composefs/install: Copy /etc contents to state

For bind mounting /etc we copy the contents of the EROFS' /etc to the
deployment's state directory

Mounting the EORFS requires help from the initramfs crate, so we also
turn it into a library crate.

Signed-off-by: Johan-Liebert1 <pragyanpoudyal41999@gmail.com>

Author: Johan-Liebert1

Cargo.lock

@@ -22,6 +22,7 @@ bootc-sysusers = { path = "../sysusers" }
 bootc-tmpfiles = { path = "../tmpfiles" }
 bootc-utils = { package = "bootc-internal-utils", path = "../utils", version = "0.0.0" }
 ostree-ext = { path = "../ostree-ext", features = ["bootc"] }
+bootc-initramfs-setup = { path = "../initramfs" }
 
 # Workspace dependencies
 anstream = { workspace = true }

crates/lib/Cargo.toml

@@ -0,0 +1 @@
+pub(crate) mod state;

crates/lib/src/bootc_composefs/mod.rs

@@ -0,0 +1,47 @@
+use std::process::Command;
+
+use anyhow::{Context, Result};
+use bootc_utils::CommandRunExt;
+use camino::Utf8PathBuf;
+use fn_error_context::context;
+
+use rustix::{
+    fs::{open, Mode, OFlags, CWD},
+    mount::{unmount, UnmountFlags},
+    path::Arg,
+};
+
+/// Mounts an EROFS image and copies the pristine /etc to the deployment's /etc
+#[context("Copying etc")]
+pub(crate) fn copy_etc_to_state(
+    sysroot_path: &Utf8PathBuf,
+    erofs_id: &String,
+    state_path: &Utf8PathBuf,
+) -> Result<()> {
+    let sysroot_fd = open(
+        sysroot_path.as_std_path(),
+        OFlags::PATH | OFlags::DIRECTORY | OFlags::CLOEXEC,
+        Mode::empty(),
+    )
+    .context("Opening sysroot")?;
+
+    let composefs_fd = bootc_initramfs_setup::mount_composefs_image(&sysroot_fd, &erofs_id, false)?;
+
+    let tempdir = tempfile::tempdir().context("Creating tempdir")?;
+
+    bootc_initramfs_setup::mount_at_wrapper(composefs_fd, CWD, tempdir.path())?;
+
+    // TODO: Replace this with a function to cap_std_ext
+    let cp_ret = Command::new("cp")
+        .args([
+            "-a",
+            &format!("{}/etc/.", tempdir.path().as_str()?),
+            &format!("{state_path}/etc/."),
+        ])
+        .run_capture_stderr();
+
+    // Unmount regardless of copy succeeding
+    unmount(tempdir.path(), UnmountFlags::DETACH).context("Unmounting composefs")?;
+
+    cp_ret
+}

crates/lib/src/bootc_composefs/state.rs

@@ -77,6 +77,7 @@ use serde::{Deserialize, Serialize};
 
 #[cfg(feature = "install-to-disk")]
 use self::baseline::InstallBlockDeviceOpts;
+use crate::bootc_composefs::state::copy_etc_to_state;
 use crate::boundimage::{BoundImage, ResolvedBoundImage};
 use crate::composefs_consts::{
     BOOT_LOADER_ENTRIES, COMPOSEFS_CMDLINE, COMPOSEFS_STAGED_DEPLOYMENT_FNAME,
@@ -2247,8 +2248,9 @@ pub(crate) fn write_composefs_state(
 ) -> Result<()> {
     let state_path = root_path.join(format!("{STATE_DIR_RELATIVE}/{}", deployment_id.to_hex()));
 
-    create_dir_all(state_path.join("etc/upper"))?;
-    create_dir_all(state_path.join("etc/work"))?;
+    create_dir_all(state_path.join("etc"))?;
+
+    copy_etc_to_state(&root_path, &deployment_id.to_hex(), &state_path)?;
 
     let actual_var_path = root_path.join(SHARED_VAR_PATH);
     create_dir_all(&actual_var_path)?;

crates/lib/src/install.rs

@@ -4,6 +4,7 @@
 //! to provide a fully "container native" tool for using
 //! bootable container images.
 
+mod bootc_composefs;
 pub(crate) mod bootc_kargs;
 mod bootloader;
 mod boundimage;