Hi, Mark
It works fine.
Thanks
Atsushi SAKAI
Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx> wrote:
> Hi, Mark
>
> Thank you for your suggestion.
> I just compiled it sucessfuly.
> It should be work.
> I will do test it tomorrow.
>
> Thanks
> Atsushi SAKAI
>
> Mark McLoughlin <markmc@xxxxxxxxxx> wrote:
>
> > Hi,
> > Thanks for that ...
> >
> > On Tue, 2007-02-20 at 13:51 +0900, Atsushi SAKAI wrote:
> >
> > > > > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_family = AF_INET;
> > > > > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr = inaddr;
> > > > > + ((struct sockaddr_in *)((void *)&ifr.ifr_addr))->sin_family = AF_INET;
> > > > > + ((struct sockaddr_in *)((void *)&ifr.ifr_addr))->sin_addr = inaddr;
> >
> > > bridge.c: In function 'brSetInetAddr':
> > > bridge.c:344: warning: cast increases required alignment of target type
> > > bridge.c:345: warning: cast increases required alignment of target type
> > > bridge.c: In function 'brGetInetAddr':
> > > bridge.c:381: warning: cast increases required alignment of target type
> >
> > Okay, my understanding of this is that:
> >
> > - The warning is caused by -Wcast-align
> >
> > - Our problem is that we're casting between pointers to struct
> > sockaddr and struct sockaddr_in, which look like
> >
> > struct sockaddr
> > {
> > unsigned short int sa_family;
> > };
> >
> > struct sockaddr_in
> > {
> > unsigned short int sin_family;
> > uint16_t sin_port;
> > struct { uint32_t s_addr } sin_addr;
> > };
> >
> > - Because of the uint32_t, struct sockaddr_in is required to be
> > aligned to a 4 byte boundary, whereas on ia64 struct sockaddr is
> > only required to be aligned to a 2 byte boundary
> >
> > - If we look at in the context of struct ifreq, though:
> >
> > struct ifreq
> > {
> > ....
> > union {
> > struct sockaddr ifru_addr;
> > ....
> > void *ifru_data;
> > } ifr_ifru;
> > };
> > #define ifr_addr ifr_ifru.ifru_addr
> > #define ifr_data ifr_ifru.ifru_data
> >
> > we see that because of the void pointer in the union, the struct
> > sockaddr is actually guaranteed to be aligned to 8 bytes and so the
> > warning can be ignored.
> >
> > - I'd prefer to avoid the void pointer cast as someone could come
> > along and wonder whether the cast is hiding a genuine problem.
> >
> > - So, I think I'll go ahead and do it this way instead:
> >
> > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_family = AF_INET;
> > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr = inaddr;
> > + ((struct sockaddr_in *)&ifr.ifr_data)->sin_family = AF_INET;
> > + ((struct sockaddr_in *)&ifr.ifr_data)->sin_addr = inaddr;
> >
> > Cheers,
> > Mark.
> >
>
>
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