[pve-devel] [PATCH installer v3 1/2] assistant: keep prepared iso bootable on uefi with flash drives

[Aaron Lauterer]

By mapping files into the ISO, the UUID for the partitions change as
they depend on the timestamp. The result is, that grub cannot find its
partition anymore and the user ends up on the grub shell.

This only happens when booting from a blockdev in UEFI mode. E.g. a USB
flash drive. Alternatively one can `dd` the ISO to a small (2GiB) VM
disk and mark it as the first boot device.

When booting in legacy mode or via CDROM (e.g. pass through via IPMI),
it worked.

Xorriso can report the commands needed to recreate the source ISO. The
'-volume_date uuid' is the one needed to override the same UUIDs. We
therefore read it first from the source iso and pass it as parameter
whenever we inject a file into the iso.

Signed-off-by: Aaron Lauterer <a.lauterer at proxmox.com>
Reviewed-by: Stoiko Ivanov <s.ivanov at proxmox.com>
Tested-by: Stoiko Ivanov <s.ivanov at proxmox.com>
---
changes since:
v2:
* add missing import of format_err to patch
v1:
* improve error handling should xorriso return empty output

 proxmox-auto-install-assistant/src/main.rs | 46 ++++++++++++++++++++--
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/proxmox-auto-install-assistant/src/main.rs b/proxmox-auto-install-assistant/src/main.rs
index 0debd29..f8e5ed0 100644
--- a/proxmox-auto-install-assistant/src/main.rs
+++ b/proxmox-auto-install-assistant/src/main.rs
@@ -1,4 +1,4 @@
-use anyhow::{bail, Result};
+use anyhow::{bail, format_err, Result};
 use clap::{Args, Parser, Subcommand, ValueEnum};
 use glob::Pattern;
 use regex::Regex;
@@ -276,6 +276,7 @@ fn show_system_info(_args: &CommandSystemInfo) -> Result<()> {
 
 fn prepare_iso(args: &CommandPrepareISO) -> Result<()> {
     check_prepare_requirements(args)?;
+    let uuid = get_iso_uuid(&args.input)?;
 
     if args.fetch_from == FetchAnswerFrom::Iso && args.answer_file.is_none() {
         bail!("Missing path to the answer file required for the fetch-from 'iso' mode.");
@@ -331,10 +332,15 @@ fn prepare_iso(args: &CommandPrepareISO) -> Result<()> {
     instmode_file_tmp.push("auto-installer-mode.toml");
     fs::write(&instmode_file_tmp, toml::to_string_pretty(&config)?)?;
 
-    inject_file_to_iso(&tmp_iso, &instmode_file_tmp, "/auto-installer-mode.toml")?;
+    inject_file_to_iso(
+        &tmp_iso,
+        &instmode_file_tmp,
+        "/auto-installer-mode.toml",
+        &uuid,
+    )?;
 
     if let Some(answer_file) = &args.answer_file {
-        inject_file_to_iso(&tmp_iso, answer_file, "/answer.toml")?;
+        inject_file_to_iso(&tmp_iso, answer_file, "/answer.toml", &uuid)?;
     }
 
     println!("Moving prepared ISO to target location...");
@@ -371,11 +377,14 @@ fn final_iso_location(args: &CommandPrepareISO) -> PathBuf {
     target.to_path_buf()
 }
 
-fn inject_file_to_iso(iso: &PathBuf, file: &PathBuf, location: &str) -> Result<()> {
+fn inject_file_to_iso(iso: &PathBuf, file: &PathBuf, location: &str, uuid: &String) -> Result<()> {
     let result = Command::new("xorriso")
         .arg("--boot_image")
         .arg("any")
         .arg("keep")
+        .arg("-volume_date")
+        .arg("uuid")
+        .arg(uuid)
         .arg("-dev")
         .arg(iso)
         .arg("-map")
@@ -391,6 +400,35 @@ fn inject_file_to_iso(iso: &PathBuf, file: &PathBuf, location: &str) -> Result<(
     Ok(())
 }
 
+fn get_iso_uuid(iso: &PathBuf) -> Result<String> {
+    let result = Command::new("xorriso")
+        .arg("-dev")
+        .arg(iso)
+        .arg("-report_system_area")
+        .arg("cmd")
+        .output()?;
+    if !result.status.success() {
+        bail!(
+            "Error determining the UUID of the source ISO: {}",
+            String::from_utf8_lossy(&result.stderr)
+        );
+    }
+    let mut uuid = String::new();
+    for line in String::from_utf8(result.stdout)?.lines() {
+        if line.starts_with("-volume_date uuid") {
+            uuid = line
+                .split(' ')
+                .last()
+                .ok_or_else(|| format_err!("xorriso did behave unexpextedly"))?
+                .replace('\'', "")
+                .trim()
+                .into();
+            break;
+        }
+    }
+    Ok(uuid)
+}
+
 fn get_disks() -> Result<BTreeMap<String, BTreeMap<String, String>>> {
     let unwantend_block_devs = vec![
         "ram[0-9]*",
-- 
2.39.2