Re: [PATCH 1/5] convert: initialize attr_action in convert_attrs

["Martin Ågren" <martin.agren@gmail.com>]

On 15 August 2017 at 16:17, Torsten Bögershausen <tboegi@web.de> wrote:
> On Tue, Aug 15, 2017 at 02:53:01PM +0200, Martin Ågren wrote:
>> convert_attrs populates a struct conv_attrs. The field attr_action is
>> not set in all code paths, but still one caller unconditionally reads
>> it. Since git_check_attr always returns the same value, we'll always end
>> up in the same code path and there is no problem right now. But
>> convert_attrs is obviously trying not to rely on such an
>> implementation-detail of another component.
>>
>> Initialize attr_action to CRLF_UNDEFINED in the dead code path.
>>
>> Actually, in the code path that /is/ taken, the variable is assigned to
>> twice and the first assignment has no effect. That's not wrong, but
>> let's remove that first assignment while we're here.
>>
>> Signed-off-by: Martin Ågren <martin.agren@gmail.com>
>> ---
>> I hit a warning about attr_action possibly being uninitialized when
>> building with SANITIZE=thread. I guess it's some random interaction
>> between code added by tsan, the optimizer (-O3) and the warning
>> machinery. (This was with gcc 5.4.0.)
>>
>>  convert.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/convert.c b/convert.c
>> index 1012462e3..943d957b4 100644
>> --- a/convert.c
>> +++ b/convert.c
>> @@ -1040,7 +1040,6 @@ static void convert_attrs(struct conv_attrs *ca, const char *path)
>>               ca->crlf_action = git_path_check_crlf(ccheck + 4);
>>               if (ca->crlf_action == CRLF_UNDEFINED)
>>                       ca->crlf_action = git_path_check_crlf(ccheck + 0);
>> -             ca->attr_action = ca->crlf_action;
>
> I don't think the removal of that line is correct.

(Thanks for confirming in a follow-up mail that you meant that you /do/
think the removal is correct.)

>
>>               ca->ident = git_path_check_ident(ccheck + 1);
>>               ca->drv = git_path_check_convert(ccheck + 2);
>>               if (ca->crlf_action != CRLF_BINARY) {
>> @@ -1058,6 +1057,7 @@ static void convert_attrs(struct conv_attrs *ca, const char *path)
>>       } else {
>>               ca->drv = NULL;
>>               ca->crlf_action = CRLF_UNDEFINED;
>> +             ca->attr_action = CRLF_UNDEFINED;
>
> But this one can be avoided, when the line
> ca->attr_action = ca->crlf_action;
> would move completely out of the "if/else" block.
>
>>               ca->ident = 0;
>>       }
>>       if (ca->crlf_action == CRLF_TEXT)
>> --
>> 2.14.1.151.gdfeca7a7e
>>
>
> Thanks for spotting my mess.
> What do you think about the following:
>
>
> diff --git a/convert.c b/convert.c
> index 1012462e3c..fd91b91ada 100644
> --- a/convert.c
> +++ b/convert.c
> @@ -1040,7 +1040,6 @@ static void convert_attrs(struct conv_attrs *ca, const char *path)
>                 ca->crlf_action = git_path_check_crlf(ccheck + 4);
>                 if (ca->crlf_action == CRLF_UNDEFINED)
>                         ca->crlf_action = git_path_check_crlf(ccheck + 0);
> -               ca->attr_action = ca->crlf_action;
>                 ca->ident = git_path_check_ident(ccheck + 1);
>                 ca->drv = git_path_check_convert(ccheck + 2);
>                 if (ca->crlf_action != CRLF_BINARY) {
> @@ -1060,6 +1059,8 @@ static void convert_attrs(struct conv_attrs *ca, const char *path)
>                 ca->crlf_action = CRLF_UNDEFINED;
>                 ca->ident = 0;
>         }
> +       /* Save attr and make a decision for action */
> +       ca->attr_action = ca->crlf_action;
>         if (ca->crlf_action == CRLF_TEXT)
>                 ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
>         if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)

Yeah, makes lots of sense. Then we could also remove the second
assignment to attr_action. That is, this function would set attr_action
at one place, always. I'll do this in a v2.

Thanks.