Issue #236: Add -Wcast-qual and fix casts to retain constness.

To better distinguish between entry->k and entry->v being const within linkhash, but non-const outside, add lh_entry_v() and lh_entry_k() accessors.
Make lh_entry->k const.

diff --git a/configure.ac b/configure.ac
index 820d30e21859331edf604dea606b78acbefce2cc..18f91dc6c046f259714a3fc6ca0c9c24d6ef2815 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -103,7 +103,7 @@ AS_IF([test "x$enable_Bsymbolic" = "xcheck"],
 AS_IF([test "x$enable_Bsymbolic" = "xyes"], [JSON_BSYMBOLIC_LDFLAGS=-Wl[,]-Bsymbolic-functions])
 AC_SUBST(JSON_BSYMBOLIC_LDFLAGS)
 
-AX_APPEND_COMPILE_FLAGS([-Wall -Werror -Wno-error=deprecated-declarations])
+AX_APPEND_COMPILE_FLAGS([-Wall -Werror -Wcast-qual -Wno-error=deprecated-declarations])
 AX_APPEND_COMPILE_FLAGS([-Wextra -Wwrite-string -Wno-unused-parameter])
 AX_APPEND_COMPILE_FLAGS([-D_GNU_SOURCE -D_REENTRANT])
 

diff --git a/json_object.c b/json_object.c
index 93aefd5d35d6fae3aa5a685abd5b0e668cc694a4..24cb7abdbef4d5b5a76dcaca05ab34161ebab5cd 100644 (file)
--- a/json_object.c
+++ b/json_object.c
@@ -84,7 +84,7 @@ static void json_object_fini(void)
                           json_object_table->count);
                        lh_foreach(json_object_table, ent)
                        {
-                               struct json_object* obj = (struct json_object*)ent->v;
+                               struct json_object* obj = (struct json_object*)lh_entry_v(ent);
                                MC_DEBUG("\t%s:%p\n", json_type_to_name(obj->o_type), obj);
                        }
                }
@@ -385,8 +385,8 @@ static int json_object_object_to_json_string(struct json_object* jso,
 static void json_object_lh_entry_free(struct lh_entry *ent)
 {
        if (!ent->k_is_constant)
-               free(ent->k);
-       json_object_put((struct json_object*)ent->v);
+               free(lh_entry_k(ent));
+       json_object_put((struct json_object*)lh_entry_v(ent));
 }
 
 static void json_object_object_delete(struct json_object* jso)
@@ -435,17 +435,17 @@ void json_object_object_add_ex(struct json_object* jso,
        // and re-adding it, so the existing key remains valid.
        json_object *existing_value = NULL;
        struct lh_entry *existing_entry;
-       const unsigned long hash = lh_get_hash(jso->o.c_object, (void*)key);
+       const unsigned long hash = lh_get_hash(jso->o.c_object, (const void *)key);
        existing_entry = (opts & JSON_C_OBJECT_ADD_KEY_IS_NEW) ? NULL : 
-                             lh_table_lookup_entry_w_hash(jso->o.c_object, (void*)key, hash);
+                             lh_table_lookup_entry_w_hash(jso->o.c_object, (const void *)key, hash);
        if (!existing_entry)
        {
-               void *const k = (opts & JSON_C_OBJECT_KEY_IS_CONSTANT) ?
-                                       (void*)key : strdup(key);
+               const void *const k = (opts & JSON_C_OBJECT_KEY_IS_CONSTANT) ?
+                                       (const void *)key : strdup(key);
                lh_table_insert_w_hash(jso->o.c_object, k, val, hash, opts);
                return;
        }
-       existing_value = (json_object *)existing_entry->v;
+       existing_value = (json_object *)lh_entry_v(existing_entry);
        if (existing_value)
                json_object_put(existing_value);
        existing_entry->v = val;
@@ -458,8 +458,8 @@ int json_object_object_add(struct json_object* jso, const char *key,
        // and re-adding it, so the existing key remains valid.
        json_object *existing_value = NULL;
        struct lh_entry *existing_entry;
-       const unsigned long hash = lh_get_hash(jso->o.c_object, (void*)key);
-       existing_entry = lh_table_lookup_entry_w_hash(jso->o.c_object, (void*)key, hash);
+       const unsigned long hash = lh_get_hash(jso->o.c_object, (const void *)key);
+       existing_entry = lh_table_lookup_entry_w_hash(jso->o.c_object, (const void *)key, hash);
        if (!existing_entry)
        {
                char *keydup = strdup(key);
@@ -468,7 +468,7 @@ int json_object_object_add(struct json_object* jso, const char *key,
 
                return lh_table_insert_w_hash(jso->o.c_object, keydup, val, hash, 0);
        }
-       existing_value = (json_object  *)existing_entry->v;
+       existing_value = (json_object *)lh_entry_v(existing_entry);
        if (existing_value)
                json_object_put(existing_value);
        existing_entry->v = val;
@@ -500,7 +500,7 @@ json_bool json_object_object_get_ex(const struct json_object* jso, const char *k
        switch(jso->o_type)
        {
        case json_type_object:
-               return lh_table_lookup_ex(jso->o.c_object, (void*)key, (void**)value);
+               return lh_table_lookup_ex(jso->o.c_object, (const void *)key, (void**)value);
        default:
                if (value != NULL)
                        *value = NULL;
@@ -865,7 +865,7 @@ struct json_object* json_object_new_string_len(const char *s, int len)
                }
                dstbuf = jso->o.c_string.str.ptr;
        }
-       memcpy(dstbuf, (void *)s, len);
+       memcpy(dstbuf, (const void *)s, len);
        dstbuf[len] = '\0';
        jso->o.c_string.len = len;
        return jso;

diff --git a/json_object.h b/json_object.h
index 33b0d2fbcb87d8ec66ab05da614c64b8aeed91e7..4bcfcbcca17697b4b8b15918011d251bc0a8a6bb 100644 (file)
--- a/json_object.h
+++ b/json_object.h
@@ -455,8 +455,8 @@ extern void json_object_object_del(struct json_object* obj, const char *key);
        struct json_object *val __attribute__((__unused__)) = NULL; \
        for(struct lh_entry *entry ## key = json_object_get_object(obj)->head, *entry_next ## key = NULL; \
                ({ if(entry ## key) { \
-                       key = (char*)entry ## key->k; \
-                       val = (struct json_object*)entry ## key->v; \
+                       key = (char*)lh_entry_k(entry ## key); \
+                       val = (struct json_object*)lh_entry_v(entry ## key); \
                        entry_next ## key = entry ## key->next; \
                } ; entry ## key; }); \
                entry ## key = entry_next ## key )
@@ -470,8 +470,8 @@ extern void json_object_object_del(struct json_object* obj, const char *key);
        struct lh_entry *entry_next ## key = NULL; \
        for(entry ## key = json_object_get_object(obj)->head; \
                (entry ## key ? ( \
-                       key = (char*)entry ## key->k, \
-                       val = (struct json_object*)entry ## key->v, \
+                       key = (char*)lh_entry_k(entry ## key), \
+                       val = (struct json_object*)lh_entry_v(entry ## key), \
                        entry_next ## key = entry ## key->next, \
                        entry ## key) : 0); \
                entry ## key = entry_next ## key)
@@ -483,7 +483,9 @@ extern void json_object_object_del(struct json_object* obj, const char *key);
  * @param iter the object iterator
  */
 #define json_object_object_foreachC(obj,iter) \
- for(iter.entry = json_object_get_object(obj)->head; (iter.entry ? (iter.key = (char*)iter.entry->k, iter.val = (struct json_object*)iter.entry->v, iter.entry) : 0); iter.entry = iter.entry->next)
+ for(iter.entry = json_object_get_object(obj)->head; \
+     (iter.entry ? (iter.key = (char*)lh_entry_k(iter.entry), iter.val = (struct json_object*)lh_entry_v(iter.entry), iter.entry) : 0); \
+     iter.entry = iter.entry->next)
 
 /* Array type methods */
 

diff --git a/json_object_iterator.c b/json_object_iterator.c
index 7066649c3bc5cca67841aac44c758bebd0172342..7c2a25b0c10190b001ad3215bb5fcbc997a419bd 100644 (file)
--- a/json_object_iterator.c
+++ b/json_object_iterator.c
@@ -105,7 +105,7 @@ json_object_iter_next(struct json_object_iterator* iter)
     JASSERT(NULL != iter);
     JASSERT(kObjectEndIterValue != iter->opaque_);
 
-    iter->opaque_ = ((struct lh_entry *)iter->opaque_)->next;
+    iter->opaque_ = ((const struct lh_entry *)iter->opaque_)->next;
 }
 
 
@@ -118,7 +118,7 @@ json_object_iter_peek_name(const struct json_object_iterator* iter)
     JASSERT(NULL != iter);
     JASSERT(kObjectEndIterValue != iter->opaque_);
 
-    return (const char*)(((struct lh_entry *)iter->opaque_)->k);
+    return (const char*)(((const struct lh_entry *)iter->opaque_)->k);
 }
 
 
@@ -131,7 +131,7 @@ json_object_iter_peek_value(const struct json_object_iterator* iter)
     JASSERT(NULL != iter);
     JASSERT(kObjectEndIterValue != iter->opaque_);
 
-    return (struct json_object*)(((struct lh_entry *)iter->opaque_)->v);
+    return (struct json_object*)lh_entry_v((const struct lh_entry *)iter->opaque_);
 }
 
 

diff --git a/linkhash.c b/linkhash.c
index 1a5c1b8bfc979081e9b5cad0a06c39d8224ad0ea..64074ac62a99ed70fd043b35764f8dce14e87055 100644 (file)
--- a/linkhash.c
+++ b/linkhash.c
@@ -441,7 +441,7 @@ static uint32_t hashlittle( const void *key, size_t length, uint32_t initval)
  */
 static unsigned long lh_perllike_str_hash(const void *k) 
 {
-    const char *rkey = (char*) k;
+    const char *rkey = (const char *)k;
     unsigned hashval = 1;
 
     while (*rkey)
@@ -572,7 +572,7 @@ void lh_table_free(struct lh_table *t)
 }
 
 
-int lh_table_insert_w_hash(struct lh_table *t, void *k, const void *v, const unsigned long h, const unsigned opts)
+int lh_table_insert_w_hash(struct lh_table *t, const void *k, const void *v, const unsigned long h, const unsigned opts)
 {
        unsigned long n;
 
@@ -604,7 +604,7 @@ int lh_table_insert_w_hash(struct lh_table *t, void *k, const void *v, const uns
 
        return 0;
 }
-int lh_table_insert(struct lh_table *t, void *k, const void *v)
+int lh_table_insert(struct lh_table *t, const void *k, const void *v)
 {
        return lh_table_insert_w_hash(t, k, v, lh_get_hash(t, k), 0);
 }
@@ -641,11 +641,11 @@ json_bool lh_table_lookup_ex(struct lh_table* t, const void* k, void **v)
 {
        struct lh_entry *e = lh_table_lookup_entry(t, k);
        if (e != NULL) {
-               if (v != NULL) *v = (void *)e->v;
+               if (v != NULL) *v = lh_entry_v(e);
                return TRUE; /* key found */
        }
        if (v != NULL) *v = NULL;
-       return FALSE; /* key not found */
+               return FALSE; /* key not found */
 }
 
 int lh_table_delete_entry(struct lh_table *t, struct lh_entry *e)

diff --git a/linkhash.h b/linkhash.h
index ead4818405e551247ed4a593a2605e8b9000c10f..8be625a7f2098ee075112165194de531cc7aa3ca 100644 (file)
--- a/linkhash.h
+++ b/linkhash.h
@@ -78,12 +78,16 @@ typedef int (lh_equal_fn) (const void *k1, const void *k2);
  */
 struct lh_entry {
        /**
-        * The key.
+        * The key.  Use lh_entry_k() instead of accessing this directly.
+        */
+       const void *k;
+       /**
+        * A flag for users of linkhash to know whether or not they
+        * need to free k.
         */
-       void *k;
        int k_is_constant;
        /**
-        * The value.
+        * The value.  Use lh_entry_v() instead of accessing this directly.
         */
        const void *v;
        /**
@@ -211,7 +215,7 @@ extern void lh_table_free(struct lh_table *t);
  * @return On success, <code>0</code> is returned.
  *     On error, a negative value is returned.
  */
-extern int lh_table_insert(struct lh_table *t, void *k, const void *v);
+extern int lh_table_insert(struct lh_table *t, const void *k, const void *v);
 
 
 /**
@@ -226,7 +230,7 @@ extern int lh_table_insert(struct lh_table *t, void *k, const void *v);
  * @param h hash value of the key to insert
  * @param opts opts, a subset of JSON_OBJECT_ADD_* flags is supported
  */
-extern int lh_table_insert_w_hash(struct lh_table *t, void *k, const void *v, const unsigned long h, const unsigned opts);
+extern int lh_table_insert_w_hash(struct lh_table *t, const void *k, const void *v, const unsigned long h, const unsigned opts);
 
 
 /**
@@ -335,6 +339,28 @@ static inline unsigned long lh_get_hash(const struct lh_table *t, const void *k)
        return t->hash_fn(k);
 }
 
+/* Don't use this outside of linkhash.h: */
+#ifdef __UNCONST
+#define _LH_UNCONST(a) __UNCONST(a)
+#else
+#define _LH_UNCONST(a) ((void *)(unsigned long)(const void *)(a))
+#endif
+
+/**
+ * Return a non-const version of lh_entry->k.
+ * k is const to indicate and help ensure that linkhash itself doesn't modify
+ * it, but callers are allowed to do what they want with it.
+ * See also lh_entry->k_is_constant
+ */
+#define lh_entry_k(entry) _LH_UNCONST((entry)->k)
+
+/**
+ * Return a non-const version of lh_entry->v.
+ * v is const to indicate and help ensure that linkhash itself doesn't modify
+ * it, but callers are allowed to do what they want with it.
+ */
+#define lh_entry_v(entry) _LH_UNCONST((entry)->v)
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/tests/test4.c b/tests/test4.c
index 23e97dac1b891648eefa418a4ad1d6dccca95933..628fef5668ddcb945498c6640a9cda3f17d205ed 100644 (file)
--- a/tests/test4.c
+++ b/tests/test4.c
@@ -28,7 +28,7 @@ int main()
 {
        const char *input = "\"\\ud840\\udd26,\\ud840\\udd27,\\ud800\\udd26,\\ud800\\udd27\"";
        const char *expected = "\xF0\xA0\x84\xA6,\xF0\xA0\x84\xA7,\xF0\x90\x84\xA6,\xF0\x90\x84\xA7";
-       struct json_object *parse_result = json_tokener_parse((char*)input);
+       struct json_object *parse_result = json_tokener_parse(input);
        const char *unjson = json_object_get_string(parse_result);
 
        printf("input: %s\n", input);