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Message-ID: <CAK4o1WzU-VxRJAx8_mDY--b9q9T0yXMHJWT9yopGOkh_qFyMyg@mail.gmail.com>
Date: Mon, 30 Dec 2013 22:10:59 +0000
From: Justin Cormack <justin@...cialbusservice.com>
To: musl@...ts.openwall.com
Subject: Re: stat64 on mips

On Mon, Dec 30, 2013 at 10:03 PM, Rich Felker <dalias@...ifal.cx> wrote:
> 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@...ifal.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.

But isnt the kernel dev_t 32 bit for all archs?

Justin

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