Re: [PATCH v2 11/24] stat.2: Cast to 'unsigned long' rather than 'long' when printing with "%lx"

Michael Kerrisk (man-pages)
2020-09-11T09:19:57Z

On 9/11/20 11:16 AM, Alejandro Colomar wrote:
> Hi Michael,
>
> On 2020-09-11 09:25, Michael Kerrisk (man-pages) wrote:
>> See my reply to patch 10/24.
>
> As with 10/24, here's the new version.

Thanks, Alex. Applied.

Cheers,

Michael

> --------------------------------------------------------
> From 911c791f0168851cdfdb30a65b6935011e4a161c Mon Sep 17 00:00:00 2001
> From: Alejandro Colomar <colomar.6.4.3@gmail.com>
> Date: Fri, 11 Sep 2020 10:52:14 +0200
> Subject: [PATCH v2 11/24] stat.2: Cast to 'unsigned long' rather than 'long'
> when printing with "%lx"
>
> From the email conversation:
>
> On 2020-09-11 09:24, Michael Kerrisk (man-pages) wrote:
> > Hi Alex,
> >
> > On 9/10/20 11:13 PM, Alejandro Colomar wrote:
> >> Both major(3) and minor(3) return an 'unsigned int',
> >> so there is no need to use a 'long' for printing.
> >> Moreover, it should have been 'unsigned long',
> >> as "%lx" expects an unsigned type.
> >
> > This may be true on Linux, but is not true on other systems.
> > For example, on HP-UX, according to one header file I'm
> > looking at, the return value is 'long'.
> >
> > These kinds of casts are intended to improve code portability
> > across UNIX implementations, so I think they should stay
> > (although, I do wonder if they would be even better as casts
> > to 'unsigned long')
> >
> > Thanks,
> >
> > Michael
>
> Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
> ---
> man2/stat.2 | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/man2/stat.2 b/man2/stat.2
> index b35e3c615..08af24c56 100644
> --- a/man2/stat.2
> +++ b/man2/stat.2
> @@ -665,7 +665,8 @@ main(int argc, char *argv[])
> }
>
> printf("ID of containing device: [%lx,%lx]\en",
> - (long) major(sb.st_dev), (long) minor(sb.st_dev));
> + (unsigned long) major(sb.st_dev),
> + (unsigned long) minor(sb.st_dev));
>
> printf("File type: ");
>

--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/