Re: [PATCH v5 2/4] tools/nolibc: add integer types and integer limit macros

Vincent Dagonneau
2023-02-23T00:35:53Z

Hi Thomas,

On Tue, Feb 21, 2023, at 12:40, Thomas Weißschuh wrote:
> On Mon, Feb 20, 2023 at 03:20:08PM -0500, Vincent Dagonneau wrote:
>> This commit adds some of the missing integer types to stdint.h and adds
>> limit macros (e.g. INTN_{MIN,MAX}).
>>
>> The reference used for adding these types is
>> https://pubs.opengroup.org/onlinepubs/009695399/basedefs/stdint.h.html.
>>
>> We rely on the compiler-defined __LONG_MAX__ to get the right limits for
>> ssize_t, size_t, intptr_t, uintptr_t and ptrdiff_t. This compiler
>> constant seem to have been defined at least since GCC 4.1.2 and clang
>> 3.0.0 on x86_64. It is also defined on ARM (32&64), mips and RISC-V.
>>
>> Note that the maximum size of size_t is implementation-defined (>65535),
>> in this case I chose to go with unsigned long on all platforms since
>> unsigned long == unsigned int on all the platforms we care about. Note
>> that the kernel uses either unsigned int or unsigned long in
>> linux/include/uapi/asm-generic/posix_types.h. These should be equivalent
>> for the plaforms we are targeting.
>>
>> Also note that the 'fast*' flavor of the types have been chosen to be
>> always 1 byte for '*fast8*' and always long (a.k.a. size_t/ssize_t) for
>> the other variants. I have never seen the 'fast*' types in use in the wild
>> but that seems to be what glibc does.
>>
>> Signed-off-by: Vincent Dagonneau <v@vda.io>
>> Signed-off-by: Willy Tarreau <w@1wt.eu>
>> ---
>> tools/include/nolibc/stdint.h | 77 +++++++++++++++++++++++++++++++++++
>> 1 file changed, 77 insertions(+)
>>
>> diff --git a/tools/include/nolibc/stdint.h b/tools/include/nolibc/stdint.h
>> index 4ba264031df9..f7179a583f61 100644
>> --- a/tools/include/nolibc/stdint.h
>> +++ b/tools/include/nolibc/stdint.h
>> @@ -21,4 +21,81 @@ typedef unsigned long uintptr_t;
>> typedef signed long intptr_t;
>> typedef signed long ptrdiff_t;
>>
>> +typedef int8_t int_least8_t;
>> +typedef uint8_t uint_least8_t;
>> +typedef int16_t int_least16_t;
>> +typedef uint16_t uint_least16_t;
>> +typedef int32_t int_least32_t;
>> +typedef uint32_t uint_least32_t;
>> +typedef int64_t int_least64_t;
>> +typedef uint64_t uint_least64_t;
>> +
>> +typedef int8_t int_fast8_t;
>> +typedef uint8_t uint_fast8_t;
>> +typedef ssize_t int_fast16_t;
>> +typedef size_t uint_fast16_t;
>> +typedef ssize_t int_fast32_t;
>> +typedef size_t uint_fast32_t;
>> +typedef ssize_t int_fast64_t;
>> +typedef size_t uint_fast64_t;
>> +
>> +typedef int64_t intmax_t;
>> +typedef uint64_t uintmax_t;
>> +
>> +/* limits of integral types */
>> +
>> +#define INT8_MIN (-128)
>> +#define INT16_MIN (-32767-1)
>> +#define INT32_MIN (-2147483647-1)
>> +#define INT64_MIN (-9223372036854775807LL-1)
>> +
>> +#define INT8_MAX (127)
>> +#define INT16_MAX (32767)
>> +#define INT32_MAX (2147483647)
>> +#define INT64_MAX (9223372036854775807LL)
>> +
>> +#define UINT8_MAX (255)
>> +#define UINT16_MAX (65535)
>> +#define UINT32_MAX (4294967295U)
>> +#define UINT64_MAX (18446744073709551615ULL)
>> +
>> +#define INT_LEAST8_MIN INT8_MIN
>> +#define INT_LEAST16_MIN INT16_MIN
>> +#define INT_LEAST32_MIN INT32_MIN
>> +#define INT_LEAST64_MIN INT64_MIN
>> +
>> +#define INT_LEAST8_MAX INT8_MAX
>> +#define INT_LEAST16_MAX INT16_MAX
>> +#define INT_LEAST32_MAX INT32_MAX
>> +#define INT_LEAST64_MAX INT64_MAX
>> +
>> +#define UINT_LEAST8_MAX UINT8_MAX
>> +#define UINT_LEAST16_MAX UINT16_MAX
>> +#define UINT_LEAST32_MAX UINT32_MAX
>> +#define UINT_LEAST64_MAX UINT64_MAX
>> +
>> +#define SIZE_MAX ((size_t)(__LONG_MAX__) * 2 + 1)
>> +#define SSIZE_MIN (-__LONG_MAX__ - 1)
>
> SSIZE_MIN is not defined by a standard.
> It also doesn't really make sense to have, as ssize_t is only supposed
> to store [-1,SSIZE_MAX].
>
>> +#define SSIZE_MAX __LONG_MAX__
>
> Apparently SSIZE_MAX can also defined via the compilers <limits.h> as
> used by nolibc-test.c leading to a warning.
> Maybe wrap it in #ifndef SSIZE_MAX.
>
> In file included from sysroot/x86/include/std.h:21,
> from sysroot/x86/include/stdio.h:12,
> from nolibc-test.c:15:
> sysroot/x86/include/stdint.h:79: warning: "SSIZE_MAX" redefined
> 79 | #define SSIZE_MAX __LONG_MAX__
> |
> In file included from /usr/include/limits.h:195,
> from
> /usr/lib/gcc/x86_64-pc-linux-gnu/12.2.1/include-fixed/limits.h:203,
> from
> /usr/lib/gcc/x86_64-pc-linux-gnu/12.2.1/include-fixed/syslimits.h:7,
> from
> /usr/lib/gcc/x86_64-pc-linux-gnu/12.2.1/include-fixed/limits.h:34,
> from nolibc-test.c:6:
> /usr/include/bits/posix1_lim.h:169: note: this is the location of
> the previous definition
> 169 | # define SSIZE_MAX LONG_MAX
> |
>

Ok, I'll remove the SSIZE_MIN and SSIZE_MAX since neither seem to be in the standards page anyway.

Note that ssize_t is still defined in this file. It pre-dates my patch.

>> +#define INTPTR_MIN SSIZE_MIN
>> +#define INTPTR_MAX SSIZE_MAX
>> +#define PTRDIFF_MIN SSIZE_MIN
>> +#define PTRDIFF_MAX SSIZE_MAX
>> +#define UINTPTR_MAX SIZE_MAX
>> +
>> +#define INT_FAST8_MIN INT8_MIN
>> +#define INT_FAST16_MIN SSIZE_MIN
>> +#define INT_FAST32_MIN SSIZE_MIN
>> +#define INT_FAST64_MIN SSIZE_MIN
>> +
>> +#define INT_FAST8_MAX INT8_MAX
>> +#define INT_FAST16_MAX SSIZE_MAX
>> +#define INT_FAST32_MAX SSIZE_MAX
>> +#define INT_FAST64_MAX SSIZE_MAX
>> +
>> +#define UINT_FAST8_MAX UINT8_MAX
>> +#define UINT_FAST16_MAX SIZE_MAX
>> +#define UINT_FAST32_MAX SIZE_MAX
>> +#define UINT_FAST64_MAX SIZE_MAX
>
> Alignment of values within lines is inconsistent.
>

Thanks, I did a whole lot of alignment in the latest version, hopefully it should be ok now.

>> +
>> #endif /* _NOLIBC_STDINT_H */
>> --
>> 2.39.2
>>

Thanks for the review,
Vincent.