Handle `SIGWINCH` with `use_pty` enabled

[pvdrz]

Describe the changes done on this pull request This PR updates the use_pty behavior so it can handle SIGWINCH correctly.

I couldn't find a way to write a compliance test for this as stty doesn't send SIGWINCH when used to update the terminal size.

Pull Request Checklist

• [x] I have read and accepted the code of conduct for this project.
• [x] I have tested, formatted and ran clippy over my changes.
• [x] I have commented and documented my changes.
• [ ] This pull request will fix issue https://github.com/memorysafety/sudo-rs/issues/<#issue> where a proper discussion about a solution has taken place.

[github-actions[bot]]

Number of dependencies and binary size impact report

Metric	main	PR #649	Delta
Direct dependencies	3	3	-
Total dependencies	4	4	-
Binary size	978.4 KiB	983.6 KiB	+0.5%
Text size	570.1 KiB	572.6 KiB	+0.4%

Dependencies diff

```diff └─ sudo-rs [v0.2.0-dev.20230703] ├─ glob [v0.3.1] ├─ libc [v0.2.147] └─ log [v0.4.19] ```

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: -0.36 :warning:

Comparison is base (4f7c03f) 59.50% compared to head (af8af21) 59.15%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #649 +/- ## ========================================== - Coverage 59.50% 59.15% -0.36% ========================================== Files 66 66 Lines 8781 8830 +49 ========================================== - Hits 5225 5223 -2 - Misses 3556 3607 +51 ``` | [Impacted Files](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety) | Coverage Δ | | |---|---|---| | [src/exec/no\_pty.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL2V4ZWMvbm9fcHR5LnJz) | `0.00% <0.00%> (ø)` | | | [src/exec/use\_pty/parent.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL2V4ZWMvdXNlX3B0eS9wYXJlbnQucnM=) | `0.00% <0.00%> (ø)` | | | [src/system/term/mod.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N5c3RlbS90ZXJtL21vZC5ycw==) | `63.90% <0.00%> (-8.13%)` | :arrow_down: | | [src/system/term/user\_term.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N5c3RlbS90ZXJtL3VzZXJfdGVybS5ycw==) | `0.00% <0.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/649/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety)

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[japaric]

I couldn't find a way to write a compliance test for this as stty doesn't send SIGWINCH when used to update the terminal size.

you can send SIGWINCH to a process using kill. even if you can't actually resize the terminal, you can at least test that the ioctl calls don't fail and that the signal gets forwarded to the child

[pvdrz]

I couldn't find a way to write a compliance test for this as stty doesn't send SIGWINCH when used to update the terminal size.

you can send SIGWINCH to a process using kill. even if you can't actually resize the terminal, you can at least test that the ioctl calls don't fail and that the signal gets forwarded to the child

Apparently the shell notices this change

I couldn't find a way to write a compliance test for this as stty doesn't send SIGWINCH when used to update the terminal size.

you can send SIGWINCH to a process using kill. even if you can't actually resize the terminal, you can at least test that the ioctl calls don't fail and that the signal gets forwarded to the child

Apparently the shell sends SIGWINCH to the foreground process group if you change the size with stty. So if you open a terminal and run

# to get the terminal path
tty 
sh -c "trap \"echo GOT SIGWINCH\" WINCH; sleep 20"

and then, from another terminal you run

stty -F/dev/pts/N cols 42

You'll see the GOT SIGWINCH message in the first terminal after 20 secs