feat: git object deserialization

rust/vcs/src/git/objects.rs

@@ -1,3 +1,6 @@
+use std::collections::HashMap;
+use std::fmt::format;
+use std::io::Bytes;
 
 pub(crate) trait BinSerializable {
     /// Read git object contents without header or compression.
@@ -44,3 +47,144 @@ impl BinSerializable for GitBlob {
         self.data
     }
 }
+
+// https://wyag.thb.lt/#orgfe2859f
+pub struct GitCommit {
+    /// Reference to a tree object.
+    tree: String,
+    /// References to commits this commit is based on.
+    ///
+    /// - merge commits may have multiple
+    /// - the first commit may have none
+    parent: Vec<String>,
+    author: String,
+    commiter: String,
+    /// PGP signature of the object.
+    gpgsig: String,
+}
+
+/// Recursively parse a Key-Value List with Message.
+///
+/// Returns keys and values in the order they were parsed and the message with a
+/// `__message__` key.
+fn kvlm_parse(mut raw: Bytes<&[u8]>) -> Vec<(String, String)> {
+    // https://git-scm.com/book/en/v2/Git-Internals-Git-Objects#_git_commit_objects
+    let mut lines = Vec::new();
+    {
+        let mut line = String::new();
+        while let Some(Ok(byte)) = raw.next() {
+            line.push(char::from(byte));
+            if byte == b'\n' {
+                lines.push(line);
+                line = String::new();
+            }
+        }
+        lines.push(line);
+    }
+
+    let mut kv_entries = Vec::new();
+    let mut in_message_block = false;
+    {
+        let mut key: Option<String> = None;
+        let mut value = String::new();
+        for line in lines {
+            print!("{}, {}", in_message_block, &line);
+            if in_message_block {
+                value.push_str(line.as_str());
+            } else if line.starts_with(" ") || line.is_empty() {
+                // Value continues in this line
+                value.push_str(line.as_str());
+            } else if line == "\n" {
+                // Start message block
+                if let Some(last_key) = key {
+                    let last_value = value.replace("\n ", "\n");
+                    kv_entries.push((last_key, last_value));
+                    value = String::new();
+                    key = None;
+                }
+                in_message_block = true;
+                value = String::new();
+
+            } else {
+                // New value: save old kv and start new
+                if let Some(last_key) = key {
+                    let last_value = value.replace("\n ", "\n");
+                    kv_entries.push((last_key, last_value));
+                    value = String::new();
+                    key = None;
+                }
+                if let Some((k, v)) = line.split_once(" ") {
+                    key = Some(k.to_string());
+                    assert!(value.is_empty());
+                    value = v.to_string();
+                } // non conformant lines are ignored as comments
+            }
+
+        }
+
+        if in_message_block {
+            kv_entries.push((String::from("__message__"), value));
+        }
+    }
+
+    kv_entries
+}
+
+fn kvlm_serialize(kvlm: Vec<(String, String)>) -> Vec<u8> { // TODO: test
+    let mut out = String::new();
+    for (k, v) in kvlm {
+        let v = v.replace("\n", "\n ");
+        if k == "__message__" {
+            out.push_str(format!("\n{v}").as_str())
+        } else {
+            out.push_str(format!("{k} {v} \n").as_str());
+        }
+    }
+    out.as_bytes().to_vec()
+}
+
+#[cfg(test)]
+mod tests {
+    use std::io::Read;
+    use crate::git::objects::kvlm_parse;
+
+    #[test]
+    fn kvlm_parses() {
+        let parsed = kvlm_parse("tree 29ff16c9c14e2652b22f8b78bb08a5a07930c147
+parent 206941306e8a8af65b66eaaaea388a7ae24d49a0
+author Thibault Polge <[email protected]> 1527025023 +0200
+committer Thibault Polge <[email protected]> 1527025044 +0200
+gpgsig -----BEGIN PGP SIGNATURE-----\n \n iQIzBAABCAAdFiEExwXquOM8bWb4Q2zVGxM2FxoLkGQFAlsEjZQACgkQGxM2FxoL
+ kGQdcBAAqPP+ln4nGDd2gETXjvOpOxLzIMEw4A9gU6CzWzm+oB8mEIKyaH0UFIPh
+ rNUZ1j7/ZGFNeBDtT55LPdPIQw4KKlcf6kC8MPWP3qSu3xHqx12C5zyai2duFZUU
+ wqOt9iCFCscFQYqKs3xsHI+ncQb+PGjVZA8+jPw7nrPIkeSXQV2aZb1E68wa2YIL
+ 3eYgTUKz34cB6tAq9YwHnZpyPx8UJCZGkshpJmgtZ3mCbtQaO17LoihnqPn4UOMr
+ V75R/7FjSuPLS8NaZF4wfi52btXMSxO/u7GuoJkzJscP3p4qtwe6Rl9dc1XC8P7k
+ NIbGZ5Yg5cEPcfmhgXFOhQZkD0yxcJqBUcoFpnp2vu5XJl2E5I/quIyVxUXi6O6c
+ /obspcvace4wy8uO0bdVhc4nJ+Rla4InVSJaUaBeiHTW8kReSFYyMmDCzLjGIu1q
+ doU61OM3Zv1ptsLu3gUE6GU27iWYj2RWN3e3HE4Sbd89IFwLXNdSuM0ifDLZk7AQ
+ WBhRhipCCgZhkj9g2NEk7jRVslti1NdN5zoQLaJNqSwO1MtxTmJ15Ksk3QP6kfLB
+ Q52UWybBzpaP9HEd4XnR+HuQ4k2K0ns2KgNImsNvIyFwbpMUyUWLMPimaV1DWUXo
+ 5SBjDB/V/W2JBFR+XKHFJeFwYhj7DD/ocsGr4ZMx/lgc8rjIBkI=
+ =lgTX
+ -----END PGP SIGNATURE-----
+
+Create first draft".as_bytes().bytes());
+        // TODO: verify \n is wanted
+        assert_eq!(parsed.get(0).unwrap().0, "tree");
+        assert_eq!(parsed.get(0).unwrap().1, "29ff16c9c14e2652b22f8b78bb08a5a07930c147\n");
+        assert_eq!(parsed.get(1).unwrap().0, "parent");
+        assert_eq!(parsed.get(1).unwrap().1, "206941306e8a8af65b66eaaaea388a7ae24d49a0\n");
+        assert_eq!(parsed.get(2).unwrap().0, "author");
+        assert_eq!(parsed.get(2).unwrap().1, "Thibault Polge <[email protected]> 1527025023 +0200\n");
+        assert_eq!(parsed.get(3).unwrap().0, "committer");
+        assert_eq!(parsed.get(3).unwrap().1, "Thibault Polge <[email protected]> 1527025044 +0200\n");
+        assert_eq!(parsed.get(4).unwrap().0, "gpgsig");
+        let v4 = parsed.get(4).unwrap().1.clone();
+        assert!(v4.clone().contains("-----BEGIN PGP SIGNATURE-----"));
+        assert!(v4.clone().contains("iQIzBAABCAAdFiEExwXquOM8bWb4Q2zVGxM2FxoLkGQFAlsEjZQACgkQGxM2FxoL"));
+        assert!(v4.contains("-----END PGP SIGNATURE-----"));
+        assert_eq!(parsed.get(5).unwrap().0, "__message__");
+        assert_eq!(parsed.get(5).unwrap().1, "Create first draft");
+    }
+}

rust/vcs/src/git/repo.rs

@@ -146,7 +146,7 @@ impl Repository {
                 let mut data = data.bytes();
                 let mut obj_type = String::new();
                 while let Some(Ok(byte)) = data.next() {
-                    if byte == 20 {
+                    if byte == b' ' {
                         break;
                     }
                     obj_type.push(char::from(byte));