4 files changed, 178 insertions, 0 deletions
diff --git a/js/copy_file.ts b/js/copy_file.ts
new file mode 100644
index 000000000..ff08cc00b
--- /dev/null
+++ b/js/copy_file.ts
@@ -0,0 +1,46 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+import * as fbs from "gen/msg_generated";
+import { flatbuffers } from "flatbuffers";
+import * as dispatch from "./dispatch";
+
+/**
+ * Copies the contents of a file to another by name synchronously.
+ * Creates a new file if target does not exists, and if target exists,
+ * overwrites original content of the target file.
+ * It would also copy the permission of the original file
+ * to the destination.
+ *
+ *     import { copyFileSync } from "deno";
+ *     copyFileSync("from.txt", "to.txt");
+ */
+export function copyFileSync(from: string, to: string): void {
+  dispatch.sendSync(...req(from, to));
+}
+
+/**
+ * Copies the contents of a file to another by name.
+ * Creates a new file if target does not exists, and if target exists,
+ * overwrites original content of the target file.
+ * It would also copy the permission of the original file
+ * to the destination.
+ *
+ *     import { copyFile } from "deno";
+ *     await copyFile("from.txt", "to.txt");
+ */
+export async function copyFile(from: string, to: string): Promise<void> {
+  await dispatch.sendAsync(...req(from, to));
+}
+
+function req(
+  from: string,
+  to: string
+): [flatbuffers.Builder, fbs.Any, flatbuffers.Offset] {
+  const builder = new flatbuffers.Builder();
+  const from_ = builder.createString(from);
+  const to_ = builder.createString(to);
+  fbs.CopyFile.startCopyFile(builder);
+  fbs.CopyFile.addFrom(builder, from_);
+  fbs.CopyFile.addTo(builder, to_);
+  const msg = fbs.CopyFile.endCopyFile(builder);
+  return [builder, fbs.Any.CopyFile, msg];
+}
diff --git a/js/copy_file_test.ts b/js/copy_file_test.ts
new file mode 100644
index 000000000..846cfcbc4
--- /dev/null
+++ b/js/copy_file_test.ts
@@ -0,0 +1,130 @@
+import { testPerm, assert, assertEqual } from "./test_util.ts";
+import * as deno from "deno";
+
+function readFileString(filename: string): string {
+  const dataRead = deno.readFileSync(filename);
+  const dec = new TextDecoder("utf-8");
+  return dec.decode(dataRead);
+}
+
+function writeFileString(filename: string, s: string) {
+  const enc = new TextEncoder();
+  const data = enc.encode(s);
+  deno.writeFileSync(filename, data, 0o666);
+}
+
+function assertSameContent(filename1: string, filename2: string) {
+  const data1 = deno.readFileSync(filename1);
+  const data2 = deno.readFileSync(filename2);
+  assertEqual(data1, data2);
+}
+
+testPerm({ write: true }, function copyFileSyncSuccess() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  writeFileString(fromFilename, "Hello world!");
+  deno.copyFileSync(fromFilename, toFilename);
+  // No change to original file
+  assertEqual(readFileString(fromFilename), "Hello world!");
+  // Original == Dest
+  assertSameContent(fromFilename, toFilename);
+});
+
+testPerm({ write: true }, function copyFileSyncFailure() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  // We skip initial writing here, from.txt does not exist
+  let err;
+  try {
+    deno.copyFileSync(fromFilename, toFilename);
+  } catch (e) {
+    err = e;
+  }
+  assert(!!err);
+  // Rust deem non-existent path as invalid input
+  assertEqual(err.kind, deno.ErrorKind.InvalidInput);
+  assertEqual(err.name, "InvalidInput");
+});
+
+testPerm({ write: true }, function copyFileSyncOverwrite() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  writeFileString(fromFilename, "Hello world!");
+  // Make Dest exist and have different content
+  writeFileString(toFilename, "Goodbye!");
+  deno.copyFileSync(fromFilename, toFilename);
+  // No change to original file
+  assertEqual(readFileString(fromFilename), "Hello world!");
+  // Original == Dest
+  assertSameContent(fromFilename, toFilename);
+});
+
+testPerm({ write: false }, function copyFileSyncPerm() {
+  let err;
+  try {
+    deno.copyFileSync("/from.txt", "/to.txt");
+  } catch (e) {
+    err = e;
+  }
+  assert(!!err);
+  assertEqual(err.kind, deno.ErrorKind.PermissionDenied);
+  assertEqual(err.name, "PermissionDenied");
+});
+
+testPerm({ write: true }, async function copyFileSuccess() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  writeFileString(fromFilename, "Hello world!");
+  await deno.copyFile(fromFilename, toFilename);
+  // No change to original file
+  assertEqual(readFileString(fromFilename), "Hello world!");
+  // Original == Dest
+  assertSameContent(fromFilename, toFilename);
+});
+
+testPerm({ write: true }, async function copyFileFailure() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  // We skip initial writing here, from.txt does not exist
+  let err;
+  try {
+    await deno.copyFile(fromFilename, toFilename);
+  } catch (e) {
+    err = e;
+  }
+  assert(!!err);
+  // Rust deem non-existent path as invalid input
+  assertEqual(err.kind, deno.ErrorKind.InvalidInput);
+  assertEqual(err.name, "InvalidInput");
+});
+
+testPerm({ write: true }, async function copyFileOverwrite() {
+  const tempDir = deno.makeTempDirSync();
+  const fromFilename = tempDir + "/from.txt";
+  const toFilename = tempDir + "/to.txt";
+  writeFileString(fromFilename, "Hello world!");
+  // Make Dest exist and have different content
+  writeFileString(toFilename, "Goodbye!");
+  await deno.copyFile(fromFilename, toFilename);
+  // No change to original file
+  assertEqual(readFileString(fromFilename), "Hello world!");
+  // Original == Dest
+  assertSameContent(fromFilename, toFilename);
+});
+
+testPerm({ write: false }, async function copyFilePerm() {
+  let err;
+  try {
+    await deno.copyFile("/from.txt", "/to.txt");
+  } catch (e) {
+    err = e;
+  }
+  assert(!!err);
+  assertEqual(err.kind, deno.ErrorKind.PermissionDenied);
+  assertEqual(err.name, "PermissionDenied");
+});
diff --git a/js/deno.ts b/js/deno.ts
index cd290bfa3..03f3d1a89 100644
--- a/js/deno.ts
+++ b/js/deno.ts
@@ -9,6 +9,7 @@ export { makeTempDirSync, makeTempDir } from "./make_temp_dir";
 export { removeSync, remove, removeAllSync, removeAll } from "./remove";
 export { renameSync, rename } from "./rename";
 export { readFileSync, readFile } from "./read_file";
+export { copyFileSync, copyFile } from "./copy_file";
 export { readlinkSync, readlink } from "./read_link";
 export { FileInfo, statSync, lstatSync, stat, lstat } from "./stat";
 export { symlinkSync, symlink } from "./symlink";
diff --git a/js/unit_tests.ts b/js/unit_tests.ts
index 2eea6c17b..e33fcf245 100644
--- a/js/unit_tests.ts
+++ b/js/unit_tests.ts
@@ -8,6 +8,7 @@ import "./os_test.ts";
 import "./files_test.ts";
 import "./read_file_test.ts";
 import "./write_file_test.ts";
+import "./copy_file_test.ts";
 import "./mkdir_test.ts";
 import "./make_temp_dir_test.ts";
 import "./stat_test.ts";