env: Simplify the reverse_strstr() interface

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>

diff --git a/common/env_attr.c b/common/env_attr.c
index e791f442002c5c0d37987c840ce3dd63257802e5..6e13184d7e8cd095ffe5a98714bc256e8013a8ac 100644 (file)
--- a/common/env_attr.c
+++ b/common/env_attr.c
@@ -109,33 +109,59 @@ 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 (*search_for == '\0')
-               return (char *)searched;
+       if (result)
+               *result = NULL;
+
+       if (*search_for == '\0') {
+               if (result)
+                       *result = searched;
+               return strlen(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 >= searched)
+                       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 &&
+                   prevch != searched - 1)
+                       continue;
+               if (*nextch != ENV_ATTR_SEP &&
+                   *nextch != ENV_ATTR_LIST_DELIM &&
+                   *nextch != '\0')
+                       continue;
+
+               if (result)
+                       *result = match;
+               result_size = strlen(search_for);
        }
 
-       return result;
+       return result_size;
 }
 
 /*
@@ -145,6 +171,7 @@ 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 +180,12 @@ 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++;