successed in simple test while failed in my project

[janlely]

the under code works fine in a simple test program, but failed in my project under Ubuntu 14.04,
however success in my mac pro

i debug into my project, it got a "segmentation fault" at line 9

this is the out put:
////
Process 27360 stopped

• thread Undefined symbol: json_object_from_file #2: tid = 27411, 0x00007ffff6ea3c37 libc.so.6__GI_raise(sig=6) + 55 at raise.c:56, name = 'xxxxx', stop reason = signal SIGABRT frame #0: 0x00007ffff6ea3c37 libc.so.6__GI_raise(sig=6) + 55 at raise.c:56

////

here is my code:

1. void put_int_value_to_jsonstring(char *dest, const char *key, int value)
2. {

3. if(dest == NULL){
   

4.     return;
   

5. }
   

6. json_object *jobj = NULL;
   

7. if(strlen(dest) == 0 || !is_json_string(dest)){
   

8.     json_object *new_jobj = json_object_new_object();
   

9.     json_object_object_add(new_jobj, key, json_object_new_int(value));
   

10.     const char *jstr = json_object_to_json_string(new_jobj);
    

11.     strcpy(dest, jstr);
    

12.     json_object_put(new_jobj);
    

13. }else{
    

14.     jobj = json_tokener_parse(dest);
    

15.     json_object *exist_value = json_object_object_get(jobj, key);
    

16.     if(exist_value == NULL){
    

17.         json_object_object_add(jobj, key, json_object_new_int(value));
    

18.     }else{
    

19.         json_object_object_del(jobj, key);
    

20.         json_object_object_add(jobj, key, json_object_new_int(value));
    

21.     }
    

22.     const char *jstr = json_object_to_json_string_ext(jobj, JSON_C_TO_STRING_NOSLASHESCAPE);
    

23.     strcpy(dest, jstr);
    

24.     json_object_put(jobj);
    

25. }
    

27. }

[hawicz]

Doing a blind strcpy like you have here is asking for trouble. My guess is that you're overrunning the size of what you have allocated for dest, but without seeing how you're calling this func who knows.
Even if thats not the problem this could benefit from an adjusted API, where you pass in the length of dest to check that you're within range and either return a failure or alloc a new buffer and return that.

You don't show a stack backtrace, and you don't show how that function is called, so there's no way to tell what is going wrong here.
How do you know it's crashing on line 9?
.

[janlely]

Thank you! I found it, it was the allocate problem