[U-Boot] [PATCH 05/11] env: Simplify the reverse_strstr() interface

Simon Glass
2015-04-24T04:34:00Z

Hi Joe,

On 21 April 2015 at 16:02, Joe Hershberger <joe.hershberger@ni.com> wrote:
> The logic to find the whole matching name was split needlessly between
> the reverse_strstr function and its caller. Fully contain it to make the
> interface for calling it more consistent.
>
> Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
> ---
>
> common/env_attr.c | 79 +++++++++++++++++++++++++++++--------------------------
> 1 file changed, 41 insertions(+), 38 deletions(-)
>

You could perhaps add some environment tests in test/ for this
function, or access it through getenv(), etc.

> diff --git a/common/env_attr.c b/common/env_attr.c
> index e791f44..d266142 100644
> --- a/common/env_attr.c
> +++ b/common/env_attr.c
> @@ -109,33 +109,55 @@ int env_attr_walk(const char *attr_list,
> }
>
> /*
> - * Search for the last matching string in another string with the option to
> - * start looking at a certain point (i.e. ignore anything beyond that point).
> + * Search for the last exactly matching name in an attribute list
> */
> -static char *reverse_strstr(const char *searched, const char *search_for,
> - const char *searched_start)
> +static int reverse_name_search(const char *searched, const char *search_for,
> + const char **result)
> {
> - char *result = NULL;
> + int result_size = 0;
> + const char *cur_searched = searched;
> +
> + if (result)
> + *result = NULL;
>
> if (*search_for == '\0')
> return (char *)searched;
>
> for (;;) {
> - char *match = strstr(searched, search_for);
> -
> - /*
> - * Stop looking if no new match is found or looking past the
> - * searched_start pointer
> - */
> - if (match == NULL || (searched_start != NULL &&
> - match + strlen(search_for) > searched_start))
> + const char *match = strstr(cur_searched, search_for);
> + const char *prevch;
> + const char *nextch;
> +
> + /* Stop looking if no new match is found */
> + if (match == NULL)
> break;
>
> - result = match;
> - searched = match + 1;
> + prevch = match - 1;
> + nextch = match + strlen(search_for);
> +
> + /* Skip spaces */
> + while (*prevch == ' ')
> + prevch--;
> + while (*nextch == ' ')
> + nextch++;
> +
> + /* Start looking past the current match so last is found */
> + cur_searched = match + 1;
> +
> + /* Check for an exact match */
> + if (match != searched &&
> + *prevch != ENV_ATTR_LIST_DELIM)
> + continue;
> + if (*nextch != ENV_ATTR_SEP &&
> + *nextch != ENV_ATTR_LIST_DELIM &&
> + *nextch != '\0')
> + continue;
> +
> + *result = match;
> + result_size = strlen(search_for);
> }
>
> - return result;
> + return result_size;
> }
>
> /*
> @@ -145,6 +167,7 @@ static char *reverse_strstr(const char *searched, const char *search_for,
> int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
> {
> const char *entry = NULL;
> + int entry_len;
>
> if (!attributes)
> /* bad parameter */
> @@ -153,32 +176,12 @@ int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
> /* list not found */
> return -EINVAL;
>
> - entry = reverse_strstr(attr_list, name, NULL);
> - while (entry != NULL) {
> - const char *prevch = entry - 1;
> - const char *nextch = entry + strlen(name);
> -
> - /* Skip spaces */
> - while (*prevch == ' ')
> - prevch--;
> - while (*nextch == ' ')
> - nextch++;
> -
> - /* check for an exact match */
> - if ((entry == attr_list ||
> - *prevch == ENV_ATTR_LIST_DELIM) &&
> - (*nextch == ENV_ATTR_SEP ||
> - *nextch == ENV_ATTR_LIST_DELIM ||
> - *nextch == '\0'))
> - break;
> -
> - entry = reverse_strstr(attr_list, name, entry);
> - }
> + entry_len = reverse_name_search(attr_list, name, &entry);
> if (entry != NULL) {
> int len;
>
> /* skip the name */
> - entry += strlen(name);
> + entry += entry_len;
> /* skip spaces */
> while (*entry == ' ')
> entry++;
> --
> 1.7.11.5

Regards,
Simon