bare-bones loose object integrity check (#287)

Author: Byron

git-odb/src/store_impls/loose/verify.rs

@@ -1,5 +1,5 @@
-#![allow(missing_docs)]
 use crate::loose::Store;
+use crate::Write;
 
 ///
 pub mod integrity {
@@ -14,21 +14,49 @@ pub mod integrity {
             id: git_hash::ObjectId,
         },
         #[error("{kind} object {expected} wasn't re-encoded without change - new hash is {actual}")]
-        ObjectEncodeMismatch {
+        ObjectHashMismatch {
             kind: git_object::Kind,
             actual: git_hash::ObjectId,
             expected: git_hash::ObjectId,
         },
+        #[error("Objects were deleted during iteration - try again")]
+        Retry,
     }
 
+    /// The outcome returned by [`verify_integrity()`][super::Store::verify_integrity()].
     pub struct Outcome {
         /// The amount of loose objects we checked.
         pub num_objects: usize,
     }
 }
 
 impl Store {
+    /// Check all loose objects for their integrity checking their hash matches the actual data and by decoding them fully.
     pub fn verify_integrity(&self) -> Result<integrity::Outcome, integrity::Error> {
-        todo!()
+        let mut buf = Vec::new();
+        let mut num_objects = 0;
+        let sink = crate::sink(self.object_hash);
+
+        for id in self.iter().filter_map(Result::ok) {
+            let object = self
+                .try_find(id, &mut buf)
+                .map_err(|_| integrity::Error::Retry)?
+                .ok_or(integrity::Error::Retry)?;
+            let actual_id = sink.write_buf(object.kind, object.data).expect("sink never fails");
+            if actual_id != id {
+                return Err(integrity::Error::ObjectHashMismatch {
+                    kind: object.kind,
+                    actual: actual_id,
+                    expected: id,
+                });
+            }
+            object.decode().map_err(|err| integrity::Error::ObjectDecode {
+                source: err,
+                kind: object.kind,
+                id,
+            })?;
+            num_objects += 1;
+        }
+        Ok(integrity::Outcome { num_objects })
     }
 }

git-odb/tests/odb/store/loose.rs

@@ -33,11 +33,10 @@ pub fn locate_oid(id: git_hash::ObjectId, buf: &mut Vec<u8>) -> git_object::Data
 }
 
 #[test]
-#[ignore]
 fn verify_integrity() {
     let db = ldb();
     let outcome = db.verify_integrity().unwrap();
-    assert_eq!(outcome.num_objects, 42);
+    assert_eq!(outcome.num_objects, 7);
 }
 
 mod write {