On Tue, 2006-12-19 at 18:00 +0200, Momchil Velikov wrote: > Ming Zhang wrote: > > On Tue, 2006-12-19 at 12:56 +0200, Momchil Velikov wrote: > >> Arjan van de Ven wrote: > >>> On Mon, 2006-12-18 at 17:12 -0500, Ming Zhang wrote: > >>>> See this code piece > >>>> > >>>> http://lxr.linux.no/source/drivers/scsi/libata-scsi.c?v=2.6.18#L1049 > >>>> > >>>> 1056 lba |= ((u64)scsicmd[2]) << 24; > >>>> 1057 lba |= ((u64)scsicmd[3]) << 16; > >>>> 1058 lba |= ((u64)scsicmd[4]) << 8; > >>>> 1059 lba |= ((u64)scsicmd[5]); > >>>> > >>>> it can also be written as > >>>> > >>>> lba = be32_to_cpu(*(u32 *)(&scsicmd[2]) > >> ISO/IEC 9899:1999(E) "6.5 Expressions" [#7] > > > > read but still can not understand why u list this here. > > Because this code > > ba = be32_to_cpu(*(u32 *)(&scsicmd[2]) > > violates this requirement > > ISO/IEC 9899:1999(E) "6.5 Expressions" [#7] > > unless you have checked in all callers of ``scsi_10_lba_len'' (and > transitively in their callers, if necessary) that the first parameter in > fact does refer to an object of type ``u32'', in which case the above > code becomes simply non-robust instead of outright non-conforming. > scsicmd is u8*, so scsicmd + 2 is also u8*, why can not cast it to u32*? u* is a unsigned char so a character type" right? > ~velco > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
