Re: [libmicrohttpd] bug in MHD_create_response_from_fd_at_offset()

[Christian Grothoff]

You're right, my interpretation of "total_size" was wrong (it is just the 
total size of the response, not (necessarily) the total size of the file).

Fixed in SVN 14633.

-Christian

On Friday, March 11, 2011 09:32:21 pm Eivind Sarto wrote:
> There appears to be a bug in  MHD_create_response_from_fd_at_offset().
> Calling this function with anything other than a zero offset will cause
> wrong data or no data (sendfile fails if length < 0).
> 
> If you use this call with any application that uses ranges, this bug will
> trigger.
> 
> In src/daemon/daemon.c: send_param_adapter()
>       .....
>       /* can use sendfile */
>       offset = (off_t) connection->response_write_position +
> connection->response->fd_off; #ifdef BUGFIX
>       /* correct */
>       left = connection->response->total_size - 
> connection->response_write_position; #else
>       left = connection->response->total_size - offset;
> #endif
>       if (left > SSIZE_MAX)
>         left = SSIZE_MAX; /* cap at return value limit */
>       ret = sendfile (connection->socket_fd,
>                       fd,
>                       &offset,
>                       left);
> 
> 
> -eivind