From: Zack Weinberg via Libc-alpha <libc-alpha@sourceware.org>
To: "Adhemerval Zanella" <adhemerval.zanella@linaro.org>,
"Rich Felker" <dalias@libc.org>
Cc: linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
libc-alpha@sourceware.org, linux-kernel@vger.kernel.org,
ltp@lists.linux.it
Subject: Re: [PATCH] uapi: Make __{u,s}64 match {u,}int64_t in userspace
Date: Thu, 02 Dec 2021 19:10:52 -0500 [thread overview]
Message-ID: <9d24f699-386a-4881-b09a-ebd747310187@www.fastmail.com> (raw)
In-Reply-To: <855a47d1-a89c-bbc8-7ddd-b89104c6138a@linaro.org>
On Thu, Dec 2, 2021, at 6:43 PM, Adhemerval Zanella via Libc-alpha wrote:
> On 02/12/2021 20:29, Rich Felker wrote:
>> On Thu, Dec 02, 2021 at 10:34:23AM -0500, Rich Felker wrote:
>>> On Mon, Nov 22, 2021 at 10:19:59PM +0000, Zack Weinberg via Libc-alpha wrote:
>>>> On Mon, Nov 22, 2021, at 4:43 PM, Cyril Hrubis wrote:
>>>>> This changes the __u64 and __s64 in userspace on 64bit platforms from
>>>>> long long (unsigned) int to just long (unsigned) int in order to match
>>>>> the uint64_t and int64_t size in userspace.
>>>> ....
>>>>> +
>>>>> +#include <asm/bitsperlong.h>
>>>>> +
>>>>> /*
>>>>> - * int-ll64 is used everywhere now.
>>>>> + * int-ll64 is used everywhere in kernel now.
>>>>> */
>>>>> -#include <asm-generic/int-ll64.h>
>>>>> +#if __BITS_PER_LONG == 64 && !defined(__KERNEL__)
>>>>> +# include <asm-generic/int-l64.h>
>>>>> +#else
>>>>> +# include <asm-generic/int-ll64.h>
>>>>> +#endif
>>>>
>>>> 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.
>>>
>>> We (musl) don't have an equivalent header or __-prefixed versions of
>>> these types.
>>>
>>> FWIW I don't think stdint.h exposes anything that would be problematic
>>> alongside arbitrary use of kernel headers.
>>
>> Also, per glibc's bits/types.h:
>>
>> /*
>> * Never include this file directly; use <sys/types.h> instead.
>> */
>>
>> it's not permitted (not supported usage) to #include <bits/types.h>.
>> So I think the above patch is wrong for glibc too. As I understand it,
>> this is general policy for bits/* -- they're only intended to work as
>> included by the libc system headers, not directly by something else.
>
> You are right, the idea is to allow glibc to create and remove internal headers.
As a general rule yes, but we could make a deal that some specific bits headers are permanent API for use by things like this. They probably should be less of a dumping ground than bits/types.h though.
next prev parent reply other threads:[~2021-12-03 0:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 16:43 [PATCH] uapi: Make __{u,s}64 match {u,}int64_t in userspace Cyril Hrubis
2021-11-22 16:51 ` Alejandro Colomar (mailing lists) via Libc-alpha
2021-11-22 20:48 ` Arnd Bergmann
2021-11-23 9:14 ` Cyril Hrubis
2021-11-23 14:18 ` Arnd Bergmann
2021-11-23 19:50 ` Florian Weimer via Libc-alpha
2021-11-24 10:17 ` Alejandro Colomar (man-pages) via Libc-alpha
2021-11-22 22:19 ` Zack Weinberg via Libc-alpha
2021-11-23 9:15 ` Cyril Hrubis
2021-12-02 15:34 ` Rich Felker
2021-12-02 23:29 ` Rich Felker
2021-12-02 23:43 ` Adhemerval Zanella via Libc-alpha
2021-12-03 0:10 ` Zack Weinberg via Libc-alpha [this message]
2021-12-03 12:32 ` Adhemerval Zanella via Libc-alpha
2021-12-03 12:54 ` Alejandro Colomar (man-pages) via Libc-alpha
2021-11-23 16:47 ` David Howells via Libc-alpha
2021-11-23 16:58 ` David Laight via Libc-alpha
2021-11-29 11:58 ` Cyril Hrubis
2021-11-29 14:34 ` Arnd Bergmann
2021-12-02 14:55 ` Zack Weinberg via Libc-alpha
2021-12-02 15:01 ` David Howells via Libc-alpha
2021-12-02 20:48 ` Zack Weinberg via Libc-alpha
2021-12-08 15:33 ` Cyril Hrubis
2022-06-17 12:13 ` Ping: " Alejandro Colomar via Libc-alpha
2022-06-17 15:04 ` Ping: [PATCH] uapi: Make __{u, s}64 match {u, }int64_t " Cyril Hrubis
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