Diagnostics

All functions return -1 if an error occurs. Typically, the functions will return 0 on success, but the data exchange functions (cs_get, cs_put, cs_more) follow special rules. Consult their descriptions.

When a function (including the data exchange functions) reports an error condition, use the function cs_errno() to determine the cause of the problem. The function

    void cs_perror(COMSTACK handle char *message);
   

works like perror(2) and prints the message argument, along with a system message, to stderr. Use the character array

    extern const char *cs_errlist[];
   

to get hold of the message, if you want to process it differently. The function

    const char *cs_stackerr(COMSTACK handle);
   

Returns an error message from the lower layer, if one has been provided.