[pbs-devel] [PATCH v2 stable-2 proxmox-backup 2/2] client: pxar: bail on incompatible format versions

[Christian Ebner]

Implementing the change detection mode with reusable file payloads
required a breaking change in the pxar file format. Unfortunately,
there initial format does not encode a version for clients to check
compatibility to. Therefore, a pxar format version entry is
introduced in version 2 of the file format.

Add a compatibility check based on that entry also for the client,
making it possible to bail early when an incompatible archive is
encountered.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-client/src/catalog_shell.rs |  2 +-
 pbs-client/src/pxar/extract.rs  |  3 +++
 pbs-client/src/pxar/tools.rs    | 14 ++++++++------
 pxar-bin/src/main.rs            |  6 +++++-
 4 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/pbs-client/src/catalog_shell.rs b/pbs-client/src/catalog_shell.rs
index 98af5699..8bb2f3e0 100644
--- a/pbs-client/src/catalog_shell.rs
+++ b/pbs-client/src/catalog_shell.rs
@@ -767,7 +767,7 @@ impl Shell {
 
         let file = Self::walk_pxar_archive(&self.accessor, &mut stack).await?;
         std::io::stdout()
-            .write_all(crate::pxar::format_multi_line_entry(file.entry()).as_bytes())?;
+            .write_all(crate::pxar::format_multi_line_entry(file.entry())?.as_bytes())?;
         Ok(())
     }
 
diff --git a/pbs-client/src/pxar/extract.rs b/pbs-client/src/pxar/extract.rs
index f6c1991f..e8412c3d 100644
--- a/pbs-client/src/pxar/extract.rs
+++ b/pbs-client/src/pxar/extract.rs
@@ -119,6 +119,9 @@ where
             None => current_match,
         };
         match (did_match, entry.kind()) {
+            (_, EntryKind::Version(_)) => {
+                bail!("got format version incompatible with this client");
+            }
             (_, EntryKind::Directory) => {
                 callback(entry.path());
 
diff --git a/pbs-client/src/pxar/tools.rs b/pbs-client/src/pxar/tools.rs
index 844a0f73..afc17dff 100644
--- a/pbs-client/src/pxar/tools.rs
+++ b/pbs-client/src/pxar/tools.rs
@@ -120,12 +120,13 @@ fn format_mtime(mtime: &StatxTimestamp) -> String {
     format!("{}.{}", mtime.secs, mtime.nanos)
 }
 
-pub fn format_single_line_entry(entry: &Entry) -> String {
+pub fn format_single_line_entry(entry: &Entry) -> Result<String, Error> {
     let mode_string = mode_string(entry);
 
     let meta = entry.metadata();
 
     let (size, link) = match entry.kind() {
+        EntryKind::Version(_) => bail!("got format version incompatible with this client"),
         EntryKind::File { size, .. } => (format!("{}", *size), String::new()),
         EntryKind::Symlink(link) => ("0".to_string(), format!(" -> {:?}", link.as_os_str())),
         EntryKind::Hardlink(link) => ("0".to_string(), format!(" -> {:?}", link.as_os_str())),
@@ -135,7 +136,7 @@ pub fn format_single_line_entry(entry: &Entry) -> String {
 
     let owner_string = format!("{}/{}", meta.stat.uid, meta.stat.gid);
 
-    format!(
+    Ok(format!(
         "{} {:<13} {} {:>8} {:?}{}",
         mode_string,
         owner_string,
@@ -143,15 +144,16 @@ pub fn format_single_line_entry(entry: &Entry) -> String {
         size,
         entry.path(),
         link,
-    )
+    ))
 }
 
-pub fn format_multi_line_entry(entry: &Entry) -> String {
+pub fn format_multi_line_entry(entry: &Entry) -> Result<String, Error> {
     let mode_string = mode_string(entry);
 
     let meta = entry.metadata();
 
     let (size, link, type_name) = match entry.kind() {
+        EntryKind::Version(_) => bail!("got format version incompatible with this client"),
         EntryKind::File { size, .. } => (format!("{}", *size), String::new(), "file"),
         EntryKind::Symlink(link) => (
             "0".to_string(),
@@ -185,7 +187,7 @@ pub fn format_multi_line_entry(entry: &Entry) -> String {
         Err(_) => std::borrow::Cow::Owned(format!("{:?}", entry.path())),
     };
 
-    format!(
+    Ok(format!(
         "  File: {}{}\n  \
            Size: {:<13} Type: {}\n\
          Access: ({:o}/{})  Uid: {:<5} Gid: {:<5}\n\
@@ -199,5 +201,5 @@ pub fn format_multi_line_entry(entry: &Entry) -> String {
         meta.stat.uid,
         meta.stat.gid,
         format_mtime(&meta.stat.mtime),
-    )
+    ))
 }
diff --git a/pxar-bin/src/main.rs b/pxar-bin/src/main.rs
index 90887321..9b7de8f4 100644
--- a/pxar-bin/src/main.rs
+++ b/pxar-bin/src/main.rs
@@ -13,6 +13,7 @@ use tokio::signal::unix::{signal, SignalKind};
 
 use pathpatterns::{MatchEntry, MatchType, PatternFlag};
 use pbs_client::pxar::{format_single_line_entry, Flags, PxarExtractOptions, ENCODER_MAX_ENTRIES};
+use pxar::EntryKind;
 
 use proxmox_router::cli::*;
 use proxmox_schema::api;
@@ -409,9 +410,12 @@ async fn mount_archive(archive: String, mountpoint: String, verbose: bool) -> Re
 fn dump_archive(archive: String) -> Result<(), Error> {
     for entry in pxar::decoder::Decoder::open(archive)? {
         let entry = entry?;
+        if let EntryKind::Version(_) = entry.kind() {
+            bail!("got format version incompatible with this client");
+        }
 
         if log::log_enabled!(log::Level::Debug) {
-            log::debug!("{}", format_single_line_entry(&entry));
+            log::debug!("{}", format_single_line_entry(&entry)?);
         } else {
             log::info!("{:?}", entry.path());
         }
-- 
2.30.2