Rough VeraCrypt integration

Needs some more error handling and messaging. Only tested on OS X.

app/components/Export.js

@@ -6,6 +6,8 @@ import CopyButton from './CopyButton';
 import SaveFileButton from './SaveFileButton';
 import PuzzleIcon from './PuzzleIcon';
 import Modal from './Modal';
+import { remote } from 'electron';
+import openVolume from 'app/lib/veracrypt';
 
 
 export default class Export extends Component {
@@ -25,7 +27,21 @@ export default class Export extends Component {
   }
 
   handleVeracrypt() {
-    console.log('veracrypt');
+    return new Promise((resolve, reject) => {
+      remote.dialog.showOpenDialog({
+        title: 'Select VeraCrypt volume',
+        properties: ['openFile']
+      }, (filenames) => {
+        const path = filenames[0];
+        openVolume(path, this.props.secret)
+          .then(resolve) // Nothing to do on success
+          .catch((err) => {
+            // TODO: Display an error message.
+            console.log(err);
+            reject(err);
+          });
+      });
+    });
   }
 
   render() {

app/lib/veracrypt.js

@@ -0,0 +1,52 @@
+import { remote } from 'electron';
+/* eslint-disable camelcase */
+const child_process = remote.require('child_process');
+/* eslint-enable */
+
+export default function openVolume(path, password) {
+  // There is some work to do to make this work cross-platform.
+  // The VeraCrypt linux installer puts a symlink to the binary in /usr/bin,
+  // but the Mac installer doesn't (annoyingly). The Windows binary has a
+  // different interface entirely, documented at
+  // https://veracrypt.codeplex.com/wikipage?title=Command%20Line%20Usage.
+  let binary;
+  let fallbackBinary;
+  let args = `--mount ${path} --password ${password} --explore`;
+  if (process.platform === 'darwin') {
+    binary = '/Applications/VeraCrypt.app/Contents/MacOS/VeraCrypt';
+    fallbackBinary = 'veracrypt';
+  } else if (process.platform === 'linux') {
+    binary = 'veracrypt';
+  } else if (process.platform === 'win32') {
+    binary = 'VeraCrypt.exe';
+    args = `/volume ${path} /password ${password} /explore`;
+  } else {
+    return Promise.reject('Unsupported platform');
+  }
+
+  return execPromise(`${binary} ${args}`)
+    .catch((errObj) => {
+      if (fallbackBinary) {
+        return execPromise(`${fallbackBinary} ${args}`)
+          .catch(parseErrors);
+      }
+      return errObj;
+    }).catch(parseErrors);
+}
+
+function execPromise(command) {
+  return new Promise((resolve, reject) => {
+    child_process.exec(command, (err, stdout, stderr) => {
+      if (err) {
+        reject({ err, stderr });
+      }
+
+      resolve(stdout);
+    });
+  });
+}
+
+function parseErrors(errObj) {
+  // TODO: Figure out if this needs to be better
+  return errObj.err;
+}