1 files changed, 93 insertions, 0 deletions
diff --git a/src/git/repo.rs b/src/git/repo.rs
new file mode 100644
index 0000000..3fb8a16
--- /dev/null
+++ b/src/git/repo.rs
@@ -0,0 +1,93 @@
+// Copyright © 2022 Kim Altintop <kim@eagain.io>
+// SPDX-License-Identifier: GPL-2.0-only WITH openvpn-openssl-exception
+
+use std::{
+    collections::HashSet,
+    ffi::OsString,
+    io::{
+        BufReader,
+        Seek,
+        Write,
+    },
+    iter,
+    path::Path,
+    result::Result as StdResult,
+};
+
+use super::{
+    if_not_found_then,
+    Result,
+};
+use crate::{
+    fs::LockedFile,
+    io::Lines,
+};
+
+pub fn open<P: AsRef<Path>>(path: P) -> Result<git2::Repository> {
+    git2::Repository::open_ext(
+        path,
+        git2::RepositoryOpenFlags::FROM_ENV,
+        iter::empty::<OsString>(),
+    )
+}
+
+pub fn open_bare<P: AsRef<Path>>(path: P) -> Result<git2::Repository> {
+    git2::Repository::open_ext(
+        path,
+        git2::RepositoryOpenFlags::FROM_ENV | git2::RepositoryOpenFlags::BARE,
+        iter::empty::<OsString>(),
+    )
+}
+
+pub fn open_or_init<P: AsRef<Path>>(path: P, opts: InitOpts) -> Result<git2::Repository> {
+    if_not_found_then(open(path.as_ref()), || init(path, opts))
+}
+
+pub struct InitOpts<'a> {
+    pub bare: bool,
+    pub description: &'a str,
+    pub initial_head: &'a str,
+}
+
+pub fn init<P: AsRef<Path>>(path: P, opts: InitOpts) -> Result<git2::Repository> {
+    git2::Repository::init_opts(
+        path,
+        git2::RepositoryInitOptions::new()
+            .no_reinit(true)
+            .mkdir(true)
+            .mkpath(true)
+            .bare(opts.bare)
+            .description(opts.description)
+            .initial_head(opts.initial_head),
+    )
+}
+
+pub fn add_alternates<'a, I>(repo: &git2::Repository, alt: I) -> crate::Result<()>
+where
+    I: IntoIterator<Item = &'a git2::Repository>,
+{
+    let (mut persistent, known) = {
+        let mut lock = LockedFile::atomic(
+            repo.path().join("objects").join("info").join("alternates"),
+            false,
+            LockedFile::DEFAULT_PERMISSIONS,
+        )?;
+        lock.seek(std::io::SeekFrom::Start(0))?;
+        let mut bufread = BufReader::new(lock);
+        let known = Lines::new(&mut bufread).collect::<StdResult<HashSet<String>, _>>()?;
+        (bufread.into_inner(), known)
+    };
+    {
+        let odb = repo.odb()?;
+        for alternate in alt {
+            let path = format!("{}", alternate.path().join("objects").display());
+            odb.add_disk_alternate(&path)?;
+            if !known.contains(&path) {
+                writeln!(&mut persistent, "{}", path)?
+            }
+        }
+    }
+    persistent.persist()?;
+
+    Ok(())
+}