feat: add ensureLink/ensureLinkSync for fs

fs/ensure_link.ts

@@ -0,0 +1,53 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as path from "./path/mod.ts";
+import { ensureDir, ensureDirSync } from "./ensure_dir.ts";
+import { exists, existsSync } from "./exists.ts";
+import { PathType, getFileInfoType } from "./utils.ts";
+
+/**
+ * Ensures that the hard link exists.
+ * If the directory structure does not exist, it is created.
+ *
+ * @param src the source file path. Directory hard links are not allowed.
+ * @param dest the destination link path
+ */
+export async function ensureLink(src: string, dest: string): Promise<void> {
+  if (await exists(dest)) {
+    const destStatInfo = await Deno.lstat(dest);
+    const destFilePathType = getFileInfoType(destStatInfo);
+    if (destFilePathType !== PathType.file) {
+      throw new Error(
+        `Ensure path exists, expected 'file', got '${destFilePathType}'`
+      );
+    }
+    return;
+  }
+
+  await ensureDir(path.dirname(dest));
+
+  await Deno.link(src, dest);
+}
+
+/**
+ * Ensures that the hard link exists.
+ * If the directory structure does not exist, it is created.
+ *
+ * @param src the source file path. Directory hard links are not allowed.
+ * @param dest the destination link path
+ */
+export function ensureLinkSync(src: string, dest: string): void {
+  if (existsSync(dest)) {
+    const destStatInfo = Deno.lstatSync(dest);
+    const destFilePathType = getFileInfoType(destStatInfo);
+    if (destFilePathType !== PathType.file) {
+      throw new Error(
+        `Ensure path exists, expected 'file', got '${destFilePathType}'`
+      );
+    }
+    return;
+  }
+
+  ensureDirSync(path.dirname(dest));
+
+  Deno.linkSync(src, dest);
+}

fs/ensure_link_test.ts

@@ -0,0 +1,170 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// TODO(axetroy): Add test for Windows once symlink is implemented for Windows.
+import { test } from "../testing/mod.ts";
+import {
+  assertEquals,
+  assertThrows,
+  assertThrowsAsync
+} from "../testing/asserts.ts";
+import { ensureLink, ensureLinkSync } from "./ensure_link.ts";
+import * as path from "./path/mod.ts";
+
+const testdataDir = path.resolve("fs", "testdata");
+
+test(async function ensureLinkIfItNotExist() {
+  const srcDir = path.join(testdataDir, "ensure_link_1");
+  const destDir = path.join(testdataDir, "ensure_link_1_2");
+  const testFile = path.join(srcDir, "test.txt");
+  const linkFile = path.join(destDir, "link.txt");
+
+  await assertThrowsAsync(async () => {
+    await ensureLink(testFile, linkFile);
+  });
+
+  await Deno.remove(destDir, { recursive: true });
+});
+
+test(function ensureLinkSyncIfItNotExist() {
+  const testDir = path.join(testdataDir, "ensure_link_2");
+  const testFile = path.join(testDir, "test.txt");
+  const linkFile = path.join(testDir, "link.txt");
+
+  assertThrows(() => {
+    ensureLinkSync(testFile, linkFile);
+  });
+
+  Deno.removeSync(testDir, { recursive: true });
+});
+
+test(async function ensureLinkIfItExist() {
+  const testDir = path.join(testdataDir, "ensure_link_3");
+  const testFile = path.join(testDir, "test.txt");
+  const linkFile = path.join(testDir, "link.txt");
+
+  await Deno.mkdir(testDir, true);
+  await Deno.writeFile(testFile, new Uint8Array());
+
+  await ensureLink(testFile, linkFile);
+
+  const srcStat = await Deno.lstat(testFile);
+  const linkStat = await Deno.lstat(linkFile);
+
+  assertEquals(srcStat.isFile(), true);
+  assertEquals(linkStat.isFile(), true);
+
+  // har link success. try to change one of them. they should be change both.
+
+  // let's change origin file.
+  await Deno.writeFile(testFile, new TextEncoder().encode("123"));
+
+  const testFileContent1 = new TextDecoder().decode(
+    await Deno.readFile(testFile)
+  );
+  const linkFileContent1 = new TextDecoder().decode(
+    await Deno.readFile(testFile)
+  );
+
+  assertEquals(testFileContent1, "123");
+  assertEquals(testFileContent1, linkFileContent1);
+
+  // let's change link file.
+  await Deno.writeFile(testFile, new TextEncoder().encode("abc"));
+
+  const testFileContent2 = new TextDecoder().decode(
+    await Deno.readFile(testFile)
+  );
+  const linkFileContent2 = new TextDecoder().decode(
+    await Deno.readFile(testFile)
+  );
+
+  assertEquals(testFileContent2, "abc");
+  assertEquals(testFileContent2, linkFileContent2);
+
+  await Deno.remove(testDir, { recursive: true });
+});
+
+test(function ensureLinkSyncIfItExist() {
+  const testDir = path.join(testdataDir, "ensure_link_4");
+  const testFile = path.join(testDir, "test.txt");
+  const linkFile = path.join(testDir, "link.txt");
+
+  Deno.mkdirSync(testDir, true);
+  Deno.writeFileSync(testFile, new Uint8Array());
+
+  ensureLinkSync(testFile, linkFile);
+
+  const srcStat = Deno.lstatSync(testFile);
+
+  const linkStat = Deno.lstatSync(linkFile);
+
+  assertEquals(srcStat.isFile(), true);
+  assertEquals(linkStat.isFile(), true);
+
+  // har link success. try to change one of them. they should be change both.
+
+  // let's change origin file.
+  Deno.writeFileSync(testFile, new TextEncoder().encode("123"));
+
+  const testFileContent1 = new TextDecoder().decode(
+    Deno.readFileSync(testFile)
+  );
+  const linkFileContent1 = new TextDecoder().decode(
+    Deno.readFileSync(testFile)
+  );
+
+  assertEquals(testFileContent1, "123");
+  assertEquals(testFileContent1, linkFileContent1);
+
+  // let's change link file.
+  Deno.writeFileSync(testFile, new TextEncoder().encode("abc"));
+
+  const testFileContent2 = new TextDecoder().decode(
+    Deno.readFileSync(testFile)
+  );
+  const linkFileContent2 = new TextDecoder().decode(
+    Deno.readFileSync(testFile)
+  );
+
+  assertEquals(testFileContent2, "abc");
+  assertEquals(testFileContent2, linkFileContent2);
+
+  Deno.removeSync(testDir, { recursive: true });
+});
+
+test(async function ensureLinkDirectoryIfItExist() {
+  const testDir = path.join(testdataDir, "ensure_link_origin_3");
+  const linkDir = path.join(testdataDir, "ensure_link_link_3");
+  const testFile = path.join(testDir, "test.txt");
+
+  await Deno.mkdir(testDir, true);
+  await Deno.writeFile(testFile, new Uint8Array());
+
+  await assertThrowsAsync(
+    async () => {
+      await ensureLink(testDir, linkDir);
+    },
+    Deno.DenoError,
+    "Operation not permitted (os error 1)"
+  );
+
+  Deno.removeSync(testDir, { recursive: true });
+});
+
+test(function ensureLinkSyncDirectoryIfItExist() {
+  const testDir = path.join(testdataDir, "ensure_link_origin_3");
+  const linkDir = path.join(testdataDir, "ensure_link_link_3");
+  const testFile = path.join(testDir, "test.txt");
+
+  Deno.mkdirSync(testDir, true);
+  Deno.writeFileSync(testFile, new Uint8Array());
+
+  assertThrows(
+    () => {
+      ensureLinkSync(testDir, linkDir);
+    },
+    Deno.DenoError,
+    "Operation not permitted (os error 1)"
+  );
+
+  Deno.removeSync(testDir, { recursive: true });
+});

fs/mod.ts

@@ -2,6 +2,7 @@
 export * from "./empty_dir.ts";
 export * from "./ensure_dir.ts";
 export * from "./ensure_file.ts";
+export * from "./ensure_link.ts";
 export * from "./ensure_symlink.ts";
 export * from "./exists.ts";
 export * from "./glob.ts";