1 files changed, 67 insertions, 0 deletions
diff --git a/odb/streaming.h b/odb/streaming.h
new file mode 100644
index 0000000000..c7861f7e13
--- /dev/null
+++ b/odb/streaming.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2011, Google Inc.
+ */
+#ifndef STREAMING_H
+#define STREAMING_H 1
+
+#include "object.h"
+
+struct object_database;
+struct odb_read_stream;
+struct stream_filter;
+
+typedef int (*odb_read_stream_close_fn)(struct odb_read_stream *);
+typedef ssize_t (*odb_read_stream_read_fn)(struct odb_read_stream *, char *, size_t);
+
+/*
+ * A stream that can be used to read an object from the object database without
+ * loading all of it into memory.
+ */
+struct odb_read_stream {
+	odb_read_stream_close_fn close;
+	odb_read_stream_read_fn read;
+	enum object_type type;
+	unsigned long size; /* inflated size of full object */
+};
+
+/*
+ * Create a new object stream for the given object database. An optional filter
+ * can be used to transform the object's content.
+ *
+ * Returns the stream on success, a `NULL` pointer otherwise.
+ */
+struct odb_read_stream *odb_read_stream_open(struct object_database *odb,
+					     const struct object_id *oid,
+					     struct stream_filter *filter);
+
+/*
+ * Close the given read stream and release all resources associated with it.
+ * Returns 0 on success, a negative error code otherwise.
+ */
+int odb_read_stream_close(struct odb_read_stream *stream);
+
+/*
+ * Read data from the stream into the buffer. Returns 0 on EOF and the number
+ * of bytes read on success. Returns a negative error code in case reading from
+ * the stream fails.
+ */
+ssize_t odb_read_stream_read(struct odb_read_stream *stream, void *buf, size_t len);
+
+/*
+ * Look up the object by its ID and write the full contents to the file
+ * descriptor. The object must be a blob, or the function will fail. When
+ * provided, the filter is used to transform the blob contents.
+ *
+ * `can_seek` should be set to 1 in case the given file descriptor can be
+ * seek(3p)'d on. This is used to support files with holes in case a
+ * significant portion of the blob contains NUL bytes.
+ *
+ * Returns a negative error code on failure, 0 on success.
+ */
+int odb_stream_blob_to_fd(struct object_database *odb,
+			  int fd,
+			  const struct object_id *oid,
+			  struct stream_filter *filter,
+			  int can_seek);
+
+#endif /* STREAMING_H */