Re: [PATCH] rtla: Fix parsing of multi-character short options

[Tomas Glozar]

út 2. 6. 2026 v 14:55 odesílatel Tomas Glozar <tglozar@xxxxxxxxxx> napsal:
>
> A bug was reported where the parsing of multi-character short options,
> be it a short option with an argument specified without space (e.g.
> "-p100") or multiple short options in one argument (e.g. -un), ignores
> options specific to individual tools.
>
> Furthermore, if the rest of the option is supposed to be an argument, it
> gets reinterpreted as a string of options. For example, -p100 gets
> interpreted as -100, which is due to hackish implementation read as
> --no-thread --no-irq --no-irq with timerlat hist, causing rtla to error
> out:
>
> $ rtla timerlat hist -p100
> no-irq and no-thread set, there is nothing to do here
>
> This behavior is caused by getopt_long() being called twice on each
> argument, once in common_parse_options(), once in [tool]_parse_args():
>
> - common_parse_options() calls getopt_long() with an array of options
>   common for all rtla tools, while suppressing errors (opterr = 0).
> - If the option fails to parse, common_parse_options() returns 0.
> - If 0 is returned from common_parse_options(), [tool]_parse_args()
>   calls getopt_long() again, with its own set of options.
>
> * [tool] means one of {osnoise,timerlat}_{top,hist}
>
> At least in glibc, getopt_long() increments its internal nextchar
> variable even if the option is not recognized. That means that in the
> case of "-p100", common_parse_options() sets nextchar pointing to '1',
> and timerlat_hist_parse_args() sees '1', not 'p'; the same then repeats
> for the first and second '0'.
>
> As there is no way to restore the correct internal state of
> getopt_long() reliably, fix the issue by merging the common options back
> to the longopt array and option string of the [tool]_parse_args()
> functions using a macro; only the switch part is left in the original
> function, which is renamed to set_common_option().
>
> Fixes: 850cd24cb6d6 ("tools/rtla: Add common_parse_options()")
> Reported-by: John Kacur <jkacur@xxxxxxxxxx>
> Signed-off-by: Tomas Glozar <tglozar@xxxxxxxxxx>
> ---

Forgot to add note to the original email: This fix is only for 7.1,
7.0 needs tweaking of the commit, 7.2 will remove the command line
parsing logic entirely and replace it with libsubcmd, where this
works.

Tomas