Re: [PATCH] ioctl_tty.2: Document ioctls: TCGETS2, TCSETS2, TCSETSW2, TCSETSF2

["Alejandro Colomar \(man-pages\) via Libc-alpha" <libc-alpha@sourceware.org>]

CC += glibc

On 7/30/21 2:09 AM, Pali Rohár wrote:
> Hello!
> 
> On Friday 30 July 2021 01:39:11 Alejandro Colomar (man-pages) wrote:
>> Hi Pali,
>>
>> On 7/29/21 7:31 PM, Pali Rohár wrote:
>>>
>>>>> +.IR "<asm/termbits.h>" .
>>
>> Is that the header that the user should include?
> 
> Yes.
> 
>> I don't know.  I typically avoid 'asm/' includes, but maybe in this case
>> it's the correct one.  Shouldn't the user maybe include <linux/termios.h>?
> 
> Problem is that you cannot include <linux/termios.h> together with
> <sys/ioctl.h>. It cause redefinition of symbols and compile errors.
> 
> And without <sys/ioctl.h> you cannot call ioctl() function which
> basically means that you cannot use TCGETS2 (as it is ioctl).

Seems fair.

> 
> Probably this is a bug in glibc header files...

I CCed glibc just in case they want to comment.

> 
> So currently it is needed to include <asm/termbits.h> file to use
> TCGETS2 ioctl. I'm not sure if it is "correct", but it is the only
> possible option for now about which I know (unless you want to
> copy+paste structures and macros from that file into your program, to
> avoid inclusion of asm/* files).

Re copy&paste: no thanks :)

> 
> If you want, I can send a patch for ioctl_tty.2 example section with
> simple C program to show how to use TCGETS2/TCSETS2 ioctl.

Great!  Please CC glibc in the patch.

> 
>> user@sqli:/usr/include$ grep -rn 'struct termios {'
>> asm-generic/termbits.h:12:struct termios {
>> user@sqli:/usr/include$ grep -rn '<asm-generic/termbits.h>'
>> x86_64-linux-gnu/asm/termbits.h:1:#include <asm-generic/termbits.h>
>> user@sqli:/usr/include$ grep -rn '<asm/termbits.h>'
>> asm-generic/termios.h:12:#include <asm/termbits.h>
>> user@sqli:/usr/include$ grep -rn '<asm-generic/termios.h>'
>> x86_64-linux-gnu/asm/termios.h:1:#include <asm-generic/termios.h>
>> user@sqli:/usr/include$ grep -rn '<asm/termios.h>'
>> linux/termios.h:6:#include <asm/termios.h>
>> user@sqli:/usr/include$ grep -rn '<linux/termios.h>'
>> user@sqli:/usr/include$
>>
>>
>>>>> +These ioctls are not supported on all architectures.
>>>>> +.IP
>>>>> +.BI "TCGETS2	struct termios2 *" argp
>>>>
>>>> Please follow the same style as in the rest of the page:
>>>>
>>>> .TP
>>>> .B TCGETS2
>>>> Argument:
>>>> .BI "struct termios2 *" argp
>>>>
>>>> Unless there's a good reason not to.
>>>
>>> Few lines below in this file is:
>>>
>>> .IR "struct termios\ *" .
>>> .IP
>>> .BI "TCGETA	struct termio *" argp
>>> .IP
>>> .BI "TCSETA	const struct termio *" argp
>>> .IP
>>> .BI "TCSETAW	const struct termio *" argp
>>> .IP
>>> .BI "TCSETAF	const struct termio *" argp
>>>
>>> Therefore I used same style for TCGETS2...
>>>
>>> So, how should I format this part to be consistent?
>>
>>
>> Hmm, sorry, I didn't see those.
> 
> Ah, now I see that Michael one hour later (after I sent this patch)
> fixed above style to another. See commit aceee9e827e6.
> 
> But changed it to another new style:
> 
> .RS
> .TS
> lb l.
> TCGETA	\fBstruct termio *\fPargp
> TCSETA	\fBconst struct termio *\fPargp
> TCSETAW	\fBconst struct termio *\fPargp
> TCSETAF	\fBconst struct termio *\fPargp
> .TE
> .RE
> 
>> So there's a mix in the file.
>> The more correct form is the one I used, so please use that one (the one
>> with .TP)
> 
> So, could you check with Michael which style to use? Because now there
> are 3 different (yours, Michael's and the one which was there before)
> and I'm really not sure what is correct...

Sorry, I was also confused, as I had Michael's version, and didn't see 
the table he reformatted, which I now understand was what you were doing 
(in the old format).  So if what you wrote corresponds to what Michael 
reformatted, please use Michael's new format (the table).

Thanks,

Alex

> 
>>
>> Thanks,
>>
>> Alex
>>
>>
>>>
>>>>> +.IP
>>>>> +.BI "TCSETS2	const struct termios2 *" argp
>>>>> +.IP
>>>>> +.BI "TCSETSW2	const struct termios2 *" argp
>>>>> +.IP
>>>>> +.BI "TCSETSF2	const struct termios2 *" argp
>>>>> +.PP
>>>>> +The following four ioctls are just like
>>>>> +.BR TCGETS ,
>>>>> +.BR TCSETS ,
>>>>> +.BR TCSETSW ,
>>>>> +.BR TCSETSF ,
>>>>> +except that they take a
>>>>>     .I "struct termio\ *"
>>>>>     instead of a
>>>>>     .IR "struct termios\ *" .
>>>>>
>>>>
>>>>
>>>> -- 
>>>> Alejandro Colomar
>>>> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
>>>> http://www.alejandro-colomar.es/
>>
>>
>> -- 
>> Alejandro Colomar
>> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
>> http://www.alejandro-colomar.es/


-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/