Fallback to which tar if no system tar

__tests__/tar.test.ts

@@ -6,17 +6,11 @@ jest.mock("@actions/exec");
 jest.mock("@actions/io");
 
 beforeAll(() => {
-    process.env["windir"] = "C:";
-
     jest.spyOn(io, "which").mockImplementation(tool => {
         return Promise.resolve(tool);
     });
 });
 
-afterAll(() => {
-    delete process.env["windir"];
-});
-
 test("extract tar", async () => {
     const mkdirMock = jest.spyOn(io, "mkdirP");
     const execMock = jest.spyOn(exec, "exec");
@@ -28,7 +22,7 @@ test("extract tar", async () => {
     expect(mkdirMock).toHaveBeenCalledWith(targetDirectory);
 
     const IS_WINDOWS = process.platform === "win32";
-    const tarPath = IS_WINDOWS ? "C:\\System32\\tar.exe" : "tar";
+    const tarPath = IS_WINDOWS ? `${process.env["windir"]}\\System32\\tar.exe` : "tar";
     expect(execMock).toHaveBeenCalledTimes(1);
     expect(execMock).toHaveBeenCalledWith(`"${tarPath}"`, [
         "-xz",
@@ -47,7 +41,7 @@ test("create tar", async () => {
     await tar.createTar(archivePath, sourceDirectory);
 
     const IS_WINDOWS = process.platform === "win32";
-    const tarPath = IS_WINDOWS ? "C:\\System32\\tar.exe" : "tar";
+    const tarPath = IS_WINDOWS ? `${process.env["windir"]}\\System32\\tar.exe` : "tar";
     expect(execMock).toHaveBeenCalledTimes(1);
     expect(execMock).toHaveBeenCalledWith(`"${tarPath}"`, [
         "-cz",

src/tar.ts

@@ -1,12 +1,31 @@
 import { exec } from "@actions/exec";
 import * as io from "@actions/io";
+import { existsSync } from "fs";
 
 async function getTarPath(): Promise<string> {
     // Explicitly use BSD Tar on Windows
     const IS_WINDOWS = process.platform === "win32";
-    return IS_WINDOWS
+    if (IS_WINDOWS) {
-        ? `${process.env["windir"]}\\System32\\tar.exe`
+        const systemTar = `${process.env["windir"]}\\System32\\tar.exe`;
-        : await io.which("tar", true);
+        if (existsSync(systemTar)) {
+            return systemTar;
+        }
+    }
+    return await io.which("tar", true);
+}
+
+async function execTar(args: string[]): Promise<void> {
+    try {
+        await exec(`"${await getTarPath()}"`, args);
+    } catch (error) {
+        const IS_WINDOWS = process.platform === "win32";
+        if (IS_WINDOWS) {
+            throw new Error(
+                `Tar failed with error: ${error?.message}. Ensure BSD tar is installed and on the PATH.`
+            );
+        }
+        throw new Error(`Tar failed with error: ${error?.message}`);
+    }
 }
 
 export async function extractTar(
@@ -15,19 +34,14 @@ export async function extractTar(
 ): Promise<void> {
     // Create directory to extract tar into
     await io.mkdirP(targetDirectory);
-
-    // http://man7.org/linux/man-pages/man1/tar.1.html
-    // tar [-options] <name of the tar archive> [files or directories which to add into archive]
     const args = ["-xz", "-f", archivePath, "-C", targetDirectory];
-    await exec(`"${await getTarPath()}"`, args);
+    await execTar(args);
 }
 
 export async function createTar(
     archivePath: string,
     sourceDirectory: string
 ): Promise<void> {
-    // http://man7.org/linux/man-pages/man1/tar.1.html
-    // tar [-options] <name of the tar archive> [files or directories which to add into archive]
     const args = ["-cz", "-f", archivePath, "-C", sourceDirectory, "."];
-    await exec(`"${await getTarPath()}"`, args);
+    await execTar(args);
 }