Re: [LTP] [PATCH v5] swapon03: Try to swapon() as many files until it fails

[Andrea Cervesato via ltp <ltp@lists.linux.it>]

Hi!

On Mon Jan 5, 2026 at 8:49 AM CET, Petr Vorel wrote:
> > Hi!
>
> > > -	char cmd_buffer[256];
> > > +	char cmd_buffer[FILENAME_MAX+28];
>
> > I'm not sure if +28 is needed.
>
> I described the reason in the commit message:
>
> 	It was required to increase cmd_buffer size to avoid directive output
>     may be truncated warning.
>
> I get warning on smaller size:
>
> swapon03.c:74:60: warning: ‘%s’ directive output may be truncated writing up to 4095 bytes into a region of size 4087 [-Wformat-truncation=]
>    74 |         snprintf(cmd_buffer, sizeof(cmd_buffer), "grep -q '%s.*file' /proc/swaps", filename);
>       |                                                            ^~
> ......
>    94 |                 check_and_swapoff(filename);
>       |                                   ~~~~~~~~
> In file included from /usr/include/stdio.h:970,
>                  from swapon03.c:17:
> In function ‘snprintf’,
>     inlined from ‘check_and_swapoff’ at swapon03.c:74:2,
>     inlined from ‘clean_swap’ at swapon03.c:94:3:
> /usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output between 29 and 4124 bytes into a destination of size 4096
>    68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
>       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    69 |                                    __glibc_objsize (__s), __fmt,
>       |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    70 |                                    __va_arg_pack ());
>
> Kind regards,
> Petr

Sorry, I missed the git comment. Can you also comment the source code
please? So we don't guess what's going on in the buffer, based on
git message.

Besides that,

Reviewed-by: Andrea Cervesato <andrea.cervesato@suse.com>

-- 
Andrea Cervesato
SUSE QE Automation Engineer Linux
andrea.cervesato@suse.com


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