[Cocci] how to consider castings in semantic patchs

Julia Lawall
2013-03-13T08:43:46Z

On Tue, 12 Mar 2013, Andr?s More wrote:

> Hi, I've been playing with Coccinele, I find it really useful.
>
> I'm trying to create a semantic patch to rename a structure (and its
> fields).
> I could get almost everything in place in several patches: the structure
> gets renamed, also variables of that type, also their attributes. However,
> the code (not mine) uses some explicit castings and I couldn't find a way to
> cover those cases also.
>
> I've tried to follow the documented grammar but I think I got lost without
> finding how to declare such castings.?
>
> I'm appending the last version of the semantic patch I've been working on
> just to give the rough idea how what I am trying to describe. The code is a
> Linux kernel staging driver (VIA VT6656), using their own Ethernet packet
> struct.
>
> Thanks, I will really appreciate any hints on how to consider explicit
> casting.
>
> -- Andres
> Sample Line not covered
> pMACHeader = (PS802_11Header) (pbyRxBufferAddr + cbHeaderSize);

What would you like to generate in this case? Is it just to change the
cast name? In that case, what you are missing is probably the typedef
declaration. You could say:

@@
typedef PS802_11Header, newtype;
expression e;
@@

(
- PS802_11Header
+ newtype
)
e

You only need to declare a type using typedef once. It is remembered for
subsequent rules.

julia

>
> Semantic patch I could get done
> $ cat test.cocci
> @rule1@
> identifier h;
> @@
> -PSEthernetHeader h;
> +struct ethhdr * h;
>
> @rule2@
> identifier h;
> @@
> -PS802_11Header h;
> +struct ieee80211_hdr *h;
>
> @rule5@
> identifier h;
> @@
> -SEthernetHeader h;
> +struct ethhdr h;
>
> @rule6@
> identifier h;
> @@
> -S802_11Header h;
> +struct ieee80211_hdr h;
>
> @rule3@
> struct ethhdr *h;
> @@
> (
> -h->abyDstAddr
> +h->h_dest
> |
> -h->abySrcAddr
> +h->h_source
> |
> -h->wType
> +h->h_proto
> )
>
> @rule4@
> struct ieee80211_hdr *h;
> @@
> (
> -h->wFrameCtl
> +h->frame_control
> |
> -h->wDurationID
> +h->duration_id
> |
> -h->abyAddr1
> +h->addr1
> |
> -h->abyAddr2
> +h->addr2
> |
> -h->abyAddr3
> +h->addr3
> |
> -h->wSeqCtl
> +h->seq_ctrl
> |
> -h->abyAddr4
> +h->addr4
> )
>
>
>