improve documentation of some functions and more readme work

src/config.rs

@@ -4,23 +4,35 @@ use crate::entries::EntryDeclaration;
 use crate::extractors::ExtractorDeclaration;
 use crate::generators::GeneratorDeclaration;
 use crate::phases::PhasesConfiguration;
-use crate::utils;
-use anyhow::Result;
-use anyhow::{Context, bail};
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
-use std::ops::Deref;
-use toml::Value;
-use uefi::proto::device_path::LoadedImageDevicePath;
 
+/// The configuration loader mechanisms.
+pub mod loader;
+
+/// This is the latest version of the sprout configuration format.
+/// This must be incremented when the configuration breaks compatibility.
+pub const LATEST_VERSION: u32 = 1;
+
+/// The Sprout configuration format.
 #[derive(Serialize, Deserialize, Default, Clone)]
 pub struct RootConfiguration {
+    /// The version of the configuration. This should always be declared
+    /// and be the latest version that is supported. If not specified, it is assumed
+    /// the configuration is the latest version.
     #[serde(default = "latest_version")]
     pub version: u32,
+    /// Values to be inserted into the root sprout context.
     #[serde(default)]
     pub values: BTreeMap<String, String>,
+    /// Drivers to load.
+    /// These drivers provide extra functionality like filesystem support to Sprout.
+    /// Each driver has a name which uniquely identifies it inside Sprout.
     #[serde(default)]
     pub drivers: BTreeMap<String, DriverDeclaration>,
+    /// Declares the extractors that add values to the sprout context that are calculated
+    /// at runtime. Each extractor has a name which corresponds to the value it will set
+    /// inside the sprout context.
     #[serde(default)]
     pub extractors: BTreeMap<String, ExtractorDeclaration>,
     #[serde(default)]
@@ -33,40 +45,6 @@ pub struct RootConfiguration {
     pub phases: PhasesConfiguration,
 }
 
-pub fn latest_version() -> u32 {
-    1
-}
-
-fn load_raw_config() -> Result<Vec<u8>> {
-    let current_image_device_path_protocol =
-        uefi::boot::open_protocol_exclusive::<LoadedImageDevicePath>(uefi::boot::image_handle())
-            .context("unable to get loaded image device path")?;
-    let path = current_image_device_path_protocol.deref().to_boxed();
-
-    let content = utils::read_file_contents(&path, "sprout.toml")
-        .context("unable to read sprout.toml file")?;
-    Ok(content)
-}
-
-pub fn load() -> Result<RootConfiguration> {
-    let content = load_raw_config()?;
-    let value: Value = toml::from_slice(&content).context("unable to parse sprout.toml file")?;
-
-    let version = value
-        .get("version")
-        .cloned()
-        .unwrap_or_else(|| Value::Integer(latest_version() as i64));
-
-    let version: u32 = version
-        .try_into()
-        .context("unable to get configuration version")?;
-
-    if version != latest_version() {
-        bail!("unsupported configuration version: {}", version);
-    }
-
-    let config: RootConfiguration = value
-        .try_into()
-        .context("unable to parse sprout.toml file")?;
-    Ok(config)
+fn latest_version() -> u32 {
+    LATEST_VERSION
 }

src/config/loader.rs

@@ -0,0 +1,40 @@
+use std::ops::Deref;
+use anyhow::{bail, Context, Result};
+use toml::Value;
+use uefi::proto::device_path::LoadedImageDevicePath;
+use crate::config::{latest_version, RootConfiguration};
+use crate::utils;
+
+fn load_raw_config() -> Result<Vec<u8>> {
+    let current_image_device_path_protocol =
+        uefi::boot::open_protocol_exclusive::<LoadedImageDevicePath>(uefi::boot::image_handle())
+            .context("unable to get loaded image device path")?;
+    let path = current_image_device_path_protocol.deref().to_boxed();
+
+    let content = utils::read_file_contents(&path, "sprout.toml")
+        .context("unable to read sprout.toml file")?;
+    Ok(content)
+}
+
+pub fn load() -> Result<RootConfiguration> {
+    let content = load_raw_config()?;
+    let value: Value = toml::from_slice(&content).context("unable to parse sprout.toml file")?;
+
+    let version = value
+        .get("version")
+        .cloned()
+        .unwrap_or_else(|| Value::Integer(latest_version() as i64));
+
+    let version: u32 = version
+        .try_into()
+        .context("unable to get configuration version")?;
+
+    if version != latest_version() {
+        bail!("unsupported configuration version: {}", version);
+    }
+
+    let config: RootConfiguration = value
+        .try_into()
+        .context("unable to parse sprout.toml file")?;
+    Ok(config)
+}

src/entries.rs

@@ -1,11 +1,18 @@
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 
+/// Declares a boot entry to display in the boot menu.
+///
+/// Entries are the user-facing concept of Sprout, making it possible
+/// to run a set of actions with a specific context.
 #[derive(Serialize, Deserialize, Default, Clone)]
 pub struct EntryDeclaration {
+    /// The title of the entry which will be display in the boot menu.
     pub title: String,
+    /// The actions to run when the entry is selected.
     #[serde(default)]
     pub actions: Vec<String>,
+    /// The values to insert into the context when the entry is selected.
     #[serde(default)]
     pub values: BTreeMap<String, String>,
 }

src/main.rs

@@ -1,3 +1,4 @@
+#![doc = include_str!("../README.md")]
 #![feature(uefi_std)]
 
 use crate::context::{RootContext, SproutContext};
@@ -20,15 +21,20 @@ pub mod phases;
 pub mod setup;
 pub mod utils;
 
+/// The main entrypoint of sprout.
+/// It is possible this function will not return if actions that are executed
+/// exit boot services or do not return control to sprout.
 fn main() -> Result<()> {
+    // Initialize the basic UEFI environment.
     setup::init()?;
 
-    let config = config::load()?;
-
-    if config.version != config::latest_version() {
-        bail!("unsupported configuration version: {}", config.version);
-    }
+    // Load the configuration of sprout.
+    // At this point, the configuration has been validated and the specified
+    // version is checked to ensure compatibility.
+    let config = config::loader::load()?;
 
+    // Load the root context.
+    // This is done in a block to ensure the release of the LoadedImageDevicePath protocol.
     let mut root = {
         let current_image_device_path_protocol = uefi::boot::open_protocol_exclusive::<
             LoadedImageDevicePath,
@@ -42,16 +48,25 @@ fn main() -> Result<()> {
         RootContext::new(loaded_image_path)
     };
 
+    // Insert the configuration actions into the root context.
     root.actions_mut().extend(config.actions.clone());
 
+    // Create a new sprout context with the root context.
     let mut context = SproutContext::new(root);
+
+    // Insert the configuration values into the sprout context.
     context.insert(&config.values);
+
+    // Freeze the sprout context so it can be shared and cheaply cloned.
     let context = context.freeze();
 
+    // Execute the early phase.
     phase(context.clone(), &config.phases.early).context("unable to execute early phase")?;
 
+    // Load all configured drivers.
     drivers::load(context.clone(), &config.drivers).context("unable to load drivers")?;
 
+    // Run all the extractors declared in the configuration.
     let mut extracted = BTreeMap::new();
     for (name, extractor) in &config.extractors {
         let value = extractors::extract(context.clone(), extractor)
@@ -60,50 +75,69 @@ fn main() -> Result<()> {
         extracted.insert(name.clone(), value);
     }
     let mut context = context.fork();
+    // Insert the extracted values into the sprout context.
     context.insert(&extracted);
     let context = context.freeze();
 
+    // Execute the late phase.
     phase(context.clone(), &config.phases.startup).context("unable to execute startup phase")?;
 
-    let mut all_entries = Vec::new();
+    let mut staged_entries = Vec::new();
 
+    // Insert all the static entries from the configuration into the entry list.
     for (_name, entry) in config.entries {
-        all_entries.push((context.clone(), entry));
+        // Associate the main context with the static entry.
+        staged_entries.push((context.clone(), entry));
     }
 
+    // Run all the generators declared in the configuration.
     for (_name, generator) in config.generators {
         let context = context.fork().freeze();
 
+        // Add all the entries generated by the generator to the entry list.
+        // The generator specifies the context associated with the entry.
         for entry in generators::generate(context.clone(), &generator)? {
-            all_entries.push(entry);
+            staged_entries.push(entry);
         }
     }
 
+    // Build a list of all the final boot entries.
     let mut final_entries = Vec::new();
-    for (context, entry) in all_entries {
+    for (context, entry) in staged_entries {
         let mut context = context.fork();
+        // Insert the values from the entry configuration into the
+        // sprout context to use with the entry itself.
         context.insert(&entry.values);
         let context = context.finalize().freeze();
 
+        // Insert the entry configuration into final boot entries with the extended context.
         final_entries.push((context, entry));
     }
 
+    // TODO(azenla): Implement boot menu here.
+    // For now, we just print all of the entries.
     info!("entries:");
     for (index, (context, entry)) in final_entries.iter().enumerate() {
         let title = context.stamp(&entry.title);
         info!("  entry {}: {}", index + 1, title);
     }
 
+    // Execute the late phase.
     phase(context.clone(), &config.phases.late).context("unable to execute late phase")?;
 
+    // Pick the first entry from the list of final entries until a boot menu is implemented.
     let Some((context, entry)) = final_entries.first() else {
         bail!("no entries found");
     };
 
+    // Execute all the actions for the selected entry.
     for action in &entry.actions {
         let action = context.stamp(action);
         actions::execute(context.clone(), &action)
             .context(format!("unable to execute action '{}'", action))?;
     }
+
+    // Sprout doesn't necessarily guarantee anything was booted.
+    // If we reach here, we will exit back to whoever called us.
     Ok(())
 }

src/phases.rs

@@ -1,29 +1,40 @@
 use crate::actions;
 use crate::context::SproutContext;
-use anyhow::Context;
+use anyhow::{Context, Result};
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 use std::rc::Rc;
 
+/// Configures the various phases of the boot process.
+/// This allows hooking various phases to run actions.
 #[derive(Serialize, Deserialize, Default, Clone)]
 pub struct PhasesConfiguration {
+    /// The early phase is run before drivers are loaded.
     #[serde(default)]
     pub early: Vec<PhaseConfiguration>,
+    /// The startup phase is run after drivers are loaded, but before entries are displayed.
     #[serde(default)]
     pub startup: Vec<PhaseConfiguration>,
+    /// The late phase is run after the entry is chosen, but before the actions are executed.
     #[serde(default)]
     pub late: Vec<PhaseConfiguration>,
 }
 
 #[derive(Serialize, Deserialize, Default, Clone)]
 pub struct PhaseConfiguration {
+    /// The actions to run when the phase is executed.
     #[serde(default)]
     pub actions: Vec<String>,
+    /// The values to insert into the context when the phase is executed.
     #[serde(default)]
     pub values: BTreeMap<String, String>,
 }
 
-pub fn phase(context: Rc<SproutContext>, phase: &[PhaseConfiguration]) -> anyhow::Result<()> {
+/// Executes the specified [phase] of the boot process.
+/// The value [phase] should be a reference of a specific phase in the [PhasesConfiguration].
+/// Any error from the actions is propagated into the [Result] and will interrupt further
+/// execution of phase actions.
+pub fn phase(context: Rc<SproutContext>, phase: &[PhaseConfiguration]) -> Result<()> {
     for item in phase {
         let mut context = context.fork();
         context.insert(&item.values);