typedef struct message message; struct message { message *prev; /* doubly linked list for messages */ message *next; message *extent; /* singly linked list for range of messages */ string *sender; string *date; string *body; int pos; int size; int status; }; extern message *m_get(); extern int m_print(); extern int read_mbox(); extern int write_mbox(); extern void V(); extern int P(); /* message status */ #define DELETED 1 extern message *mlist,*mlast,*mzero; /* list of messages */