-/* LBS: An LFS-inspired filesystem backup system
- * Copyright (C) 2006 Michael Vrable
+/* Cumulus: Efficient Filesystem Backup to the Cloud
+ * Copyright (C) 2006-2008 The Cumulus Developers
+ * See the AUTHORS file for a list of contributors.
*
- * Backup data is stored in a collection of objects, which are grouped together
+ * 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
- * is built on top of libtar, and represents segments as TAR files and objects
- * as files within them. */
+ * represents segments as TAR files and objects as files within them. */
#ifndef _LBS_STORE_H
#define _LBS_STORE_H
#include <stdint.h>
-#include <libtar.h>
#include <list>
#include <map>
+#include <memory>
#include <set>
#include <string>
#include <iostream>
#include <sstream>
-#include "sha1.h"
+#include "localdb.h"
+#include "remote.h"
#include "ref.h"
+#include "third_party/sha1.h"
class LbsObject;
* 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;
+/* 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];
+};
+
+class FileFilter {
public:
- explicit IOException(const std::string &err) { error = err; }
- virtual ~IOException() throw () { }
- std::string getError() const { return error; }
+ // It is valid for program to be NULL or empty; if so, no filtering is
+ // done.
+ static FileFilter *New(int fd, const char *program);
+
+ // Wait for the filter process to terminate.
+ int wait();
+
+ // Accessors for the file descriptors.
+ int get_raw_fd() const { return fd_raw; }
+ int get_wrapped_fd() const { return fd_wrapped; }
+
+private:
+ FileFilter(int raw, int wrapped, pid_t pid);
+
+ // 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.
+ static int spawn_filter(int fd_out, const char *program, pid_t *filter_pid);
+
+ // The original file descriptor passed when creating the FileFilter object.
+ int fd_raw;
+
+ // The wrapped file descriptor: writes here are piped through the filter
+ // program.
+ int fd_wrapped;
+
+ // The filter process if one was launched, or -1 if there is no filter
+ // program.
+ pid_t pid;
};
/* A simple wrapper around a single TAR file to represent a segment. Objects
* first; incremental writing is not supported. */
class Tarfile {
public:
- Tarfile(const std::string &path, const std::string &segment);
+ Tarfile(RemoteFile *file, const std::string &segment);
~Tarfile();
- int spawn_filter(int fd_out);
void write_object(int id, const char *data, size_t len);
// Return an estimate of the size of the file.
size_t size_estimate();
- void internal_write_object(const std::string &path,
- const char *data, size_t len);
-
private:
size_t size;
std::string segment_name;
- TAR *t;
- /* Filter support. */
- int real_fd, filter_fd;
- pid_t filter_pid;
+ RemoteFile *file;
+ std::unique_ptr<FileFilter> filter;
+
+ // Write data to the tar file
+ void tar_write(const char *data, size_t size);
};
class TarSegmentStore {
public:
// New segments will be stored in the given directory.
- TarSegmentStore(const std::string &path) { this->path = path; }
+ TarSegmentStore(RemoteStore *remote,
+ LocalDb *db = NULL)
+ { this->remote = remote; this->db = db; }
~TarSegmentStore() { sync(); }
// Writes an object to segment in the store, and returns the name
// 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 = "");
+ const std::string &group = "",
+ const std::string &checksum = "",
+ double age = 0.0);
// Ensure all segments have been fully written.
void sync();
private:
struct segment_info {
Tarfile *file;
+ std::string group;
std::string name; // UUID
int count; // Objects written to this segment
+ int data_size; // Combined size of objects written
+ std::string basename; // Name of segment without directory
+ RemoteFile *rf;
};
- std::string path;
+ 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);
// 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; }
+ // called. If checksum is non-NULL then it is assumed to contain a hash
+ // value for the data; this provides an optimization in case the caller has
+ // already checksummed the data. Otherwise the set_data will compute a
+ // hash of the data itself.
+ void set_data(const char *d, size_t len, const char *checksum);
+
+ // Explicitly sets the age of the data, for later garbage-collection or
+ // repacking purposes. If not set, the age defaults to the current time.
+ // The age is stored in the database as a floating point value, expressing
+ // the time in Julian days.
+ void set_age(double age) { this->age = age; }
// 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;
+ double age;
const char *data;
size_t data_len;
+ std::string checksum;
bool written;
ObjectReference ref;
projects / cumulus.git / blobdiff