[PATCH 1/1] makedevs: set path size to match linux

[Denys Vlasenko]

On Thu, Jul 6, 2017 at 3:31 AM, Kang-Che Sung <explorer09 at gmail.com> wrote:
> On Thu, Jul 6, 2017 at 8:04 AM, Denys Vlasenko <vda.linux at googlemail.com> wrote:
>> On Tue, Jun 27, 2017 at 3:20 PM, Kang-Che Sung <explorer09 at gmail.com> wrote:
>>> Hello. Can I suggest another way?
>>> How about modifying the `line` buffer so it can be used directly as the name,
>>> and avoid the malloc problem or STRINGIFY(PATH_MAX) altogether.
>>>
>>> My suggestion (warning, this code is not tested):
>>>
>>> --- a/miscutils/makedevs.c
>>> +++ b/miscutils/makedevs.c
>>> @@ -209,23 +209,27 @@ int makedevs_main(int argc UNUSED_PARAM, char **argv)
>>>   unsigned increment = 0;
>>>   unsigned start = 0;
>>>   char name[41];
>>> + int name_len;
>>>   char user[41];
>>>   char group[41];
>>> - char *full_name = name;
>>> + char *full_name;
>>>   uid_t uid;
>>>   gid_t gid;
>>>
>>>   linenum = parser->lineno;
>>>
>>> - if ((2 > sscanf(line, "%40s %c %o %40s %40s %u %u %u %u %u",
>>> - name, &type, &mode, user, group,
>>> + if ((1 > sscanf(line, "%*s%n %c %o %40s %40s %u %u %u %u %u",
>>> + &name_len, &type, &mode, user, group,
>>>   &major, &minor, &start, &increment, &count))
>>> + || (PATH_MAX > name_len + 1)
>>>   || ((unsigned)(major | minor | start | count | increment) > 255)
>>>   ) {
>>>   bb_error_msg("invalid line %d: '%s'", linenum, line);
>>>   ret = EXIT_FAILURE;
>>>   continue;
>>>   }
>>> + line[name_len] = '\0';
>>> + full_name = line;
>>
>> Good idea!
>>
>> Applied, thanks!
>
> Wait. I was not expecting the patch be applied directly. I was expecting it
> be tested first.

I did test it.

> I think my code has a bug:
> If the line begins with whitespaces, the initial whitespaces will be included
> in `full_name` while the original code won't.

config_read() removes leading whitespace.