src: restore stdio on program exit

[bnoordhuis]

Record the state of the stdio file descriptors on start-up and restore
them to that state on exit. This should prevent issues where node.js
sometimes leaves stdio in raw or non-blocking mode.

Fixes: #14752
CI: https://ci.nodejs.org/job/node-test-commit/14917/

Still pondering how to write a good test. The specific issue of #14752 is when fds 1 and 2 both refer to the write end of the same pipe but that's kind of hard to test without resorting to hacks and internals.

[addaleax]

LGTM, but I have two questions:

• Would this kind of code maybe have a better home in libuv?
• Does this affect child processes’ inherited stdio? i.e. if the parent of a detached child exits first, does the stdio mode for the child process also get reset?

[bnoordhuis]

Would this kind of code maybe have a better home in libuv?

I should have anticipated that question. :-)

Yes, maybe it can, but #14752 is not really a libuv issue. Node.js turns the stdio file descriptors non-blocking with net.Socket({ fd: fd }) but doesn't clean up afterwards.

This code could migrate to libuv over time but I don't know if it's useful outside of node.js.

Does this affect child processes’ inherited stdio?

Yes, but so does the existing code. Let me think about whether there's a way we can do better.

[BridgeAR]

New CI https://ci.nodejs.org/job/node-test-pull-request/12411/

[joyeecheung]

Previous CI expired. New CI: https://ci.nodejs.org/job/node-test-pull-request/12567/

[joyeecheung]

The build is not working on centos6-64

https://ci.nodejs.org/job/node-test-commit-linux/15597/nodes=centos6-64/console

[ -x ./node ] && ./node tools/doc/addon-verify.js || node tools/doc/addon-verify.js
[28174]: ../src/node.cc:4150:void node::PlatformInit(): Assertion `errno == ENODEV || errno == ENOTTY || errno == EOPNOTSUPP' failed.
 1: node::Abort() [./node]
 2: 0x121b84b [./node]
 3: node::PlatformInit() [./node]
 4: node::Start(int, char**) [./node]
 5: __libc_start_main [/lib64/libc.so.6]
 6: 0x8a8341 [./node]
/bin/sh: line 1: 28174 Aborted                 (core dumped) ./node tools/doc/addon-verify.js

[Fishrock123]

@bnoordhuis any status here?

[BridgeAR]

Ping @bnoordhuis

[joyeecheung]

BTW, I think this might fix one of the issues lurking around our CI these days:

https://ci.nodejs.org/job/node-test-commit-linux-containered/nodes=ubuntu1604_sharedlibs_openssl110_x64/2062/console

05:39:29 make[2]: write error: stdout
05:39:29 gyp infoMakefile:619: recipe for target 'doc-only' failed

[bnoordhuis]

I'll try to revisit this in the next few days. I can't reproduce the centos6 failure locally so I'll probably have to do some printf-style debugging on the CI.

[BridgeAR]

Ping @bnoordhuis

[BridgeAR]

Ping @bnoordhuis again

[BridgeAR]

Closing due to inactivity. Please feel free to reopen when you plan on working on this again @bnoordhuis

[ktaborski]

I think, that the error from @joyeecheung is caused, when node is run in non-terminal environment
like Jenkins.

The tcgetattr() function shall fail if:

EBADF
The fildes argument is not a valid file descriptor.
ENOTTY
The file associated with fildes is not a terminal.

errno is EINVAL.

[ktaborski]

In my opinions isatty check should be added. Something like this:

if( isatty(fd) ){
      do {
        err = tcgetattr(fd, &s.termios);
      } while (err == -1 && errno == EINTR);
      if (err == 0) {
        s.isatty = true;
      } else {
        // tcgetattr() is not supposed to return ENODEV or EOPNOTSUPP
        // but it does so anyway on MacOS.
        CHECK(errno == ENODEV || errno == ENOTTY || errno == EOPNOTSUPP );
      }
    }