Use x/term on Unix systems, deduplicate tscreen_*.go

[niten94]

Reasons why syscall.Syscall6(syscall.SYS_IOCTL, ...) has to be replaced are written below:

• Syscall(...) and Go 1.23 or newer has to be used with SYS_IOCTL since syscall(2) is removed in OpenBSD 7.5
• unsafe.Pointer has to be converted to uintptr in arguments like written in 4th pattern in documentation

There may be changes in any platform where using syscall.Syscall* will not work, so calls are replaced with functions in x/sys and x/term instead.

Input is drained as an attempt to remove code that is duplicated to address bug(s) on MacOS, but I wasn't able to understand how they exactly occur. There only seemed to be one occuring when I tried searching about the explanations in source code comments.

The addressed bug probably occurs when closing /dev/tty since polling done internally with os.File doesn't work on MacOS.¹² I am also not sure if this workaround in upstream addresses the same bug or should be done in the fork. Code could be reduplidcated if not practical to come up with a better fix.

Micro started up properly when I tested using an OpenBSD 7.6 VM. I do not have a MacOS machine so I cannot test if there are no bugs on MacOS. The changes may not be tested and thought well enough.

Fixes zyedidia/micro#3557

Footnotes

1. https://github.com/gokcehan/lf/issues/480#issuecomment-782896586 ↩

2. https://nathancraddock.com/blog/macos-dev-tty-polling/ ↩

[niten94]

Another file descriptor is opened upstream to fix the bug and there is no duplicate code just on MacOS, but I have not tried checking how much does the code structure need to be changed when using the same method yet.

[JoeKar]

Unfortunately I've no MacOS for tests too.

[niten94]

I have split the changes into different commits since not all are similar.

Unfortunately I've no MacOS for tests too.

Would it be possible if Zachary could test if bugs don't occur when running shell commands in Micro with this pull request, and if they do on the commit before e701458 (1482264)?

I remember seeing old comments in issues where he seemed to have MacOS, but I'll re-add tscreen_darwin.go or use poller in tscreen_unix.go if no one could test or bugs are introduced.

[niten94]

Sorry, I realized that there were files I did not add so I added them now.