[PATCH] avoid GCC 10 warning -Wstringop-truncation

[Gedare Bloom]

On Thu, Jul 30, 2020 at 9:55 AM Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
>
> On 30/07/2020 17:53, Gedare Bloom wrote:
>
> > On Thu, Jul 30, 2020 at 9:44 AM Sebastian Huber
> > <sebastian.huber at embedded-brains.de>  wrote:
> >> On 30/07/2020 13:36, Aschref Ben-Thabet wrote:
> >>
> >>> diff --git a/testsuites/psxtests/psxndbm01/init.c b/testsuites/psxtests/psxndbm01/init.c
> >>> index a13afa7315..b524aff0df 100644
> >>> --- a/testsuites/psxtests/psxndbm01/init.c
> >>> +++ b/testsuites/psxtests/psxndbm01/init.c
> >>> @@ -218,7 +218,7 @@ rtems_task Init(rtems_task_argument ignored)
> >>>
> >>>      puts( "Fetch non-existing record and confirm error." );
> >>>      test_strings = (char*)malloc(6);
> >>> -  strncpy( test_strings, "Hello", 5 );
> >>> +  memcpy( test_strings, "Hello", 5 );
> >>>
> >>>      test_strings[5] = '\0';
> >> In the glibc devel list this approach was suggested for problems like this:
> >>
> >> *(char *) mempcpy( test_strings, "Hello", 5 ) = '\0';
> >>
> >> https://sourceware.org/legacy-ml/libc-alpha/2000-08/msg00061.html
> >>
> > This code is suspect/wrong. that should create a NUL at the start of
> > the test_strings. I'd rather see the memcpy followed by appending the
> > NUL. It is easy enough to understand I think.
> Yes, this was also my impression then I did read this code snippet.
> Please note that this is memPcpy(), a GNU extension.
thanks, I had missed that.

I don't think there is an easy generalized way to do the delimiting
with the standard memcpy. You could do it in one line, if we really
wanted something like:

((char *) memcpy (test_strings, "Hello", 5 ))[5] = '\0';

We could even create a little helper to do it if it is a common pattern.