Rewrite readFile and writeFile (#2000)

Using open/read/write

js/buffer.ts

@@ -5,7 +5,7 @@
 // https://github.com/golang/go/blob/master/LICENSE
 
 //import * as io from "./io";
-import { Reader, Writer, ReadResult } from "./io";
+import { Reader, Writer, ReadResult, SyncReader, SyncWriter } from "./io";
 import { assert } from "./util";
 import { TextDecoder } from "./text_encoding";
 import { DenoError, ErrorKind } from "./errors";
@@ -32,7 +32,7 @@ function copyBytes(dst: Uint8Array, src: Uint8Array, off = 0): number {
 /** A Buffer is a variable-sized buffer of bytes with read() and write()
  * methods. Based on https://golang.org/pkg/bytes/#Buffer
  */
-export class Buffer implements Reader, Writer {
+export class Buffer implements Reader, SyncReader, Writer, SyncWriter {
   private buf: Uint8Array; // contents are the bytes buf[off : len(buf)]
   private off = 0; // read at buf[off], write at buf[buf.byteLength]
 
@@ -126,11 +126,11 @@ export class Buffer implements Reader, Writer {
     this.buf = new Uint8Array(this.buf.buffer, 0, len);
   }
 
-  /** read() reads the next len(p) bytes from the buffer or until the buffer
+  /** readSync() reads the next len(p) bytes from the buffer or until the buffer
    * is drained. The return value n is the number of bytes read. If the
    * buffer has no data to return, eof in the response will be true.
    */
-  async read(p: Uint8Array): Promise<ReadResult> {
+  readSync(p: Uint8Array): ReadResult {
     if (this.empty()) {
       // Buffer is empty, reset to recover space.
       this.reset();
@@ -145,11 +145,21 @@ export class Buffer implements Reader, Writer {
     return { nread, eof: false };
   }
 
-  async write(p: Uint8Array): Promise<number> {
+  async read(p: Uint8Array): Promise<ReadResult> {
+    const rr = this.readSync(p);
+    return Promise.resolve(rr);
+  }
+
+  writeSync(p: Uint8Array): number {
     const m = this._grow(p.byteLength);
     return copyBytes(this.buf, p, m);
   }
 
+  async write(p: Uint8Array): Promise<number> {
+    const n = this.writeSync(p);
+    return Promise.resolve(n);
+  }
+
   /** _grow() grows the buffer to guarantee space for n more bytes.
    * It returns the index where bytes should be written.
    * If the buffer can't grow it will throw with ErrTooLarge.
@@ -226,6 +236,27 @@ export class Buffer implements Reader, Writer {
       }
     }
   }
+
+  /** Sync version of `readFrom`
+   */
+  readFromSync(r: SyncReader): number {
+    let n = 0;
+    while (true) {
+      try {
+        const i = this._grow(MIN_READ);
+        this._reslice(i);
+        const fub = new Uint8Array(this.buf.buffer, i);
+        const { nread, eof } = r.readSync(fub);
+        this._reslice(i + nread);
+        n += nread;
+        if (eof) {
+          return n;
+        }
+      } catch (e) {
+        return n;
+      }
+    }
+  }
 }
 
 /** Read `r` until EOF and return the content as `Uint8Array`.
@@ -235,3 +266,11 @@ export async function readAll(r: Reader): Promise<Uint8Array> {
   await buf.readFrom(r);
   return buf.bytes();
 }
+
+/** Read synchronously `r` until EOF and return the content as `Uint8Array`.
+ */
+export function readAllSync(r: SyncReader): Uint8Array {
+  const buf = new Buffer();
+  buf.readFromSync(r);
+  return buf.bytes();
+}