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

Thomas Weißschuh
2023-02-21T17:40:12Z

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
|

> +#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.

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