Fix emulator launching on Linux

Summary:
The Android SDK installation on Linux is really dumb. The emulator binary
is dynamically linked and ships with some `.so`s that need to be either in `LD_LIBRARY_PATH` or `$CWD`.
For some reason, there's no script, so you have to manually `cd` into the directory in order to
run it. ¯\_(ツ)_/¯

Reviewed By: jknoxville

Differential Revision: D13589660

fbshipit-source-id: e3bdd7468108f1fb1e52f23ae45e21cacc5480f9

flow-typed/npm/which_v1.x.x.js

@@ -0,0 +1,13 @@
+declare module "which" {
+  declare type Options = {|path?: string, pathExt?: string, all?: boolean|};
+  declare function whichAsync(cmd: string, cb: (err: ?Error, path: string) => void): void;
+  declare function whichAsync(cmd: string, options: Options, cb: (err: ?Error, path: string) => void): void;
+
+  declare function whichSync(cmd: string, options?: Options): string;
+  declare function whichSync(cmd: string, options: {|...Options, noThrow?: false|}): string;
+  declare function whichSync(cmd: string, options: {|...Options, noThrow: true|}): ?string;
+  declare module.exports: {
+  [[call]]: typeof whichAsync,
+    sync: typeof whichSync
+  }
+}

package.json

@@ -92,6 +92,7 @@
     "string-natural-compare": "^2.0.2",
     "tmp": "^0.0.33",
     "websocket": "^1.0.24",
+    "which": "^1.3.1",
     "xml2js": "^0.4.19",
     "yargs": "^11.0.0"
   },

src/chrome/DevicesButton.js

@@ -8,9 +8,14 @@
 import {Component, Button, styled} from 'flipper';
 import {connect} from 'react-redux';
 import {spawn} from 'child_process';
+import {dirname} from 'path';
 import {selectDevice, preferDevice} from '../reducers/connections.js';
+import {default as which} from 'which';
+import {promisify} from 'util';
 import type BaseDevice from '../devices/BaseDevice.js';
 
+const whichPromise = promisify(which);
+
 type Props = {
   selectedDevice: ?BaseDevice,
   androidEmulators: Array<string>,
@@ -27,13 +32,18 @@ const DropdownButton = styled(Button)({
 /* eslint-disable prettier/prettier */
 class DevicesButton extends Component<Props> {
   launchEmulator = (name: string) => {
-    const child = spawn('emulator', [`@${name}`], {
+    // On Linux, you must run the emulator from the directory it's in because
+    // reasons ...
+    whichPromise('emulator').then(emulatorPath => {
+      const child = spawn(emulatorPath, [`@${name}`], {
         detached: true,
+        cwd: dirname(emulatorPath),
       });
       child.stderr.on('data', data => {
         console.error(`Android emulator error: ${data}`);
       });
       child.on('error', console.error);
+    }).catch(console.error);
     this.props.preferDevice(name);
   };
 

yarn.lock

@@ -6696,7 +6696,7 @@ which-module@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/which-module/-/which-module-2.0.0.tgz#d9ef07dce77b9902b8a3a8fa4b31c3e3f7e6e87a"
 
-which@^1.2.12, which@^1.2.9, which@^1.3.0:
+which@^1.2.12, which@^1.2.9, which@^1.3.0, which@^1.3.1:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/which/-/which-1.3.1.tgz#a45043d54f5805316da8d62f9f50918d3da70b0a"
   dependencies: