Verify JDK downloads with vendor checksums (#1167)

* Verify JDK downloads with vendor checksums

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Handle missing vendor checksum values

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Preserve checksum error during cleanup failure

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Validate checksum metadata value types

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Clarify checksum documentation

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Expand vendor checksum verification

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Accept SHA-256 or SHA-512 for JetBrains checksum sibling

JetBrains publishes a single, generically-named ".checksum" sibling
whose digest algorithm isn't disclosed by the filename. Older JBR 11
builds (e.g. jbrsdk_nomod-11_0_16-*-b2043.64.tar.gz) publish a SHA-256
digest there, while newer builds publish SHA-512. The JetBrains
installer previously assumed SHA-512 unconditionally, so verification
failed with "Malformed sha512 checksum metadata ... expected a
128-character hexadecimal digest" for those older builds, breaking the
jetbrains 11 e2e job on macOS and Windows.

fetchChecksum now accepts a list of candidate algorithms and infers
the actual algorithm from the returned digest's length, preferring the
strongest match. The JetBrains installer passes ['sha512', 'sha256'];
all other callers are unaffected since they already pass a single,
vendor-disclosed algorithm.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

* Use SapMachine archive checksum files

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

---------

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: a800a031-600e-4d28-b23e-be309555d38d

__tests__/distributors/microsoft-installer.test.ts

@@ -103,9 +103,12 @@ const util = await import('../../src/util.js');
 describe('findPackageForDownload', () => {
   let distribution: InstanceType<typeof MicrosoftDistributions>;
   let spyGetManifestFromRepo: any;
+  let spyHttpClientGet: any;
   let spyDebug: any;
   let spyCoreError: any;
 
+  const MICROSOFT_CHECKSUM = 'b'.repeat(64);
+
   beforeEach(() => {
     mockOsArch.mockReturnValue('x64');
     mockOsPlatform.mockReturnValue(process.platform);
@@ -124,6 +127,15 @@ describe('findPackageForDownload', () => {
       headers: {}
     });
 
+    // Every resolved release fetches `${download_url}.sha256sum.txt`; stub
+    // it with a GNU-style `<hex>  <filename>` payload so tests never reach
+    // the real network.
+    spyHttpClientGet = jest.spyOn(HttpClient.prototype, 'get');
+    spyHttpClientGet.mockResolvedValue({
+      message: {statusCode: 200},
+      readBody: async () => `${MICROSOFT_CHECKSUM}  microsoft-jdk.tar.gz\n`
+    });
+
     spyDebug = core.debug as jest.Mock;
     spyDebug.mockImplementation(() => {});
 
@@ -311,6 +323,34 @@ describe('findPackageForDownload', () => {
       'https://example.test/jdk.tar.gz.custom.sig'
     );
   });
+
+  it('fetches the authoritative sha256 checksum from the GNU-style sibling file', async () => {
+    mockOsPlatform.mockReturnValue(process.platform);
+
+    const result = await distribution['findPackageForDownload']('17.0.7');
+
+    expect(result.checksum).toEqual({
+      algorithm: 'sha256',
+      value: MICROSOFT_CHECKSUM,
+      source: `${result.url}.sha256sum.txt`
+    });
+    expect(spyHttpClientGet).toHaveBeenCalledWith(
+      `${result.url}.sha256sum.txt`
+    );
+    expect(spyHttpClientGet).toHaveBeenCalledTimes(1);
+  });
+
+  it('parses only the first whitespace-delimited token from the GNU checksum payload', async () => {
+    spyHttpClientGet.mockResolvedValue({
+      message: {statusCode: 200},
+      readBody: async () =>
+        `${MICROSOFT_CHECKSUM}  microsoft-jdk-17.0.7-linux-x64.tar.gz\n`
+    });
+
+    const result = await distribution['findPackageForDownload']('17.0.7');
+
+    expect(result.checksum?.value).toBe(MICROSOFT_CHECKSUM);
+  });
 });
 
 describe('downloadTool', () => {