On Wed, Oct 30, 2002 at 12:03:12PM +0100, Jakub Jelinek wrote: > On Wed, Oct 30, 2002 at 10:52:30AM +0100, Wolfram Gloger wrote: > > > > [That is: two pointers to a buffer, of different types; walk through > > > > the buffer, reading one object of the first type and writing out an > > > > object of the second lesser-or-equal sized type.] > > > > > > No, there's no standard C way to do that. An object can only have one > > > type at a time. You have to use another buffer as an intermediate. > > > > AFAICS, the code already has intermediate buffers: > > > > dp = (DIRENT_TYPE *)buf; > > kdp = (struct kernel_dirent64 *) kbuf; > > > > uint64_t d_ino = kdp->d_ino; > > int64_t d_off = kdp->d_off; > > unsigned char d_type = kdp->d_type; > > > > DIRENT_SET_DP_INO (dp, d_ino); > > dp->d_off = d_off; > > > > So, why not just use a char* ptr to write out the data using memcpy(), > > do away with dp and e.g. change the last line into: > > > > memcpy(buf + offsetof(DIRENT_TYPE, d_off), &d_off, sizeof d_off); > > > > (the DIRENT_SET_DP_INO line of course needs to be handled a little > > differently). Since char* can alias anything, that would remain > > portable C. > > But that intermediate buffer is in registers (on sane arches), while using > memcpy would mean at least with current compilers memory. > glibc requires gcc (even 3.2+) to compile anyway, so IMHO just using the > union as drow posted seems best to me.
If my patch is OK, could someone commit it, please? -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
