[Piglit] [PATCH] Fix infinite loop in piglit_is_extension_in_string.

[Brian Paul]

On Tue, Dec 20, 2011 at 10:04 AM, Paul Berry <stereotype441 at gmail.com> wrote:
> On 20 December 2011 08:19, Paul Berry <stereotype441 at gmail.com> wrote:
>>
>> On 20 December 2011 06:56, Brian Paul <brianp at vmware.com> wrote:
>>>
>>> On 12/19/2011 10:46 PM, Paul Berry wrote:
>>>>
>>>> If piglit_is_extension_in_string() finds an extension whose name
>>>> begins with the name it is searching for, but is not equal to the name
>>>> it is searching for (e.g. it is searching for EXT_transform_feedback
>>>> but it finds EXT_transform_feedback2), we need it to advance by one
>>>> character before restarting the search, otherwise it will loop
>>>> indefinitely.
>>>>
>>>> Prevents a hang when running some transform feedback tests on nVidia's
>>>> proprietary Linux driver.
>>>> ---
>>>>  tests/util/piglit-util.c |   16 ++++++++++++----
>>>>  1 files changed, 12 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/tests/util/piglit-util.c b/tests/util/piglit-util.c
>>>> index 65b02f5..3241528 100644
>>>> --- a/tests/util/piglit-util.c
>>>> +++ b/tests/util/piglit-util.c
>>>> @@ -145,15 +145,23 @@ bool piglit_is_extension_in_string(const char
>>>> *haystack, const char *needle)
>>>>        if (needle_len == 0)
>>>>                return false;
>>>>
>>>> -       while (haystack != NULL) {
>>>> +       while (true) {
>>>>                const char *const s = strstr(haystack, needle);
>>>>
>>>> -               if (s != NULL
>>>> -               &&  (s[needle_len] == ' ' || s[needle_len] == '\0')) {
>>>> +               if (s == NULL)
>>>> +                       return false;
>>>> +
>>>> +               if (s[needle_len] == ' ' || s[needle_len] == '\0') {
>>>>                        return true;
>>>>                }
>>>>
>>>> -               haystack = s;
>>>> +               /* strstr found an extension whose name begins with
>>>> +                * needle, but whose name is not equal to needle.
>>>> +                * Restart the search at s + 1 so that we don't just
>>>> +                * find the same extension again and go into an
>>>> +                * infinite loop.
>>>> +                */
>>>> +               haystack = s + 1;
>>>
>>>
>>> Actually, I think you could do "haystack = s + needle_len" but it's no
>>> big deal.
>>
>>
>> Oh yeah.  That's a better idea.
>>
>>>
>>>
>>>>        }
>>>>
>>>>        return false;
>>>
>>>
>>> -Brian
>>
>>
>
> Just double checked on my nVidia system, and "haystack = s + needle_len"
> works fine, as expected.  Brian, can I take that as a "reviewed by" if I
> make that change?

Sure.  Reviewed-by: Brian Paul <brianp at vmware.com>