Make openssl check async

Summary:
This was the last eslint warning for `flipper-server-core` and the only call-site
was async already.

Reviewed By: mweststrate

Differential Revision: D32026626

fbshipit-source-id: 0d6f06086c33707b26f58f668ad533daca9de7dd

desktop/flipper-server-core/src/utils/CertificateProvider.tsx

@@ -173,7 +173,7 @@ export default class CertificateProvider {
     if (csr === '') {
       return Promise.reject(new Error(`Received empty CSR from ${os} device`));
     }
-    this.ensureOpenSSLIsAvailable();
+    await this.ensureOpenSSLIsAvailable();
     const rootFolder = await promisify(tmp.dir)();
     const certFolder = rootFolder + '/FlipperCerts/';
     const certsZipPath = rootFolder + '/certs.zip';
@@ -249,8 +249,8 @@ export default class CertificateProvider {
     return Promise.resolve('unknown');
   }
 
-  private ensureOpenSSLIsAvailable(): void {
-    if (!opensslInstalled()) {
+  private async ensureOpenSSLIsAvailable(): Promise<void> {
+    if (!(await opensslInstalled())) {
       const e = Error(
         "It looks like you don't have OpenSSL installed. Please install it to continue.",
       );

desktop/flipper-server-core/src/utils/openssl-wrapper-with-promises.tsx

@@ -8,7 +8,7 @@
  */
 
 import {exec as opensslWithCallback, Action} from 'openssl-wrapper';
-import child_process from 'child_process';
+import {spawn} from 'promisify-child-process';
 
 export function openssl(action: Action, options: {}): Promise<string> {
   return new Promise((resolve, reject) => {
@@ -22,6 +22,11 @@ export function openssl(action: Action, options: {}): Promise<string> {
   });
 }
 
-export function isInstalled(): boolean {
-  return !child_process.spawnSync('openssl', ['version']).error;
+export async function isInstalled(): Promise<boolean> {
+  try {
+    const result = await spawn('openssl', ['version']);
+    return result.code === 0;
+  } catch (_e) {
+    return false;
+  }
 }