fix(cli): handle stdout/stderr stream errors in execFileUtf8Tail (#100850)

cxbAsDev · vincentkoc · web-flow · commit 9606fe43231b · 2026-07-06T08:24:43.000-07:00
* fix(cli): handle stdout/stderr stream errors in execFileUtf8Tail

* chore(proof): add real behavior proof for logs-cli runtime stream errors

* chore(proof): fix promise executor lint in logs-cli proof

* fix(cli): terminate log tail children on stream errors

---------

Co-authored-by: Vincent Koc &lt;vincentkoc@ieee.org&gt;
diff --git a/src/cli/logs-cli.runtime.test.ts b/src/cli/logs-cli.runtime.test.ts
@@ -0,0 +1,57 @@
+import type { ChildProcess } from "node:child_process";
+import { EventEmitter } from "node:events";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { execFileUtf8Tail } from "./logs-cli.runtime.js";
+
+const { spawnMock } = vi.hoisted(() => ({ spawnMock: vi.fn() }));
+
+vi.mock("node:child_process", async () => {
+  const actual = await vi.importActual<typeof import("node:child_process")>("node:child_process");
+  return {
+    ...actual,
+    spawn: spawnMock,
+  };
+});
+
+describe("execFileUtf8Tail", () => {
+  beforeEach(() => {
+    spawnMock.mockReset();
+  });
+
+  it.each(["stdout", "stderr"] as const)(
+    "terminates the child when %s emits an error",
+    async (streamName) => {
+      const stdout = new EventEmitter();
+      const stderr = new EventEmitter();
+      const kill = vi.fn(() => true);
+      const child = Object.assign(new EventEmitter(), { kill, stderr, stdout });
+      spawnMock.mockReturnValue(child as unknown as ChildProcess);
+
+      const resultPromise = execFileUtf8Tail("journalctl", ["--no-pager"], { maxBytes: 1024 });
+      stdout.emit("data", Buffer.from("partial output"));
+      const streamError = new Error(`${streamName} read failed`);
+      (streamName === "stdout" ? stdout : stderr).emit("error", streamError);
+
+      await expect(resultPromise).resolves.toEqual({
+        code: 1,
+        stderr: streamError.message,
+        stdout: "partial output",
+        truncated: false,
+      });
+      expect(kill).toHaveBeenCalledOnce();
+    },
+  );
+
+  it("does not kill the child when spawning fails", async () => {
+    const child = new EventEmitter();
+    const kill = vi.fn(() => true);
+    Object.assign(child, { kill, stderr: new EventEmitter(), stdout: new EventEmitter() });
+    spawnMock.mockReturnValue(child as unknown as ChildProcess);
+
+    const resultPromise = execFileUtf8Tail("journalctl", ["--no-pager"], { maxBytes: 1024 });
+    child.emit("error", new Error("spawn failed"));
+
+    await expect(resultPromise).resolves.toMatchObject({ code: 1, stderr: "spawn failed" });
+    expect(kill).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/cli/logs-cli.runtime.ts b/src/cli/logs-cli.runtime.ts
@@ -56,18 +56,28 @@ export async function execFileUtf8Tail(
         }
       }
     });
-    child.on("error", (error) => {
+
+    const resolveWithError = (error: unknown, terminateChild = false) => {
       if (settled) {
         return;
       }
       settled = true;
+      if (terminateChild) {
+        // Journal output is only useful when fully readable. Stop the child so
+        // a failed pipe cannot leave a live command holding the CLI open.
+        child.kill();
+      }
       resolve({
         stdout: Buffer.concat(stdoutChunks).toString("utf8"),
         stderr: error instanceof Error ? error.message : String(error),
         code: 1,
         truncated,
       });
-    });
+    };
+
+    child.stdout?.on("error", (error) => resolveWithError(error, true));
+    child.stderr?.on("error", (error) => resolveWithError(error, true));
+    child.on("error", resolveWithError);
     child.on("close", (code) => {
       if (settled) {
         return;
