strbuffer_value: Return a read-only pointer rather than duplicating the value

src/dump.c

@@ -222,7 +222,7 @@ char *json_dumps(const json_t *json, uint32_t flags)
     if(dump_to_strbuffer("\n", 1, (void *)&strbuff))
         return NULL;
 
-    result = strbuffer_value(&strbuff);
+    result = strdup(strbuffer_value(&strbuff));
     strbuffer_close(&strbuff);
 
     return result;

src/strbuffer.c

@@ -20,9 +20,9 @@ void strbuffer_close(strbuffer_t *strbuff)
     strbuffer_init(strbuff);
 }
 
-char *strbuffer_value(strbuffer_t *strbuff)
+const char *strbuffer_value(strbuffer_t *strbuff)
 {
-    return strdup(strbuff->value);
+    return strbuff->value;
 }
 
 char *strbuffer_steal_value(strbuffer_t *strbuff)

src/strbuffer.h

@@ -10,7 +10,7 @@ typedef struct {
 void strbuffer_init(strbuffer_t *strbuff);
 void strbuffer_close(strbuffer_t *strbuff);
 
-char *strbuffer_value(strbuffer_t *strbuff);
+const char *strbuffer_value(strbuffer_t *strbuff);
 char *strbuffer_steal_value(strbuffer_t *strbuff);
 
 int strbuffer_append(strbuffer_t *strbuff, const char *string);