Re: [lwip-users] Problem with NULL pcb->callback_arg

[Baptiste Chaboud-crousaz]

Simon,

The code I sent the last time checked that the arg is not NULL. But this is a fix: in the version provided by contrib/ no check is done to ensure that arg is not NULL. In my case, if arg is NULL the next instructions: hcs = arg and hcs->retries++ consists in access a NULL pointer that raises an error (named hard fault exception - you access 0x0!!!!!!).

By checking that arg is not NULL the hard fault exception is avoided but it means that the HTTP server does not work as expected because http_sent is called to send data but nothing is done!

Baptiste

Quoting Simon Goldschmidt <address@hidden>:

>
> Baptiste Chaboud-crousaz wrote:
>> Can you explain me what is the purpose of this function?
>>
>
> The poll function is used for timeout handling. For example, the http
> server closes connections that are idle for too long (poll is called
> twice without data sent or received in between).
>
>
> Regarding your initial problem, I know it's not correct that arg is
> NULL in http_sent (and I'm afraid I don't know why - doesn't happen
> here with the httpd in contrib), but why do you get a "hardfault
> exception" (whatever that is)? The code you sent last time seemed
to
> check for a NULL-pointer correctly...
>
> Simon
>
>
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