Date:   Tue, 23 Nov 2021 10:15:12 +0100
From:   Cyril Hrubis <chrubis@suse.cz>
To:     Zack Weinberg <zack@owlfolio.org>
Cc:     linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-api@vger.kernel.org, libc-alpha@sourceware.org,
        ltp@lists.linux.it
Subject: Re: [PATCH] uapi: Make __{u,s}64 match {u,}int64_t in userspace
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Hi!
> I am all for matching __uN / __sN to uintN_t / intN_t in userspace, but may I suggest the technically simpler and guaranteed-to-be-accurate
> 
>  /*
> - * int-ll64 is used everywhere now.
> + * int-ll64 is used everywhere in kernel now.
> + * In user space match <stdint.h>.
>   */
> +#ifdef __KERNEL__
>  # include <asm-generic/int-ll64.h>
> +#elif __has_include (<bits/types.h>)
> +# include <bits/types.h>
> +typedef __int8_t __s8;
> +typedef __uint8_t __u8;
> +typedef __int16_t __s16;
> +typedef __uint16_t __u16;
> +typedef __int32_t __s32;
> +typedef __uint32_t __u32;
> +typedef __int64_t __s64;
> +typedef __uint64_t __u64;
> +#else
> +# include <stdint.h>
> +typedef int8_t __s8;
> +typedef uint8_t __u8;
> +typedef int16_t __s16;
> +typedef uint16_t __u16;
> +typedef int32_t __s32;
> +typedef uint32_t __u32;
> +typedef int64_t __s64;
> +typedef uint64_t __u64;
> +#endif
> 
> The middle clause could be dropped if we are okay with all uapi headers potentially exposing the non-implementation-namespace names defined by <stdint.h>.  I do not know what the musl libc equivalent of <bits/types.h> is.

If it's okay to depend on a header defined by a libc this is better
solution.

-- 
Cyril Hrubis
chrubis@suse.cz