int dump_med(const char *fname, struct medico **headpp)
{
    struct medico tmp;

    FILE *f = fopen(fname, "r");
    if (f == NULL)
    {
        perror(fname);
        return -1;
    }

    while (fscanf(f, "%[^\n]", tmp.nome) == 1 &&
           fscanf(f, "%s %d.%d--%d.%d\n",
                  tmp.especialidade, &(tmp.entrada.h), &(tmp.entrada.m),
                  &(tmp.saida.h), &(tmp.saida.m)) == 5)
    {
        if (!(*headpp = malloc(sizeof **headpp)))
        {
            perror("Failed to allocate new list node: ");
            return -1;
        }

        // save, have headpp address the next pointer of the new node
        **headpp = tmp;
        headpp = &(*headpp)->next;
    }
    *headpp = NULL; // terminated

    fclose(f);
    return 0;
}