fix: start the macOS local terminal when the shell or spawn helper is broken (Support#1418)

electron/local-shell.cjs

@@ -1,4 +1,16 @@
-function resolveLocalShell(platform, requestedShell, env = process.env) {
+const fs = require("node:fs");
+const path = require("node:path");
+
+function isUsableShell(file, exists) {
+  return !!file && (!path.isAbsolute(file) || exists(file));
+}
+
+function resolveLocalShell(
+  platform,
+  requestedShell,
+  env = process.env,
+  exists = fs.existsSync,
+) {
   if (platform === "win32") {
     if (requestedShell === "wsl") {
       return { file: "wsl.exe", args: [] };
@@ -9,13 +21,47 @@ function resolveLocalShell(platform, requestedShell, env = process.env) {
     };
   }
 
-  return {
-    file:
-      env.TERMIX_LOCAL_SHELL ||
-      env.SHELL ||
-      (platform === "darwin" ? "/bin/zsh" : "/bin/bash"),
-    args: ["-l"],
-  };
+  // A SHELL left pointing at an uninstalled shell makes the spawn fail.
+  const fallbacks =
+    platform === "darwin"
+      ? ["/bin/zsh", "/bin/bash", "/bin/sh"]
+      : ["/bin/bash", "/bin/sh"];
+  const file =
+    [env.TERMIX_LOCAL_SHELL, env.SHELL, ...fallbacks].find((candidate) =>
+      isUsableShell(candidate, exists),
+    ) || fallbacks[0];
+  return { file, args: ["-l"] };
 }
 
-module.exports = { resolveLocalShell };
+/**
+ * node-pty starts every shell through its spawn-helper binary, and a packaged
+ * copy that lost its execute bit fails with "posix_spawnp failed". Returns
+ * how many helpers were fixed.
+ */
+function repairSpawnHelpers(ptyDir, fsImpl = fs) {
+  const dir = ptyDir.replace(/app\.asar(?!\.unpacked)/, "app.asar.unpacked");
+  const candidates = [
+    path.join(dir, "build", "Release", "spawn-helper"),
+    path.join(
+      dir,
+      "prebuilds",
+      `${process.platform}-${process.arch}`,
+      "spawn-helper",
+    ),
+  ];
+  let fixed = 0;
+  for (const helper of candidates) {
+    try {
+      const mode = fsImpl.statSync(helper).mode;
+      if ((mode & 0o111) === 0) {
+        fsImpl.chmodSync(helper, mode | 0o755);
+        fixed += 1;
+      }
+    } catch {
+      // Missing or read-only; nothing to fix here.
+    }
+  }
+  return fixed;
+}
+
+module.exports = { resolveLocalShell, repairSpawnHelpers };

electron/main.cjs

@@ -33,7 +33,7 @@ const { launchNativeRdp } = require("./native-rdp.cjs");
 const { isCloseActiveTabInput } = require("./keyboard-shortcuts.cjs");
 const { quitApp } = require("./app-quit.cjs");
 const { selectLinuxPasswordStore } = require("./linux-password-store.cjs");
-const { resolveLocalShell } = require("./local-shell.cjs");
+const { resolveLocalShell, repairSpawnHelpers } = require("./local-shell.cjs");
 const { registerLocalFileHandlers } = require("./local-files.cjs");
 
 const localTerminalSessions = new Map();
@@ -3240,17 +3240,32 @@ ipcMain.handle("local-terminal-start", (event, dimensions = {}) => {
   const rows = Math.min(300, Math.max(1, Number(dimensions.rows) || 24));
   const sessionId = crypto.randomUUID();
   const shellConfig = resolveLocalShell(process.platform, dimensions.shell);
-  const child = pty.spawn(shellConfig.file, shellConfig.args, {
-    name: "xterm-256color",
-    cols,
-    rows,
-    cwd: os.homedir(),
-    env: {
-      ...process.env,
-      TERM: "xterm-256color",
-      COLORTERM: "truecolor",
-    },
-  });
+  const spawnShell = () =>
+    pty.spawn(shellConfig.file, shellConfig.args, {
+      name: "xterm-256color",
+      cols,
+      rows,
+      cwd: os.homedir(),
+      env: {
+        ...process.env,
+        TERM: "xterm-256color",
+        COLORTERM: "truecolor",
+      },
+    });
+  let child;
+  try {
+    child = spawnShell();
+  } catch (error) {
+    const ptyDir = path.dirname(require.resolve("node-pty/package.json"));
+    if (
+      !String(error?.message).includes("posix_spawnp") ||
+      repairSpawnHelpers(ptyDir) === 0
+    ) {
+      throw error;
+    }
+    logToFile("[local-terminal] restored the spawn-helper execute bit");
+    child = spawnShell();
+  }
   const ownerId = event.sender.id;
   const session = { ownerId, process: child, ready: false, buffered: "" };
   localTerminalSessions.set(sessionId, session);