[LTP] [PATCH 1/1] tst_tmpdir: Remove possible double/trailing slashes from TMPDIR

[Li Wang]

On Wed, Apr 19, 2023 at 2:47 PM Li Wang <liwang@redhat.com> wrote:

> Hi Petr,
>
> On Thu, Apr 13, 2023 at 7:14 PM Petr Vorel <pvorel@suse.cz> wrote:
>
>> Similarly to previous commit, which normalized TMPDIR for shell API,
>> do the same for C API.
>>
>> Unlike for shell API, here we modify $TMPDIR directly, because
>> tst_get_tmpdir_root() is used o more places.
>>
>> Signed-off-by: Petr Vorel <pvorel@suse.cz>
>> ---
>> Follow up of the same change in shell API:
>> https://lore.kernel.org/ltp/20230412073953.1983857-1-pvorel@suse.cz/
>>
>> Kind regards,
>> Petr
>>
>>  lib/tst_tmpdir.c | 16 ++++++++++++++--
>>  1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/tst_tmpdir.c b/lib/tst_tmpdir.c
>> index b73b5c66f..8db5c47e8 100644
>> --- a/lib/tst_tmpdir.c
>> +++ b/lib/tst_tmpdir.c
>> @@ -124,16 +124,28 @@ char *tst_get_tmpdir(void)
>>
>>  const char *tst_get_tmpdir_root(void)
>>  {
>> -       const char *env_tmpdir = getenv("TMPDIR");
>> +       char *env_tmpdir = getenv("TMPDIR");
>>
>
> It seems that modifying the environment variables is generally
> not a good practice.
>
> The getenv() function returns a pointer to the value of an
> environment variable, which is stored in the memory managed
> by the system. Any attempt to modify this memory directly can
> cause unexpected behavior or even crash the program.
>
> Instead of modifying the return value of getenv(), it is recommended
> to create a copy of the value and modify the copy instead.
>

Btw, the wise method is to use setenv() function to reset
environment variables if really needed.

This is a different part of shell API I have to say.



> Or, the simplest way I guess is just TBROK and tell users why
> this TMPDIR is unusable.
>
>
>
>> -       if (!env_tmpdir)
>> +       if (env_tmpdir) {
>> +               /* remove duplicate slashes */
>> +               for (char *p = env_tmpdir, *q = env_tmpdir; *q;) {
>> +                       if (*++q != '/' || *p != '/')
>> +                               *++p = *q;
>> +               }
>> +               /* Remove slash on the last place  */
>> +               size_t last = strlen(env_tmpdir)-1;
>> +               if (env_tmpdir[last] == '/')
>> +                       env_tmpdir[last] = '\0';
>> +       } else {
>>                 env_tmpdir = TEMPDIR;
>> +       }
>>
>>         if (env_tmpdir[0] != '/') {
>>                 tst_brkm(TBROK, NULL, "You must specify an absolute "
>>                                 "pathname for environment variable
>> TMPDIR");
>>                 return NULL;
>>         }
>> +
>>         return env_tmpdir;
>>  }
>>
>> --
>> 2.40.0
>>
>>
>
> --
> Regards,
> Li Wang
>


-- 
Regards,
Li Wang