pty: Add forkpty #1042

keur · 2019-04-09T11:13:46Z

No description provided.

keur · 2019-04-09T11:16:38Z

Note: forkpty re-added to linux in rust-lang/libc#1313

keur · 2019-04-09T21:32:13Z

Err... failed CI for OSX but it passed all the tests?

asomers · 2019-04-09T21:34:45Z

It hung on OSX. Probably a bug in test_forkpty. It also appears to be hanging on FreeBSD. I'll terminate it.

keur · 2019-04-10T03:20:22Z

@asomers yeah... i think i relied on linux kernel for how it handles a read after write. will fix in a bit.

keur · 2019-04-11T01:11:31Z

@asomers Got CI passing. Can you take a look

asomers · 2019-04-11T01:44:54Z

test/test_pty.rs

+        Child => {
+            write(0, string.as_bytes()).unwrap();
+            pause();  // we need the child to stay alive until the parent calls read
+        },


In a Rust test, you cannot return from a forked child. That can cause deadlocks. Instead, you must _exit(0). The SIGTERM will probably suffice, but I would _exit(0) just in case.

asomers · 2019-04-11T01:46:37Z

src/pty.rs

+/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's
+/// terminal settings of the slave will be set to the values in `termios`.
+#[inline]
+pub fn forkpty<'a, 'b, T: Into<Option<&'a Winsize>>, U: Into<Option<&'b Termios>>>(winsize: T, termios: U) -> Result<ForkptyResult> {


80 cols, please.

asomers · 2019-04-11T01:47:07Z

src/pty.rs

+/// If `winsize` is not `None`, the window size of the slave will be set to
+/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's
+/// terminal settings of the slave will be set to the values in `termios`.
+#[inline]


Why inline such a big function? In fact, it's rarely a good idea to use #[inline] at all. Better to let the compiler decide.

asomers · 2019-04-11T01:52:19Z

src/pty.rs

+
+    let mut master: libc::c_int = unsafe { mem::uninitialized() };
+    let res = {
+        match (termios.into(), winsize.into()) {


I think you could considerably shorten this block by using something like termios.into().unwrap_or(ptr::null_mut()).

asomers · 2019-04-11T01:53:23Z

src/pty.rs

+/// This is returned by `forkpty`. Note that this type does *not* implement `Drop`, so the user
+/// must manually close the file descriptors.
+#[derive(Clone, Copy)]
+#[allow(missing_debug_implementations)]


Why not derive Debug?

Now that you've derived Debug, you should remove the #[allow(missing_debug_implementations)]

asomers · 2019-04-11T01:55:26Z

test/test_pty.rs

+    let pty = forkpty(None, None).unwrap();
+    match pty.fork_result {
+        Child => {
+            write(0, string.as_bytes()).unwrap();


Yikes! Can you eliminate that magic number?

keur · 2019-04-11T07:13:44Z

@asomers Made the suggested changes.

asomers · 2019-04-14T15:46:24Z

src/pty.rs

+/// This is returned by `forkpty`. Note that this type does *not* implement `Drop`, so the user
+/// must manually close the file descriptors.
+#[derive(Clone, Copy)]
+#[allow(missing_debug_implementations)]


Now that you've derived Debug, you should remove the #[allow(missing_debug_implementations)]

asomers · 2019-04-14T15:55:53Z

src/pty.rs

+        None => ptr::null_mut(),
+    };
+
+    let win = match winsize.into() {


FYI, instead of match winsize.into() you could equivalently do winsize.into().map(|ws| ws as *const Winsize).unwrap_or(ptr::null_mut()). It's just a matter of which style you prefer. Either is acceptable.

keur · 2019-04-14T23:28:03Z

@asomers Thanks for the comments. I made the changes. Since the initial code was based largely off of openpty a lot of the review comments could be applied to that function; I am happy to make another PR to refactor that.

keur · 2019-04-21T08:36:05Z

@asomers anything left to fix for this?

asomers · 2019-04-21T14:47:52Z

src/pty.rs

+
+    Ok(ForkptyResult {
+        master: master,
+        fork_result: fork_result,


If libc::forkpty fails, then master will be uninitialized here. For that matter, the return value will be wrong, too. You should ensure that it returns Err if libc::forkpty fails.

Errno::result(res) should convert to an Err if forkpty fails, and ? on line 320 should propagate the error.

Ahh, I didn't see that little ?.

asomers

Ok, this looks good. All you need to do is add a CHANGELOG entry and squash.

asomers · 2019-04-23T14:55:22Z

src/pty.rs

+
+    Ok(ForkptyResult {
+        master: master,
+        fork_result: fork_result,


Ahh, I didn't see that little ?.

keur · 2019-04-23T21:38:32Z

@asomers done

asomers

Thanks for your contribution!

bors r+

1042: pty: Add forkpty r=asomers a=keur Co-authored-by: Kevin Kuehler <keur@ocf.berkeley.edu>

bors · 2019-04-23T22:20:03Z

Build succeeded

continuous-integration/travis-ci/push
FreeBSD 11.2

keur force-pushed the forkpty branch 2 times, most recently from 94bf05f to e0f1a90 Compare April 9, 2019 20:48

keur force-pushed the forkpty branch 2 times, most recently from 648b81d to 67688aa Compare April 10, 2019 22:58

asomers reviewed Apr 11, 2019

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keur force-pushed the forkpty branch from 3cec8da to 3a95beb Compare April 14, 2019 23:25

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src/pty.rs

Ok(ForkptyResult {

master: master,

fork_result: fork_result,

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Ahh, I didn't see that little ?.

keur force-pushed the forkpty branch from 3a95beb to dcbc3c8 Compare April 23, 2019 20:17

pty: Add forkpty

26bd036

keur force-pushed the forkpty branch from dcbc3c8 to 26bd036 Compare April 23, 2019 20:19

asomers approved these changes Apr 23, 2019

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bors bot added a commit that referenced this pull request Apr 23, 2019

Merge #1042

71b35a0

1042: pty: Add forkpty r=asomers a=keur Co-authored-by: Kevin Kuehler <keur@ocf.berkeley.edu>

bors bot merged commit 26bd036 into nix-rust:master Apr 23, 2019

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pty: Add forkpty #1042

pty: Add forkpty #1042

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pty: Add forkpty #1042

pty: Add forkpty #1042

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keur commented Apr 9, 2019

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