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

[Brian Paul]

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.

>   	}
>
>   	return false;

-Brian