Re: [pbs-devel] [PATCH v3 proxmox 1/3] sys: add function to get boot_mode

[Gabriel Goller <g.goller@proxmox.com>]

Thanks for the review!

On 11/27/23 13:48, Wolfgang Bumiller wrote:

> On Mon, Nov 27, 2023 at 11:16:42AM +0100, Gabriel Goller wrote:
>> +// Returns the current bootmode (BIOS, EFI, or EFI(Secure Boot))
>> +pub fn boot_mode() -> BootModeInformation {
>> +    lazy_static::lazy_static!(
>> +        static ref BOOT_MODE: Mutex<Option<BootModeInformation>> = Mutex::new(None);
>> +    );
>> +
>> +    let mut last = BOOT_MODE.lock().unwrap();
>> +    let value = last.or_else(|| {
>> +        if std::path::Path::new("/sys/firmware/efi").exists() {
>> +            // Check if SecureBoot is enabled
>> +            // Attention: this file is not seekable!
>> +            // Spec: https://uefi.org/specs/UEFI/2.10/03_Boot_Manager.html?highlight=8be4d#globally-defined-variables
>> +            let efivar = std::fs::File::open(
>> +                "/sys/firmware/efi/efivars/SecureBoot-8be4df61-93ca-11d2-aa0d-00e098032b8c",
>> +            );
>> +            if let Ok(mut file) = efivar {
>> +                let mut buf = [0; 5];
>> +                let Ok(_) = file.read_exact(&mut buf) else {
>> +                    return Some(BootModeInformation::Efi(SecureBoot::Disabled));
>> +                };
>> +                if buf[4..] == [1] {
> This doesn't need to be a range comparison, just use `buf[4] == 1`
> Or rather,, should we instead use `!= 0`?
> Depending on how we want to treat a "reserved" mode...
Oh, right! I agree with the `buf[4] == 1`.
Hmm I think a more "conservative" matching here is better. A false
negative is better than a false positive imo.