1

注意：我已经找到了解决此问题的方法，将其发布在此处以供后代使用。查看所选答案。

以下（简化的）代码会引发无法捕获的“write EPIPE”（在某些情况下是“write EOF”）错误：

const { exec } = require("child_process");

const veryLargeString = "x".repeat(10 * 1024 * 1024);

const p = exec("gibberishThatWillFailImmediately");

p.stdin.write(veryLargeString);

我在这个问题上的失败尝试：

  • 写入前检查stdin.destroyed标志
  • 写入前检查stdin.writeableEnded标志
  • 对输入进行分块并stdin.writeableEnded在每个块之前进行检查。这会导致不确定的行为。
  • stdin.write(data)用 try-catch换行
  • 调用stdin.end(data)而不是stdin.write(data)
  • 传递stdin.write()一个回调，该回调应该得到发生的任何错误。回调得到了错误，但并没有阻止它被抛出。
4

1 回答 1

1

向流注册一个“错误”处理程序stdin似乎可以防止抛出错误。像这样：

const { exec } = require("child_process");

const veryLargeString = "x".repeat(10 * 1024 * 1024);

const p = exec("gibberishThatWillFailImmediately");

p.stdin.on('error', (error) => console.log("error caught: ", error));

p.stdin.write(veryLargeString);

这是一个示例，它返回一个包含错误的承诺，如果没有发生错误，则返回 null：

const { exec } = require("child_process");

const veryLargeString = "x".repeat(10 * 1024 * 1024);

function safelyWriteDataToStdin(stdin, data) {
  // Register an awaitable callback that will capture any error occuring during the write operation
  const promise = new Promise((resolve, _reject) => {
    // Using once() and not on() to remove the listener after the first catch.
    stdin.once("error", (error) => resolve(error));

    // stdin.end(data, callback) can probably be used here, but I keep the `write()` just in case `end()`'s callback is called before the 'error' event, since the docs are not clear about that. (docs say: "The callback is invoked before 'finish' or on error." for node version 15.0.0. Is "on error" how node people say "after error"? idk.)
    stdin.write(
      data,
      (error) => {
        if (!error) resolve(null); // The condition is necessary because when an error occurs, the callback is called before the 'error' event handler
      } // Signal the promise to complete when the write operation is complete with no errors. I don't simply use this `error` parameter because the exception will still be thrown if I don't listen to the 'error' event, and the docs say: "If an error occurs, the callback may or may not be called with the error as its first argument. To reliably detect write errors, add a listener for the 'error' event.". Also, I tested it myself and got two different errors in this callback and in the 'error' event handler.
    );
  });

  return promise;
}

const p = exec("gibberishThatWillFailImmediately");

safelyWriteDataToStdin(p.stdin, veryLargeString).then((error)=>console.log("The error is:", error ));
于 2021-04-28T08:54:44.410 回答