Try get terminal size of "/dev/tty" if stdout fails

[imwints]

LLDB does not set the terminal sizes for stdout so try to get them for "/dev/tty". This helps to get back traces on arm64 where gdb is not supported

[aristocratos]

Great idea!

But I think this could be reworked to be a bit more efficient.
For example if the deafult STDOUT_FILENO fails, setting a bool that switches over to using /dev/tty instead.

[imwints]

@aristocratos

Great idea!

But I think this could be reworked to be a bit more efficient. For example if the deafult STDOUT_FILENO fails, setting a bool that switches over to using /dev/tty instead.

I can't quite follow what you mean by that. Currently it is checked if STDOUT_FILENO can be used to get valid terminal dimensions, if it's not the case it tries to fall back to /dev/tty ...

Where would the bool come into play?

[aristocratos]

Where would the bool come into play?

Term::refresh is called at a minimum once every update cycle, since SIGWINCH isn't always reliable.
So if we are running on a system where STDOUT_FILENO fails to get current size, we will continue to make that same syscall every time we run Term::refresh even though it's gonna fail every time.

Syscalls cost a lot more than branching.

[imwints]

@aristocratos
Yeah this makes sense. Addressed this in the latest commit