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format/examples: add header type PXAR_PAYLOAD_REF

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Introduces the header type `PXAR_PAYLOAD_REF` to mark regular file
entry payloads, not encoded within the regular pxar archive but
rather redirected to a dedicated payload output writer.
It therefore substitutes the `PXAR_PAYLOAD` header type for these
entries.

The header marks the start and size for a `PayloadRef` typed object
in the archive, storing the offset to the payload header offset in the
payload stream of the dedicated payload output as well as the payload
size.

The `PayloadRef` provides the means to store, serialize and
deserialize the entry.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
This commit is contained in:
Christian Ebner 2024-02-01 12:51:56 +01:00
parent 48431e5e38
commit d3447d0149
2 changed files with 25 additions and 0 deletions
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5
examples/mk-format-hashes.rs
View File

@ -41,6 +41,11 @@ const CONSTANTS: &[(&str, &str, &str)] = &[
"PXAR_PAYLOAD",
"__PROXMOX_FORMAT_PXAR_PAYLOAD__",
),
(
"Marks the beginning of a payload reference for regular files",
"PXAR_PAYLOAD_REF",
"__PROXMOX_FORMAT_PXAR_PAYLOAD_REF__",
),
(
"Marks item as entry of goodbye table",
"PXAR_GOODBYE",

20
src/format/mod.rs
View File

@ -22,6 +22,7 @@
//! * `FCAPS` -- file capability in Linux disk format
//! * `QUOTA_PROJECT_ID` -- the ext4/xfs quota project ID
//! * `PAYLOAD` -- file contents, if it is one
//! * `PAYLOAD_REF` -- reference to file offset in optional payload file (introduced in v2)
//! * `SYMLINK` -- symlink target, if it is one
//! * `DEVICE` -- device major/minor, if it is a block/char device
//!
@ -99,6 +100,8 @@ pub const PXAR_QUOTA_PROJID: u64 = 0xe07540e82f7d1cbb;
pub const PXAR_HARDLINK: u64 = 0x51269c8422bd7275;
/// Marks the beginning of the payload (actual content) of regular files
pub const PXAR_PAYLOAD: u64 = 0x28147a1b0b7c1a25;
/// Marks the beginning of a payload reference for regular files
pub const PXAR_PAYLOAD_REF: u64 = 0x419d3d6bc4ba977e;
/// Marks item as entry of goodbye table
pub const PXAR_GOODBYE: u64 = 0x2fec4fa642d5731d;
/// The end marker used in the GOODBYE object
@ -152,6 +155,7 @@ impl Header {
PXAR_QUOTA_PROJID => size_of::<QuotaProjectId>() as u64,
PXAR_ENTRY => size_of::<Stat>() as u64,
PXAR_PAYLOAD | PXAR_GOODBYE => u64::MAX - (size_of::<Self>() as u64),
PXAR_PAYLOAD_REF => size_of::<PayloadRef>() as u64,
_ => u64::MAX - (size_of::<Self>() as u64),
}
}
@ -192,6 +196,7 @@ impl Display for Header {
PXAR_QUOTA_PROJID => "QUOTA_PROJID",
PXAR_ENTRY => "ENTRY",
PXAR_PAYLOAD => "PAYLOAD",
PXAR_PAYLOAD_REF => "PAYLOAD_REF",
PXAR_GOODBYE => "GOODBYE",
_ => "UNKNOWN",
};
@ -723,6 +728,21 @@ impl GoodbyeItem {
}
}
/// References a regular file payload found in a separated payload archive
#[derive(Clone, Debug, Endian)]
pub struct PayloadRef {
pub offset: u64,
pub size: u64,
}
impl PayloadRef {
pub(crate) fn data(&self) -> Vec<u8> {
let mut data = self.offset.to_le_bytes().to_vec();
data.append(&mut self.size.to_le_bytes().to_vec());
data
}
}
/// Hash a file name for use in the goodbye table.
pub fn hash_filename(name: &[u8]) -> u64 {
use std::hash::Hasher;