libc: perror behaves incorrectly when its input is an empty string

[Lukáš Zaoral]

Hi,
perror should print only the error message, when its input is an empty string. See ​https://pubs.opengroup.org/onlinepubs/9699919799/functions/perror.html.

Code:

#include <errno.h>
#include <stdio.h>

int main(void)
{
    errno = 0;
    perror("");
}

Issue:

$ divine exec perror.c
compiling perror.c
loading bitcode … DiOS … LART … RR … constants … done
booting … done
: Success
a report was written to p.report

The ": " part should not be there and the enclosed patch fixes it.

[Henrich Lauko]

Patch accepted.