Re: [PATCH] Y2038: add struct __timespec64

[Joseph Myers <joseph at codesourcery dot com>]

On Wed, 19 Sep 2018, Albert ARIBAUD (3ADEV) wrote:

> diff --git a/time/bits/types/struct_timespec64.h b/time/bits/types/struct_timespec64.h
> new file mode 100644
> index 0000000000..2221bed8bc
> --- /dev/null
> +++ b/time/bits/types/struct_timespec64.h

Since it's actually defining struct __timespec64, the header needs to be 
bits/types/struct___timespec64.h.  bits/types/struct_timespec64.h would 
define a type struct timespec64, but we don't have such a type.

> +/* Y2036proof structure for a time value.  This is like a `struct timeval' but
> +   has nanoseconds instead of microseconds.  To keep tings Posix-ish, we keep
> +   the nanoseconds field a signed long, but since Linux has a 64-bit signed int,
> +   we pad it with a 32-bit int, which should always be 0.
> +   Note that the public type has an anonymous bitfield as padding, so that
> +   it cannot be written into (or read from). */ 

The bit-fields needs to be *anonymous* for initializers to work as 
intended.  It can't have the name tv_pad that it has in this patch, or any 
other name, with our without leading underscores.

> +#if BYTE_ORDER == BIG_ENDIAN

These macros are in the user namespace.  You have to use __BYTE_ORDER / 
__BIG_ENDIAN.

> +struct __timespec64
> +{
> +  __time64_t tv_sec;		/* Seconds */
> +  int tv_pad: 32;		/* Padding named for checking/setting */
> +  __syscall_slong_t tv_nsec;	/* Nanoseconds */
> +};

You also need a separate x86 version of the header that avoids inserting 
the padding for x32, given the (nonconforming) 64-bit __syscall_slong_t 
there.  Then, the wrapper in include/ will be wrong for x86, so the 
generic one probably needs to move from time/ to the top-level bits/ 
directory so the correct header is found in all cases.

-- 
Joseph S. Myers
joseph@codesourcery.com