basic/set: let set_put_strdup() create the set with string hash ops

If we're using a set with _put_strdup(), most of the time we want to use
string hash ops on the set, and free the strings when done. This defines
the appropriate a new string_hash_ops_free structure to automatically free
the keys when removing the set, and makes set_put_strdup() and set_put_strdupv()
instantiate the set with those hash ops.

hashmap_put_strdup() was already doing something similar.

(It is OK to instantiate the set earlier, possibly with a different hash ops
structure. set_put_strdup() will then use the existing set. It is also OK
to call set_free_free() instead of set_free() on a set with
string_hash_ops_free, the effect is the same, we're just overriding the
override of the cleanup function.)

No functional change intended.

src/basic/conf-files.c

@@ -77,8 +77,10 @@ static int files_add(
                 /* Is this a masking entry? */
                 if ((flags & CONF_FILES_FILTER_MASKED))
                         if (null_or_empty(&st)) {
+                                assert(masked);
+
                                 /* Mark this one as masked */
-                                r = set_put_strdup(masked, de->d_name);
+                                r = set_put_strdup(&masked, de->d_name);
                                 if (r < 0)
                                         return r;
 

src/basic/hash-funcs.c

@@ -10,6 +10,8 @@ void string_hash_func(const char *p, struct siphash *state) {
 }
 
 DEFINE_HASH_OPS(string_hash_ops, char, string_hash_func, string_compare_func);
+DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(string_hash_ops_free,
+                                    char, string_hash_func, string_compare_func, free);
 DEFINE_HASH_OPS_FULL(string_hash_ops_free_free,
                      char, string_hash_func, string_compare_func, free,
                      char, free);

src/basic/hash-funcs.h

@@ -76,6 +76,7 @@ struct hash_ops {
 void string_hash_func(const char *p, struct siphash *state);
 #define string_compare_func strcmp
 extern const struct hash_ops string_hash_ops;
+extern const struct hash_ops string_hash_ops_free;
 extern const struct hash_ops string_hash_ops_free_free;
 
 void path_hash_func(const char *p, struct siphash *state);

src/basic/hashmap.c

@@ -1793,23 +1793,28 @@ int hashmap_put_strdup(Hashmap **h, const char *k, const char *v) {
         return 0;
 }
 
-int set_put_strdup(Set *s, const char *p) {
+int set_put_strdup(Set **s, const char *p) {
         char *c;
+        int r;
 
         assert(s);
         assert(p);
 
-        if (set_contains(s, (char*) p))
+        r = set_ensure_allocated(s, &string_hash_ops_free);
+        if (r < 0)
+                return r;
+
+        if (set_contains(*s, (char*) p))
                 return 0;
 
         c = strdup(p);
         if (!c)
                 return -ENOMEM;
 
-        return set_consume(s, c);
+        return set_consume(*s, c);
 }
 
-int set_put_strdupv(Set *s, char **l) {
+int set_put_strdupv(Set **s, char **l) {
         int n = 0, r;
         char **i;
 

src/basic/set.h

@@ -113,8 +113,8 @@ static inline char **set_get_strv(Set *s) {
 }
 
 int set_consume(Set *s, void *value);
-int set_put_strdup(Set *s, const char *p);
-int set_put_strdupv(Set *s, char **l);
+int set_put_strdup(Set **s, const char *p);
+int set_put_strdupv(Set **s, char **l);
 int set_put_strsplit(Set *s, const char *v, const char *separators, ExtractFlags flags);
 
 #define SET_FOREACH(e, s, i) \