SQSCANGHA-140 Fix GPG path handling for Windows

Fix GPG signature verification on Windows by converting Windows-style
paths to Unix-style paths that GPG expects. GPG on Windows (from Git
for Windows) is a Unix tool that requires Unix-style paths.

Issue: GPG was receiving Windows paths like C:\a\_temp\gpg-home and
attempting to use them, resulting in malformed paths like
/c/a/sonarqube-scan-action/C:\a\_temp\gpg-home and errors:
- "keyblock resource: No such file or directory"
- "can't connect to the dirmngr: No such file or directory"
- "keyserver receive failed: No dirmngr"

Solution:
- Add convertToUnixPath() function to convert Windows paths to Unix-style
  (e.g., C:\a\_temp\gpg -> /c/a/_temp/gpg)
- Apply conversion in tryImportKey() and runGpgVerify() before calling GPG
- No-op on non-Windows platforms
- Add comprehensive tests for path conversion

This ensures GPG signature verification works on all platforms (Linux,
macOS, and Windows).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main/__tests__/gpg-verification.test.js

@@ -18,16 +18,17 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-import { describe, it, afterEach, beforeEach } from "node:test";
+import { describe, it, afterEach } from "node:test";
 import assert from "node:assert/strict";
-import * as fs from "fs";
-import * as path from "path";
-import * as os from "os";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
 import {
   getGpgCommand,
   setupGpgHome,
   cleanupGpgHome,
   importSonarSourceKey,
+  convertToUnixPath,
 } from "../gpg-verification.js";
 
 describe("gpg-verification", () => {
@@ -54,6 +55,80 @@ describe("gpg-verification", () => {
     });
   });
 
+  describe("convertToUnixPath", () => {
+    it("should convert Windows path with drive letter to Unix path", () => {
+      // Mock Windows platform
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", {
+        value: "win32",
+        writable: true,
+        configurable: true,
+      });
+
+      try {
+        assert.equal(
+          convertToUnixPath("C:\\a\\_temp\\gpg-home"),
+          "/c/a/_temp/gpg-home"
+        );
+        assert.equal(
+          convertToUnixPath("D:\\Users\\test\\file.txt"),
+          "/d/Users/test/file.txt"
+        );
+      } finally {
+        // Restore original platform
+        Object.defineProperty(process, "platform", {
+          value: originalPlatform,
+          writable: true,
+          configurable: true,
+        });
+      }
+    });
+
+    it("should handle mixed slashes on Windows", () => {
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", {
+        value: "win32",
+        writable: true,
+        configurable: true,
+      });
+
+      try {
+        assert.equal(
+          convertToUnixPath("C:\\a/_temp\\gpg-home"),
+          "/c/a/_temp/gpg-home"
+        );
+      } finally {
+        Object.defineProperty(process, "platform", {
+          value: originalPlatform,
+          writable: true,
+          configurable: true,
+        });
+      }
+    });
+
+    it("should return path unchanged on non-Windows platforms", () => {
+      const originalPlatform = process.platform;
+      Object.defineProperty(process, "platform", {
+        value: "linux",
+        writable: true,
+        configurable: true,
+      });
+
+      try {
+        assert.equal(
+          convertToUnixPath("/tmp/gpg-home"),
+          "/tmp/gpg-home"
+        );
+      } finally {
+        Object.defineProperty(process, "platform", {
+          value: originalPlatform,
+          writable: true,
+          configurable: true,
+        });
+      }
+    });
+  });
+
   describe("setupGpgHome", () => {
     it("should create a temporary GPG home directory", () => {
       const gpgHome = setupGpgHome();
@@ -65,8 +140,8 @@ describe("gpg-verification", () => {
       // Check directory permissions (on Unix systems)
       if (process.platform !== "win32") {
         const stats = fs.statSync(gpgHome);
-        const mode = stats.mode & parseInt("777", 8);
-        assert.equal(mode, parseInt("700", 8));
+        const mode = stats.mode & Number.parseInt("777", 8);
+        assert.equal(mode, Number.parseInt("700", 8));
       }
     });
 

src/main/gpg-verification.js

@@ -20,9 +20,9 @@
 
 import * as core from "@actions/core";
 import * as exec from "@actions/exec";
-import * as fs from "fs";
-import * as os from "os";
-import * as path from "path";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
 
 // SonarSource public key fingerprint for verifying scanner signatures
 const SONARSOURCE_KEY_FINGERPRINT = "679F1EE92B19609DE816FDE81DB198F93525EC1A";
@@ -99,6 +99,28 @@ export function getGpgCommand() {
   return "gpg";
 }
 
+/**
+ * Converts a Windows path to Unix-style path for GPG
+ * GPG on Windows (from Git for Windows) expects Unix-style paths
+ * @param {string} windowsPath - Windows path (e.g., C:\a\_temp\gpg-home)
+ * @returns {string} Unix-style path (e.g., /c/a/_temp/gpg-home)
+ */
+export function convertToUnixPath(windowsPath) {
+  if (process.platform !== "win32") {
+    return windowsPath;
+  }
+
+  // Convert backslashes to forward slashes
+  let unixPath = windowsPath.replace(/\\/g, "/");
+
+  // Convert drive letter (e.g., C: -> /c)
+  unixPath = unixPath.replace(/^([A-Za-z]):/, (match, drive) => {
+    return `/${drive.toLowerCase()}`;
+  });
+
+  return unixPath;
+}
+
 /**
  * Creates a temporary GPG home directory
  * @returns {string} Path to the temporary GPG home directory
@@ -122,12 +144,14 @@ export function setupGpgHome() {
  */
 async function tryImportKey(gpgHome, keyFingerprint, keyserver) {
   const gpgCommand = getGpgCommand();
+  // Convert Windows paths to Unix-style for GPG compatibility
+  const gpgHomePath = convertToUnixPath(gpgHome);
 
   await exec.exec(
     gpgCommand,
     [
       "--homedir",
-      gpgHome,
+      gpgHomePath,
       "--batch",
       "--keyserver",
       keyserver,
@@ -192,9 +216,17 @@ export async function runGpgVerify(zipPath, signaturePath, gpgHome) {
 
   try {
     core.info("Verifying GPG signature...");
+    // Convert Windows paths to Unix-style for GPG compatibility
     await exec.exec(
       gpgCommand,
-      ["--homedir", gpgHome, "--batch", "--verify", signaturePath, zipPath],
+      [
+        "--homedir",
+        convertToUnixPath(gpgHome),
+        "--batch",
+        "--verify",
+        convertToUnixPath(signaturePath),
+        convertToUnixPath(zipPath),
+      ],
       {
         silent: false,
       }