pg_resetxlog.c

PostgreSQL7.4.6 for Linux

		return true;
	}

	/* Looks like it's a mess. */
	fprintf(stderr, _("%s: pg_control exists but is broken or unknown version; ignoring it\n"),
			progname);
	return false;
}


/*
 * Guess at pg_control values when we can't read the old ones.
 */
static void
GuessControlValues(void)
{
	char	   *localeptr;

	/*
	 * Set up a completely default set of pg_control values.
	 */
	guessed = true;
	memset(&ControlFile, 0, sizeof(ControlFile));

	ControlFile.pg_control_version = PG_CONTROL_VERSION;
	ControlFile.catalog_version_no = CATALOG_VERSION_NO;

	ControlFile.checkPointCopy.redo.xlogid = 0;
	ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogPHD;
	ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
	ControlFile.checkPointCopy.ThisStartUpID = 0;
	ControlFile.checkPointCopy.nextXid = (TransactionId) 514;	/* XXX */
	ControlFile.checkPointCopy.nextOid = BootstrapObjectIdData;
	ControlFile.checkPointCopy.time = time(NULL);

	ControlFile.state = DB_SHUTDOWNED;
	ControlFile.time = time(NULL);
	ControlFile.logId = 0;
	ControlFile.logSeg = 1;
	ControlFile.checkPoint = ControlFile.checkPointCopy.redo;

	ControlFile.blcksz = BLCKSZ;
	ControlFile.relseg_size = RELSEG_SIZE;
	ControlFile.nameDataLen = NAMEDATALEN;
	ControlFile.funcMaxArgs = FUNC_MAX_ARGS;
#ifdef HAVE_INT64_TIMESTAMP
	ControlFile.enableIntTimes = TRUE;
#else
	ControlFile.enableIntTimes = FALSE;
#endif
	ControlFile.localeBuflen = LOCALE_NAME_BUFLEN;

	localeptr = setlocale(LC_COLLATE, "");
	if (!localeptr)
	{
		fprintf(stderr, _("%s: invalid LC_COLLATE setting\n"), progname);
		exit(1);
	}
	StrNCpy(ControlFile.lc_collate, localeptr, LOCALE_NAME_BUFLEN);
	localeptr = setlocale(LC_CTYPE, "");
	if (!localeptr)
	{
		fprintf(stderr, _("%s: invalid LC_CTYPE setting\n"), progname);
		exit(1);
	}
	StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);

	/*
	 * XXX eventually, should try to grovel through old XLOG to develop
	 * more accurate values for startupid, nextXID, and nextOID.
	 */
}


/*
 * Print the guessed pg_control values when we had to guess.
 *
 * NB: this display should be just those fields that will not be
 * reset by RewriteControlFile().
 */
static void
PrintControlValues(bool guessed)
{
	if (guessed)
		printf(_("Guessed pg_control values:\n\n"));
	else
		printf(_("pg_control values:\n\n"));

	printf(_("pg_control version number:            %u\n"), ControlFile.pg_control_version);
	printf(_("Catalog version number:               %u\n"), ControlFile.catalog_version_no);
	printf(_("Current log file ID:                  %u\n"), ControlFile.logId);
	printf(_("Next log file segment:                %u\n"), ControlFile.logSeg);
	printf(_("Latest checkpoint's StartUpID:        %u\n"), ControlFile.checkPointCopy.ThisStartUpID);
	printf(_("Latest checkpoint's NextXID:          %u\n"), ControlFile.checkPointCopy.nextXid);
	printf(_("Latest checkpoint's NextOID:          %u\n"), ControlFile.checkPointCopy.nextOid);
	printf(_("Database block size:                  %u\n"), ControlFile.blcksz);
	printf(_("Blocks per segment of large relation: %u\n"), ControlFile.relseg_size);
	printf(_("Maximum length of identifiers:        %u\n"), ControlFile.nameDataLen);
	printf(_("Maximum number of function arguments: %u\n"), ControlFile.funcMaxArgs);
	printf(_("Date/time type storage:               %s\n"),
		   (ControlFile.enableIntTimes ? _("64-bit integers") : _("floating-point numbers")));
	printf(_("Maximum length of locale name:        %u\n"), ControlFile.localeBuflen);
	printf(_("LC_COLLATE:                           %s\n"), ControlFile.lc_collate);
	printf(_("LC_CTYPE:                             %s\n"), ControlFile.lc_ctype);
}


/*
 * Write out the new pg_control file.
 */
static void
RewriteControlFile(void)
{
	int			fd;
	char		buffer[BLCKSZ]; /* need not be aligned */

	/*
	 * Adjust fields as needed to force an empty XLOG starting at the next
	 * available segment.
	 */
	newXlogId = ControlFile.logId;
	newXlogSeg = ControlFile.logSeg;
	/* be sure we wrap around correctly at end of a logfile */
	NextLogSeg(newXlogId, newXlogSeg);

	ControlFile.checkPointCopy.redo.xlogid = newXlogId;
	ControlFile.checkPointCopy.redo.xrecoff =
		newXlogSeg * XLogSegSize + SizeOfXLogPHD;
	ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
	ControlFile.checkPointCopy.time = time(NULL);

	ControlFile.state = DB_SHUTDOWNED;
	ControlFile.time = time(NULL);
	ControlFile.logId = newXlogId;
	ControlFile.logSeg = newXlogSeg + 1;
	ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
	ControlFile.prevCheckPoint.xlogid = 0;
	ControlFile.prevCheckPoint.xrecoff = 0;

	/* Contents are protected with a CRC */
	INIT_CRC64(ControlFile.crc);
	COMP_CRC64(ControlFile.crc,
			   (char *) &ControlFile + sizeof(crc64),
			   sizeof(ControlFileData) - sizeof(crc64));
	FIN_CRC64(ControlFile.crc);

	/*
	 * We write out BLCKSZ bytes into pg_control, zero-padding the excess
	 * over sizeof(ControlFileData).  This reduces the odds of
	 * premature-EOF errors when reading pg_control.  We'll still fail
	 * when we check the contents of the file, but hopefully with a more
	 * specific error than "couldn't read pg_control".
	 */
	if (sizeof(ControlFileData) > BLCKSZ)
	{
		fprintf(stderr,
				_("%s: internal error -- sizeof(ControlFileData) is too large ... fix xlog.c\n"),
				progname);
		exit(1);
	}

	memset(buffer, 0, BLCKSZ);
	memcpy(buffer, &ControlFile, sizeof(ControlFileData));

	unlink(ControlFilePath);

	fd = open(ControlFilePath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR);
	if (fd < 0)
	{
		fprintf(stderr, _("%s: could not create pg_control file: %s\n"),
				progname, strerror(errno));
		exit(1);
	}

	errno = 0;
	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
	{
		/* if write didn't set errno, assume problem is no disk space */
		if (errno == 0)
			errno = ENOSPC;
		fprintf(stderr, _("%s: could not write pg_control file: %s\n"),
				progname, strerror(errno));
		exit(1);
	}

	if (fsync(fd) != 0)
	{
		fprintf(stderr, _("%s: fsync error: %s\n"), progname, strerror(errno));
		exit(1);
	}

	close(fd);
}


/*
 * Remove existing XLOG files
 */
static void
KillExistingXLOG(void)
{
	DIR		   *xldir;
	struct dirent *xlde;
	char		path[MAXPGPATH];

	xldir = opendir(XLogDir);
	if (xldir == NULL)
	{
		fprintf(stderr, _("%s: could not open directory \"%s\": %s\n"),
				progname, XLogDir, strerror(errno));
		exit(1);
	}

	errno = 0;
	while ((xlde = readdir(xldir)) != NULL)
	{
		if (strlen(xlde->d_name) == 16 &&
			strspn(xlde->d_name, "0123456789ABCDEF") == 16)
		{
			snprintf(path, MAXPGPATH, "%s/%s", XLogDir, xlde->d_name);
			if (unlink(path) < 0)
			{
				fprintf(stderr, _("%s: could not delete file \"%s\": %s\n"),
						progname, path, strerror(errno));
				exit(1);
			}
		}
		errno = 0;
	}

	if (errno)
	{
		fprintf(stderr, _("%s: could not read from directory \"%s\": %s\n"),
				progname, XLogDir, strerror(errno));
		exit(1);
	}
	closedir(xldir);
}


/*
 * Write an empty XLOG file, containing only the checkpoint record
 * already set up in ControlFile.
 */
static void
WriteEmptyXLOG(void)
{
	char	   *buffer;
	XLogPageHeader page;
	XLogRecord *record;
	crc64		crc;
	char		path[MAXPGPATH];
	int			fd;
	int			nbytes;

	/* Use malloc() to ensure buffer is MAXALIGNED */
	buffer = (char *) malloc(BLCKSZ);
	page = (XLogPageHeader) buffer;

	/* Set up the first page with initial record */
	memset(buffer, 0, BLCKSZ);
	page->xlp_magic = XLOG_PAGE_MAGIC;
	page->xlp_info = 0;
	page->xlp_sui = ControlFile.checkPointCopy.ThisStartUpID;
	page->xlp_pageaddr.xlogid =
		ControlFile.checkPointCopy.redo.xlogid;
	page->xlp_pageaddr.xrecoff =
		ControlFile.checkPointCopy.redo.xrecoff - SizeOfXLogPHD;
	record = (XLogRecord *) ((char *) page + SizeOfXLogPHD);
	record->xl_prev.xlogid = 0;
	record->xl_prev.xrecoff = 0;
	record->xl_xact_prev = record->xl_prev;
	record->xl_xid = InvalidTransactionId;
	record->xl_len = sizeof(CheckPoint);
	record->xl_info = XLOG_CHECKPOINT_SHUTDOWN;
	record->xl_rmid = RM_XLOG_ID;
	memcpy(XLogRecGetData(record), &ControlFile.checkPointCopy,
		   sizeof(CheckPoint));

	INIT_CRC64(crc);
	COMP_CRC64(crc, &ControlFile.checkPointCopy, sizeof(CheckPoint));
	COMP_CRC64(crc, (char *) record + sizeof(crc64),
			   SizeOfXLogRecord - sizeof(crc64));
	FIN_CRC64(crc);
	record->xl_crc = crc;

	/* Write the first page */
	XLogFileName(path, newXlogId, newXlogSeg);

	unlink(path);

	fd = open(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
			  S_IRUSR | S_IWUSR);
	if (fd < 0)
	{
		fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
				progname, path, strerror(errno));
		exit(1);
	}

	errno = 0;
	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
	{
		/* if write didn't set errno, assume problem is no disk space */
		if (errno == 0)
			errno = ENOSPC;
		fprintf(stderr, _("%s: could not write file \"%s\": %s\n"),
				progname, path, strerror(errno));
		exit(1);
	}

	/* Fill the rest of the file with zeroes */
	memset(buffer, 0, BLCKSZ);
	for (nbytes = BLCKSZ; nbytes < XLogSegSize; nbytes += BLCKSZ)
	{
		errno = 0;
		if (write(fd, buffer, BLCKSZ) != BLCKSZ)
		{
			if (errno == 0)
				errno = ENOSPC;
			fprintf(stderr, _("%s: could not write file \"%s\": %s\n"),
					progname, path, strerror(errno));
			exit(1);
		}
	}

	if (fsync(fd) != 0)
	{
		fprintf(stderr, _("%s: fsync error: %s\n"), progname, strerror(errno));
		exit(1);
	}

	close(fd);
}


static void
usage(void)
{
	printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
	printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
	printf(_("Options:\n"));
	printf(_("  -f              force update to be done\n"));
	printf(_("  -l FILEID,SEG   force minimum WAL starting location for new transaction log\n"));
	printf(_("  -n              no update, just show extracted control values (for testing)\n"));
	printf(_("  -o OID          set next OID\n"));
	printf(_("  -x XID          set next transaction ID\n"));
	printf(_("  --help          show this help, then exit\n"));
	printf(_("  --version       output version information, then exit\n"));
	printf(_("\nReport bugs to <[e-mail]>.\n"));
}