4 files changed, 263 insertions, 0 deletions
diff --git a/vendor/gix-index/src/file/init.rs b/vendor/gix-index/src/file/init.rs
new file mode 100644
index 000000000..534f1f08b
--- /dev/null
+++ b/vendor/gix-index/src/file/init.rs
@@ -0,0 +1,81 @@
+#![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.
+    ///
+    /// 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,
+        options: decode::Options,
+    ) -> Result<Self, Error> {
+        let path = path.into();
+        Ok(match Self::at(&path, object_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.
+    pub fn at(path: impl Into<PathBuf>, object_hash: gix_hash::Kind, options: decode::Options) -> Result<Self, Error> {
+        let path = path.into();
+        let (data, mtime) = {
+            // SAFETY: we have to take the risk of somebody changing the file underneath. Git never writes into the same file.
+            let file = std::fs::File::open(&path)?;
+            #[allow(unsafe_code)]
+            let data = unsafe { Mmap::map(&file)? };
+            (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: Some(checksum),
+        };
+        if let Some(mut link) = file.link.take() {
+            link.dissolve_into(&mut file, object_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: crate::State, path: impl Into<PathBuf>) -> Self {
+        File {
+            state,
+            path: path.into(),
+            checksum: None,
+        }
+    }
+}
diff --git a/vendor/gix-index/src/file/mod.rs b/vendor/gix-index/src/file/mod.rs
new file mode 100644
index 000000000..40332abbd
--- /dev/null
+++ b/vendor/gix-index/src/file/mod.rs
@@ -0,0 +1,90 @@
+mod impls {
+    use std::ops::{Deref, DerefMut};
+
+    use crate::{File, State};
+
+    impl Deref for File {
+        type Target = State;
+
+        fn deref(&self) -> &Self::Target {
+            &self.state
+        }
+    }
+
+    impl DerefMut for File {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.state
+        }
+    }
+}
+
+mod impl_ {
+    use std::fmt::Formatter;
+
+    use crate::{File, State};
+
+    impl std::fmt::Debug for File {
+        fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+            f.debug_struct("File")
+                .field("path", &self.path.display())
+                .field("checksum", &self.checksum)
+                .finish_non_exhaustive()
+        }
+    }
+
+    impl From<File> for State {
+        fn from(f: File) -> Self {
+            f.state
+        }
+    }
+}
+
+mod access {
+    use crate::File;
+
+    /// Consumption
+    impl File {
+        /// Take all non-copy parts of the index.
+        pub fn into_parts(self) -> (crate::State, std::path::PathBuf) {
+            (self.state, self.path)
+        }
+    }
+
+    /// Access
+    impl File {
+        /// The path from which the index was read or to which it is supposed to be written when used with [`File::from_state()`].
+        pub fn path(&self) -> &std::path::Path {
+            &self.path
+        }
+
+        /// The checksum over the file that was read or written to disk, or `None` if the state in memory was never serialized.
+        ///
+        /// Note that even if `Some`, it will only represent the state in memory right after reading or [writing][File::write()].
+        pub fn checksum(&self) -> Option<gix_hash::ObjectId> {
+            self.checksum
+        }
+    }
+}
+
+mod mutation {
+    use std::path::PathBuf;
+
+    use crate::File;
+
+    /// Mutating access
+    impl File {
+        /// Set the path at which we think we are located to the given `path`.
+        ///
+        /// This is useful to change the location of the index *once* it is written via [`write()`][File::write()].
+        pub fn set_path(&mut self, path: impl Into<PathBuf>) {
+            self.path = path.into();
+        }
+    }
+}
+
+///
+pub mod init;
+///
+pub mod verify;
+///
+pub mod write;
diff --git a/vendor/gix-index/src/file/verify.rs b/vendor/gix-index/src/file/verify.rs
new file mode 100644
index 000000000..6743b37a7
--- /dev/null
+++ b/vendor/gix-index/src/file/verify.rs
@@ -0,0 +1,41 @@
+use std::sync::atomic::AtomicBool;
+
+use crate::File;
+
+mod error {
+    /// The error returned by [File::verify_integrity()][super::File::verify_integrity()].
+    #[derive(Debug, thiserror::Error)]
+    #[allow(missing_docs)]
+    pub enum Error {
+        #[error("Could not read index file to generate hash")]
+        Io(#[from] std::io::Error),
+        #[error("Index checksum should have been {expected}, but was {actual}")]
+        ChecksumMismatch {
+            actual: gix_hash::ObjectId,
+            expected: gix_hash::ObjectId,
+        },
+        #[error("Checksum of in-memory index wasn't computed yet")]
+        NoChecksum,
+    }
+}
+pub use error::Error;
+
+impl File {
+    /// Verify the integrity of the index to assure its consistency.
+    pub fn verify_integrity(&self) -> Result<(), Error> {
+        let checksum = self.checksum.ok_or(Error::NoChecksum)?;
+        let num_bytes_to_hash = self.path.metadata()?.len() - checksum.as_bytes().len() as u64;
+        let should_interrupt = AtomicBool::new(false);
+        let actual = gix_features::hash::bytes_of_file(
+            &self.path,
+            num_bytes_to_hash as usize,
+            checksum.kind(),
+            &mut gix_features::progress::Discard,
+            &should_interrupt,
+        )?;
+        (actual == checksum).then_some(()).ok_or(Error::ChecksumMismatch {
+            actual,
+            expected: checksum,
+        })
+    }
+}
diff --git a/vendor/gix-index/src/file/write.rs b/vendor/gix-index/src/file/write.rs
new file mode 100644
index 000000000..1e8afc07d
--- /dev/null
+++ b/vendor/gix-index/src/file/write.rs
@@ -0,0 +1,51 @@
+use gix_features::hash;
+
+use crate::{write, File, Version};
+
+/// The error produced by [`File::write()`].
+#[derive(Debug, thiserror::Error)]
+#[allow(missing_docs)]
+pub enum Error {
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+    #[error("Could not acquire lock for index file")]
+    AcquireLock(#[from] gix_lock::acquire::Error),
+    #[error("Could not commit lock for index file")]
+    CommitLock(#[from] gix_lock::commit::Error<gix_lock::File>),
+}
+
+impl File {
+    /// Write the index to `out` with `options`, to be readable by [`File::at()`], returning the version that was actually written
+    /// to retain all information of this index.
+    pub fn write_to(
+        &self,
+        mut out: impl std::io::Write,
+        options: write::Options,
+    ) -> std::io::Result<(Version, gix_hash::ObjectId)> {
+        let mut hasher = hash::Write::new(&mut out, self.state.object_hash);
+        let version = self.state.write_to(&mut hasher, options)?;
+
+        let hash = hasher.hash.digest();
+        out.write_all(&hash)?;
+        Ok((version, gix_hash::ObjectId::from(hash)))
+    }
+
+    /// Write ourselves to the path we were read from after acquiring a lock, using `options`.
+    ///
+    /// Note that the hash produced will be stored which is why we need to be mutable.
+    pub fn write(&mut self, options: write::Options) -> Result<(), Error> {
+        let mut lock = std::io::BufWriter::new(gix_lock::File::acquire_to_update_resource(
+            &self.path,
+            gix_lock::acquire::Fail::Immediately,
+            None,
+        )?);
+        let (version, digest) = self.write_to(&mut lock, options)?;
+        match lock.into_inner() {
+            Ok(lock) => lock.commit()?,
+            Err(err) => return Err(err.into_error().into()),
+        };
+        self.state.version = version;
+        self.checksum = Some(digest);
+        Ok(())
+    }
+}