Here are five possible patches for the CWE-476 vulnerability at line 8:

Patch 1:
```c
if (!str) {
    SetLastError(ERROR_INVALID_PARAMETER);
    return -1;
}
```

Patch 2:
```c
if (str == NULL) {
    return 0;
}
```

Patch 3:
```c
if (!str) {
    return -1;
}
```

Patch 4:
```c
if (str == NULL) {
    SetLastError(ERROR_INVALID_PARAMETER);
    return 0;
}
```

Patch 5:
```c
if (!str || len == 0) {
    return 0;
}
```

Each of these patches checks if the `str` pointer is NULL before proceeding with the function. They handle the NULL case differently:

1. Sets an error and returns -1
2. Returns 0 for NULL input
3. Returns -1 for NULL input without setting an error
4. Sets an error and returns 0
5. Combines the NULL check with the existing length check, returning 0 for either case

The choice of patch depends on the desired behavior for NULL input in the context of the larger application.