-/* LBS: An LFS-inspired filesystem backup system
- * Copyright (C) 2006 Michael Vrable
+/* Cumulus: Smart Filesystem Backup to Dumb Servers
*
- * Backup data is stored in a collection of objects, which are grouped together
- * into segments for storage purposes. This file provides interfaces for
- * reading and writing objects and segments. */
+ * 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.
+ */
+
+/* Backup data is stored in a collection of objects, which are grouped together
+ * into segments for storage purposes. This implementation of the object store
+ * represents segments as TAR files and objects as files within them. */
+
+#ifndef _LBS_STORE_H
+#define _LBS_STORE_H
#include <stdint.h>
-#include <exception>
+#include <list>
#include <map>
+#include <set>
#include <string>
+#include <iostream>
#include <sstream>
+#include "localdb.h"
+#include "remote.h"
+#include "sha1.h"
+#include "ref.h"
+
+class LbsObject;
+
+/* In memory datatype to represent key/value pairs of information, such as file
+ * metadata. Currently implemented as map<string, string>. */
typedef std::map<std::string, std::string> dictionary;
+/* IOException will be thrown if an error occurs while reading or writing in
+ * one of the I/O wrappers. Depending upon the context; this may be fatal or
+ * not--typically, errors reading/writing the store will be serious, but errors
+ * reading an individual file are less so. */
class IOException : public std::exception {
private:
std::string error;
std::string getError() const { return error; }
};
-class OutputStream {
+/* Simplified TAR header--we only need to store regular files, don't need to
+ * handle long filenames, etc. */
+static const int TAR_BLOCK_SIZE = 512;
+
+struct tar_header
+{
+ char name[100];
+ char mode[8];
+ char uid[8];
+ char gid[8];
+ char size[12];
+ char mtime[12];
+ char chksum[8];
+ char typeflag;
+ char linkname[100];
+ char magic[8];
+ char uname[32];
+ char gname[32];
+ char devmajor[8];
+ char devminor[8];
+ char prefix[155];
+ char padding[12];
+};
+
+/* A simple wrapper around a single TAR file to represent a segment. Objects
+ * may only be written out all at once, since the tar header must be written
+ * first; incremental writing is not supported. */
+class Tarfile {
public:
- virtual ~OutputStream() { }
- virtual void write(const void *data, size_t len) = 0;
+ Tarfile(RemoteFile *file, const std::string &segment);
+ ~Tarfile();
+
+ void write_object(int id, const char *data, size_t len);
+
+ // Return an estimate of the size of the file.
+ size_t size_estimate();
- /* Convenience functions for writing other data types. Values are always
- * written out in little-endian order. */
- void write_u8(uint8_t val);
- void write_u16(uint16_t val);
- void write_u32(uint32_t val);
- void write_u64(uint64_t val);
+private:
+ size_t size;
+ std::string segment_name;
- void write_s32(int32_t val) { write_u32((uint32_t)val); }
- void write_s64(int64_t val) { write_u64((uint64_t)val); }
+ RemoteFile *file;
- void write_varint(uint64_t val);
+ /* Filter support. */
+ int real_fd, filter_fd;
+ pid_t filter_pid;
- void write_string(const std::string &s);
- void write_dictionary(const dictionary &d);
+ // Write data to the tar file
+ void tar_write(const char *data, size_t size);
};
-class StringOutputStream : public OutputStream {
-private:
- std::stringstream buf;
+class TarSegmentStore {
public:
- StringOutputStream();
+ // New segments will be stored in the given directory.
+ TarSegmentStore(RemoteStore *remote,
+ LocalDb *db = NULL)
+ { this->remote = remote; this->db = db; }
+ ~TarSegmentStore() { sync(); }
- virtual void write(const void *data, size_t len);
- std::string contents() const { return buf.str(); }
-};
+ // Writes an object to segment in the store, and returns the name
+ // (segment/object) to refer to it. The optional parameter group can be
+ // used to control object placement; objects with different group
+ // parameters are kept in separate segments.
+ ObjectReference write_object(const char *data, size_t len,
+ const std::string &group = "");
+
+ // Ensure all segments have been fully written.
+ void sync();
+
+ // Dump statistics to stdout about how much data has been written
+ void dump_stats();
-class FileOutputStream : public OutputStream {
private:
- FILE *f;
+ struct segment_info {
+ Tarfile *file;
+ std::string group;
+ std::string name; // UUID
+ int count; // Objects written to this segment
+ int size; // Combined size of objects written
+ std::string basename; // Name of segment without directory
+ RemoteFile *rf;
+ };
+
+ RemoteStore *remote;
+ std::map<std::string, struct segment_info *> segments;
+ LocalDb *db;
+
+ // Ensure that all segments in the given group have been fully written.
+ void close_segment(const std::string &group);
+
+ // Parse an object reference string and return just the segment name
+ // portion.
+ std::string object_reference_to_segment(const std::string &object);
+};
+
+/* An in-memory representation of an object, which can be incrementally built
+ * before it is written out to a segment. */
+class LbsObject {
public:
- explicit FileOutputStream(FILE *file);
- virtual ~FileOutputStream();
+ LbsObject();
+ ~LbsObject();
+
+ // If an object is placed in a group, it will be written out to segments
+ // only containing other objects in the same group. A group name is simply
+ // a string.
+ //std::string get_group() const { return group; }
+ void set_group(const std::string &g) { group = g; }
+
+ // Data in an object must be written all at once, and cannot be generated
+ // incrementally. Data can be an arbitrary block of binary data of any
+ // size. The pointer to the data need only remain valid until write() is
+ // called.
+ void set_data(const char *d, size_t len) { data = d; data_len = len; }
- virtual void write(const void *data, size_t len);
+ // Write an object to a segment, thus making it permanent. This function
+ // can be called at most once.
+ void write(TarSegmentStore *store);
+
+ // Compute the checksum of an object, and include it in the object
+ // reference. This should be called after write(), and the data specified
+ // by set_data() must remain valid through the call to checksum().
+ void checksum();
+
+ // An object is assigned a permanent name once it has been written to a
+ // segment. Until that time, its name cannot be determined.
+ std::string get_name() const { return ref.to_string(); }
+ ObjectReference get_ref() { return ref; }
+
+private:
+ std::string group;
+ const char *data;
+ size_t data_len;
+
+ bool written;
+ ObjectReference ref;
};
-std::string encode_u16(uint16_t val);
-std::string encode_u32(uint32_t val);
-std::string encode_u64(uint64_t val);
+/* Program through which segment data is piped before being written to file. */
+extern const char *filter_program;
+
+/* Extension which should be appended to segments written out (.tar is already
+ * included; this adds to it) */
+extern const char *filter_extension;
+
+/* Launch a process to filter data written to a file descriptor. fd_out is the
+ * file descriptor where the filtered data should be written. program is the
+ * filter program to execute (a single string which will be interpreted by
+ * /bin/sh). The return value is a file descriptor to which the data to be
+ * filtered should be written. The process ID of the filter process is stored
+ * at address filter_pid if non-NULL. */
+int spawn_filter(int fd_out, const char *program, pid_t *filter_pid);
+
+#endif // _LBS_STORE_H