introduce abstractions to make Flatpak integration easier

app/src/lib/editors/found-editor.ts

@@ -1,5 +1,11 @@
 export interface IFoundEditor<T> {
   readonly editor: T
   readonly path: string
+  /**
+   * Indicate to Desktop to launch the editor with the `shell: true` option included.
+   *
+   * This is available to all platforms, but is only currently used by some Windows
+   * editors as their launch programs end in `.cmd`
+   */
   readonly usesShell?: boolean
 }

app/src/lib/editors/launch.ts

@@ -1,7 +1,25 @@
 import { spawn, SpawnOptions } from 'child_process'
-import { pathExists } from 'fs-extra'
+import { pathExists as pathExistsDefault } from 'fs-extra'
+import { pathExists as pathExistsLinux, spawnEditor } from '../helpers/linux'
 import { ExternalEditorError, FoundEditor } from './shared'
 
+/**
+ * Use a platform-specific pathExists based on the platform, to simplify changes
+ * to the application logic
+ *
+ * @param path the location of some program on disk
+ *
+ * @returns `true` if the path exists on disk, or `false` otherwise
+ *
+ */
+function pathExists(path: string) {
+  if (__LINUX__) {
+    return pathExistsLinux(path)
+  } else {
+    return pathExistsDefault(path)
+  }
+}
+
 /**
  * Open a given file or folder in the desired external editor.
  *
@@ -35,6 +53,8 @@ export async function launchExternalEditor(
     // In macOS we can use `open`, which will open the right executable file
     // for us, we only need the path to the editor .app folder.
     spawn('open', ['-a', editorPath, fullPath], opts)
+  } else if (__LINUX__) {
+    spawnEditor(editorPath, fullPath, opts)
   } else {
     spawn(editorPath, [fullPath], opts)
   }

app/src/lib/editors/linux.ts

@@ -1,4 +1,4 @@
-import { pathExists } from 'fs-extra'
+import { pathExists } from '../helpers/linux'
 
 import { IFoundEditor } from './found-editor'
 
@@ -34,7 +34,11 @@ const editors: ILinuxExternalEditor[] = [
   },
   {
     name: 'VSCodium',
-    paths: ['/usr/bin/codium', '/var/lib/flatpak/app/com.vscodium.codium'],
+    paths: [
+      '/usr/bin/codium',
+      '/var/lib/flatpak/app/com.vscodium.codium',
+      '/usr/share/vscodium-bin/bin/codium',
+    ],
   },
   {
     name: 'Sublime Text',

app/src/lib/helpers/linux.ts

@@ -0,0 +1,93 @@
+import { join } from 'path'
+import { pathExists as pathExistsInternal } from 'fs-extra'
+import {
+  ChildProcess,
+  spawn,
+  SpawnOptionsWithoutStdio,
+  SpawnOptions,
+} from 'child_process'
+
+export function isFlatpakBuild() {
+  return __LINUX__ && process.env.FLATPAK_HOST === '1'
+}
+
+/**
+ * Convert an executable path to be relative to the flatpak host
+ *
+ * @param path a path to an executable relative to the root of the filesystem
+ *
+ */
+export function convertToFlatpakPath(path: string) {
+  if (!__LINUX__) {
+    return path
+  }
+
+  if (path.startsWith('/opt/')) {
+    return path
+  }
+
+  return join('/var/run/host', path)
+}
+
+/**
+ * Checks the file path on disk exists before attempting to launch a specific shell
+ *
+ * @param path
+ *
+ * @returns `true` if the path can be resolved, or `false` otherwise
+ */
+export async function pathExists(path: string): Promise<boolean> {
+  if (isFlatpakBuild()) {
+    path = convertToFlatpakPath(path)
+  }
+
+  try {
+    return await pathExistsInternal(path)
+  } catch {
+    return false
+  }
+}
+
+/**
+ * Spawn a particular shell in a way that works for Flatpak-based usage
+ *
+ * @param path path to shell, relative to the root of the filesystem
+ * @param args arguments to provide to the shell
+ * @param options additional options to provide to spawn function
+ *
+ * @returns a child process to observe and monitor
+ */
+export function spawnShell(
+  path: string,
+  args: string[],
+  options?: SpawnOptionsWithoutStdio
+): ChildProcess {
+  if (isFlatpakBuild()) {
+    return spawn('flatpak-spawn', ['--host', path, ...args], options)
+  }
+
+  return spawn(path, args, options)
+}
+
+/**
+ * Spawn a given editor in a way that works for Flatpak-based usage
+ *
+ * @param path path to editor, relative to the root of the filesystem
+ * @param workingDirectory working directory to open initially in editor
+ * @param options additional options to provide to spawn function
+ */
+export function spawnEditor(
+  path: string,
+  workingDirectory: string,
+  options: SpawnOptions
+): ChildProcess {
+  if (isFlatpakBuild()) {
+    return spawn(
+      'flatpak-spawn',
+      ['--host', path, `"${workingDirectory}"`],
+      options
+    )
+  } else {
+    return spawn(path, [workingDirectory], options)
+  }
+}

app/src/lib/shells/linux.ts

@@ -1,8 +1,8 @@
-import { spawn, ChildProcess } from 'child_process'
-import { pathExists } from 'fs-extra'
+import { ChildProcess } from 'child_process'
 import { assertNever } from '../fatal-error'
 import { IFoundShell } from './found-shell'
 import { parseEnumValue } from '../enum'
+import { pathExists as pathExistsLinux, spawnShell } from '../helpers/linux'
 
 export enum Shell {
   Gnome = 'GNOME Terminal',
@@ -27,7 +27,7 @@ export function parse(label: string): Shell {
 }
 
 async function getPathIfAvailable(path: string): Promise<string | null> {
-  return (await pathExists(path)) ? path : null
+  return (await pathExistsLinux(path)) ? path : null
 }
 
 function getShellPath(shell: Shell): Promise<string | null> {
@@ -164,21 +164,25 @@ export function launch(
     case Shell.Terminator:
     case Shell.XFCE:
     case Shell.Alacritty:
-      return spawn(foundShell.path, ['--working-directory', path])
+      return spawnShell(foundShell.path, ['--working-directory', path])
     case Shell.Urxvt:
-      return spawn(foundShell.path, ['-cd', path])
+      return spawnShell(foundShell.path, ['-cd', path])
     case Shell.Konsole:
-      return spawn(foundShell.path, ['--workdir', path])
+      return spawnShell(foundShell.path, ['--workdir', path])
     case Shell.Xterm:
-      return spawn(foundShell.path, ['-e', '/bin/bash'], { cwd: path })
+      return spawnShell(foundShell.path, ['-e', '/bin/bash'], { cwd: path })
     case Shell.Terminology:
-      return spawn(foundShell.path, ['-d', path])
+      return spawnShell(foundShell.path, ['-d', path])
     case Shell.Deepin:
-      return spawn(foundShell.path, ['-w', path])
+      return spawnShell(foundShell.path, ['-w', path])
     case Shell.Elementary:
-      return spawn(foundShell.path, ['-w', path])
+      return spawnShell(foundShell.path, ['-w', path])
     case Shell.Kitty:
-      return spawn(foundShell.path, ['--single-instance', '--directory', path])
+      return spawnShell(foundShell.path, [
+        '--single-instance',
+        '--directory',
+        path,
+      ])
     default:
       return assertNever(shell, `Unknown shell: ${shell}`)
   }

app/src/lib/shells/shared.ts

@@ -1,9 +1,10 @@
 import { ChildProcess } from 'child_process'
-import { pathExists } from 'fs-extra'
+import { pathExists as pathExistsDefault } from 'fs-extra'
 
 import * as Darwin from './darwin'
 import * as Win32 from './win32'
 import * as Linux from './linux'
+import { pathExists as pathExistsLinux } from '../helpers/linux'
 import { IFoundShell } from './found-shell'
 import { ShellError } from './error'
 
@@ -72,6 +73,23 @@ export async function findShellOrDefault(shell: Shell): Promise<FoundShell> {
   }
 }
 
+/**
+ * Use a platform-specific pathExists based on the platform, to simplify changes
+ * to the application logic
+ *
+ * @param path the location of some program on disk
+ *
+ * @returns `true` if the path exists on disk, or `false` otherwise
+ *
+ */
+function pathExists(path: string) {
+  if (__LINUX__) {
+    return pathExistsLinux(path)
+  } else {
+    return pathExistsDefault(path)
+  }
+}
+
 /** Launch the given shell at the path. */
 export async function launchShell(
   shell: FoundShell,

app/test/unit/helpers/linux-test.ts

@@ -0,0 +1,30 @@
+import { convertToFlatpakPath } from '../../../src/lib/helpers/linux'
+
+describe('convertToFlatpakPath()', () => {
+  if (__LINUX__) {
+    it('converts /usr paths', () => {
+      const path = '/usr/bin/subl'
+      const expectedPath = '/var/run/host/usr/bin/subl'
+      expect(convertToFlatpakPath(path)).toEqual(expectedPath)
+    })
+
+    it('preserves /opt paths', () => {
+      const path = '/opt/slickedit-pro2018/bin/vs'
+      expect(convertToFlatpakPath(path)).toEqual(path)
+    })
+  }
+
+  if (__WIN32__) {
+    it('returns same path', () => {
+      const path = 'C:\\Windows\\System32\\Notepad.exe'
+      expect(convertToFlatpakPath(path)).toEqual(path)
+    })
+  }
+
+  if (__DARWIN__) {
+    it('returns same path', () => {
+      const path = '/usr/local/bin/code'
+      expect(convertToFlatpakPath(path)).toEqual(path)
+    })
+  }
+})