From: Peter Korsgaard <peter@korsgaard.com>
To: Edgar Bonet <bonet@grenoble.cnrs.fr>
Cc: buildroot@buildroot.org
Subject: Re: [Buildroot] Issue with capture of emulator output in runtime test infra
Date: Mon, 04 Oct 2021 13:55:21 +0200 [thread overview]
Message-ID: <878rz9j97a.fsf@dell.be.48ers.dk> (raw)
In-Reply-To: <11632800-793a-6d2d-8ee4-0182092c8f35@grenoble.cnrs.fr> (Edgar Bonet's message of "Mon, 20 Sep 2021 10:55:30 +0200")
>>>>> "Edgar" == Edgar Bonet <bonet@grenoble.cnrs.fr> writes:
> Hello!
> Yesterday I wrote:
>> Is it just a coincidence that the line got wrapped at exactly 80
>> columns [...]
> I think I found where the spurious line break comes from. Busybox's
> lineedit library has a trick to work around the VT100's automargin
> feature.[1] When a character is printed on the last column of the
> terminal, lineedit adds a carriage return in order to force the cursor
> to the next line:
> /* we go to the next line */
> #if HACK_FOR_WRONG_WIDTH
> /* This works better if our idea of term width is wrong
> * and it is actually wider (often happens on serial lines).
> * Printing CR,LF *forces* cursor to next line.
> * OTOH if terminal width is correct AND terminal does NOT
> * have automargin (IOW: it is moving cursor to next line
> * by itself (which is wrong for VT-10x terminals)),
> * this will break things: there will be one extra empty line */
> puts("\r"); /* + implicit '\n' */
> There doesn't seem to be a way to override this behavior, but we could
> make busybox believe our terminal is ultra wide. Busybox gets its idea
> of the terminal width from the kernel, via the TIOCGWINSZ ioctl[2]. The
> kernel within the emulator may not be able to know the host's terminal
> width, in which case setting the dimensions attribute in pexpect.spawn()
> may not have any effect. We can, however, override the terminal width
> using the "COLUMNS" environment variable[3], but beware that values
> larger than 29999 are ignored.
29999 chars should be enough for anybody (tm) ;)
Care to send a patch for this?
--
Bye, Peter Korsgaard
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next prev parent reply other threads:[~2021-10-04 11:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-19 12:10 [Buildroot] Issue with capture of emulator output in runtime test infra Thomas Petazzoni
2021-09-19 16:59 ` Edgar Bonet
2021-09-20 8:55 ` Edgar Bonet
2021-10-04 11:55 ` Peter Korsgaard [this message]
2021-10-04 20:46 ` Edgar Bonet
2021-10-05 5:33 ` Yann E. MORIN
2021-10-05 8:54 ` Edgar Bonet
2021-10-05 16:04 ` Yann E. MORIN
2021-10-04 11:52 ` Peter Korsgaard
2021-10-04 12:14 ` Thomas Petazzoni
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