Re: [Minios-devel] [UNIKRAFT PATCHv3 24/25] nolibc: Clear a -Wstringop-overflow warning for strncpy

[Jia He <jiakernel2@xxxxxxxxx>]

Hi Sharan

On 2019/1/17 19:00, Sharan Santhanam wrote:
> Hello Wei Chen,
>
> Please find my comments inline.
>
> Thanks & Regards
> Sharan
>
> On 12/13/18 10:15 AM, Wei Chen wrote:
> > The strncpy needs a signed integer for 3rd parameter, but the SIZE_MAX
> > is unsigned integer. We will get following error:
> > /lib/nolibc/string.c:155:9: warning: ‘strncpy’: specified size
> > 18446744073709551615 exceeds maximum object size 9223372036854775807
> > [-Wstringop-overflow=]
> >    return strncpy(dst, src, SIZE_MAX);
>
> [1] show the posix standard function declaration strncpy using 
> size_t[2] as the third parameter. The upstream code seems to be 
> correct. I am not sure if we need this patch.
Ok I will drop this patch in the next version

Thanks


Cheers,

Justin

> >           ^
> > Using SSIZE_MAX to replace SIZE_MAX to fix this warning.
> >
> > Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> > ---
> >   lib/nolibc/string.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/nolibc/string.c b/lib/nolibc/string.c
> > index 6f853ba..fa450c9 100644
> > --- a/lib/nolibc/string.c
> > +++ b/lib/nolibc/string.c
> > @@ -152,7 +152,7 @@ char *strncpy(char *dst, const char *src, size_t 
> > len)
> >     char *strcpy(char *dst, const char *src)
> >   {
> > -    return strncpy(dst, src, SIZE_MAX);
> > +    return strncpy(dst, src, SSIZE_MAX);
> >   }
> >     int strncmp(const char *str1, const char *str2, size_t len)
> [1] http://pubs.opengroup.org/onlinepubs/009696899/functions/strncpy.html
> [2] 
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html
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