[pbs-devel] [PATCH proxmox-backup v2] fix #2998: encode mtime as i64 instead of u64
Dominik Csapak
d.csapak at proxmox.com
Wed Oct 21 14:32:37 CEST 2020
saves files mtime as i64 instead of u64 which enables backup of
files with negative mtime
the catalog_decode_i64 is compatible to encoded u64 values (if < 2^63)
but not reverse, so all "old" catalogs can be read with the new
decoder, but catalogs that contain negative mtimes will decode wrongly
on older clients
also remove the arbitrary maximum value of 2^63 - 1 for
encode_u64 (we just use up to 10 bytes now) and correctly
decode them and update the comments accordingly
Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* remove limit from de/encode_u64 methods
* fix comments
src/backup/catalog.rs | 81 +++++++++++++++++++++++++++++++++++++------
src/pxar/catalog.rs | 2 +-
src/pxar/create.rs | 2 +-
3 files changed, 73 insertions(+), 12 deletions(-)
diff --git a/src/backup/catalog.rs b/src/backup/catalog.rs
index d1f519e5..6ba40c6b 100644
--- a/src/backup/catalog.rs
+++ b/src/backup/catalog.rs
@@ -78,7 +78,7 @@ pub struct DirEntry {
#[derive(Clone, Debug, PartialEq)]
pub enum DirEntryAttribute {
Directory { start: u64 },
- File { size: u64, mtime: u64 },
+ File { size: u64, mtime: i64 },
Symlink,
Hardlink,
BlockDevice,
@@ -89,7 +89,7 @@ pub enum DirEntryAttribute {
impl DirEntry {
- fn new(etype: CatalogEntryType, name: Vec<u8>, start: u64, size: u64, mtime:u64) -> Self {
+ fn new(etype: CatalogEntryType, name: Vec<u8>, start: u64, size: u64, mtime: i64) -> Self {
match etype {
CatalogEntryType::Directory => {
DirEntry { name, attr: DirEntryAttribute::Directory { start } }
@@ -184,7 +184,7 @@ impl DirInfo {
catalog_encode_u64(writer, name.len() as u64)?;
writer.write_all(name)?;
catalog_encode_u64(writer, *size)?;
- catalog_encode_u64(writer, *mtime)?;
+ catalog_encode_i64(writer, *mtime)?;
}
DirEntry { name, attr: DirEntryAttribute::Symlink } => {
writer.write_all(&[CatalogEntryType::Symlink as u8])?;
@@ -234,7 +234,7 @@ impl DirInfo {
Ok((self.name, data))
}
- fn parse<C: FnMut(CatalogEntryType, &[u8], u64, u64, u64) -> Result<bool, Error>>(
+ fn parse<C: FnMut(CatalogEntryType, &[u8], u64, u64, i64) -> Result<bool, Error>>(
data: &[u8],
mut callback: C,
) -> Result<(), Error> {
@@ -265,7 +265,7 @@ impl DirInfo {
}
CatalogEntryType::File => {
let size = catalog_decode_u64(&mut cursor)?;
- let mtime = catalog_decode_u64(&mut cursor)?;
+ let mtime = catalog_decode_i64(&mut cursor)?;
callback(etype, name, 0, size, mtime)?
}
_ => {
@@ -362,7 +362,7 @@ impl <W: Write> BackupCatalogWriter for CatalogWriter<W> {
Ok(())
}
- fn add_file(&mut self, name: &CStr, size: u64, mtime: u64) -> Result<(), Error> {
+ fn add_file(&mut self, name: &CStr, size: u64, mtime: i64) -> Result<(), Error> {
let dir = self.dirstack.last_mut().ok_or_else(|| format_err!("outside root"))?;
let name = name.to_bytes().to_vec();
dir.entries.push(DirEntry { name, attr: DirEntryAttribute::File { size, mtime } });
@@ -587,14 +587,74 @@ impl <R: Read + Seek> CatalogReader<R> {
}
}
+/// Serialize i64 as short, variable length byte sequence
+///
+/// Stores 7 bits per byte, Bit 8 indicates the end of the sequence (when not set).
+/// If the value is negative, we end with a zero byte (0x00).
+pub fn catalog_encode_i64<W: Write>(writer: &mut W, v: i64) -> Result<(), Error> {
+ let mut enc = Vec::new();
+
+ let mut d = if v < 0 {
+ (-1 * v) as u64
+ } else {
+ v as u64
+ };
+
+ loop {
+ if d < 128 {
+ if v < 0 {
+ enc.push(128 | d as u8);
+ enc.push(0u8);
+ } else {
+ enc.push(d as u8);
+ }
+ break;
+ }
+ enc.push((128 | (d & 127)) as u8);
+ d = d >> 7;
+ }
+ writer.write_all(&enc)?;
+
+ Ok(())
+}
+
+/// Deserialize i64 from variable length byte sequence
+///
+/// We currently read maximal 10 bytes, which give a maximum of 63 bits + sign.
+/// this method is compatible with catalog_encode_u64 iff the
+/// value encoded is <= 2^63 (values > 2^63 cannot be represented in an i64)
+pub fn catalog_decode_i64<R: Read>(reader: &mut R) -> Result<i64, Error> {
+
+ let mut v: u64 = 0;
+ let mut buf = [0u8];
+
+ for i in 0..10 { // only allow 10 bytes (63 bits + sign marker)
+ if buf.is_empty() {
+ bail!("decode_i64 failed - unexpected EOB");
+ }
+ reader.read_exact(&mut buf)?;
+
+ let t = buf[0];
+
+ if t == 0 {
+ return Ok(v as i64 * -1);
+ } else if t < 128 {
+ v |= (t as u64) << (i*7);
+ return Ok(v as i64);
+ } else {
+ v |= ((t & 127) as u64) << (i*7);
+ }
+ }
+
+ bail!("decode_i64 failed - missing end marker");
+}
+
/// Serialize u64 as short, variable length byte sequence
///
/// Stores 7 bits per byte, Bit 8 indicates the end of the sequence (when not set).
-/// We limit values to a maximum of 2^63.
pub fn catalog_encode_u64<W: Write>(writer: &mut W, v: u64) -> Result<(), Error> {
let mut enc = Vec::new();
- if (v & (1<<63)) != 0 { bail!("catalog_encode_u64 failed - value >= 2^63"); }
let mut d = v;
loop {
if d < 128 {
@@ -611,13 +671,14 @@ pub fn catalog_encode_u64<W: Write>(writer: &mut W, v: u64) -> Result<(), Error>
/// Deserialize u64 from variable length byte sequence
///
-/// We currently read maximal 9 bytes, which give a maximum of 63 bits.
+/// We currently read maximal 10 bytes, which give a maximum of 70 bits,
+/// but we currently only encode up to 64 bits
pub fn catalog_decode_u64<R: Read>(reader: &mut R) -> Result<u64, Error> {
let mut v: u64 = 0;
let mut buf = [0u8];
- for i in 0..9 { // only allow 9 bytes (63 bits)
+ for i in 0..10 { // only allow 10 bytes (70 bits)
if buf.is_empty() {
bail!("decode_u64 failed - unexpected EOB");
}
diff --git a/src/pxar/catalog.rs b/src/pxar/catalog.rs
index 96b42427..02b57dfa 100644
--- a/src/pxar/catalog.rs
+++ b/src/pxar/catalog.rs
@@ -9,7 +9,7 @@ use std::ffi::CStr;
pub trait BackupCatalogWriter {
fn start_directory(&mut self, name: &CStr) -> Result<(), Error>;
fn end_directory(&mut self) -> Result<(), Error>;
- fn add_file(&mut self, name: &CStr, size: u64, mtime: u64) -> Result<(), Error>;
+ fn add_file(&mut self, name: &CStr, size: u64, mtime: i64) -> Result<(), Error>;
fn add_symlink(&mut self, name: &CStr) -> Result<(), Error>;
fn add_hardlink(&mut self, name: &CStr) -> Result<(), Error>;
fn add_block_device(&mut self, name: &CStr) -> Result<(), Error>;
diff --git a/src/pxar/create.rs b/src/pxar/create.rs
index 74c49050..6ba6f15c 100644
--- a/src/pxar/create.rs
+++ b/src/pxar/create.rs
@@ -535,7 +535,7 @@ impl<'a, 'b> Archiver<'a, 'b> {
let file_size = stat.st_size as u64;
if let Some(ref mut catalog) = self.catalog {
- catalog.add_file(c_file_name, file_size, stat.st_mtime as u64)?;
+ catalog.add_file(c_file_name, file_size, stat.st_mtime)?;
}
let offset: LinkOffset =
--
2.20.1
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