[pbs-devel] [PATCH v4 proxmox 1/5] sys: add helper to get bootmode and secureboot status

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

Helper that return the current boot_mode and secureboot status.
Detection works the same as in pve, we use `/sys/firmware/efi` and
the `efivars/SecureBoot-xxx..` file.

Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
 proxmox-sys/src/boot_mode.rs | 72 ++++++++++++++++++++++++++++++++++++
 proxmox-sys/src/lib.rs       |  1 +
 2 files changed, 73 insertions(+)
 create mode 100644 proxmox-sys/src/boot_mode.rs

diff --git a/proxmox-sys/src/boot_mode.rs b/proxmox-sys/src/boot_mode.rs
new file mode 100644
index 0000000..dc9d4f5
--- /dev/null
+++ b/proxmox-sys/src/boot_mode.rs
@@ -0,0 +1,72 @@
+use std::{io::Read, sync::Mutex};
+
+#[derive(Clone, Copy)]
+pub enum SecureBoot {
+    /// SecureBoot is enabled
+    Enabled,
+    /// SecureBoot is disabled
+    Disabled,
+}
+
+/// The possible BootModes
+#[derive(Clone, Copy)]
+pub enum BootMode {
+    /// The BootMode is EFI/UEFI
+    Efi,
+    /// The BootMode is Legacy BIOS
+    Bios,
+}
+
+impl BootMode {
+    /// Returns the current bootmode (BIOS or EFI)
+    pub fn query() -> BootMode {
+        lazy_static::lazy_static!(
+            static ref BOOT_MODE: Mutex<Option<BootMode>> = Mutex::new(None);
+        );
+
+        let mut last = BOOT_MODE.lock().unwrap();
+        let value = last.or_else(|| {
+            if std::path::Path::new("/sys/firmware/efi").exists() {
+                Some(BootMode::Efi)
+            } else {
+                Some(BootMode::Bios)
+            }
+        });
+        *last = value;
+        value.unwrap()
+    }
+}
+
+impl SecureBoot {
+    /// Checks if secure boot is enabled
+    pub fn query() -> SecureBoot {
+        lazy_static::lazy_static!(
+            static ref SECURE_BOOT: Mutex<Option<SecureBoot>> = Mutex::new(None);
+        );
+
+        let mut last = SECURE_BOOT.lock().unwrap();
+        let value = last.or_else(|| {
+            // 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(SecureBoot::Disabled);
+                    };
+                if buf[4] == 1 {
+                    Some(SecureBoot::Enabled)
+                } else {
+                    Some(SecureBoot::Disabled)
+                }
+            } else {
+                Some(SecureBoot::Disabled)
+            }
+        });
+        *last = value;
+        value.unwrap()
+    }
+}
diff --git a/proxmox-sys/src/lib.rs b/proxmox-sys/src/lib.rs
index 7e59058..8ea7073 100644
--- a/proxmox-sys/src/lib.rs
+++ b/proxmox-sys/src/lib.rs
@@ -1,5 +1,6 @@
 use std::os::unix::ffi::OsStrExt;
 
+pub mod boot_mode;
 pub mod command;
 #[cfg(feature = "crypt")]
 pub mod crypt;
-- 
2.39.2