feat(initrd): support chaining multiple initrds (#101)

Add linux-initrd-chain to the chainload action and initrd-chain to the
edera action. Each file in the list is read in order and concatenated
into a single initrd. The chain can't be combined with the single
initrd option on the same action.

BLS entries with multiple initrds, either as repeated initrd lines or
as multiple paths on one line, previously only loaded the last one.
Parse all of them and set them in the initrd-0 through initrd-7 slots,
which the autoconfigured BLS action now chains. Unused slots stamp to
the filesystem root and are skipped. Entries with more than 8 initrds
are skipped with a warning.

crates/bls/src/lib.rs

@@ -2,6 +2,7 @@
 extern crate alloc;
 
 use alloc::string::{String, ToString};
+use alloc::vec::Vec;
 use anyhow::{Error, Result};
 use core::{cmp::Ordering, iter::Peekable, str::FromStr};
 
@@ -15,8 +16,8 @@ pub struct BlsEntry {
     pub options: Option<String>,
     /// The path to the linux kernel.
     pub linux: Option<String>,
-    /// The path to the initrd.
-    pub initrd: Option<String>,
+    /// The paths to the initrds, in the order they appear.
+    pub initrd: Vec<String>,
     /// The path to an EFI image.
     pub efi: Option<String>,
     /// The sort key for the entry.
@@ -38,7 +39,7 @@ impl FromStr for BlsEntry {
         let mut title: Option<String> = None;
         let mut options: Option<String> = None;
         let mut linux: Option<String> = None;
-        let mut initrd: Option<String> = None;
+        let mut initrd: Vec<String> = Vec::new();
         let mut efi: Option<String> = None;
         let mut sort_key: Option<String> = None;
         let mut version: Option<String> = None;
@@ -75,9 +76,10 @@ impl FromStr for BlsEntry {
                     linux = Some(value.trim().to_string());
                 }
 
-                // The path to the initrd.
+                // The path to an initrd. An entry can have multiple initrds, either as
+                // repeated initrd lines or as multiple paths separated by whitespace.
                 "initrd" => {
-                    initrd = Some(value.trim().to_string());
+                    initrd.extend(value.split_whitespace().map(|path| path.to_string()));
                 }
 
                 // The path to an EFI image.
@@ -134,12 +136,13 @@ impl BlsEntry {
             .map(|path| path.replace('/', "\\").trim_start_matches('\\').to_string())
     }
 
-    /// Fetches the path to an initrd to pass to the kernel, if any.
+    /// Fetches the paths to the initrds to pass to the kernel, in order.
     /// It also converts / to \\ to match EFI path style.
-    pub fn initrd_path(&self) -> Option<String> {
+    pub fn initrd_paths(&self) -> Vec<String> {
         self.initrd
-            .clone()
+            .iter()
             .map(|path| path.replace('/', "\\").trim_start_matches('\\').to_string())
+            .collect()
     }
 
     /// Fetches the options to pass to the kernel, if any.
@@ -431,7 +434,7 @@ mod tests {
         assert!(entry.title.is_none());
         assert!(entry.linux.is_none());
         assert!(entry.efi.is_none());
-        assert!(entry.initrd.is_none());
+        assert!(entry.initrd.is_empty());
         assert!(entry.options.is_none());
         assert!(entry.sort_key.is_none());
         assert!(entry.version.is_none());
@@ -455,7 +458,7 @@ efi        /EFI/fedora/shimx64.efi
         assert_eq!(entry.version.as_deref(), Some("6.5.6-300.fc39.x86_64"));
         assert_eq!(entry.machine_id.as_deref(), Some("abc123def456"));
         assert_eq!(entry.linux.as_deref(), Some("/boot/vmlinuz-6.5.6"));
-        assert_eq!(entry.initrd.as_deref(), Some("/boot/initrd-6.5.6.img"));
+        assert_eq!(entry.initrd, ["/boot/initrd-6.5.6.img"]);
         assert_eq!(entry.options.as_deref(), Some("root=/dev/sda1 ro quiet"));
         assert_eq!(entry.sort_key.as_deref(), Some("fedora"));
         assert_eq!(entry.efi.as_deref(), Some("/EFI/fedora/shimx64.efi"));
@@ -555,15 +558,29 @@ efi        /EFI/fedora/shimx64.efi
     }
 
     #[test]
-    fn initrd_path_normalises_slashes() {
-        let entry: BlsEntry = "linux /vmlinuz\ninitrd /boot/initrd.img\n".parse().unwrap();
-        assert_eq!(entry.initrd_path().as_deref(), Some("boot\\initrd.img"));
+    fn parse_multiple_initrd_lines_in_order() {
+        let input = "linux /vmlinuz\ninitrd /intel-ucode.img\ninitrd /initramfs.img\n";
+        let entry: BlsEntry = input.parse().unwrap();
+        assert_eq!(entry.initrd, ["/intel-ucode.img", "/initramfs.img"]);
     }
 
     #[test]
-    fn initrd_path_none_when_not_set() {
+    fn parse_multiple_initrds_on_one_line() {
+        let input = "linux /vmlinuz\ninitrd /intel-ucode.img  /initramfs.img\n";
+        let entry: BlsEntry = input.parse().unwrap();
+        assert_eq!(entry.initrd, ["/intel-ucode.img", "/initramfs.img"]);
+    }
+
+    #[test]
+    fn initrd_paths_normalises_slashes() {
+        let entry: BlsEntry = "linux /vmlinuz\ninitrd /boot/initrd.img\n".parse().unwrap();
+        assert_eq!(entry.initrd_paths(), ["boot\\initrd.img"]);
+    }
+
+    #[test]
+    fn initrd_paths_empty_when_not_set() {
         let entry: BlsEntry = "linux /vmlinuz\n".parse().unwrap();
-        assert!(entry.initrd_path().is_none());
+        assert!(entry.initrd_paths().is_empty());
     }
 
     #[test]