[pbs-devel] [PATCH v3 pxar 13/58] format: add pxar format version entry
Christian Ebner
c.ebner at proxmox.com
Thu Mar 28 13:36:22 CET 2024
Adds an additional entry type at the start of each pxar archive
signaling the encoding format version. If not present, the default
version 1 is assumed.
This allows to early on detect the pxar encoding version, allowing tools
to switch mode or bail on non compatible encoder/decoder functionality.
Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
changes since version 2:
- not present in previous version
examples/mk-format-hashes.rs | 5 +++++
src/decoder/mod.rs | 29 ++++++++++++++++++++++++++--
src/encoder/mod.rs | 37 +++++++++++++++++++++++++++++++++---
src/format/mod.rs | 11 +++++++++++
src/lib.rs | 3 +++
5 files changed, 80 insertions(+), 5 deletions(-)
diff --git a/examples/mk-format-hashes.rs b/examples/mk-format-hashes.rs
index 35cff99..e5d69b1 100644
--- a/examples/mk-format-hashes.rs
+++ b/examples/mk-format-hashes.rs
@@ -1,6 +1,11 @@
use pxar::format::hash_filename;
const CONSTANTS: &[(&str, &str, &str)] = &[
+ (
+ "Pxar format version entry, fallback to version 1 if not present",
+ "PXAR_FORMAT_VERSION",
+ "__PROXMOX_FORMAT_VERSION__",
+ ),
(
"Beginning of an entry (current version).",
"PXAR_ENTRY",
diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index 00d9abf..5b2fafb 100644
--- a/src/decoder/mod.rs
+++ b/src/decoder/mod.rs
@@ -17,7 +17,7 @@ use std::task::{Context, Poll};
use endian_trait::Endian;
-use crate::format::{self, Header};
+use crate::format::{self, FormatVersion, Header};
use crate::util::{self, io_err_other};
use crate::{Entry, EntryKind, Metadata};
@@ -164,6 +164,8 @@ pub(crate) struct DecoderImpl<T> {
/// The random access code uses decoders for sub-ranges which may not end in a `PAYLOAD` for
/// entries like FIFOs or sockets, so there we explicitly allow an item to terminate with EOF.
eof_after_entry: bool,
+ /// The format version as determined by the format version header
+ version: format::FormatVersion,
}
enum State {
@@ -242,6 +244,7 @@ impl<I: SeqRead> DecoderImpl<I> {
payload_input,
payload_consumed,
eof_after_entry,
+ version: FormatVersion::default(),
};
// this.read_next_entry().await?;
@@ -258,7 +261,16 @@ impl<I: SeqRead> DecoderImpl<I> {
loop {
match self.state {
State::Eof => return Ok(None),
- State::Begin => return self.read_next_entry().await.map(Some),
+ State::Begin => {
+ let entry = self.read_next_entry().await.map(Some);
+ if let Ok(Some(ref entry)) = entry {
+ if let EntryKind::Version(version) = entry.kind() {
+ self.version = version.clone();
+ return self.read_next_entry().await.map(Some);
+ }
+ }
+ return entry;
+ }
State::Default => {
// we completely finished an entry, so now we're going "up" in the directory
// hierarchy and parse the next PXAR_FILENAME or the PXAR_GOODBYE:
@@ -412,6 +424,11 @@ impl<I: SeqRead> DecoderImpl<I> {
self.entry.metadata = Metadata::default();
self.entry.kind = EntryKind::Hardlink(self.read_hardlink().await?);
+ Ok(Some(self.entry.take()))
+ } else if header.htype == format::PXAR_FORMAT_VERSION {
+ self.current_header = header;
+ self.entry.kind = EntryKind::Version(self.read_format_version().await?);
+
Ok(Some(self.entry.take()))
} else if header.htype == format::PXAR_ENTRY || header.htype == format::PXAR_ENTRY_V1 {
if header.htype == format::PXAR_ENTRY {
@@ -777,6 +794,14 @@ impl<I: SeqRead> DecoderImpl<I> {
seq_read_entry(&mut self.input).await
}
+
+ async fn read_format_version(&mut self) -> io::Result<format::FormatVersion> {
+ match seq_read_entry(&mut self.input).await? {
+ 1u64 => Ok(format::FormatVersion::Version1),
+ 2u64 => Ok(format::FormatVersion::Version2),
+ _ => io_bail!("unexpected pxar format version"),
+ }
+ }
}
/// Reader for file contents inside a pxar archive.
diff --git a/src/encoder/mod.rs b/src/encoder/mod.rs
index 88c0ed5..9270153 100644
--- a/src/encoder/mod.rs
+++ b/src/encoder/mod.rs
@@ -17,7 +17,7 @@ use endian_trait::Endian;
use crate::binary_tree_array;
use crate::decoder::{self, SeqRead};
-use crate::format::{self, GoodbyeItem, PayloadRef};
+use crate::format::{self, FormatVersion, GoodbyeItem, PayloadRef};
use crate::Metadata;
pub mod aio;
@@ -307,6 +307,8 @@ pub(crate) struct EncoderImpl<'a, T: SeqWrite + 'a> {
/// Since only the "current" entry can be actively writing files, we share the file copy
/// buffer.
file_copy_buffer: Arc<Mutex<Vec<u8>>>,
+ /// Pxar format version to encode
+ version: format::FormatVersion,
}
impl<'a, T: SeqWrite + 'a> EncoderImpl<'a, T> {
@@ -320,11 +322,14 @@ impl<'a, T: SeqWrite + 'a> EncoderImpl<'a, T> {
}
let mut state = EncoderState::default();
- if let Some(payload_output) = payload_output.as_mut() {
+ let version = if let Some(payload_output) = payload_output.as_mut() {
let header = format::Header::with_content_size(format::PXAR_PAYLOAD_START_MARKER, 0);
header.check_header_size()?;
seq_write_struct(payload_output, header, &mut state.payload_write_position).await?;
- }
+ format::FormatVersion::Version2
+ } else {
+ format::FormatVersion::default()
+ };
let mut this = Self {
output,
@@ -334,8 +339,10 @@ impl<'a, T: SeqWrite + 'a> EncoderImpl<'a, T> {
file_copy_buffer: Arc::new(Mutex::new(unsafe {
crate::util::vec_new_uninitialized(1024 * 1024)
})),
+ version,
};
+ this.encode_format_version().await?;
this.encode_metadata(metadata).await?;
let state = this.state_mut()?;
state.files_offset = state.position();
@@ -522,6 +529,10 @@ impl<'a, T: SeqWrite + 'a> EncoderImpl<'a, T> {
file_size: u64,
payload_offset: PayloadOffset,
) -> io::Result<()> {
+ if self.version == FormatVersion::Version1 {
+ io_bail!("payload references not supported pxar format version 1");
+ }
+
if self.payload_output.as_mut().is_none() {
io_bail!("unable to add payload reference");
}
@@ -729,6 +740,26 @@ impl<'a, T: SeqWrite + 'a> EncoderImpl<'a, T> {
Ok(())
}
+ async fn encode_format_version(&mut self) -> io::Result<()> {
+ let version_bytes = match self.version {
+ format::FormatVersion::Version1 => return Ok(()),
+ format::FormatVersion::Version2 => 2u64.to_le_bytes(),
+ };
+
+ let (output, state) = self.output_state()?;
+ if state.write_position != 0 {
+ io_bail!("pxar format version must be encoded at the beginning of an archive");
+ }
+
+ seq_write_pxar_entry(
+ output,
+ format::PXAR_FORMAT_VERSION,
+ &version_bytes,
+ &mut state.write_position,
+ )
+ .await
+ }
+
async fn encode_metadata(&mut self, metadata: &Metadata) -> io::Result<()> {
let (output, state) = self.output_state()?;
seq_write_pxar_struct_entry(
diff --git a/src/format/mod.rs b/src/format/mod.rs
index a672d19..2bf33c9 100644
--- a/src/format/mod.rs
+++ b/src/format/mod.rs
@@ -6,6 +6,7 @@
//! item data.
//!
//! An archive contains items in the following order:
+//! * `FORMAT_VERSION` -- (optional for v1), version of encoding format
//! * `ENTRY` -- containing general stat() data and related bits
//! * `XATTR` -- one extended attribute
//! * ... -- more of these when there are multiple defined
@@ -80,6 +81,8 @@ pub mod mode {
}
// Generated by `cargo run --example mk-format-hashes`
+/// Pxar format version entry, fallback to version 1 if not present
+pub const PXAR_FORMAT_VERSION: u64 = 0x730f6c75df16a40d;
/// Beginning of an entry (current version).
pub const PXAR_ENTRY: u64 = 0xd5956474e588acef;
/// Previous version of the entry struct
@@ -186,6 +189,7 @@ impl Header {
impl Display for Header {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let readable = match self.htype {
+ PXAR_FORMAT_VERSION => "FORMAT_VERSION",
PXAR_FILENAME => "FILENAME",
PXAR_SYMLINK => "SYMLINK",
PXAR_HARDLINK => "HARDLINK",
@@ -551,6 +555,13 @@ impl From<&std::fs::Metadata> for Stat {
}
}
+#[derive(Clone, Debug, Default, PartialEq)]
+pub enum FormatVersion {
+ #[default]
+ Version1,
+ Version2,
+}
+
#[derive(Clone, Debug)]
pub struct Filename {
pub name: Vec<u8>,
diff --git a/src/lib.rs b/src/lib.rs
index ef81a85..a87b5ac 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -342,6 +342,9 @@ impl Acl {
/// Identifies whether the entry is a file, symlink, directory, etc.
#[derive(Clone, Debug)]
pub enum EntryKind {
+ /// Pxar file format version
+ Version(format::FormatVersion),
+
/// Symbolic links.
Symlink(format::Symlink),
--
2.39.2
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