*
* 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. */
#include <assert.h>
+#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
+#include <algorithm>
#include <list>
+#include <map>
#include <set>
#include <string>
#include <iostream>
#include "store.h"
#include "ref.h"
+using std::max;
using std::list;
+using std::map;
using std::set;
using std::string;
-static char *const filter_program[] = {"bzip2", "-c", NULL};
+/* Default filter program is bzip2 */
+const char *filter_program = "bzip2 -c";
+const char *filter_extension = ".bz2";
static void cloexec(int fd)
{
: size(0),
segment_name(segment)
{
- real_fd = open(path.c_str(), O_WRONLY | O_CREAT, 0600);
+ assert(sizeof(struct tar_header) == TAR_BLOCK_SIZE);
+
+ real_fd = open(path.c_str(), O_WRONLY | O_CREAT, 0666);
if (real_fd < 0)
throw IOException("Error opening output file");
filter_fd = spawn_filter(real_fd);
-
- if (tar_fdopen(&t, filter_fd, (char *)path.c_str(), NULL,
- O_WRONLY | O_CREAT, 0600, TAR_VERBOSE | TAR_GNU) == -1)
- throw IOException("Error opening Tarfile");
}
Tarfile::~Tarfile()
{
- /* Close the tar file... */
- tar_append_eof(t);
+ char buf[TAR_BLOCK_SIZE];
+
+ /* Append the EOF marker: two blocks filled with nulls. */
+ memset(buf, 0, sizeof(buf));
+ tar_write(buf, TAR_BLOCK_SIZE);
+ tar_write(buf, TAR_BLOCK_SIZE);
- if (tar_close(t) != 0)
+ if (close(filter_fd) != 0)
throw IOException("Error closing Tarfile");
/* ...and wait for filter process to finish. */
close(fd_out);
/* Exec the filter program. */
- execvp(filter_program[0], filter_program);
+ execlp("/bin/sh", "/bin/sh", "-c", filter_program, NULL);
/* Should not reach here except for error cases. */
fprintf(stderr, "Could not exec filter: %m\n");
return fds[1];
}
+void Tarfile::tar_write(const char *data, size_t len)
+{
+ size += len;
+
+ while (len > 0) {
+ int res = write(filter_fd, data, len);
+
+ if (res < 0) {
+ if (errno == EINTR)
+ continue;
+ fprintf(stderr, "Write error: %m\n");
+ throw IOException("Write error");
+ }
+
+ len -= res;
+ data += res;
+ }
+}
+
void Tarfile::write_object(int id, const char *data, size_t len)
{
char buf[64];
void Tarfile::internal_write_object(const string &path,
const char *data, size_t len)
{
- memset(&t->th_buf, 0, sizeof(struct tar_header));
-
- th_set_type(t, S_IFREG | 0600);
- th_set_user(t, 0);
- th_set_group(t, 0);
- th_set_mode(t, 0600);
- th_set_size(t, len);
- th_set_mtime(t, time(NULL));
- th_set_path(t, const_cast<char *>(path.c_str()));
- th_finish(t);
-
- if (th_write(t) != 0)
- throw IOException("Error writing tar header");
+ struct tar_header header;
+ memset(&header, 0, sizeof(header));
+
+ assert(path.size() < 100);
+ memcpy(header.name, path.data(), path.size());
+ sprintf(header.mode, "%07o", 0600);
+ sprintf(header.uid, "%07o", 0);
+ sprintf(header.gid, "%07o", 0);
+ sprintf(header.size, "%011o", len);
+ sprintf(header.mtime, "%011o", (int)time(NULL));
+ header.typeflag = '0';
+ strcpy(header.magic, "ustar ");
+ strcpy(header.uname, "root");
+ strcpy(header.gname, "root");
+
+ memset(header.chksum, ' ', sizeof(header.chksum));
+ int checksum = 0;
+ for (int i = 0; i < TAR_BLOCK_SIZE; i++) {
+ checksum += ((uint8_t *)&header)[i];
+ }
+ sprintf(header.chksum, "%06o", checksum);
- size += T_BLOCKSIZE;
+ tar_write((const char *)&header, TAR_BLOCK_SIZE);
if (len == 0)
return;
- size_t blocks = (len + T_BLOCKSIZE - 1) / T_BLOCKSIZE;
- size_t padding = blocks * T_BLOCKSIZE - len;
-
- for (size_t i = 0; i < blocks - 1; i++) {
- if (tar_block_write(t, &data[i * T_BLOCKSIZE]) == -1)
- throw IOException("Error writing tar block");
- }
-
- char block[T_BLOCKSIZE];
- memset(block, 0, sizeof(block));
- memcpy(block, &data[T_BLOCKSIZE * (blocks - 1)], T_BLOCKSIZE - padding);
- if (tar_block_write(t, block) == -1)
- throw IOException("Error writing final tar block");
+ tar_write(data, len);
- size += blocks * T_BLOCKSIZE;
+ char padbuf[TAR_BLOCK_SIZE];
+ size_t blocks = (len + TAR_BLOCK_SIZE - 1) / TAR_BLOCK_SIZE;
+ size_t padding = blocks * TAR_BLOCK_SIZE - len;
+ memset(padbuf, 0, padding);
+ tar_write(padbuf, padding);
}
/* Estimate the size based on the size of the actual output file on disk.
- * However, the filter may not have written all data yet, and in the event that
- * it is buffering data to a large extent, also use */
+ * However, it might be the case that the filter program is buffering all its
+ * data, and might potentially not write a single byte until we have closed
+ * our end of the pipe. If we don't do so until we see data written, we have
+ * a problem. So, arbitrarily pick an upper bound on the compression ratio
+ * that the filter will achieve (128:1), and return a size estimate which is
+ * the larger of a) bytes actually seen written to disk, and b) input
+ * bytes/128. */
size_t Tarfile::size_estimate()
{
struct stat statbuf;
- if (fstat(real_fd, &statbuf) == 0) {
- size_t disk_size = statbuf.st_size;
-
- if (disk_size >= size / 128)
- return disk_size;
- }
+ if (fstat(real_fd, &statbuf) == 0)
+ return max((int64_t)statbuf.st_size, (int64_t)(size / 128));
+ /* Couldn't stat the file on disk, so just return the actual number of
+ * bytes, before compression. */
return size;
}
static const size_t SEGMENT_SIZE = 4 * 1024 * 1024;
+static map<string, int64_t> group_sizes;
+
ObjectReference TarSegmentStore::write_object(const char *data, size_t len,
const std::string &group)
{
segment->name = generate_uuid();
- string filename = path + "/" + segment->name + ".tar.bz2";
+ string filename = path + "/" + segment->name + ".tar";
+ filename += filter_extension;
segment->file = new Tarfile(filename, segment->name);
segment->count = 0;
segment->file->write_object(id, data, len);
segment->count++;
+ group_sizes[group] += len;
+
ObjectReference ref(segment->name, id_buf);
// If this segment meets or exceeds the size target, close it so that
close_segment(segments.begin()->first);
}
+void TarSegmentStore::dump_stats()
+{
+ printf("Data written:\n");
+ for (map<string, int64_t>::iterator i = group_sizes.begin();
+ i != group_sizes.end(); ++i) {
+ printf(" %s: %lld\n", i->first.c_str(), i->second);
+ }
+}
+
void TarSegmentStore::close_segment(const string &group)
{
struct segment_info *segment = segments[group];
projects / cumulus.git / blobdiff