Re: stat64 on mips

[Rich Felker <dalias@aerifal.cx>]

On Mon, Dec 30, 2013 at 10:02:19PM +0000, Justin Cormack wrote:
> On Mon, Dec 30, 2013 at 9:29 PM, Rich Felker <dalias@aerifal.cx> wrote:
> > On Mon, Dec 30, 2013 at 06:20:46PM +0000, Justin Cormack wrote:
> >> MIPS is the most confusing architecture, but as far as I can make out,
> >> the definition of struct stat64 that Musl has is probably the right
> >> one for mips n32 but wrong for mips o32 which should be
> >>
> >> struct stat {
> >>   unsigned long   st_dev;
> >>   unsigned long   __st_pad0[3];
> >>   unsigned long long      st_ino;
> >>   mode_t          st_mode;
> >>   nlink_t         st_nlink;
> >>   uid_t           st_uid;
> >>   gid_t           st_gid;
> >>   unsigned long   st_rdev;
> >>   unsigned long   __st_pad1[3];
> >>   long long       st_size;
> >>   time_t          st_atime;
> >>   unsigned long   st_atime_nsec;
> >>   time_t          st_mtime;
> >>   unsigned long   st_mtime_nsec;
> >>   time_t          st_ctime;
> >>   unsigned long   st_ctime_nsec;
> >>   unsigned long   st_blksize;
> >>   unsigned long   __st_pad2;
> >>   long long       st_blocks;
> >> };
> >>
> >> It does appear that the syscalls for the two ABIs differ in this...
> >
> > This structure is identical to the one in musl except that it has
> > 32-bit dev_t plus padding in place of 64-bit dev_t, and the musl
> > version has reserved space at the end. Can you check whether the dev_t
> > issue is actually a problem (it might be, based on endianness, and if
> > so I think it would require ugly fixups in userspace)?
> 
> Ah no, my mistake, you are right, the padding seems correct and I was
> getting confused as usual by dev_t. However the 64 bit dev_t is a
> problem on bigendian mips.
> 
> (Whats the reason for Musl using 64 bit dev_t? glibc compatibility?)

And room for expansion, and consistency of the type between archs.
There's no justification for dev_t or similar types to be
arch-specific.

Rich