crates: Add discoverable partition module

This fleshes out what we had with a more rigorous
binding to the spec.

Assisted-by: Claude Code
Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

Cargo.lock

@@ -36,6 +36,7 @@ anyhow = "1.0.82"
 camino = "1.1.6"
 canon-json = "0.2.1"
 cap-std-ext = "4.0.3"
+cfg-if = "1.0"
 chrono = { version = "0.4.38", default-features = false }
 clap = "4.5.4"
 clap_mangen = { version = "0.2.20" }

Cargo.toml

@@ -30,6 +30,7 @@ anyhow = { workspace = true }
 camino = { workspace = true, features = ["serde1"] }
 canon-json = { workspace = true }
 cap-std-ext = { workspace = true, features = ["fs_utf8"] }
+cfg-if = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
 clap = { workspace = true, features = ["derive","cargo"] }
 clap_mangen = { workspace = true, optional = true }

crates/lib/Cargo.toml

@@ -44,7 +44,8 @@ use crate::{
         BOOT_LOADER_ENTRIES, COMPOSEFS_CMDLINE, ORIGIN_KEY_BOOT, ORIGIN_KEY_BOOT_DIGEST,
         STAGED_BOOT_LOADER_ENTRIES, STATE_DIR_ABS, USER_CFG, USER_CFG_STAGED,
     },
-    install::{dps_uuid::DPS_UUID, RW_KARG},
+    discoverable_partition_specification::this_arch_root,
+    install::RW_KARG,
     spec::{Bootloader, Host},
 };
 
@@ -400,7 +401,7 @@ pub(crate) fn setup_composefs_bls_boot(
                 Utf8PathBuf::from("/sysroot"),
                 get_esp_partition(&sysroot_parent)?.0,
                 [
-                    format!("root=UUID={DPS_UUID}"),
+                    format!("root=UUID={}", this_arch_root()),
                     RW_KARG.to_string(),
                     format!("{COMPOSEFS_CMDLINE}={id_hex}"),
                 ]

crates/lib/src/bootc_composefs/boot.rs

@@ -10,13 +10,11 @@ use bootc_mount as mount;
 
 #[cfg(any(feature = "composefs-backend", feature = "install-to-disk"))]
 use crate::bootc_composefs::boot::mount_esp;
-use crate::utils;
+use crate::{discoverable_partition_specification, utils};
 
 /// The name of the mountpoint for efi (as a subdirectory of /boot, or at the toplevel)
 pub(crate) const EFI_DIR: &str = "efi";
 /// The EFI system partition GUID
-#[allow(dead_code)]
-pub(crate) const ESP_GUID: &str = "C12A7328-F81F-11D2-BA4B-00A0C93EC93B";
 /// Path to the bootupd update payload
 #[allow(dead_code)]
 const BOOTUPD_UPDATES: &str = "usr/lib/bootupd/updates";
@@ -26,7 +24,7 @@ pub(crate) fn esp_in(device: &PartitionTable) -> Result<&Partition> {
     device
         .partitions
         .iter()
-        .find(|p| p.parttype.as_str() == ESP_GUID)
+        .find(|p| p.parttype.as_str() == discoverable_partition_specification::ESP)
         .ok_or(anyhow::anyhow!("ESP not found in partition table"))
 }
 
@@ -86,7 +84,7 @@ pub(crate) fn install_systemd_boot(
     let esp_part = device
         .partitions
         .iter()
-        .find(|p| p.parttype.as_str() == ESP_GUID)
+        .find(|p| p.parttype.as_str() == discoverable_partition_specification::ESP)
         .ok_or_else(|| anyhow::anyhow!("ESP partition not found"))?;
 
     let esp_mount = mount_esp(&esp_part.node).context("Mounting ESP")?;