Re: Maybe too strict check for frontend/backend name conflicts

On Sat, 3 Nov 2007, Willy Tarreau wrote:

> On Sat, Nov 03, 2007 at 02:47:19AM +0100, Krzysztof Oledzki wrote:

>>>> How about adding a global "char errstr[BUFSIZE]"? Each function can then
>>>> easily return a appropriate error message. No need to pass additional
>>>> buffers and lengths.
>>>
>>> That's what I thought about first, then I realized that it would not be
>>> convenient for intermediate functions to prefix the error messages with
>>> their part of context. For instance, such a message could be completed
>>> by 4 different levels :
>>>
>>> "Proxy xxx: rule yyy: acl zzz requires HTTP mode"
>>>                             <--- level 4 ---->
>>>                     <------- level 3 -------->
>>>           <------------ level 2 ------------->
>>> <------------------ level 1 ------------------>
>>>
>>> So in certain circumstances, the error message will be on the caller's
>>> stack.
>>
>> Oh, indeed. But this still can be solved without passing
>> additional references. Attached example code that produces:
>>
>> "Proxy xxx: rule yyy: acl zzz requires HTTP mode"
>

Right...

> I'm still thinking about this, but I believe that what we need is a stack
> or text fragments that can be fed by all the functions. We would then only
> pass to each function the stack level (most always 'level+1'). We would then
> have two functions:
> - init_error_stack(int level, char *msg) : clears upper stack and inserts msg
> - set_error_msg(int level, char *msg) : inserts msg without clearing stack

OK. How about the new attachment? It generates:

Proxy xxx: rule yyy: acl zzz requires HTTP mode Proxy xxx: acl zzz requires HTTP mode

> We would also need a collapse function to merge many levels into one, which
> is handy when you need to merge the message inside another one :
> - collapse_error_levels(int level)

Hm, to merge everything starting from the "level"? This should be also possible, but in which situation it may be useful?

Best regards,

                                 Krzysztof Olêdzki