Re: [Qemu-devel] [PATCH v2 01/11] curl: introduce CURLSockInfo to BDRVCURLState.

[Stefan Hajnoczi]

On Tue, May 14, 2013 at 10:26:20AM +0800, Fam Zheng wrote:
> We use socket provided by curl in the driver.  Libcurl multi interface
> has option CURLMOPT_SOCKETFUNCTION for socket.
> 
> Per man 3 curl_multi_setopt:
> 
>     ...
>     CURLMOPT_SOCKETFUNCTION
> 
>     Pass a pointer to a function matching the curl_socket_callback
>     prototype. The curl_multi_socket_action(3) function informs the
>     application about updates in the socket (file descriptor) status by
>     doing none, one, or multiple calls to the curl_socket_callback given in
>     the param argument. They update the status with changes since the
>     previous time a curl_multi_socket(3) function was called. If the given
>     callback pointer is NULL, no callback will be called. Set the callback's
>     userp argument with CURLMOPT_SOCKETDATA. See curl_multi_socket(3) for
>     more callback details.
>     ...
> 
> The added structure store information for all the socket returned by
> libcurl. The most important field is action, which is used to keep what
> actions are needed when this socket's fd handler is called.
> 
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  block/curl.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/block/curl.c b/block/curl.c
> index b8935fd..14f4552 100644
> --- a/block/curl.c
> +++ b/block/curl.c
> @@ -75,10 +75,18 @@ typedef struct CURLState
>      char in_use;
>  } CURLState;
>  
> +typedef struct CURLSockInfo {
> +    curl_socket_t fd;
> +    int action;
> +    struct BDRVCURLState *s;
> +    QLIST_ENTRY(CURLSockInfo) next;
> +} CURLSockInfo;

This patch doesn't make sense by itself.  CURLSockInfo is unused and
->action is never assigned to.  I guess this will eventually replace
BDRVCURLState->states[] but at this point in the patch series it is hard
to tell - it would be nice to explain this in the commit description.

>  typedef struct BDRVCURLState {
>      CURLM *multi;
>      size_t len;
>      CURLState states[CURL_NUM_STATES];
> +    QLIST_HEAD(, CURLSockInfo) socks;
>      char *url;
>      size_t readahead_size;
>  } BDRVCURLState;
> @@ -90,7 +98,16 @@ static int curl_aio_flush(void *opaque);
>  static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
>                          void *s, void *sp)
>  {
> +    BDRVCURLState *bs = (BDRVCURLState *)s;

void * is automatically coerced to any pointer type.  No need for a type
cast.

>      DPRINTF("CURL (AIO): Sock action %d on fd %d\n", action, fd);
> +    CURLSockInfo *sock = (CURLSockInfo *)sp;

Same here.

> +    if (!sp) {
> +        sock = g_malloc0(sizeof(CURLSockInfo));
> +        sock->fd = fd;
> +        sock->s = bs;
> +        QLIST_INSERT_HEAD(&bs->socks, sock, next);
> +        curl_multi_assign(bs->multi, fd, sock);
> +    }
>      switch (action) {
>          case CURL_POLL_IN:
>              qemu_aio_set_fd_handler(fd, curl_multi_do, NULL, curl_aio_flush, 
> s);
> @@ -462,8 +479,8 @@ static int curl_open(BlockDriverState *bs, QDict 
> *options, int flags)
>      // initialize the multi interface!
>  
>      s->multi = curl_multi_init();
> -    curl_multi_setopt( s->multi, CURLMOPT_SOCKETDATA, s); 
> -    curl_multi_setopt( s->multi, CURLMOPT_SOCKETFUNCTION, curl_sock_cb ); 
> +    curl_multi_setopt(s->multi, CURLMOPT_SOCKETDATA, s);
> +    curl_multi_setopt(s->multi, CURLMOPT_SOCKETFUNCTION, curl_sock_cb);
>      curl_multi_do(s);
>  
>      qemu_opts_del(opts);
> -- 
> 1.8.1.4
> 
>