sorting - Linked list alphabetical sort, seg fault in c -

i'm trying sort linked list in alphabetical order, i'm getting seg fault sorting function. how can sort list alphabetically.

typedef struct  s_file {     char        *file_name;     struct      s_file *next; }               t_file;  void    sort_alpha(t_file **begin_list) {     t_file  *list;     char    *tmp;      list = *begin_list;     if (list)     {         while (list)         {             if (strcmp(list->file_name, list->next->file_name) < 0)             {                 tmp = list->file_name;                 list->file_name = list->next->file_name;                 list->next->file_name = tmp;             }             list = list->next;         }     } } 

in line

      if (strcmp(list->file_name, list->next->file_name) < 0)        // list->next null       // list->next->file_name give seg fault 

a protection needed. possible solution:

void sort_alpha(t_file **begin_list) { t_file  *list; char    *tmp;  list = *begin_list; if (list) {     while (list && list->next)     {          if (strcmp(list->file_name, list->next->file_name) < 0)         {             tmp = list->file_name;             list->file_name = list->next->file_name;             list->next->file_name = tmp;         }         list = list->next;     } } }