Initial support for efficient sub-file incrementals.

[cumulus.git] / chunk.h

diff --git a/chunk.h b/chunk.h
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+/* Cumulus: Smart Filesystem Backup to Dumb Servers
+ *
+ * Copyright (C) 2006-2008  The Regents of the University of California
+ * Written by Michael Vrable <mvrable@cs.ucsd.edu>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* Compute incremental backups at a sub-file level by chopping files up into
+ * blocks in a content-sensitive manner (using Rabin fingerprints). */
+
+#ifndef _LBS_CHUNK_H
+#define _LBS_CHUNK_H
+
+#include <stdint.h>
+#include <string>
+
+/* Block breakpoints can only be computed for a single block of memory, all
+ * loaded at once.  compute_breaks will, given a block of memory, compute the
+ * offsets at which successive blocks should end.  These will be stored into
+ * the provided memory at breakpoints.  The maximum possible number of blocks
+ * (given the block size constaints) can be computed by compute_max_num_breaks
+ * so that the breakpoints array can be properly sized.  The actual number of
+ * blocks is returned by the compute_breaks function. */
+int chunk_compute_max_num_breaks(size_t buflen);
+int chunk_compute_breaks(const char *buf, size_t len, size_t *breakpoints);
+std::string chunk_algorithm_name();
+
+#endif // _LBS_CHUNK_H