getservbyport_r: fix out-of-bounds buffer read

[musl] / src / unistd / writev.c

#include <sys/uio.h>
#include "syscall.h"

ssize_t writev(int fd, const struct iovec *iov, int count)
{
        return syscall_cp(SYS_writev, fd, iov, count);
}