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src/pxar.rs: improve docu

This commit is contained in:
Dietmar Maurer 2019-03-18 12:27:30 +01:00
parent 515688d1f1
commit 60864b1b56
1 changed files with 35 additions and 34 deletions
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src/pxar.rs
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@ -1,50 +1,51 @@
//! *pxar* Implementation
//! *pxar* Implementation (proxmox file archive format)
//!
//! This code implements a slightly modified version of the *catar*
//! format used in the [casync](https://github.com/systemd/casync)
//! toolkit (we are not 100% binary compatible). It is a file archive
//! toolkit (we are not 100\% binary compatible). It is a file archive
//! format defined by 'Lennart Poettering', specially defined for
//! efficent deduplication.
//! Every archive contains items in the following order:
//! * ENTRY -- containing general stat() data and related bits
//! * USER -- user name as text, if enabled
//! * GROUP -- group name as text, if enabled
//! * XATTR -- one extended attribute
//! * ... -- more of these when there are multiple defined
//! * ACL_USER -- one USER ACL entry
//! * ... -- more of these when there are multiple defined
//! * ACL_GROUP -- one GROUP ACL entry
//! * ... -- more of these when there are multiple defined
//! * ACL_GROUP_OBJ -- The ACL_GROUP_OBJ
//! * ACL_DEFAULT -- The various default ACL fields if there's one defined
//! * ACL_DEFAULT_USER -- one USER ACL entry
//! * ... -- more of these when multiple are defined
//! * ACL_DEFAULT_GROUP -- one GROUP ACL entry
//! * ... -- more of these when multiple are defined
//! * FCAPS -- file capability in Linux disk format
//! * QUOTA_PROJECT_ID -- the ext4/xfs quota project ID
//! * PAYLOAD -- file contents, if it is one
//! * SYMLINK -- symlink target, if it is one
//! * DEVICE -- device major/minor, if it is a block/char device
//! * `ENTRY` -- containing general stat() data and related bits
//! * `USER` -- user name as text, if enabled
//! * `GROUP` -- group name as text, if enabled
//! * `XATTR` -- one extended attribute
//! * ... -- more of these when there are multiple defined
//! * `ACL_USER` -- one `USER ACL` entry
//! * ... -- more of these when there are multiple defined
//! * `ACL_GROUP` -- one `GROUP ACL` entry
//! * ... -- more of these when there are multiple defined
//! * `ACL_GROUP_OBJ` -- The `ACL_GROUP_OBJ`
//! * `ACL_DEFAULT` -- The various default ACL fields if there's one defined
//! * `ACL_DEFAULT_USER` -- one USER ACL entry
//! * ... -- more of these when multiple are defined
//! * `ACL_DEFAULT_GROUP` -- one GROUP ACL entry
//! * ... -- more of these when multiple are defined
//! * `FCAPS` -- file capability in Linux disk format
//! * `QUOTA_PROJECT_ID` -- the ext4/xfs quota project ID
//! * `PAYLOAD` -- file contents, if it is one
//! * `SYMLINK` -- symlink target, if it is one
//! * `DEVICE` -- device major/minor, if it is a block/char device
//!
//! If we are serializing a directory, then this is followed by:
//!
//! * FILENAME -- name of the first directory entry (strictly ordered!)
//! * <archive> -- serialization of the first directory entry's metadata and contents,
//! * `FILENAME` -- name of the first directory entry (strictly ordered!)
//! * `<archive>` -- serialization of the first directory entry's metadata and contents,
//! following the exact same archive format
//! * FILENAME -- name of the second directory entry (strictly ordered!)
//! * <archive> -- serialization of the second directory entry
//! * `FILENAME` -- name of the second directory entry (strictly ordered!)
//! * `<archive>` -- serialization of the second directory entry
//! * ...
//! * GOODBYE -- lookup table at the end of a list of directory entries
//! * `GOODBYE` -- lookup table at the end of a list of directory entries
///! The original format has no way to deal with hardlinks, so we
///! extended the format by a special HARDLINK tag, which can replace
///! an ENTRY tag. The HARDLINK tag contains an 64bit offset which
///! points to the linked ENTRY inside the archive, followed by the
///! full path name of that ENTRY. HARDLINKs may not have further data
///! (user, group, acl, ...) because this is already defined by the
///! linked ENTRY.
//!
//! The original format has no way to deal with hardlinks, so we
//! extended the format by a special `HARDLINK` tag, which can replace
//! an `ENTRY` tag. The `HARDLINK` tag contains an 64bit offset which
//! points to the linked `ENTRY` inside the archive, followed by the
//! full path name of that `ENTRY`. `HARDLINK`s may not have further data
//! (user, group, acl, ...) because this is already defined by the
//! linked `ENTRY`.
mod binary_search_tree;
pub use binary_search_tree::*;