Fix buildah issue of using overlay as storage driver (#51)

Work around https://github.com/redhat-actions/buildah-build/issues/45

Signed-off-by: divyansh42 <diagrawa@redhat.com>

src/utils.ts

@@ -0,0 +1,56 @@
+import * as ini from "ini";
+import { promises as fs } from "fs";
+import * as core from "@actions/core";
+import * as path from "path";
+import * as io from "@actions/io";
+import * as os from "os";
+
+async function findStorageDriver(filePaths: string[]): Promise<string> {
+    let storageDriver = "";
+    for (const filePath of filePaths) {
+        core.debug(`Checking if the storage file exists at ${filePath}`);
+        if (await fileExists(filePath)) {
+            core.debug(`Storage file exists at ${filePath}`);
+            const fileContent = ini.parse(await fs.readFile(filePath, "utf-8"));
+            if (fileContent.storage.driver) {
+                storageDriver = fileContent.storage.driver;
+            }
+        }
+    }
+    return storageDriver;
+}
+
+export async function isStorageDriverOverlay(): Promise<boolean> {
+    let xdgConfigHome = path.join(os.homedir(), ".config");
+    if (process.env.XDG_CONFIG_HOME) {
+        xdgConfigHome = process.env.XDG_CONFIG_HOME;
+    }
+    const filePaths: string[] = [
+        "/etc/containers/storage.conf",
+        path.join(xdgConfigHome, "containers/storage.conf"),
+    ];
+    const storageDriver = await findStorageDriver(filePaths);
+    return (storageDriver === "overlay");
+}
+
+async function fileExists(filePath: string): Promise<boolean> {
+    try {
+        await fs.access(filePath);
+        return true;
+    }
+    catch (err) {
+        return false;
+    }
+}
+
+export async function findFuseOverlayfsPath(): Promise<string | undefined> {
+    let fuseOverlayfsPath;
+    try {
+        fuseOverlayfsPath = await io.which("fuse-overlayfs");
+    }
+    catch (err) {
+        core.debug(err);
+    }
+
+    return fuseOverlayfsPath;
+}