filters: introduce streaming filters

Add structures and preliminary functions to take a buffer, file or
blob and write the contents in chunks through an arbitrary number
of chained filters, finally writing into a user-provided function
accept the contents.

3 files changed, 33 insertions, 0 deletions

diff --git a/include/git2/filter.h b/include/git2/filter.h
index 5b3f40394..600356c71 100644
--- a/include/git2/filter.h
+++ b/include/git2/filter.h
@@ -137,6 +137,22 @@ GIT_EXTERN(int) git_filter_list_apply_to_blob(
 	git_filter_list *filters,
 	git_blob *blob);
 
+GIT_EXTERN(int) git_filter_list_stream_data(
+	git_filter_list *filters,
+	git_buf *data,
+	git_filter_stream *target);
+
+GIT_EXTERN(int) git_filter_list_stream_file(
+	git_filter_list *filters,
+	git_repository *repo,
+	const char *path,
+	git_filter_stream *target);
+
+GIT_EXTERN(int) git_filter_list_stream_blob(
+	git_filter_list *filters,
+	git_blob *blob,
+	git_filter_stream *target);
+
 /**
  * Free a git_filter_list
  *
diff --git a/include/git2/sys/filter.h b/include/git2/sys/filter.h
index 60248271a..cc06c54ad 100644
--- a/include/git2/sys/filter.h
+++ b/include/git2/sys/filter.h
@@ -208,6 +208,19 @@ typedef int (*git_filter_apply_fn)(
 	const git_buf *from,
 	const git_filter_source *src);
 
+struct git_filter_stream {
+	int (*write)(git_filter_stream *stream, const char *buffer, size_t len);
+	int (*close)(git_filter_stream *stream);
+	void (*free)(git_filter_stream *stream);
+};
+
+typedef int (*git_filter_stream_fn)(
+	git_filter_stream **out,
+	git_filter *self,
+	void **payload,
+	const git_filter_source *src,
+	git_filter_stream *next);
+
 /**
  * Callback to clean up after filtering has been applied
  *
@@ -247,6 +260,7 @@ struct git_filter {
 	git_filter_shutdown_fn shutdown;
 	git_filter_check_fn    check;
 	git_filter_apply_fn    apply;
+	git_filter_stream_fn   stream;
 	git_filter_cleanup_fn  cleanup;
 };
 
diff --git a/include/git2/types.h b/include/git2/types.h
index 35e1573c7..3ed97d189 100644
--- a/include/git2/types.h
+++ b/include/git2/types.h
@@ -410,6 +410,9 @@ typedef enum {
 	GIT_SUBMODULE_RECURSE_ONDEMAND = 2,
 } git_submodule_recurse_t;
 
+/** A stream to write filters. */
+typedef struct git_filter_stream git_filter_stream;
+
 /** @} */
 GIT_END_DECL