From 801b1a160558ed8b862e683c7aaf5092b0c1adb2 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 28 Jul 2019 13:21:33 +0100
Subject: Support working tree based on a commit, tag or branch

---
 src/git.cpp  | 10 ++++++++++
 src/git.h    |  7 ++++++-
 src/repo.cpp | 16 ++++++++++++++--
 src/repo.h   |  4 +++-
 4 files changed, 33 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/git.cpp b/src/git.cpp
index 045d146..b169fa2 100644
--- a/src/git.cpp
+++ b/src/git.cpp
@@ -63,6 +63,16 @@ namespace GitFS {
 			return gitSafeGet<NetFS::SystemError>(
 					git_tree_entry_bypath, git_tree_entry_free, tree.get(), path.c_str() + 1);
 		}
+		RefPtr Commitish(const RepositoryPtr & repo, const std::string & name)
+		{
+			return gitSafeGet<NetFS::ConfigError>(
+					git_reference_dwim, git_reference_free, repo.get(), name.c_str());
+		}
+		RefPtr Resolve(const RefPtr & ref)
+		{
+			return gitSafeGet<NetFS::ConfigError>(
+					git_reference_resolve, git_reference_free, ref.get());
+		}
 	}
 }
 
diff --git a/src/git.h b/src/git.h
index 56a7cf6..068e8cf 100644
--- a/src/git.h
+++ b/src/git.h
@@ -14,7 +14,7 @@ namespace GitFS {
 		void
 		gitSafe(int (*func)(P...), A ... p)
 		{
-			if (int _giterror = func(p...); _giterror != 0) {
+			if (int _giterror = func(p...)) {
 				throwError<E>(_giterror);
 			}
 		}
@@ -61,6 +61,11 @@ namespace GitFS {
 		using TreeEntryPtr = decltype(gitSafeGet<std::exception>(
 					git_tree_entry_bypath, git_tree_entry_free, nullptr, nullptr));
 		TreeEntryPtr TreeEntryByPath(const TreePtr & tree, const std::string & path);
+
+		using RefPtr = decltype(gitSafeGet<std::exception>(
+					git_reference_dwim, git_reference_free, nullptr, nullptr));
+		RefPtr Commitish(const RepositoryPtr & repo, const std::string & name);
+		RefPtr Resolve(const RefPtr &);
 	}
 }
 
diff --git a/src/repo.cpp b/src/repo.cpp
index 4059897..0da7e4a 100644
--- a/src/repo.cpp
+++ b/src/repo.cpp
@@ -11,11 +11,23 @@ std::string operator/(const std::string & a, const std::string & b)
 
 GitFS::Repo::Repo(const PropertyReader & properties) :
 	repo(Git::RepositoryOpenBare(properties("gitdir"))),
-	commit(Git::CommitLookup(repo, Git::OidParse(properties("commit")))),
-	tree(Git::TreeLookup(repo, *git_commit_tree_id(commit.get()))),
+	commitish(properties("commitish") / "master"),
 	gid(properties("gid") / "root"),
 	uid(properties("uid") / "root")
 {
+	git_oid commitId;
+	if (commitish.length() == GIT_OID_HEXSZ) {
+		commitId = Git::OidParse(commitish);
+	}
+	else {
+		auto ref = Git::Commitish(repo, commitish);
+		isBranch = git_reference_is_branch(ref.get());
+		ref = Git::Resolve(ref);
+		commitId = *git_reference_target(ref.get());
+	}
+
+	commit = Git::CommitLookup(repo, commitId);
+	tree = Git::TreeLookup(repo, *git_commit_tree_id(commit.get()));
 }
 
 void
diff --git a/src/repo.h b/src/repo.h
index 18b1057..adeac94 100644
--- a/src/repo.h
+++ b/src/repo.h
@@ -35,7 +35,9 @@ namespace GitFS {
 		private:
 			friend class Directory;
 			friend class Blob;
-			Git::RepositoryPtr repo;
+			const Git::RepositoryPtr repo;
+			const std::string commitish;
+			bool isBranch;
 			Git::CommitPtr commit;
 			Git::TreePtr tree;
 			const std::string gid, uid;
-- 
cgit v1.2.3