indexwriter: an indexwriter for repo operations

Provide git_indexwriter_init_for_operation for the common locking
pattern in merge, rebase, revert and cherry-pick.

1 files changed, 32 insertions, 0 deletions

diff --git a/src/index.c b/src/index.c
index 58575fec3..6c01b40f2 100644
--- a/src/index.c
+++ b/src/index.c
@@ -2669,6 +2669,8 @@ int git_indexwriter_init(
 {
 	int error;
 
+	GIT_REFCOUNT_INC(index);
+
 	writer->index = index;
 
 	if (!index->index_file_path)
@@ -2677,12 +2679,33 @@ int git_indexwriter_init(
 
 	if ((error = git_filebuf_open(
 		&writer->file, index->index_file_path, GIT_FILEBUF_HASH_CONTENTS, GIT_INDEX_FILE_MODE)) < 0) {
+
 		if (error == GIT_ELOCKED)
 			giterr_set(GITERR_INDEX, "The index is locked. This might be due to a concurrent or crashed process");
 
 		return error;
 	}
 
+	writer->should_write = 1;
+
+	return 0;
+}
+
+int git_indexwriter_init_for_operation(
+	git_indexwriter *writer,
+	git_repository *repo,
+	unsigned int *checkout_strategy)
+{
+	git_index *index;
+	int error;
+
+	if ((error = git_repository_index__weakptr(&index, repo)) < 0 ||
+		(error = git_indexwriter_init(writer, index)) < 0)
+		return error;
+
+	writer->should_write = (*checkout_strategy & GIT_CHECKOUT_DONT_WRITE_INDEX) == 0;
+	*checkout_strategy |= GIT_CHECKOUT_DONT_WRITE_INDEX;
+
 	return 0;
 }
 
@@ -2690,6 +2713,9 @@ int git_indexwriter_commit(git_indexwriter *writer)
 {
 	int error;
 
+	if (!writer->should_write)
+		return 0;
+
 	if (index_sort_if_needed(writer->index, true) < 0)
 		return -1;
 
@@ -2711,10 +2737,16 @@ int git_indexwriter_commit(git_indexwriter *writer)
 
 	writer->index->on_disk = 1;
 
+	git_index_free(writer->index);
+	writer->index = NULL;
+
 	return 0;
 }
 
 void git_indexwriter_cleanup(git_indexwriter *writer)
 {
 	git_filebuf_cleanup(&writer->file);
+
+	git_index_free(writer->index);
+	writer->index = NULL;
 }