Re: [libmicrohttpd] 回复:Re: Any MHD_ContentReaderCallback Example Code

[Christian Grothoff]

Hi lingweicai,

As you cannot 'update' cls, just use malloc a

struct MyContext {
  struct MyList *head_ptr;
  // possibly more stuff here
} *ctx;

and pass 'ctx' as 'cls' instead of passing 'head_ptr' directly.
That way, you can easily update 'head_ptr'.

Happy hacking!

Christian

On 02/21/2018 12:48 PM, lingweicai wrote:
> 
> Thanks Christian.
> 
>  
> 
> Can I create a MHD_response, by the crc callback to print a circleq ( a
> circle queue,generated with Macro functions /sys/queue.h ), my crc
> callback is like this :
> 
>  
> 
> ssize_t
> crc (void *cls, uint64_t pos, char *buf, size_t max)
> {
>         struct circleq_user  * cq_user_ptr = cls; 
> 
> // if last entry, end the crc 
>         if ( cq_user_ptr->entries.cqe_next == (void *) &head )
> 
>                 return MHD_CONTENT_READER_END_OF_STREAM;
> 
> 
> // pointer of next entry to assigned to cls 
>         cls  = cq_user_ptr->entries.cqe_next ;
> 
> // generate buff content
> 
>         return snprintf (buf, 256,
>                            "<a href=\"/%s\">%s</a><br>",
>                            cq_user_ptr->user_mem_list_ptr->u_base.u_name ,
>                            cq_user_ptr->user_mem_list_ptr->u_base.u_name
>                 );
> } 
> 
>  
> 
> when my circle-head pointer as the parameter of cls for crc, the above
> code always print the first entry of my circle queue. Can I assign the
> next pointer of
> "cls  = cq_user_ptr->entries.cqe_next ; " 
> 
> to re-callback the crc ? it looks this does not work. how can I transfer
> the "next pointer" of my list as the parameter to the next call crc ?
> 
> 
> Thanks,
> 
> Forrest Ling wei cai.
> 
> 
>  
> 
>  
> 
> 
>  
> 
>  
> 
>  
> 
> ----- 原始邮件 -----
> 
>  
> 
> *发件人：*Christian Grothoff<address@hidden>
> 
> *发送时间：*2018-02-05 21:58:17
> 
> *收件
> 人：*lingweicai<address@hidden>;libmicrohttpd<address@hidden>
> 
> *主 题：*Re: Any MHD_ContentReaderCallback Example Code
> 
> On 02/04/2018 03:19 AM, lingweicai wrote:
>> Dear all:
>>
>> I want to create responses with strings variables, for example , html
>> start tag, html title, css, js, head1, content, html end tag , etc.
>>
>> Can I use this callback function instead of
>> MHD_create_response_from_buffer?
> 
> In principle you can use MHD_create_response_from_callback() always
> instead of _from_buffer, as _from_callback is more general. Whether it
> makes sense in your case I cannot judge.
> 
>> I have not found any example codes on the callback.
> 
> Look here: src/examples/fileserver_example_dirs.c
> 
> 
> 
> 
> <https://mail.sohu.com/activity/prettyemail/views/>
> 
> 
>

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