strv-util: add strv_filter_prefix() helper

src/basic/strv.c

@@ -1238,3 +1238,24 @@ int strv_rebreak_lines(char **l, size_t width, char ***ret) {
         *ret = TAKE_PTR(broken);
         return 0;
 }
+
+char** strv_filter_prefix(char *const*l, const char *prefix) {
+        _cleanup_strv_free_ char **f = NULL;
+
+        /* Allocates a copy of 'l', but only copies over entries starting with 'prefix' */
+
+        if (isempty(prefix))
+                return strv_copy(l);
+
+        size_t sz = 0;
+
+        STRV_FOREACH(i, l) {
+                if (!startswith(*i, prefix))
+                        continue;
+
+                if (strv_extend_with_size(&f, &sz, *i) < 0)
+                        return NULL;
+        }
+
+        return TAKE_PTR(f);
+}

src/basic/strv.h

@@ -268,3 +268,5 @@ int _string_strv_ordered_hashmap_put(OrderedHashmap **h, const char *key, const
 #define string_strv_ordered_hashmap_put(h, k, v) _string_strv_ordered_hashmap_put(h, k, v  HASHMAP_DEBUG_SRC_ARGS)
 
 int strv_rebreak_lines(char **l, size_t width, char ***ret);
+
+char** strv_filter_prefix(char *const*l, const char *prefix);