Re: [PATCH v3 2/2] Use O_IGNORE_CTTY where appropriate

[Paul Eggert]

On 6/13/23 03:54, Sergey Bugaev wrote:

> "Do not recognize the named file as the controlling terminal, even if
> it refers to the process’s existing controlling terminal device.
> Operations on the new file descriptor will never induce job control
> signals."
>
> This is an opportunity to improve the docs!7

The first-quoted sentence is confusing and arguably wrong. If the named 
file is the process's existing controlling terminal, it will continue to 
be recognized as the controlling terminal.

What's different is that I/O to the new fd won't induce SIGTTIN etc. So 
the second sentence is correct and the first is wrong. Perhaps the first 
sentence could be replaced by:

"Cause operations on the new file descriptor to act as if the named file 
is not the process's controlling terminal, even if it is."

> you
> can't get an estimate for whether any software cares by grepping it
> for O_IGNORE_CTTY.

Fair enough. Still, I still doubt many would care if O_IGNORE_CTTY 
became the default, particularly since O_NOCTTY is 0. What's the 
scenario whereby a Bash user would care, for example?


> Speaking of Emacs, and seeing that Emacs already defines O_IGNORE_CTTY
> to 0 on non-Hurd, and that you're one of the Emacs maintainers (is
> that right?): could perhaps Emacs benefit from using O_IGNORE_CTTY
> more broadly too? I imagine loading all the .el files in ~/.emacs.d
> involves way too many pointless ctty checks, for example.

It might, I suppose. Got a patch?