client: tools: add helper to lookup ArchiveEntrys via pxar

In preparation to lookup entries via the pxar metadata archive
instead of the catalog, in order to drop encoding the catalog
for snapshots using split pxar archives altogehter.

This helper allows to lookup the directory entries via the provided
accessor instance and formats them to be compatible with the output
as produced by lookups via the catalog.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>

pbs-client/src/tools/mod.rs

@@ -1,9 +1,12 @@
 //! Shared tools useful for common CLI clients.
 use std::collections::HashMap;
 use std::env::VarError::{NotPresent, NotUnicode};
+use std::ffi::OsStr;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
+use std::os::unix::ffi::OsStrExt;
 use std::os::unix::io::FromRawFd;
+use std::path::PathBuf;
 use std::process::Command;
 
 use anyhow::{bail, format_err, Context, Error};
@@ -16,7 +19,12 @@ use proxmox_schema::*;
 use proxmox_sys::fs::file_get_json;
 
 use pbs_api_types::{Authid, BackupNamespace, RateLimitConfig, UserWithTokens, BACKUP_REPO_URL};
+use pbs_datastore::catalog::{ArchiveEntry, DirEntryAttribute};
 use pbs_datastore::BackupManifest;
+use pxar::accessor::aio::Accessor;
+use pxar::accessor::ReadAt;
+use pxar::format::SignedDuration;
+use pxar::{mode, EntryKind};
 
 use crate::{BackupRepository, HttpClient, HttpClientOptions};
 
@@ -635,3 +643,79 @@ pub fn raise_nofile_limit() -> Result<libc::rlimit64, Error> {
 
     Ok(old)
 }
+
+/// Look up the directory entries of the given directory `path` in a pxar archive via it's given
+/// `accessor` and return the entries formatted as [`ArchiveEntry`]'s, compatible with reading
+/// entries from the catalog.
+///
+/// If the optional `path_prefix` is given, all returned entry paths will be prefixed with it.
+pub async fn pxar_metadata_catalog_lookup<T: Clone + ReadAt>(
+    accessor: Accessor<T>,
+    path: &OsStr,
+    path_prefix: Option<&str>,
+) -> Result<Vec<ArchiveEntry>, Error> {
+    let root = accessor.open_root().await?;
+    let dir_entry = root
+        .lookup(&path)
+        .await
+        .map_err(|err| format_err!("lookup failed - {err}"))?
+        .ok_or_else(|| format_err!("lookup failed - error opening '{path:?}'"))?;
+
+    let mut entries = Vec::new();
+    if let EntryKind::Directory = dir_entry.kind() {
+        let dir_entry = dir_entry
+            .enter_directory()
+            .await
+            .map_err(|err| format_err!("failed to enter directory - {err}"))?;
+
+        let mut entries_iter = dir_entry.read_dir();
+        while let Some(entry) = entries_iter.next().await {
+            let entry = entry?.decode_entry().await?;
+
+            let entry_attr = match entry.kind() {
+                EntryKind::Version(_) | EntryKind::Prelude(_) | EntryKind::GoodbyeTable => continue,
+                EntryKind::Directory => DirEntryAttribute::Directory {
+                    start: entry.entry_range_info().entry_range.start,
+                },
+                EntryKind::File { size, .. } => {
+                    let mtime = match entry.metadata().mtime_as_duration() {
+                        SignedDuration::Positive(val) => i64::try_from(val.as_secs())?,
+                        SignedDuration::Negative(val) => -1 * i64::try_from(val.as_secs())?,
+                    };
+                    DirEntryAttribute::File { size: *size, mtime }
+                }
+                EntryKind::Device(_) => match entry.metadata().file_type() {
+                    mode::IFBLK => DirEntryAttribute::BlockDevice,
+                    mode::IFCHR => DirEntryAttribute::CharDevice,
+                    _ => bail!("encountered unknown device type"),
+                },
+                EntryKind::Symlink(_) => DirEntryAttribute::Symlink,
+                EntryKind::Hardlink(_) => DirEntryAttribute::Hardlink,
+                EntryKind::Fifo => DirEntryAttribute::Fifo,
+                EntryKind::Socket => DirEntryAttribute::Socket,
+            };
+
+            let entry_path = if let Some(prefix) = path_prefix {
+                let mut entry_path = PathBuf::from(prefix);
+                match entry.path().strip_prefix("/") {
+                    Ok(path) => entry_path.push(path),
+                    Err(_) => entry_path.push(entry.path()),
+                }
+                entry_path
+            } else {
+                PathBuf::from(entry.path())
+            };
+            entries.push(ArchiveEntry::new(
+                entry_path.as_os_str().as_bytes(),
+                Some(&entry_attr),
+            ));
+        }
+    } else {
+        bail!(format!(
+            "expected directory entry, got entry kind '{:?}'",
+            dir_entry.kind()
+        ));
+    }
+
+    Ok(entries)
+}