: false };
+  }
+}
diff --git a/io/readers_test.ts b/io/readers_test.ts
new file mode 100644
index 0000000000..0bc8ca36a0
--- /dev/null
+++ b/io/readers_test.ts
@@ -0,0 +1,36 @@
+import { assert, test } from "../testing/mod.ts";
+import { MultiReader, StringReader } from "./readers.ts";
+import { StringWriter } from "./writers.ts";
+import { copy } from "deno";
+import { copyN } from "./ioutil.ts";
+import { decode } from "../strings/strings.ts";
+
+test(async function ioStringReader() {
+  const r = new StringReader("abcdef");
+  const { nread, eof } = await r.read(new Uint8Array(6));
+  assert.equal(nread, 6);
+  assert.equal(eof, true);
+});
+
+test(async function ioStringReader() {
+  const r = new StringReader("abcdef");
+  const buf = new Uint8Array(3);
+  let res1 = await r.read(buf);
+  assert.equal(res1.nread, 3);
+  assert.equal(res1.eof, false);
+  assert.equal(decode(buf), "abc");
+  let res2 = await r.read(buf);
+  assert.equal(res2.nread, 3);
+  assert.equal(res2.eof, true);
+  assert.equal(decode(buf), "def");
+});
+
+test(async function ioMultiReader() {
+  const r = new MultiReader(new StringReader("abc"), new StringReader("def"));
+  const w = new StringWriter();
+  const n = await copyN(w, r, 4);
+  assert.equal(n, 4);
+  assert.equal(w.toString(), "abcd");
+  await copy(w, r);
+  assert.equal(w.toString(), "abcdef");
+});
diff --git a/io/util.ts b/io/util.ts
index 8726a18879..954808c6cd 100644
--- a/io/util.ts
+++ b/io/util.ts
@@ -1,6 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { Buffer, Reader } from "deno";
-
+import { Buffer, File, mkdir, open, Reader } from "deno";
+import { encode } from "../strings/strings.ts";
+import * as path from "../fs/path.ts";
 // `off` is the offset into `dst` where it will at which to begin writing values
 // from `src`.
 // Returns the number of bytes copied.
@@ -18,8 +19,23 @@ export function charCode(s: string): number {
   return s.charCodeAt(0);
 }
 
-const encoder = new TextEncoder();
 export function stringsReader(s: string): Reader {
-  const ui8 = encoder.encode(s);
-  return new Buffer(ui8.buffer as ArrayBuffer);
+  return new Buffer(encode(s).buffer);
+}
+
+/** Create or open a temporal file at specified directory with prefix and postfix  */
+export async function tempFile(
+  dir: string,
+  opts: {
+    prefix?: string;
+    postfix?: string;
+  } = { prefix: "", postfix: "" }
+): Promise<{ file: File; filepath: string }> {
+  const r = Math.floor(Math.random() * 1000000);
+  const filepath = path.resolve(
+    `${dir}/${opts.prefix || ""}${r}${opts.postfix || ""}`
+  );
+  await mkdir(path.dirname(filepath), true);
+  const file = await open(filepath, "a");
+  return { file, filepath };
 }
diff --git a/io/util_test.ts b/io/util_test.ts
index 90ae5d4c1b..c3f134616f 100644
--- a/io/util_test.ts
+++ b/io/util_test.ts
@@ -1,6 +1,8 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import { test, assert } from "../testing/mod.ts";
-import { copyBytes } from "./util.ts";
+import { copyBytes, tempFile } from "./util.ts";
+import { remove } from "deno";
+import * as path from "../fs/path.ts";
 
 test(function testCopyBytes() {
   let dst = new Uint8Array(4);
@@ -35,3 +37,14 @@ test(function testCopyBytes() {
   assert(len === 2);
   assert.equal(dst, Uint8Array.of(3, 4, 0, 0));
 });
+
+test(async function ioTempfile() {
+  const f = await tempFile(".", {
+    prefix: "prefix-",
+    postfix: "-postfix"
+  });
+  console.log(f.file, f.filepath);
+  const base = path.basename(f.filepath);
+  assert.assert(!!base.match(/^prefix-.+?-postfix$/));
+  await remove(f.filepath);
+});
diff --git a/io/writers.ts b/io/writers.ts
new file mode 100644
index 0000000000..15c2628aca
--- /dev/null
+++ b/io/writers.ts
@@ -0,0 +1,38 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { Writer } from "deno";
+import { decode, encode } from "../strings/strings.ts";
+
+/** Writer utility for buffering string chunks */
+export class StringWriter implements Writer {
+  private chunks: Uint8Array[] = [];
+  private byteLength: number = 0;
+
+  constructor(private base: string = "") {
+    const c = encode(base);
+    this.chunks.push(c);
+    this.byteLength += c.byteLength;
+  }
+
+  async write(p: Uint8Array): Promise<number> {
+    this.chunks.push(p);
+    this.byteLength += p.byteLength;
+    this.cache = null;
+    return p.byteLength;
+  }
+
+  private cache: string;
+
+  toString(): string {
+    if (this.cache) {
+      return this.cache;
+    }
+    const buf = new Uint8Array(this.byteLength);
+    let offs = 0;
+    for (const chunk of this.chunks) {
+      buf.set(chunk, offs);
+      offs += chunk.byteLength;
+    }
+    this.cache = decode(buf);
+    return this.cache;
+  }
+}
diff --git a/io/writers_test.ts b/io/writers_test.ts
new file mode 100644
index 0000000000..01388497cd
--- /dev/null
+++ b/io/writers_test.ts
@@ -0,0 +1,14 @@
+import { assert, test } from "../testing/mod.ts";
+import { StringWriter } from "./writers.ts";
+import { StringReader } from "./readers.ts";
+import { copyN } from "./ioutil.ts";
+import { copy } from "deno";
+
+test(async function ioStringWriter() {
+  const w = new StringWriter("base");
+  const r = new StringReader("0123456789");
+  const n = await copyN(w, r, 4);
+  assert.equal(w.toString(), "base0123");
+  await copy(w, r);
+  assert.equal(w.toString(), "base0123456789");
+});
diff --git a/multipart/fixtures/sample.txt b/multipart/fixtures/sample.txt
new file mode 100644
index 0000000000..97e9bf5531
--- /dev/null
+++ b/multipart/fixtures/sample.txt
@@ -0,0 +1,27 @@
+----------------------------434049563556637648550474
+content-disposition: form-data; name="foo"
+content-type: application/octet-stream
+
+foo
+----------------------------434049563556637648550474
+content-disposition: form-data; name="bar"
+content-type: application/octet-stream
+
+bar
+----------------------------434049563556637648550474
+content-disposition: form-data; name="file"; filename="tsconfig.json"
+content-type: application/octet-stream
+
+{
+  "compilerOptions": {
+    "target": "es2018",
+    "baseUrl": ".",
+    "paths": {
+      "deno": ["./deno.d.ts"],
+      "https://*": ["../../.deno/deps/https/*"],
+      "http://*": ["../../.deno/deps/http/*"]
+    }
+  }
+}
+
+----------------------------434049563556637648550474--
diff --git a/multipart/formfile.ts b/multipart/formfile.ts
new file mode 100644
index 0000000000..b1b63eb157
--- /dev/null
+++ b/multipart/formfile.ts
@@ -0,0 +1,24 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/** FormFile object */
+export type FormFile = {
+  /** filename  */
+  filename: string;
+  /** content-type header value of file */
+  type: string;
+  /** byte size of file */
+  size: number;
+  /** in-memory content of file. Either content or tempfile is set  */
+  content?: Uint8Array;
+  /** temporal file path. Set if file size is bigger than specified max-memory size at reading form */
+  tempfile?: string;
+};
+
+/** Type guard for FormFile */
+export function isFormFile(x): x is FormFile {
+  return (
+    typeof x === "object" &&
+    x.hasOwnProperty("filename") &&
+    x.hasOwnProperty("type")
+  );
+}
diff --git a/multipart/formfile_test.ts b/multipart/formfile_test.ts
new file mode 100644
index 0000000000..e6f73b826d
--- /dev/null
+++ b/multipart/formfile_test.ts
@@ -0,0 +1,19 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { assert, test } from "../testing/mod.ts";
+import { isFormFile } from "./formfile.ts";
+
+test(function multipartIsFormFile() {
+  assert.equal(
+    isFormFile({
+      filename: "foo",
+      type: "application/json"
+    }),
+    true
+  );
+  assert.equal(
+    isFormFile({
+      filename: "foo"
+    }),
+    false
+  );
+});
diff --git a/multipart/multipart.ts b/multipart/multipart.ts
new file mode 100644
index 0000000000..f0caa2160e
--- /dev/null
+++ b/multipart/multipart.ts
@@ -0,0 +1,492 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Buffer, Closer, copy, Reader, ReadResult, remove, Writer } from "deno";
+
+import { FormFile } from "./formfile.ts";
+import {
+  bytesFindIndex,
+  bytesFindLastIndex,
+  bytesHasPrefix,
+  bytesEqual
+} from "../bytes/bytes.ts";
+import { copyN } from "../io/ioutil.ts";
+import { MultiReader } from "../io/readers.ts";
+import { tempFile } from "../io/util.ts";
+import { BufReader, BufState, BufWriter } from "../io/bufio.ts";
+import { TextProtoReader } from "../textproto/mod.ts";
+import { encoder } from "../strings/strings.ts";
+import * as path from "../fs/path.ts";
+
+function randomBoundary() {
+  let boundary = "--------------------------";
+  for (let i = 0; i < 24; i++) {
+    boundary += Math.floor(Math.random() * 10).toString(16);
+  }
+  return boundary;
+}
+
+/** Reader for parsing multipart/form-data */
+export class MultipartReader {
+  readonly newLine = encoder.encode("\r\n");
+  readonly newLineDashBoundary = encoder.encode(`\r\n--${this.boundary}`);
+  readonly dashBoundaryDash = encoder.encode(`--${this.boundary}--`);
+  readonly dashBoundary = encoder.encode(`--${this.boundary}`);
+  readonly bufReader: BufReader;
+
+  constructor(private reader: Reader, private boundary: string) {
+    this.bufReader = new BufReader(reader);
+  }
+
+  /** Read all form data from stream.
+   * If total size of stored data in memory exceed maxMemory,
+   * overflowed file data will be written to temporal files.
+   * String field values are never written to files */
+  async readForm(
+    maxMemory: number
+  ): Promise<{ [key: string]: string | FormFile }> {
+    const result = Object.create(null);
+    let maxValueBytes = maxMemory + (10 << 20);
+    const buf = new Buffer(new Uint8Array(maxValueBytes));
+    for (;;) {
+      const p = await this.nextPart();
+      if (!p) {
+        break;
+      }
+      if (p.formName === "") {
+        continue;
+      }
+      buf.reset();
+      if (!p.fileName) {
+        // value
+        const n = await copyN(buf, p, maxValueBytes);
+        maxValueBytes -= n;
+        if (maxValueBytes < 0) {
+          throw new RangeError("message too large");
+        }
+        const value = buf.toString();
+        result[p.formName] = value;
+        continue;
+      }
+      // file
+      let formFile: FormFile;
+      const n = await copy(buf, p);
+      if (n > maxMemory) {
+        // too big, write to disk and flush buffer
+        const ext = path.extname(p.fileName);
+        const { file, filepath } = await tempFile(".", {
+          prefix: "multipart-",
+          postfix: ext
+        });
+        try {
+          const size = await copyN(
+            file,
+            new MultiReader(buf, p),
+            maxValueBytes
+          );
+          file.close();
+          formFile = {
+            filename: p.fileName,
+            type: p.headers.get("content-type"),
+            tempfile: filepath,
+            size
+          };
+        } catch (e) {
+          await remove(filepath);
+        }
+      } else {
+        formFile = {
+          filename: p.fileName,
+          type: p.headers.get("content-type"),
+          content: buf.bytes(),
+          size: buf.bytes().byteLength
+        };
+        maxMemory -= n;
+        maxValueBytes -= n;
+      }
+      result[p.formName] = formFile;
+    }
+    return result;
+  }
+
+  private currentPart: PartReader;
+  private partsRead: number;
+
+  private async nextPart(): Promise<PartReader> {
+    if (this.currentPart) {
+      this.currentPart.close();
+    }
+    if (bytesEqual(this.dashBoundary, encoder.encode("--"))) {
+      throw new Error("boundary is empty");
+    }
+    let expectNewPart = false;
+    for (;;) {
+      const [line, state] = await this.bufReader.readSlice("\n".charCodeAt(0));
+      if (state === "EOF" && this.isFinalBoundary(line)) {
+        break;
+      }
+      if (state) {
+        throw new Error("aa" + state.toString());
+      }
+      if (this.isBoundaryDelimiterLine(line)) {
+        this.partsRead++;
+        const r = new TextProtoReader(this.bufReader);
+        const [headers, state] = await r.readMIMEHeader();
+        if (state) {
+          throw state;
+        }
+        const np = new PartReader(this, headers);
+        this.currentPart = np;
+        return np;
+      }
+      if (this.isFinalBoundary(line)) {
+        break;
+      }
+      if (expectNewPart) {
+        throw new Error(`expecting a new Part; got line ${line}`);
+      }
+      if (this.partsRead === 0) {
+        continue;
+      }
+      if (bytesEqual(line, this.newLine)) {
+        expectNewPart = true;
+        continue;
+      }
+      throw new Error(`unexpected line in next(): ${line}`);
+    }
+  }
+
+  private isFinalBoundary(line: Uint8Array) {
+    if (!bytesHasPrefix(line, this.dashBoundaryDash)) {
+      return false;
+    }
+    let rest = line.slice(this.dashBoundaryDash.length, line.length);
+    return rest.length === 0 || bytesEqual(skipLWSPChar(rest), this.newLine);
+  }
+
+  private isBoundaryDelimiterLine(line: Uint8Array) {
+    if (!bytesHasPrefix(line, this.dashBoundary)) {
+      return false;
+    }
+    const rest = line.slice(this.dashBoundary.length);
+    return bytesEqual(skipLWSPChar(rest), this.newLine);
+  }
+}
+
+function skipLWSPChar(u: Uint8Array): Uint8Array {
+  const ret = new Uint8Array(u.length);
+  const sp = " ".charCodeAt(0);
+  const ht = "\t".charCodeAt(0);
+  let j = 0;
+  for (let i = 0; i < u.length; i++) {
+    if (u[i] === sp || u[i] === ht) continue;
+    ret[j++] = u[i];
+  }
+  return ret.slice(0, j);
+}
+
+let i = 0;
+
+class PartReader implements Reader, Closer {
+  n: number = 0;
+  total: number = 0;
+  bufState: BufState = null;
+  index = i++;
+
+  constructor(private mr: MultipartReader, public readonly headers: Headers) {}
+
+  async read(p: Uint8Array): Promise<ReadResult> {
+    const br = this.mr.bufReader;
+    const returnResult = (nread: number, bufState: BufState): ReadResult => {
+      if (bufState && bufState !== "EOF") {
+        throw bufState;
+      }
+      return { nread, eof: bufState === "EOF" };
+    };
+    if (this.n === 0 && !this.bufState) {
+      const [peek] = await br.peek(br.buffered());
+      const [n, state] = scanUntilBoundary(
+        peek,
+        this.mr.dashBoundary,
+        this.mr.newLineDashBoundary,
+        this.total,
+        this.bufState
+      );
+      this.n = n;
+      this.bufState = state;
+      if (this.n === 0 && !this.bufState) {
+        const [_, state] = await br.peek(peek.length + 1);
+        this.bufState = state;
+        if (this.bufState === "EOF") {
+          this.bufState = new RangeError("unexpected eof");
+        }
+      }
+    }
+    if (this.n === 0) {
+      return returnResult(0, this.bufState);
+    }
+
+    let n = 0;
+    if (p.byteLength > this.n) {
+      n = this.n;
+    }
+    const buf = p.slice(0, n);
+    const [nread] = await this.mr.bufReader.readFull(buf);
+    p.set(buf);
+    this.total += nread;
+    this.n -= nread;
+    if (this.n === 0) {
+      return returnResult(n, this.bufState);
+    }
+    return returnResult(n, null);
+  }
+
+  close(): void {}
+
+  private contentDisposition: string;
+  private contentDispositionParams: { [key: string]: string };
+
+  private getContentDispositionParams() {
+    if (this.contentDispositionParams) return this.contentDispositionParams;
+    const cd = this.headers.get("content-disposition");
+    const params = {};
+    const comps = cd.split(";");
+    this.contentDisposition = comps[0];
+    comps
+      .slice(1)
+      .map(v => v.trim())
+      .map(kv => {
+        const [k, v] = kv.split("=");
+        if (v) {
+          const s = v.charAt(0);
+          const e = v.charAt(v.length - 1);
+          if ((s === e && s === '"') || s === "'") {
+            params[k] = v.substr(1, v.length - 2);
+          } else {
+            params[k] = v;
+          }
+        }
+      });
+    return (this.contentDispositionParams = params);
+  }
+
+  get fileName(): string {
+    return this.getContentDispositionParams()["filename"];
+  }
+
+  get formName(): string {
+    const p = this.getContentDispositionParams();
+    if (this.contentDisposition === "form-data") {
+      return p["name"];
+    }
+    return "";
+  }
+}
+
+export function scanUntilBoundary(
+  buf: Uint8Array,
+  dashBoundary: Uint8Array,
+  newLineDashBoundary: Uint8Array,
+  total: number,
+  state: BufState
+): [number, BufState] {
+  if (total === 0) {
+    if (bytesHasPrefix(buf, dashBoundary)) {
+      switch (matchAfterPrefix(buf, dashBoundary, state)) {
+        case -1:
+          return [dashBoundary.length, null];
+        case 0:
+          return [0, null];
+        case 1:
+          return [0, "EOF"];
+      }
+      if (bytesHasPrefix(dashBoundary, buf)) {
+        return [0, state];
+      }
+    }
+  }
+  const i = bytesFindIndex(buf, newLineDashBoundary);
+  if (i >= 0) {
+    switch (matchAfterPrefix(buf.slice(i), newLineDashBoundary, state)) {
+      case -1:
+        return [i + newLineDashBoundary.length, null];
+      case 0:
+        return [i, null];
+      case 1:
+        return [i, "EOF"];
+    }
+  }
+  if (bytesHasPrefix(newLineDashBoundary, buf)) {
+    return [0, state];
+  }
+  const j = bytesFindLastIndex(buf, newLineDashBoundary.slice(0, 1));
+  if (j >= 0 && bytesHasPrefix(newLineDashBoundary, buf.slice(j))) {
+    return [j, null];
+  }
+  return [buf.length, state];
+}
+
+export function matchAfterPrefix(
+  a: Uint8Array,
+  prefix: Uint8Array,
+  bufState: BufState
+): number {
+  if (a.length === prefix.length) {
+    if (bufState) {
+      return 1;
+    }
+    return 0;
+  }
+  const c = a[prefix.length];
+  if (
+    c === " ".charCodeAt(0) ||
+    c === "\t".charCodeAt(0) ||
+    c === "\r".charCodeAt(0) ||
+    c === "\n".charCodeAt(0) ||
+    c === "-".charCodeAt(0)
+  ) {
+    return 1;
+  }
+  return -1;
+}
+
+class PartWriter implements Writer {
+  closed = false;
+  private readonly partHeader: string;
+  private headersWritten: boolean = false;
+
+  constructor(
+    private writer: Writer,
+    readonly boundary: string,
+    public headers: Headers,
+    isFirstBoundary: boolean
+  ) {
+    let buf = "";
+    if (isFirstBoundary) {
+      buf += `--${boundary}\r\n`;
+    } else {
+      buf += `\r\n--${boundary}\r\n`;
+    }
+    for (const [key, value] of headers.entries()) {
+      buf += `${key}: ${value}\r\n`;
+    }
+    buf += `\r\n`;
+    this.partHeader = buf;
+  }
+
+  close(): void {
+    this.closed = true;
+  }
+
+  async write(p: Uint8Array): Promise<number> {
+    if (this.closed) {
+      throw new Error("part is closed");
+    }
+    if (!this.headersWritten) {
+      await this.writer.write(encoder.encode(this.partHeader));
+      this.headersWritten = true;
+    }
+    return this.writer.write(p);
+  }
+}
+
+function checkBoundary(b: string) {
+  if (b.length < 1 || b.length > 70) {
+    throw new Error("invalid boundary length: " + b.length);
+  }
+  const end = b.length - 1;
+  for (let i = 0; i < end; i++) {
+    const c = b.charAt(i);
+    if (!c.match(/[a-zA-Z0-9'()+_,\-./:=?]/) || (c === " " && i !== end)) {
+      throw new Error("invalid boundary character: " + c);
+    }
+  }
+  return b;
+}
+
+/** Writer for creating multipart/form-data */
+export class MultipartWriter {
+  private readonly _boundary: string;
+
+  get boundary() {
+    return this._boundary;
+  }
+
+  private lastPart: PartWriter;
+  private bufWriter: BufWriter;
+  private isClosed: boolean = false;
+
+  constructor(private readonly writer: Writer, boundary?: string) {
+    if (boundary !== void 0) {
+      this._boundary = checkBoundary(boundary);
+    } else {
+      this._boundary = randomBoundary();
+    }
+    this.bufWriter = new BufWriter(writer);
+  }
+
+  formDataContentType(): string {
+    return `multipart/form-data; boundary=${this.boundary}`;
+  }
+
+  private createPart(headers: Headers): Writer {
+    if (this.isClosed) {
+      throw new Error("multipart: writer is closed");
+    }
+    if (this.lastPart) {
+      this.lastPart.close();
+    }
+    const part = new PartWriter(
+      this.writer,
+      this.boundary,
+      headers,
+      !this.lastPart
+    );
+    this.lastPart = part;
+    return part;
+  }
+
+  createFormFile(field: string, filename: string): Writer {
+    const h = new Headers();
+    h.set(
+      "Content-Disposition",
+      `form-data; name="${field}"; filename="${filename}"`
+    );
+    h.set("Content-Type", "application/octet-stream");
+    return this.createPart(h);
+  }
+
+  createFormField(field: string): Writer {
+    const h = new Headers();
+    h.set("Content-Disposition", `form-data; name="${field}"`);
+    h.set("Content-Type", "application/octet-stream");
+    return this.createPart(h);
+  }
+
+  async writeField(field: string, value: string) {
+    const f = await this.createFormField(field);
+    await f.write(encoder.encode(value));
+  }
+
+  async writeFile(field: string, filename: string, file: Reader) {
+    const f = await this.createFormFile(field, filename);
+    await copy(f, file);
+  }
+
+  private flush(): Promise<BufState> {
+    return this.bufWriter.flush();
+  }
+
+  /** Close writer. No additional data can be writen to stream */
+  async close() {
+    if (this.isClosed) {
+      throw new Error("multipart: writer is closed");
+    }
+    if (this.lastPart) {
+      this.lastPart.close();
+      this.lastPart = void 0;
+    }
+    await this.writer.write(encoder.encode(`\r\n--${this.boundary}--\r\n`));
+    await this.flush();
+    this.isClosed = true;
+  }
+}
diff --git a/multipart/multipart_test.ts b/multipart/multipart_test.ts
new file mode 100644
index 0000000000..3181e45c1b
--- /dev/null
+++ b/multipart/multipart_test.ts
@@ -0,0 +1,208 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { assert, test } from "../testing/mod.ts";
+import {
+  matchAfterPrefix,
+  MultipartReader,
+  MultipartWriter,
+  scanUntilBoundary
+} from "./multipart.ts";
+import { Buffer, copy, open, remove } from "deno";
+import * as path from "../fs/path.ts";
+import { FormFile, isFormFile } from "./formfile.ts";
+import { StringWriter } from "../io/writers.ts";
+
+const e = new TextEncoder();
+const d = new TextDecoder();
+const boundary = "--abcde";
+const dashBoundary = e.encode("--" + boundary);
+const nlDashBoundary = e.encode("\r\n--" + boundary);
+
+test(function multipartScanUntilBoundary1() {
+  const data = `--${boundary}`;
+  const [n, err] = scanUntilBoundary(
+    e.encode(data),
+    dashBoundary,
+    nlDashBoundary,
+    0,
+    "EOF"
+  );
+  assert.equal(n, 0);
+  assert.equal(err, "EOF");
+});
+
+test(function multipartScanUntilBoundary2() {
+  const data = `foo\r\n--${boundary}`;
+  const [n, err] = scanUntilBoundary(
+    e.encode(data),
+    dashBoundary,
+    nlDashBoundary,
+    0,
+    "EOF"
+  );
+  assert.equal(n, 3);
+  assert.equal(err, "EOF");
+});
+
+test(function multipartScanUntilBoundary4() {
+  const data = `foo\r\n--`;
+  const [n, err] = scanUntilBoundary(
+    e.encode(data),
+    dashBoundary,
+    nlDashBoundary,
+    0,
+    null
+  );
+  assert.equal(n, 3);
+  assert.equal(err, null);
+});
+
+test(function multipartScanUntilBoundary3() {
+  const data = `foobar`;
+  const [n, err] = scanUntilBoundary(
+    e.encode(data),
+    dashBoundary,
+    nlDashBoundary,
+    0,
+    null
+  );
+  assert.equal(n, data.length);
+  assert.equal(err, null);
+});
+
+test(function multipartMatchAfterPrefix1() {
+  const data = `${boundary}\r`;
+  const v = matchAfterPrefix(e.encode(data), e.encode(boundary), null);
+  assert.equal(v, 1);
+});
+
+test(function multipartMatchAfterPrefix2() {
+  const data = `${boundary}hoge`;
+  const v = matchAfterPrefix(e.encode(data), e.encode(boundary), null);
+  assert.equal(v, -1);
+});
+
+test(function multipartMatchAfterPrefix3() {
+  const data = `${boundary}`;
+  const v = matchAfterPrefix(e.encode(data), e.encode(boundary), null);
+  assert.equal(v, 0);
+});
+
+test(async function multipartMultipartWriter() {
+  const buf = new Buffer();
+  const mw = new MultipartWriter(buf);
+  await mw.writeField("foo", "foo");
+  await mw.writeField("bar", "bar");
+  const f = await open(path.resolve("./multipart/fixtures/sample.txt"), "r");
+  await mw.writeFile("file", "sample.txt", f);
+  await mw.close();
+});
+
+test(function multipartMultipartWriter2() {
+  const w = new StringWriter();
+  assert.throws(
+    () => new MultipartWriter(w, ""),
+    Error,
+    "invalid boundary length"
+  );
+  assert.throws(
+    () =>
+      new MultipartWriter(
+        w,
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+      ),
+    Error,
+    "invalid boundary length"
+  );
+  assert.throws(
+    () => new MultipartWriter(w, "aaa aaa"),
+    Error,
+    "invalid boundary character"
+  );
+  assert.throws(
+    () => new MultipartWriter(w, "boundary¥¥"),
+    Error,
+    "invalid boundary character"
+  );
+});
+
+test(async function multipartMultipartWriter3() {
+  const w = new StringWriter();
+  const mw = new MultipartWriter(w);
+  await mw.writeField("foo", "foo");
+  await mw.close();
+  await assert.throwsAsync(
+    async () => {
+      await mw.close();
+    },
+    Error,
+    "closed"
+  );
+  await assert.throwsAsync(
+    async () => {
+      await mw.writeFile("bar", "file", null);
+    },
+    Error,
+    "closed"
+  );
+  await assert.throwsAsync(
+    async () => {
+      await mw.writeField("bar", "bar");
+    },
+    Error,
+    "closed"
+  );
+  assert.throws(
+    () => {
+      mw.createFormField("bar");
+    },
+    Error,
+    "closed"
+  );
+  assert.throws(
+    () => {
+      mw.createFormFile("bar", "file");
+    },
+    Error,
+    "closed"
+  );
+});
+
+test(async function multipartMultipartReader() {
+  // FIXME: path resolution
+  const o = await open(path.resolve("./multipart/fixtures/sample.txt"));
+  const mr = new MultipartReader(
+    o,
+    "--------------------------434049563556637648550474"
+  );
+  const form = await mr.readForm(10 << 20);
+  assert.equal(form["foo"], "foo");
+  assert.equal(form["bar"], "bar");
+  const file = form["file"] as FormFile;
+  assert.equal(isFormFile(file), true);
+  assert.assert(file.content !== void 0);
+});
+
+test(async function multipartMultipartReader2() {
+  const o = await open(path.resolve("./multipart/fixtures/sample.txt"));
+  const mr = new MultipartReader(
+    o,
+    "--------------------------434049563556637648550474"
+  );
+  const form = await mr.readForm(20); //
+  try {
+    assert.equal(form["foo"], "foo");
+    assert.equal(form["bar"], "bar");
+    const file = form["file"] as FormFile;
+    assert.equal(file.type, "application/octet-stream");
+    const f = await open(file.tempfile);
+    const w = new StringWriter();
+    await copy(w, f);
+    const json = JSON.parse(w.toString());
+    assert.equal(json["compilerOptions"]["target"], "es2018");
+    f.close();
+  } finally {
+    const file = form["file"] as FormFile;
+    await remove(file.tempfile);
+  }
+});
diff --git a/strings/strings.ts b/strings/strings.ts
new file mode 100644
index 0000000000..266c611656
--- /dev/null
+++ b/strings/strings.ts
@@ -0,0 +1,15 @@
+/** A default TextEncoder instance */
+export const encoder = new TextEncoder();
+
+/** Shorthand for new TextEncoder().encode() */
+export function encode(input?: string): Uint8Array {
+  return encoder.encode(input);
+}
+
+/** A default TextDecoder instance */
+export const decoder = new TextDecoder();
+
+/** Shorthand for new TextDecoder().decode() */
+export function decode(input?: Uint8Array): string {
+  return decoder.decode(input);
+}
diff --git a/test.ts b/test.ts
index a0f5d67e90..92d916e410 100755
--- a/test.ts
+++ b/test.ts
@@ -4,12 +4,19 @@ import "colors/test.ts";
 import "datetime/test.ts";
 import "examples/test.ts";
 import "flags/test.ts";
+import "io/bufio_test.ts";
+import "io/ioutil_test.ts";
+import "io/util_test.ts";
+import "io/writers_test.ts";
+import "io/readers_test.ts";
 import "fs/path/test.ts";
 import "io/test.ts";
 import "http/server_test.ts";
 import "http/file_server_test.ts";
 import "log/test.ts";
 import "media_types/test.ts";
+import "multipart/formfile_test.ts";
+import "multipart/multipart_test.ts";
 import "prettier/main_test.ts";
 import "testing/test.ts";
 import "textproto/test.ts";