getopt: fix null pointer arithmetic ub

[musl] / src / unistd / readlinkat.c

#include <unistd.h>
#include "syscall.h"

ssize_t readlinkat(int fd, const char *restrict path, char *restrict buf, size_t bufsize)
{
        char dummy[1];
        if (!bufsize) {
                buf = dummy;
                bufsize = 1;
        }
        int r = __syscall(SYS_readlinkat, fd, path, buf, bufsize);
        if (buf == dummy && r > 0) r = 0;
        return __syscall_ret(r);
}