Any good idioms for error handling in straight C programs?

Question

Getting back in to some C work.

Many of my functions look like this:

int err = do_something(arg1, arg2, arg3, &result);

With th

Answer 1

Provided you are working with a specific context, I think the following pattern is very nice. The basic idea is that operations on an error-set state are no-ops, so error checking can be postponed to when it is convenient!

A concrete example: A deserialization context. Decoding of any element can fail, but the function may continue without error checking because all the decode_* functions are no-ops when the serialization record is in an error state. It's a matter of convenience or opportunity or optimization to insert decode_has_error. In the example below, there is no error check, the caller will take care of that.

void list_decode(struct serialization_record *rec,                       
                 struct list *list,                                     
                 void *(*child_decode)(struct serialization_record *)) {
    uint32_t length;                                                             
    decode_begin(rec, TAG);                                  
    decode_uint32(rec, &length);                                          
    for (uint32_t i = 0; i < length; i++) {                                
        list_append(list, child_decode(rec));
    }                                                                        
    decode_end(rec, TAG);
}