gix_pack/
lib.rs

1//! Git stores all of its data as _Objects_, which are data along with a hash over all data. Storing objects efficiently
2//! is what git packs are concerned about.
3//!
4//! Packs consist of [data files][data::File] and [index files][index::File]. The latter can be generated from a data file
5//! and make accessing objects within a pack feasible.
6//!
7//! A [Bundle] conveniently combines a data pack alongside its index to allow [finding][Find] objects or verifying the pack.
8//! Objects returned by `.find(…)` are [objects][gix_object::Data] which know their pack location in order to speed up
9//! various common operations like creating new packs from existing ones.
10//!
11//! When traversing all objects in a pack, a _delta tree acceleration structure_ can be built from pack data or an index
12//! in order to decompress packs in parallel and without any waste.
13//! ## Feature Flags
14#![cfg_attr(
15    all(doc, feature = "document-features"),
16    doc = ::document_features::document_features!()
17)]
18#![cfg_attr(all(doc, feature = "document-features"), feature(doc_cfg))]
19#![deny(missing_docs, unsafe_code)]
20
21use std::{borrow::Cow, ops::Deref, path::Path};
22
23/// The default memory-backed storage for pack data and index files.
24pub use memmap2::Mmap as MMap;
25
26/// A byte-oriented backing store for pack data and indices.
27pub trait FileData: Deref<Target = [u8]> {}
28
29impl<T> FileData for T where T: Deref<Target = [u8]> {}
30
31///
32pub mod bundle;
33/// A bundle of pack data and the corresponding pack index
34pub struct Bundle {
35    /// The pack file corresponding to `index`
36    pub pack: data::File,
37    /// The index file corresponding to `pack`
38    pub index: index::File,
39}
40
41///
42pub mod find;
43
44///
45pub mod cache;
46///
47pub mod data;
48
49mod find_traits;
50pub use find_traits::{Find, FindExt};
51
52///
53pub mod index;
54///
55pub mod multi_index;
56
57///
58pub mod verify;
59
60mod mmap {
61    use std::path::Path;
62
63    pub fn read_only(path: &Path) -> std::io::Result<memmap2::Mmap> {
64        let file = std::fs::File::open(path)?;
65        // SAFETY: we have to take the risk of somebody changing the file underneath. Git never writes into the same file.
66        #[allow(unsafe_code)]
67        unsafe {
68            memmap2::MmapOptions::new().map_copy_read_only(&file)
69        }
70    }
71}
72
73/// Return a display-friendly name for pack- or index-related progress messages.
74///
75/// Prefer the file name, but fall back to the full path for paths without a terminal component.
76fn source_name(path: &Path) -> Cow<'_, str> {
77    if path.as_os_str().is_empty() {
78        Cow::Borrowed("<memory>")
79    } else if let Some(name) = path.file_name() {
80        name.to_string_lossy()
81    } else {
82        path.as_os_str().to_string_lossy()
83    }
84}
85
86#[inline]
87fn read_u32(b: &[u8]) -> u32 {
88    u32::from_be_bytes(b.try_into().unwrap())
89}
90
91#[inline]
92fn read_u64(b: &[u8]) -> u64 {
93    u64::from_be_bytes(b.try_into().unwrap())
94}
95
96fn exact_vec<T>(capacity: usize) -> Vec<T> {
97    let mut v = Vec::new();
98    v.reserve_exact(capacity);
99    v
100}
101
102#[inline]
103fn fan_is_monotonically_increasing(fan: &[u32]) -> bool {
104    !fan.windows(2).any(|window| window[0] > window[1])
105}
gix_pack/lib.rs

gix_pack/
lib.rs
