| #![allow(unused)] |
| |
| use std::path::{Path, PathBuf}; |
| |
| use memmap2::Mmap; |
| |
| use crate::{decode, extension, File, State}; |
| |
| mod error { |
| |
| /// The error returned by [File::at()][super::File::at()]. |
| #[derive(Debug, thiserror::Error)] |
| #[allow(missing_docs)] |
| pub enum Error { |
| #[error("An IO error occurred while opening the index")] |
| Io(#[from] std::io::Error), |
| #[error(transparent)] |
| Decode(#[from] crate::decode::Error), |
| #[error(transparent)] |
| LinkExtension(#[from] crate::extension::link::decode::Error), |
| } |
| } |
| |
| pub use error::Error; |
| |
| /// Initialization |
| impl File { |
| /// Try to open the index file at `path` with `options`, assuming `object_hash` is used throughout the file, or create a new |
| /// index that merely exists in memory and is empty. `skip_hash` will increase the performance by a factor of 2, at the cost of |
| /// possibly not detecting corruption. |
| /// |
| /// Note that the `path` will not be written if it doesn't exist. |
| pub fn at_or_default( |
| path: impl Into<PathBuf>, |
| object_hash: gix_hash::Kind, |
| skip_hash: bool, |
| options: decode::Options, |
| ) -> Result<Self, Error> { |
| let path = path.into(); |
| Ok(match Self::at(&path, object_hash, skip_hash, options) { |
| Ok(f) => f, |
| Err(Error::Io(err)) if err.kind() == std::io::ErrorKind::NotFound => { |
| File::from_state(State::new(object_hash), path) |
| } |
| Err(err) => return Err(err), |
| }) |
| } |
| |
| /// Open an index file at `path` with `options`, assuming `object_hash` is used throughout the file. If `skip_hash` is `true`, |
| /// we will not get or compare the checksum of the index at all, which generally increases performance of this method by a factor |
| /// of 2 or more. |
| /// |
| /// Note that the verification of the file hash depends on `options`, and even then it's performed after the file was read and not |
| /// before it is read. That way, invalid files would see a more descriptive error message as we try to parse them. |
| pub fn at( |
| path: impl Into<PathBuf>, |
| object_hash: gix_hash::Kind, |
| skip_hash: bool, |
| options: decode::Options, |
| ) -> Result<Self, Error> { |
| let _span = gix_features::trace::detail!("gix_index::File::at()"); |
| let path = path.into(); |
| let (data, mtime) = { |
| let mut file = std::fs::File::open(&path)?; |
| // SAFETY: we have to take the risk of somebody changing the file underneath. Git never writes into the same file. |
| #[allow(unsafe_code)] |
| let data = unsafe { Mmap::map(&file)? }; |
| |
| if !skip_hash { |
| // Note that even though it's trivial to offload this into a thread, which is worth it for all but the smallest |
| // index files, we choose more safety here just like git does and don't even try to decode the index if the hashes |
| // don't match. |
| // Thanks to `skip_hash`, we can get performance and it's under caller control, at the cost of some safety. |
| let expected = gix_hash::ObjectId::from(&data[data.len() - object_hash.len_in_bytes()..]); |
| if !expected.is_null() { |
| let _span = gix_features::trace::detail!("gix::open_index::hash_index", path = ?path); |
| let meta = file.metadata()?; |
| let num_bytes_to_hash = meta.len() - object_hash.len_in_bytes() as u64; |
| let actual_hash = gix_features::hash::bytes( |
| &mut file, |
| num_bytes_to_hash, |
| object_hash, |
| &mut gix_features::progress::Discard, |
| &Default::default(), |
| )?; |
| |
| if actual_hash != expected { |
| return Err(Error::Decode(decode::Error::ChecksumMismatch { |
| actual_checksum: actual_hash, |
| expected_checksum: expected, |
| })); |
| } |
| } |
| } |
| |
| (data, filetime::FileTime::from_last_modification_time(&file.metadata()?)) |
| }; |
| |
| let (state, checksum) = State::from_bytes(&data, mtime, object_hash, options)?; |
| let mut file = File { state, path, checksum }; |
| if let Some(mut link) = file.link.take() { |
| link.dissolve_into(&mut file, object_hash, skip_hash, options)?; |
| } |
| |
| Ok(file) |
| } |
| |
| /// Consume `state` and pretend it was read from `path`, setting our checksum to `null`. |
| /// |
| /// `File` instances created like that should be written to disk to set the correct checksum via `[File::write()]`. |
| pub fn from_state(state: State, path: impl Into<PathBuf>) -> Self { |
| File { |
| state, |
| path: path.into(), |
| checksum: None, |
| } |
| } |
| } |