thodg/libgit2

diff --git a/include/git2/reflog.h b/include/git2/reflog.h
index 7f2781f..53b3447 100644
--- a/include/git2/reflog.h
+++ b/include/git2/reflog.h
@@ -91,7 +91,7 @@ GIT_EXTERN(const git_reflog_entry *) git_reflog_entry_byindex(git_reflog *reflog
  * @param entry a reflog entry
  * @return the old oid
  */
-GIT_EXTERN(char *) git_reflog_entry_oidold(const git_reflog_entry *entry);
+GIT_EXTERN(const git_oid *) git_reflog_entry_oidold(const git_reflog_entry *entry);
 
 /**
  * Get the new oid
@@ -99,7 +99,7 @@ GIT_EXTERN(char *) git_reflog_entry_oidold(const git_reflog_entry *entry);
  * @param entry a reflog entry
  * @return the new oid at this time
  */
-GIT_EXTERN(char *) git_reflog_entry_oidnew(const git_reflog_entry *entry);
+GIT_EXTERN(const git_oid *) git_reflog_entry_oidnew(const git_reflog_entry *entry);
 
 /**
  * Get the committer of this entry
diff --git a/src/reflog.c b/src/reflog.c
index 7609d9a..a2dea88 100644
--- a/src/reflog.c
+++ b/src/reflog.c
@@ -113,10 +113,12 @@ static int reflog_parse(git_reflog *log, const char *buf, size_t buf_size)
 		if (entry == NULL)
 			return GIT_ENOMEM;
 
-		entry->oid_old = git__strndup(buf, GIT_OID_HEXSZ);
+		if (git_oid_fromstrn(&entry->oid_old, buf, GIT_OID_HEXSZ) < GIT_SUCCESS)
+			return GIT_ERROR;
 		seek_forward(GIT_OID_HEXSZ + 1);
 
-		entry->oid_cur = git__strndup(buf, GIT_OID_HEXSZ);
+		if (git_oid_fromstrn(&entry->oid_cur, buf, GIT_OID_HEXSZ) < GIT_SUCCESS)
+			return GIT_ERROR;
 		seek_forward(GIT_OID_HEXSZ + 1);
 
 		ptr = buf;
@@ -165,9 +167,6 @@ void git_reflog_free(git_reflog *reflog)
 	for (i=0; i < reflog->entries.length; i++) {
 		entry = git_vector_get(&reflog->entries, i);
 
-		free(entry->oid_old);
-		free(entry->oid_cur);
-
 		git_signature_free(entry->committer);
 
 		free(entry->msg);
@@ -193,8 +192,10 @@ int git_reflog_read(git_reflog **reflog, git_reference *ref)
 
 	git_path_join_n(log_path, 3, ref->owner->path_repository, GIT_REFLOG_DIR, ref->name);
 
-	if ((error = git_futils_readbuffer(&log_file, log_path)) < GIT_SUCCESS)
+	if ((error = git_futils_readbuffer(&log_file, log_path)) < GIT_SUCCESS) {
+		git_reflog_free(log);
 		return git__rethrow(error, "Failed to read reflog. Cannot read file `%s`", log_path);
+	}
 
 	error = reflog_parse(log, log_file.data, log_file.len);
 
@@ -202,6 +203,8 @@ int git_reflog_read(git_reflog **reflog, git_reference *ref)
 
 	if (error == GIT_SUCCESS)
 		*reflog = log;
+	else
+		git_reflog_free(log);
 
 	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to read reflog");
 }
@@ -255,16 +258,16 @@ const git_reflog_entry * git_reflog_entry_byindex(git_reflog *reflog, unsigned i
 	return git_vector_get(&reflog->entries, idx);
 }
 
-char * git_reflog_entry_oidold(const git_reflog_entry *entry)
+const git_oid * git_reflog_entry_oidold(const git_reflog_entry *entry)
 {
 	assert(entry);
-	return entry->oid_old;
+	return &entry->oid_old;
 }
 
-char * git_reflog_entry_oidnew(const git_reflog_entry *entry)
+const git_oid * git_reflog_entry_oidnew(const git_reflog_entry *entry)
 {
 	assert(entry);
-	return entry->oid_cur;
+	return &entry->oid_cur;
 }
 
 git_signature * git_reflog_entry_committer(const git_reflog_entry *entry)
diff --git a/src/reflog.h b/src/reflog.h
index da352ca..b6daf2a 100644
--- a/src/reflog.h
+++ b/src/reflog.h
@@ -10,8 +10,8 @@
 #define GIT_REFLOG_SIZE_MIN (2*GIT_OID_HEXSZ+2+17)
 
 struct git_reflog_entry {
-	char *oid_old;
-	char *oid_cur;
+	git_oid oid_old;
+	git_oid oid_cur;
 
 	git_signature *committer;
 
diff --git a/tests/t10-refs.c b/tests/t10-refs.c
index f80c3f5..65fbdd6 100644
--- a/tests/t10-refs.c
+++ b/tests/t10-refs.c
@@ -1026,6 +1026,7 @@ BEGIN_TEST(reflog0, "write a reflog for a given reference and ensure it can be r
 	git_signature *committer;
 	git_reflog *reflog;
 	git_reflog_entry *entry;
+	char oid_str[GIT_OID_HEXSZ+1];
 
 	must_pass(open_temp_repo(&repo, REPOSITORY_FOLDER));
 
@@ -1037,6 +1038,7 @@ BEGIN_TEST(reflog0, "write a reflog for a given reference and ensure it can be r
 	must_pass(git_signature_now(&committer, "foo", "foo@bar"));
 
 	must_pass(git_reflog_write(ref, NULL, committer, NULL));
+	must_fail(git_reflog_write(ref, NULL, committer, "no ancestor NULL for an existing reflog"));
 	must_fail(git_reflog_write(ref, NULL, committer, "no\nnewline"));
 	must_pass(git_reflog_write(ref, &oid, committer, commit_msg));
 
@@ -1054,14 +1056,18 @@ BEGIN_TEST(reflog0, "write a reflog for a given reference and ensure it can be r
 
 	entry = (git_reflog_entry *)git_vector_get(&reflog->entries, 0);
 	must_pass(assert_signature(committer, entry->committer));
-	must_be_true(strcmp("0000000000000000000000000000000000000000", entry->oid_old) == 0);
-	must_be_true(strcmp(current_master_tip, entry->oid_cur) == 0);
+	git_oid_to_string(oid_str, GIT_OID_HEXSZ+1, &entry->oid_old);
+	must_be_true(strcmp("0000000000000000000000000000000000000000", oid_str) == 0);
+	git_oid_to_string(oid_str, GIT_OID_HEXSZ+1, &entry->oid_cur);
+	must_be_true(strcmp(current_master_tip, oid_str) == 0);
 	must_be_true(entry->msg == NULL);
 
 	entry = (git_reflog_entry *)git_vector_get(&reflog->entries, 1);
 	must_pass(assert_signature(committer, entry->committer));
-	must_be_true(strcmp(current_master_tip, entry->oid_old) == 0);
-	must_be_true(strcmp(current_master_tip, entry->oid_cur) == 0);
+	git_oid_to_string(oid_str, GIT_OID_HEXSZ+1, &entry->oid_old);
+	must_be_true(strcmp(current_master_tip, oid_str) == 0);
+	git_oid_to_string(oid_str, GIT_OID_HEXSZ+1, &entry->oid_cur);
+	must_be_true(strcmp(current_master_tip, oid_str) == 0);
 	must_be_true(strcmp(commit_msg, entry->msg) == 0);
 
 	git_signature_free(committer);