142 lines
4.1 KiB
Rust
142 lines
4.1 KiB
Rust
use std::fmt;
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use std::fs;
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use std::path::{Path, PathBuf};
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use anyhow::{anyhow, Context, Result};
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use bootspec::generation::Generation as BootspecGeneration;
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use bootspec::BootJson;
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use bootspec::SpecialisationName;
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use serde::de::IntoDeserializer;
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use serde::{Deserialize, Serialize};
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#[derive(Debug, Clone, Serialize, Deserialize)]
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pub struct SecureBootExtension {
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#[serde(rename = "osRelease")]
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pub os_release: PathBuf,
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}
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#[derive(Debug, Clone)]
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pub struct ExtendedBootJson {
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pub bootspec: BootJson,
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pub extensions: SecureBootExtension,
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}
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/// A system configuration.
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///
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/// Can be built from a GenerationLink.
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///
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/// NixOS represents a generation as a symlink to a toplevel derivation. This toplevel derivation
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/// contains most of the information necessary to install the generation onto the EFI System
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/// Partition. The only information missing is the version number which is encoded in the file name
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/// of the generation link.
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#[derive(Debug)]
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pub struct Generation {
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/// Profile symlink index
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version: u64,
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/// Top-level specialisation name
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specialisation_name: Option<SpecialisationName>,
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/// Top-level extended boot specification
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pub spec: ExtendedBootJson,
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}
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impl Generation {
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pub fn from_link(link: &GenerationLink) -> Result<Self> {
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let bootspec_path = link.path.join("boot.json");
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let generation: BootspecGeneration = serde_json::from_slice(
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&fs::read(bootspec_path).context("Failed to read bootspec file")?,
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)
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.context("Failed to parse bootspec json")?;
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let bootspec: BootJson = generation
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.try_into()
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.map_err(|err: &'static str| anyhow!(err))?;
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let extensions = Self::extract_extensions(&bootspec)?;
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Ok(Self {
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version: link.version,
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specialisation_name: None,
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spec: ExtendedBootJson {
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bootspec,
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extensions,
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},
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})
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}
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fn extract_extensions(bootspec: &BootJson) -> Result<SecureBootExtension> {
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Ok(Deserialize::deserialize(
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bootspec.extensions.get("lanzaboote")
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.context("Failed to extract Lanzaboote-specific extension from Bootspec, missing lanzaboote field in `extensions`")?
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.clone()
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.into_deserializer()
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)?)
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}
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pub fn specialise(&self, name: &SpecialisationName, bootspec: &BootJson) -> Result<Self> {
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Ok(Self {
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version: self.version,
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specialisation_name: Some(name.clone()),
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spec: ExtendedBootJson {
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bootspec: bootspec.clone(),
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extensions: Self::extract_extensions(bootspec)?,
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},
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})
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}
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pub fn is_specialized(&self) -> Option<SpecialisationName> {
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self.specialisation_name.clone()
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}
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}
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impl fmt::Display for Generation {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{}", self.version)
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}
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}
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/// A link pointing to a generation.
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///
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/// Can be built from a symlink in /nix/var/nix/profiles/ alone because the name of the
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/// symlink enocdes the version number.
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#[derive(Debug)]
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pub struct GenerationLink {
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pub version: u64,
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pub path: PathBuf,
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}
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impl GenerationLink {
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pub fn from_path(path: impl AsRef<Path>) -> Result<Self> {
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Ok(Self {
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version: parse_version(&path).context("Failed to parse version")?,
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path: PathBuf::from(path.as_ref()),
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})
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}
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}
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/// Parse version number from a path.
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///
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/// Expects a path in the format of "system-{version}-link".
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fn parse_version(path: impl AsRef<Path>) -> Result<u64> {
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let generation_version = path
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.as_ref()
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.file_name()
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.and_then(|x| x.to_str())
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.and_then(|x| x.split('-').nth(1))
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.and_then(|x| x.parse::<u64>().ok())
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.with_context(|| format!("Failed to extract version from: {:?}", path.as_ref()))?;
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Ok(generation_version)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn parse_version_correctly() {
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let path = Path::new("system-2-link");
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let parsed_version = parse_version(path).unwrap();
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assert_eq!(parsed_version, 2,);
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}
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}
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