1 files changed, 130 insertions, 0 deletions
diff --git a/vendor/gix-commitgraph/src/init.rs b/vendor/gix-commitgraph/src/init.rs
new file mode 100644
index 000000000..f964aade0
--- /dev/null
+++ b/vendor/gix-commitgraph/src/init.rs
@@ -0,0 +1,130 @@
+use std::{
+    convert::TryFrom,
+    io::{BufRead, BufReader},
+    path::{Path, PathBuf},
+};
+
+use crate::{file, File, Graph, MAX_COMMITS};
+
+/// The error returned by initializations functions like [`Graph::at()`].
+#[derive(thiserror::Error, Debug)]
+#[allow(missing_docs)]
+pub enum Error {
+    #[error("{}", .path.display())]
+    File {
+        #[source]
+        err: file::Error,
+        path: PathBuf,
+    },
+    #[error("Commit-graph files mismatch: '{}' uses hash {hash1:?}, but '{}' uses hash {hash2:?}", .path1.display(), .path2.display())]
+    HashVersionMismatch {
+        path1: PathBuf,
+        hash1: gix_hash::Kind,
+        path2: PathBuf,
+        hash2: gix_hash::Kind,
+    },
+    #[error("Did not find any files that look like commit graphs at '{}'", .0.display())]
+    InvalidPath(PathBuf),
+    #[error("Could not open commit-graph file at '{}'", .path.display())]
+    Io {
+        #[source]
+        err: std::io::Error,
+        path: PathBuf,
+    },
+    #[error(
+        "Commit-graph files contain {0} commits altogether, but only {} commits are allowed",
+        MAX_COMMITS
+    )]
+    TooManyCommits(u64),
+}
+
+/// Instantiate a `Graph` from various sources.
+impl Graph {
+    /// Instantiate a commit graph from `path` which may be a directory containing graph files or the graph file itself.
+    pub fn at(path: impl AsRef<Path>) -> Result<Self, Error> {
+        Self::try_from(path.as_ref())
+    }
+
+    /// Instantiate a commit graph from the directory containing all of its files.
+    pub fn from_commit_graphs_dir(path: impl AsRef<Path>) -> Result<Self, Error> {
+        let commit_graphs_dir = path.as_ref();
+        let chain_file_path = commit_graphs_dir.join("commit-graph-chain");
+        let chain_file = std::fs::File::open(&chain_file_path).map_err(|e| Error::Io {
+            err: e,
+            path: chain_file_path.clone(),
+        })?;
+        let mut files = Vec::new();
+        for line in BufReader::new(chain_file).lines() {
+            let hash = line.map_err(|e| Error::Io {
+                err: e,
+                path: chain_file_path.clone(),
+            })?;
+            let graph_file_path = commit_graphs_dir.join(format!("graph-{hash}.graph"));
+            files.push(File::at(&graph_file_path).map_err(|e| Error::File {
+                err: e,
+                path: graph_file_path.clone(),
+            })?);
+        }
+        Self::new(files)
+    }
+
+    /// Instantiate a commit graph from a `.git/objects/info/commit-graph` or
+    /// `.git/objects/info/commit-graphs/graph-*.graph` file.
+    pub fn from_file(path: impl AsRef<Path>) -> Result<Self, Error> {
+        let path = path.as_ref();
+        let file = File::at(path).map_err(|e| Error::File {
+            err: e,
+            path: path.to_owned(),
+        })?;
+        Self::new(vec![file])
+    }
+
+    /// Instantiate a commit graph from an `.git/objects/info` directory.
+    pub fn from_info_dir(info_dir: impl AsRef<Path>) -> Result<Self, Error> {
+        Self::from_file(info_dir.as_ref().join("commit-graph"))
+            .or_else(|_| Self::from_commit_graphs_dir(info_dir.as_ref().join("commit-graphs")))
+    }
+
+    /// Create a new commit graph from a list of `files`.
+    pub fn new(files: Vec<File>) -> Result<Self, Error> {
+        let num_commits: u64 = files.iter().map(|f| u64::from(f.num_commits())).sum();
+        if num_commits > u64::from(MAX_COMMITS) {
+            return Err(Error::TooManyCommits(num_commits));
+        }
+
+        for window in files.windows(2) {
+            let f1 = &window[0];
+            let f2 = &window[1];
+            if f1.object_hash() != f2.object_hash() {
+                return Err(Error::HashVersionMismatch {
+                    path1: f1.path().to_owned(),
+                    hash1: f1.object_hash(),
+                    path2: f2.path().to_owned(),
+                    hash2: f2.object_hash(),
+                });
+            }
+        }
+
+        Ok(Self { files })
+    }
+}
+
+impl TryFrom<&Path> for Graph {
+    type Error = Error;
+
+    fn try_from(path: &Path) -> Result<Self, Self::Error> {
+        if path.is_file() {
+            // Assume we are looking at `.git/objects/info/commit-graph` or
+            // `.git/objects/info/commit-graphs/graph-*.graph`.
+            Self::from_file(path)
+        } else if path.is_dir() {
+            if path.join("commit-graph-chain").is_file() {
+                Self::from_commit_graphs_dir(path)
+            } else {
+                Self::from_info_dir(path)
+            }
+        } else {
+            Err(Error::InvalidPath(path.to_owned()))
+        }
+    }
+}