如何从gjs-gtk应用程序发送电子邮件(派生邮件)

Question

我正在尝试编写一个需要发送电子邮件的gjs应用程序。我发现这样做的方法是使用spawn_async_with_pipes()调用邮件。该应用程序似乎产生了邮件，我没有收到错误，但我没有得到任何有用的输出，也没有收到测试电子邮件。。。

我已经做了一段时间了，几乎没有发现有用的最新文档。我正在使用gtk3和gjs(以及glib)。我还尝试过生成一个shell脚本，该脚本反过来调用邮件。这导致了"无法解析主机"错误和死信队列。所以我知道我正在生成我的命令。我并不担心"无法解析主机命令"，而是因为我无法通过直接生成邮件来获得它。

我正在生成这样的邮件：

const [res, pid, in_fd, out_fd, err_fd] =
await GLib.spawn_async_with_pipes(null,
['mail',
'-V',
`-s "${msgObj.subBlock}"`,
`-r ${to}`,
`-S smtp=${HOST}`,
'-S smtp-use-starttls',
'-S smtp-auth=login',
`-S smtp-auth-user=${USER}`,
`-S smtp-auth-password=${PASS}`,
FROM
], null, GLib.SpawnFlags.SEARCH_PATH, null);
const in_reader = new Gio.DataOutputStream({
base_stream: new Gio.UnixOutputStream({fd: in_fd})
});
var feedRes = in_reader.put_string(msgObj.msgBlock, null);
const out_reader = new Gio.DataInputStream({
base_stream: new Gio.UnixInputStream({fd: out_fd})
});
const err_reader = new Gio.DataInputStream({
base_stream: new Gio.UnixInputStream({fd: err_fd})
});
var out = out_reader.read_until("", null);
var err = err_reader.read_until("", null);
print(` > out : "${out}"`);
print(` > res : "${res}"`);
print(` > feedRes : "${feedRes}"`);
print(` > err : "${err}"`);

err是0，而res只是true

我不知道输出应该是什么，但我没有得到一个可识别的错误，也没有发送电子邮件。。。如何让我的应用程序发送电子邮件？产生邮件不是办法吗？提前感谢你能给我的任何建议。

Answer 1

我认为这里有几件事让你困惑，我想我可以澄清。

await GLib.spawn_async_with_pipes(

GLib有自己的异步函数概念，当适用时，需要将其封装在Promise中才能有效地使用await关键字。在这种情况下，GLib.spawn_async_with_pipes()并不像您所想的那样是异步的，但这没关系，因为我们将使用更高级别的类Gio.Subprocess。

async function mail(msgObj, to, host, user, pass, cancellable = null) {
try {
let proc = new Gio.Subprocess({
argv: ['mail',
'-V',
// Option switches and values are separate args
'-s', `"${msgObj.subBlock}"`,
'-r', `${to}`,
'-S', `smtp=${host}`,
'-S', 'smtp-use-starttls',
'-S', 'smtp-auth=login',
'-S', `smtp-auth-user=${user}`,
'-S', `smtp-auth-password=${pass}`,
FROM
],
flags: Gio.SubprocessFlags.STDIN_PIPE |
Gio.SubprocessFlags.STDOUT_PIPE |
Gio.SubprocessFlags.STDERR_MERGE
});
// Classes that implement GInitable must be initialized before use, but
// you could use Gio.Subprocess.new(argv, flags) which will call this for you
proc.init(cancellable);
// We're going to wrap a GLib async function in a Promise so we can
// use it like a native JavaScript async function.
//
// You could alternatively return this Promise instead of awaiting it
// here, but that's up to you.
let stdout = await new Promise((resolve, reject) => {
// communicate_utf8() returns a string, communicate() returns a
// a GLib.Bytes and there are "headless" functions available as well
proc.communicate_utf8_async(
// This is your stdin, which can just be a JS string
msgObj.msgBlock,
// we've been passing this around from the function args; you can
// create a Gio.Cancellable and call `cancellable.cancel()` to
// stop the command or any other operation you've passed it to at
// any time, which will throw an "Operation Cancelled" error.
cancellable,
// This is the GAsyncReady callback, which works like any other
// callback, but we need to ensure we catch errors so we can
// propagate them with `reject()` to make the Promise work
// properly
(proc, res) => {
try {
let [ok, stdout, stderr] = proc.communicate_utf8_finish(res);
// Because we used the STDERR_MERGE flag stderr will be
// included in stdout. Obviously you could also call
// `resolve([stdout, stderr])` if you wanted to keep both
// and separate them.
// 
// This won't affect whether the proc actually return non-
// zero causing the Promise to reject()
resolve(stdout);
} catch (e) {
reject(e);
}
}
);
});
return stdout;
} catch (e) {
// This could be any number of errors, but probably it will be a GError
// in which case it will have `code` property carrying a GIOErrorEnum
// you could use to programmatically respond to, if desired.
logError(e);
}
}

总体而言，Gio.Subprocess是一个更好的选择，尤其是对于不能将参数"传出"到函数中的语言绑定。使用GLib.spawn_async_with_pipes时，通常会传入NULL，以防止打开任何不想要的管道，并始终确保关闭任何不需要的管道。由于我们在GJS中无法做到这一点，您最终可能会遇到无法关闭的悬空文件描述符。

Gio.Subprocess为您做了很多辅助工作，确保文件描述符关闭，防止僵尸进程，为您设置子监视以及其他您真正不想担心的事情。它还具有获取IO流的便利功能，因此您不必自己包装fd，以及其他有用的功能。

我在GJS中写了一篇关于异步编程的较长的入门文章，您可能会发现它在这里很有用。您应该能够很快地轻松处理它，它试图澄清GLib异步、JavaScript异步和GLib主循环与JS事件循环之间的关系。