This is it

Squashed commit of all the exploration history. Development starts here.

Signed-off-by: Kim Altintop <kim@eagain.io>

1 files changed, 111 insertions, 0 deletions

diff --git a/src/git.rs b/src/git.rs
new file mode 100644
index 0000000..f837711
--- /dev/null
+++ b/src/git.rs
@@ -0,0 +1,111 @@
+// Copyright © 2022 Kim Altintop <kim@eagain.io>
+// SPDX-License-Identifier: GPL-2.0-only WITH openvpn-openssl-exception
+
+use std::process::{
+    self,
+    Command,
+};
+
+use anyhow::{
+    anyhow,
+    ensure,
+    Context,
+};
+use once_cell::sync::Lazy;
+use sha2::{
+    Digest,
+    Sha256,
+};
+
+mod commit;
+pub use commit::{
+    commit_signed,
+    verify_commit_signature,
+};
+
+pub mod config;
+
+pub mod refs;
+pub use refs::{
+    ReferenceNames,
+    Refname,
+};
+pub mod repo;
+pub use repo::add_alternates;
+pub mod serde;
+
+pub static EMPTY_TREE: Lazy<git2::Oid> =
+    Lazy::new(|| git2::Oid::from_str("4b825dc642cb6eb9a060e54bf8d69288fbee4904").unwrap());
+
+pub type Result<T> = core::result::Result<T, git2::Error>;
+
+pub fn empty_tree(repo: &git2::Repository) -> Result<git2::Tree> {
+    repo.find_tree(*EMPTY_TREE)
+}
+
+pub fn if_not_found_none<T>(r: Result<T>) -> Result<Option<T>> {
+    if_not_found_then(r.map(Some), || Ok(None))
+}
+
+pub fn if_not_found_then<F, T>(r: Result<T>, f: F) -> Result<T>
+where
+    F: FnOnce() -> Result<T>,
+{
+    r.or_else(|e| match e.code() {
+        git2::ErrorCode::NotFound => f(),
+        _ => Err(e),
+    })
+}
+
+pub fn blob_hash(data: &[u8]) -> Result<git2::Oid> {
+    // very minimally faster than going through libgit2. not sure yet if that's
+    // worth the dependency.
+    #[cfg(feature = "sha1dc")]
+    {
+        use sha1collisiondetection::Sha1CD;
+
+        let mut hasher = Sha1CD::default();
+        hasher.update("blob ");
+        hasher.update(data.len().to_string().as_bytes());
+        hasher.update(b"\0");
+        hasher.update(data);
+        let hash = hasher.finalize_cd().expect("sha1 collision detected");
+        git2::Oid::from_bytes(&hash)
+    }
+    #[cfg(not(feature = "sha1dc"))]
+    git2::Oid::hash_object(git2::ObjectType::Blob, data)
+}
+
+pub fn blob_hash_sha2(data: &[u8]) -> [u8; 32] {
+    let mut hasher = Sha256::new();
+    hasher.update("blob ");
+    hasher.update(data.len().to_string().as_bytes());
+    hasher.update(b"\0");
+    hasher.update(data);
+    hasher.finalize().into()
+}
+
+/// Look up `key` from config and run the value as a command
+pub fn config_command(cfg: &git2::Config, key: &str) -> crate::Result<Option<String>> {
+    if_not_found_none(cfg.get_string(key))?
+        .map(|cmd| {
+            let process::Output { status, stdout, .. } = {
+                let invalid = || anyhow!("'{cmd}' is not a valid command");
+                let lex = shlex::split(&cmd).ok_or_else(invalid)?;
+                let (bin, args) = lex.split_first().ok_or_else(invalid)?;
+                Command::new(bin)
+                    .args(args)
+                    .stderr(process::Stdio::inherit())
+                    .output()?
+            };
+            ensure!(status.success(), "'{cmd}' failed");
+            const NL: u8 = b'\n';
+            let line1 = stdout
+                .into_iter()
+                .take_while(|b| b != &NL)
+                .collect::<Vec<_>>();
+            ensure!(!line1.is_empty(), "no output from '{cmd}'");
+            String::from_utf8(line1).with_context(|| format!("invalid output from '{cmd}'"))
+        })
+        .transpose()
+}