fix: time out system font listing (#3786)

src/main/system-fonts.test.ts

@@ -0,0 +1,47 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+const { execFileMock, killMock } = vi.hoisted(() => ({
+  execFileMock: vi.fn(),
+  killMock: vi.fn()
+}))
+
+vi.mock('child_process', () => ({
+  execFile: execFileMock
+}))
+
+function expectedFallbackFont(): string {
+  if (process.platform === 'darwin') {
+    return 'SF Mono'
+  }
+  if (process.platform === 'win32') {
+    return 'Cascadia Mono'
+  }
+  return 'JetBrains Mono'
+}
+
+describe('listSystemFontFamilies', () => {
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.resetModules()
+    execFileMock.mockReset()
+    killMock.mockReset()
+  })
+
+  it('falls back when the platform font command never exits', async () => {
+    vi.useFakeTimers()
+    execFileMock.mockReturnValue({ kill: killMock })
+
+    const { listSystemFontFamilies } = await import('./system-fonts')
+    const fontsPromise = listSystemFontFamilies()
+    let resolvedFonts: string[] | null = null
+    fontsPromise.then((fonts) => {
+      resolvedFonts = fonts
+    })
+
+    await vi.advanceTimersByTimeAsync(60_000)
+
+    expect(resolvedFonts).not.toBeNull()
+    expect(resolvedFonts).toContain(expectedFallbackFont())
+    expect(killMock).toHaveBeenCalledOnce()
+  })
+})

src/main/system-fonts.ts

@@ -2,6 +2,7 @@ import { execFile } from 'child_process'
 
 let cachedFonts: string[] | null = null
 let fontsPromise: Promise<string[]> | null = null
+const SYSTEM_FONT_LIST_TIMEOUT_MS = 15_000
 
 export async function listSystemFontFamilies(): Promise<string[]> {
   if (cachedFonts) {
@@ -96,13 +97,37 @@ $fonts.Families | ForEach-Object { $_.Name }
 
 function execFileText(command: string, args: string[], maxBuffer: number): Promise<string> {
   return new Promise((resolve, reject) => {
-    execFile(command, args, { encoding: 'utf8', maxBuffer }, (error, stdout) => {
+    let settled = false
+    let timer: ReturnType<typeof setTimeout> | undefined
+    const child = execFile(command, args, { encoding: 'utf8', maxBuffer }, (error, stdout) => {
+      if (settled) {
+        return
+      }
+      settled = true
+      if (timer) {
+        clearTimeout(timer)
+      }
       if (error) {
         reject(error)
         return
       }
       resolve(stdout)
     })
+    if (!settled) {
+      timer = setTimeout(() => {
+        if (settled) {
+          return
+        }
+        settled = true
+        // Why: font discovery is a startup convenience; a stuck OS font tool
+        // should fall back instead of keeping settings IPC pending forever.
+        child.kill()
+        reject(new Error(`Timed out listing system fonts with ${command}`))
+      }, SYSTEM_FONT_LIST_TIMEOUT_MS)
+      if (typeof timer === 'object' && 'unref' in timer) {
+        timer.unref()
+      }
+    }
   })
 }