xref: /haiku/src/add-ons/kernel/file_systems/ntfs/libntfs/logfile.c (revision 7ee53ed3bd2222305c93a4959f8c587c373ed97c)
1 /**
2  * logfile.c - NTFS journal handling. Originated from the Linux-NTFS project.
3  *
4  * Copyright (c) 2002-2005 Anton Altaparmakov
5  * Copyright (c) 2005 Yura Pakhuchiy
6  * Copyright (c) 2005-2009 Szabolcs Szakacsits
7  *
8  * This program/include file is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License as published
10  * by the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program/include file is distributed in the hope that it will be
14  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
15  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program (in the main directory of the NTFS-3G
20  * distribution in the file COPYING); if not, write to the Free Software
21  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
22  */
23 
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27 
28 #ifdef HAVE_STDLIB_H
29 #include <stdlib.h>
30 #endif
31 #ifdef HAVE_STRING_H
32 #include <string.h>
33 #endif
34 #ifdef HAVE_ERRNO_H
35 #include <errno.h>
36 #endif
37 
38 #include "attrib.h"
39 #include "debug.h"
40 #include "logfile.h"
41 #include "volume.h"
42 #include "mst.h"
43 #include "logging.h"
44 #include "misc.h"
45 
46 /**
47  * ntfs_check_restart_page_header - check the page header for consistency
48  * @rp:		restart page header to check
49  * @pos:	position in logfile at which the restart page header resides
50  *
51  * Check the restart page header @rp for consistency and return TRUE if it is
52  * consistent and FALSE otherwise.
53  *
54  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
55  * require the full restart page.
56  */
57 static BOOL ntfs_check_restart_page_header(RESTART_PAGE_HEADER *rp, s64 pos)
58 {
59 	u32 logfile_system_page_size, logfile_log_page_size;
60 	u16 ra_ofs, usa_count, usa_ofs, usa_end = 0;
61 	BOOL have_usa = TRUE;
62 
63 	ntfs_log_trace("Entering.\n");
64 	/*
65 	 * If the system or log page sizes are smaller than the ntfs block size
66 	 * or either is not a power of 2 we cannot handle this log file.
67 	 */
68 	logfile_system_page_size = le32_to_cpu(rp->system_page_size);
69 	logfile_log_page_size = le32_to_cpu(rp->log_page_size);
70 	if (logfile_system_page_size < NTFS_BLOCK_SIZE ||
71 			logfile_log_page_size < NTFS_BLOCK_SIZE ||
72 			logfile_system_page_size &
73 			(logfile_system_page_size - 1) ||
74 			logfile_log_page_size & (logfile_log_page_size - 1)) {
75 		ntfs_log_error("$LogFile uses unsupported page size.\n");
76 		return FALSE;
77 	}
78 	/*
79 	 * We must be either at !pos (1st restart page) or at pos = system page
80 	 * size (2nd restart page).
81 	 */
82 	if (pos && pos != logfile_system_page_size) {
83 		ntfs_log_error("Found restart area in incorrect "
84 				"position in $LogFile.\n");
85 		return FALSE;
86 	}
87 	/* We only know how to handle version 1.1. */
88 	if (sle16_to_cpu(rp->major_ver) != 1 ||
89 			sle16_to_cpu(rp->minor_ver) != 1) {
90 		ntfs_log_error("$LogFile version %i.%i is not "
91 				"supported.  (This driver supports version "
92 				"1.1 only.)\n", (int)sle16_to_cpu(rp->major_ver),
93 				(int)sle16_to_cpu(rp->minor_ver));
94 		return FALSE;
95 	}
96 	/*
97 	 * If chkdsk has been run the restart page may not be protected by an
98 	 * update sequence array.
99 	 */
100 	if (ntfs_is_chkd_record(rp->magic) && !le16_to_cpu(rp->usa_count)) {
101 		have_usa = FALSE;
102 		goto skip_usa_checks;
103 	}
104 	/* Verify the size of the update sequence array. */
105 	usa_count = 1 + (logfile_system_page_size >> NTFS_BLOCK_SIZE_BITS);
106 	if (usa_count != le16_to_cpu(rp->usa_count)) {
107 		ntfs_log_error("$LogFile restart page specifies "
108 				"inconsistent update sequence array count.\n");
109 		return FALSE;
110 	}
111 	/* Verify the position of the update sequence array. */
112 	usa_ofs = le16_to_cpu(rp->usa_ofs);
113 	usa_end = usa_ofs + usa_count * sizeof(u16);
114 	if (usa_ofs < sizeof(RESTART_PAGE_HEADER) ||
115 			usa_end > NTFS_BLOCK_SIZE - sizeof(u16)) {
116 		ntfs_log_error("$LogFile restart page specifies "
117 				"inconsistent update sequence array offset.\n");
118 		return FALSE;
119 	}
120 skip_usa_checks:
121 	/*
122 	 * Verify the position of the restart area.  It must be:
123 	 *	- aligned to 8-byte boundary,
124 	 *	- after the update sequence array, and
125 	 *	- within the system page size.
126 	 */
127 	ra_ofs = le16_to_cpu(rp->restart_area_offset);
128 	if (ra_ofs & 7 || (have_usa ? ra_ofs < usa_end :
129 			ra_ofs < sizeof(RESTART_PAGE_HEADER)) ||
130 			ra_ofs > logfile_system_page_size) {
131 		ntfs_log_error("$LogFile restart page specifies "
132 				"inconsistent restart area offset.\n");
133 		return FALSE;
134 	}
135 	/*
136 	 * Only restart pages modified by chkdsk are allowed to have chkdsk_lsn
137 	 * set.
138 	 */
139 	if (!ntfs_is_chkd_record(rp->magic) && sle64_to_cpu(rp->chkdsk_lsn)) {
140 		ntfs_log_error("$LogFile restart page is not modified "
141 				"by chkdsk but a chkdsk LSN is specified.\n");
142 		return FALSE;
143 	}
144 	ntfs_log_trace("Done.\n");
145 	return TRUE;
146 }
147 
148 /**
149  * ntfs_check_restart_area - check the restart area for consistency
150  * @rp:		restart page whose restart area to check
151  *
152  * Check the restart area of the restart page @rp for consistency and return
153  * TRUE if it is consistent and FALSE otherwise.
154  *
155  * This function assumes that the restart page header has already been
156  * consistency checked.
157  *
158  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
159  * require the full restart page.
160  */
161 static BOOL ntfs_check_restart_area(RESTART_PAGE_HEADER *rp)
162 {
163 	u64 file_size;
164 	RESTART_AREA *ra;
165 	u16 ra_ofs, ra_len, ca_ofs;
166 	u8 fs_bits;
167 
168 	ntfs_log_trace("Entering.\n");
169 	ra_ofs = le16_to_cpu(rp->restart_area_offset);
170 	ra = (RESTART_AREA*)((u8*)rp + ra_ofs);
171 	/*
172 	 * Everything before ra->file_size must be before the first word
173 	 * protected by an update sequence number.  This ensures that it is
174 	 * safe to access ra->client_array_offset.
175 	 */
176 	if (ra_ofs + offsetof(RESTART_AREA, file_size) >
177 			NTFS_BLOCK_SIZE - sizeof(u16)) {
178 		ntfs_log_error("$LogFile restart area specifies "
179 				"inconsistent file offset.\n");
180 		return FALSE;
181 	}
182 	/*
183 	 * Now that we can access ra->client_array_offset, make sure everything
184 	 * up to the log client array is before the first word protected by an
185 	 * update sequence number.  This ensures we can access all of the
186 	 * restart area elements safely.  Also, the client array offset must be
187 	 * aligned to an 8-byte boundary.
188 	 */
189 	ca_ofs = le16_to_cpu(ra->client_array_offset);
190 	if (((ca_ofs + 7) & ~7) != ca_ofs ||
191 			ra_ofs + ca_ofs > (u16)(NTFS_BLOCK_SIZE -
192 			sizeof(u16))) {
193 		ntfs_log_error("$LogFile restart area specifies "
194 				"inconsistent client array offset.\n");
195 		return FALSE;
196 	}
197 	/*
198 	 * The restart area must end within the system page size both when
199 	 * calculated manually and as specified by ra->restart_area_length.
200 	 * Also, the calculated length must not exceed the specified length.
201 	 */
202 	ra_len = ca_ofs + le16_to_cpu(ra->log_clients) *
203 			sizeof(LOG_CLIENT_RECORD);
204 	if ((u32)(ra_ofs + ra_len) > le32_to_cpu(rp->system_page_size) ||
205 			(u32)(ra_ofs + le16_to_cpu(ra->restart_area_length)) >
206 			le32_to_cpu(rp->system_page_size) ||
207 			ra_len > le16_to_cpu(ra->restart_area_length)) {
208 		ntfs_log_error("$LogFile restart area is out of bounds "
209 				"of the system page size specified by the "
210 				"restart page header and/or the specified "
211 				"restart area length is inconsistent.\n");
212 		return FALSE;
213 	}
214 	/*
215 	 * The ra->client_free_list and ra->client_in_use_list must be either
216 	 * LOGFILE_NO_CLIENT or less than ra->log_clients or they are
217 	 * overflowing the client array.
218 	 */
219 	if ((ra->client_free_list != LOGFILE_NO_CLIENT &&
220 			le16_to_cpu(ra->client_free_list) >=
221 			le16_to_cpu(ra->log_clients)) ||
222 			(ra->client_in_use_list != LOGFILE_NO_CLIENT &&
223 			le16_to_cpu(ra->client_in_use_list) >=
224 			le16_to_cpu(ra->log_clients))) {
225 		ntfs_log_error("$LogFile restart area specifies "
226 				"overflowing client free and/or in use lists.\n");
227 		return FALSE;
228 	}
229 	/*
230 	 * Check ra->seq_number_bits against ra->file_size for consistency.
231 	 * We cannot just use ffs() because the file size is not a power of 2.
232 	 */
233 	file_size = (u64)sle64_to_cpu(ra->file_size);
234 	fs_bits = 0;
235 	while (file_size) {
236 		file_size >>= 1;
237 		fs_bits++;
238 	}
239 	if (le32_to_cpu(ra->seq_number_bits) != (u32)(67 - fs_bits)) {
240 		ntfs_log_error("$LogFile restart area specifies "
241 				"inconsistent sequence number bits.\n");
242 		return FALSE;
243 	}
244 	/* The log record header length must be a multiple of 8. */
245 	if (((le16_to_cpu(ra->log_record_header_length) + 7) & ~7) !=
246 			le16_to_cpu(ra->log_record_header_length)) {
247 		ntfs_log_error("$LogFile restart area specifies "
248 				"inconsistent log record header length.\n");
249 		return FALSE;
250 	}
251 	/* Ditto for the log page data offset. */
252 	if (((le16_to_cpu(ra->log_page_data_offset) + 7) & ~7) !=
253 			le16_to_cpu(ra->log_page_data_offset)) {
254 		ntfs_log_error("$LogFile restart area specifies "
255 				"inconsistent log page data offset.\n");
256 		return FALSE;
257 	}
258 	ntfs_log_trace("Done.\n");
259 	return TRUE;
260 }
261 
262 /**
263  * ntfs_check_log_client_array - check the log client array for consistency
264  * @rp:		restart page whose log client array to check
265  *
266  * Check the log client array of the restart page @rp for consistency and
267  * return TRUE if it is consistent and FALSE otherwise.
268  *
269  * This function assumes that the restart page header and the restart area have
270  * already been consistency checked.
271  *
272  * Unlike ntfs_check_restart_page_header() and ntfs_check_restart_area(), this
273  * function needs @rp->system_page_size bytes in @rp, i.e. it requires the full
274  * restart page and the page must be multi sector transfer deprotected.
275  */
276 static BOOL ntfs_check_log_client_array(RESTART_PAGE_HEADER *rp)
277 {
278 	RESTART_AREA *ra;
279 	LOG_CLIENT_RECORD *ca, *cr;
280 	u16 nr_clients, idx;
281 	BOOL in_free_list, idx_is_first;
282 
283 	ntfs_log_trace("Entering.\n");
284 	ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
285 	ca = (LOG_CLIENT_RECORD*)((u8*)ra +
286 			le16_to_cpu(ra->client_array_offset));
287 	/*
288 	 * Check the ra->client_free_list first and then check the
289 	 * ra->client_in_use_list.  Check each of the log client records in
290 	 * each of the lists and check that the array does not overflow the
291 	 * ra->log_clients value.  Also keep track of the number of records
292 	 * visited as there cannot be more than ra->log_clients records and
293 	 * that way we detect eventual loops in within a list.
294 	 */
295 	nr_clients = le16_to_cpu(ra->log_clients);
296 	idx = le16_to_cpu(ra->client_free_list);
297 	in_free_list = TRUE;
298 check_list:
299 	for (idx_is_first = TRUE; idx != LOGFILE_NO_CLIENT_CPU; nr_clients--,
300 			idx = le16_to_cpu(cr->next_client)) {
301 		if (!nr_clients || idx >= le16_to_cpu(ra->log_clients))
302 			goto err_out;
303 		/* Set @cr to the current log client record. */
304 		cr = ca + idx;
305 		/* The first log client record must not have a prev_client. */
306 		if (idx_is_first) {
307 			if (cr->prev_client != LOGFILE_NO_CLIENT)
308 				goto err_out;
309 			idx_is_first = FALSE;
310 		}
311 	}
312 	/* Switch to and check the in use list if we just did the free list. */
313 	if (in_free_list) {
314 		in_free_list = FALSE;
315 		idx = le16_to_cpu(ra->client_in_use_list);
316 		goto check_list;
317 	}
318 	ntfs_log_trace("Done.\n");
319 	return TRUE;
320 err_out:
321 	ntfs_log_error("$LogFile log client array is corrupt.\n");
322 	return FALSE;
323 }
324 
325 /**
326  * ntfs_check_and_load_restart_page - check the restart page for consistency
327  * @log_na:	opened ntfs attribute for journal $LogFile
328  * @rp:		restart page to check
329  * @pos:	position in @log_na at which the restart page resides
330  * @wrp:       [OUT] copy of the multi sector transfer deprotected restart page
331  * @lsn:       [OUT] set to the current logfile lsn on success
332  *
333  * Check the restart page @rp for consistency and return 0 if it is consistent
334  * and errno otherwise.  The restart page may have been modified by chkdsk in
335  * which case its magic is CHKD instead of RSTR.
336  *
337  * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
338  * require the full restart page.
339  *
340  * If @wrp is not NULL, on success, *@wrp will point to a buffer containing a
341  * copy of the complete multi sector transfer deprotected page.  On failure,
342  * *@wrp is undefined.
343  *
344  * Similarly, if @lsn is not NULL, on success *@lsn will be set to the current
345  * logfile lsn according to this restart page.  On failure, *@lsn is undefined.
346  *
347  * The following error codes are defined:
348  *     EINVAL - The restart page is inconsistent.
349  *     ENOMEM - Not enough memory to load the restart page.
350  *     EIO    - Failed to reading from $LogFile.
351  */
352 static int ntfs_check_and_load_restart_page(ntfs_attr *log_na,
353 		RESTART_PAGE_HEADER *rp, s64 pos, RESTART_PAGE_HEADER **wrp,
354 		LSN *lsn)
355 {
356 	RESTART_AREA *ra;
357 	RESTART_PAGE_HEADER *trp;
358 	int err;
359 
360 	ntfs_log_trace("Entering.\n");
361 	/* Check the restart page header for consistency. */
362 	if (!ntfs_check_restart_page_header(rp, pos)) {
363 		/* Error output already done inside the function. */
364 		return EINVAL;
365 	}
366 	/* Check the restart area for consistency. */
367 	if (!ntfs_check_restart_area(rp)) {
368 		/* Error output already done inside the function. */
369 		return EINVAL;
370 	}
371 	ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
372 	/*
373 	 * Allocate a buffer to store the whole restart page so we can multi
374 	 * sector transfer deprotect it.
375 	 */
376 	trp = ntfs_malloc(le32_to_cpu(rp->system_page_size));
377 	if (!trp)
378 		return errno;
379 	/*
380 	 * Read the whole of the restart page into the buffer.  If it fits
381 	 * completely inside @rp, just copy it from there.  Otherwise read it
382 	 * from disk.
383 	 */
384 	if (le32_to_cpu(rp->system_page_size) <= NTFS_BLOCK_SIZE)
385 		memcpy(trp, rp, le32_to_cpu(rp->system_page_size));
386 	else if (ntfs_attr_pread(log_na, pos,
387 			le32_to_cpu(rp->system_page_size), trp) !=
388 			le32_to_cpu(rp->system_page_size)) {
389 		err = errno;
390 		ntfs_log_error("Failed to read whole restart page into the "
391 				"buffer.\n");
392 		if (err != ENOMEM)
393 			err = EIO;
394 		goto err_out;
395 	}
396 	/*
397 	 * Perform the multi sector transfer deprotection on the buffer if the
398 	 * restart page is protected.
399 	 */
400 	if ((!ntfs_is_chkd_record(trp->magic) || le16_to_cpu(trp->usa_count))
401 			&& ntfs_mst_post_read_fixup((NTFS_RECORD*)trp,
402 			le32_to_cpu(rp->system_page_size))) {
403 		/*
404 		 * A multi sector tranfer error was detected.  We only need to
405 		 * abort if the restart page contents exceed the multi sector
406 		 * transfer fixup of the first sector.
407 		 */
408 		if (le16_to_cpu(rp->restart_area_offset) +
409 				le16_to_cpu(ra->restart_area_length) >
410 				NTFS_BLOCK_SIZE - (int)sizeof(u16)) {
411 			ntfs_log_error("Multi sector transfer error "
412 				   "detected in $LogFile restart page.\n");
413 			err = EINVAL;
414 			goto err_out;
415 		}
416 	}
417 	/*
418 	 * If the restart page is modified by chkdsk or there are no active
419 	 * logfile clients, the logfile is consistent.  Otherwise, need to
420 	 * check the log client records for consistency, too.
421 	 */
422 	err = 0;
423 	if (ntfs_is_rstr_record(rp->magic) &&
424 			ra->client_in_use_list != LOGFILE_NO_CLIENT) {
425 		if (!ntfs_check_log_client_array(trp)) {
426 			err = EINVAL;
427 			goto err_out;
428 		}
429 	}
430 	if (lsn) {
431 		if (ntfs_is_rstr_record(rp->magic))
432 			*lsn = sle64_to_cpu(ra->current_lsn);
433 		else /* if (ntfs_is_chkd_record(rp->magic)) */
434 			*lsn = sle64_to_cpu(rp->chkdsk_lsn);
435 	}
436 	ntfs_log_trace("Done.\n");
437 	if (wrp)
438 		*wrp = trp;
439 	else {
440 err_out:
441 		free(trp);
442 	}
443 	return err;
444 }
445 
446 /**
447  * ntfs_check_logfile - check in the journal if the volume is consistent
448  * @log_na:	ntfs attribute of loaded journal $LogFile to check
449  * @rp:         [OUT] on success this is a copy of the current restart page
450  *
451  * Check the $LogFile journal for consistency and return TRUE if it is
452  * consistent and FALSE if not.  On success, the current restart page is
453  * returned in *@rp.  Caller must call ntfs_free(*@rp) when finished with it.
454  *
455  * At present we only check the two restart pages and ignore the log record
456  * pages.
457  *
458  * Note that the MstProtected flag is not set on the $LogFile inode and hence
459  * when reading pages they are not deprotected.  This is because we do not know
460  * if the $LogFile was created on a system with a different page size to ours
461  * yet and mst deprotection would fail if our page size is smaller.
462  */
463 BOOL ntfs_check_logfile(ntfs_attr *log_na, RESTART_PAGE_HEADER **rp)
464 {
465 	s64 size, pos;
466 	LSN rstr1_lsn, rstr2_lsn;
467 	ntfs_volume *vol = log_na->ni->vol;
468 	u8 *kaddr = NULL;
469 	RESTART_PAGE_HEADER *rstr1_ph = NULL;
470 	RESTART_PAGE_HEADER *rstr2_ph = NULL;
471 	int log_page_size, err;
472 	BOOL logfile_is_empty = TRUE;
473 	u8 log_page_bits;
474 
475 	ntfs_log_trace("Entering.\n");
476 	/* An empty $LogFile must have been clean before it got emptied. */
477 	if (NVolLogFileEmpty(vol))
478 		goto is_empty;
479 	size = log_na->data_size;
480 	/* Make sure the file doesn't exceed the maximum allowed size. */
481 	if (size > (s64)MaxLogFileSize)
482 		size = MaxLogFileSize;
483 	log_page_size = DefaultLogPageSize;
484 	/*
485 	 * Use generic_ffs() instead of ffs() to enable the compiler to
486 	 * optimize log_page_size and log_page_bits into constants.
487 	 */
488 	log_page_bits = ffs(log_page_size) - 1;
489 	size &= ~(log_page_size - 1);
490 
491 	/*
492 	 * Ensure the log file is big enough to store at least the two restart
493 	 * pages and the minimum number of log record pages.
494 	 */
495 	if (size < log_page_size * 2 || (size - log_page_size * 2) >>
496 			log_page_bits < MinLogRecordPages) {
497 		ntfs_log_error("$LogFile is too small.\n");
498 		return FALSE;
499 	}
500 	/* Allocate memory for restart page. */
501 	kaddr = ntfs_malloc(NTFS_BLOCK_SIZE);
502 	if (!kaddr)
503 		return FALSE;
504 	/*
505 	 * Read through the file looking for a restart page.  Since the restart
506 	 * page header is at the beginning of a page we only need to search at
507 	 * what could be the beginning of a page (for each page size) rather
508 	 * than scanning the whole file byte by byte.  If all potential places
509 	 * contain empty and uninitialized records, the log file can be assumed
510 	 * to be empty.
511 	 */
512 	for (pos = 0; pos < size; pos <<= 1) {
513 		/*
514 		 * Read first NTFS_BLOCK_SIZE bytes of potential restart page.
515 		 */
516 		if (ntfs_attr_pread(log_na, pos, NTFS_BLOCK_SIZE, kaddr) !=
517 				NTFS_BLOCK_SIZE) {
518 			ntfs_log_error("Failed to read first NTFS_BLOCK_SIZE "
519 					"bytes of potential restart page.\n");
520 			goto err_out;
521 		}
522 
523 		/*
524 		 * A non-empty block means the logfile is not empty while an
525 		 * empty block after a non-empty block has been encountered
526 		 * means we are done.
527 		 */
528 		if (!ntfs_is_empty_recordp((le32*)kaddr))
529 			logfile_is_empty = FALSE;
530 		else if (!logfile_is_empty)
531 			break;
532 		/*
533 		 * A log record page means there cannot be a restart page after
534 		 * this so no need to continue searching.
535 		 */
536 		if (ntfs_is_rcrd_recordp((le32*)kaddr))
537 			break;
538 		/* If not a (modified by chkdsk) restart page, continue. */
539 		if (!ntfs_is_rstr_recordp((le32*)kaddr) &&
540 				!ntfs_is_chkd_recordp((le32*)kaddr)) {
541 			if (!pos)
542 				pos = NTFS_BLOCK_SIZE >> 1;
543 			continue;
544 		}
545 		/*
546 		 * Check the (modified by chkdsk) restart page for consistency
547 		 * and get a copy of the complete multi sector transfer
548 		 * deprotected restart page.
549 		 */
550 		err = ntfs_check_and_load_restart_page(log_na,
551 				(RESTART_PAGE_HEADER*)kaddr, pos,
552 				!rstr1_ph ? &rstr1_ph : &rstr2_ph,
553 				!rstr1_ph ? &rstr1_lsn : &rstr2_lsn);
554 		if (!err) {
555 			/*
556 			 * If we have now found the first (modified by chkdsk)
557 			 * restart page, continue looking for the second one.
558 			 */
559 			if (!pos) {
560 				pos = NTFS_BLOCK_SIZE >> 1;
561 				continue;
562 			}
563 			/*
564 			 * We have now found the second (modified by chkdsk)
565 			 * restart page, so we can stop looking.
566 			 */
567 			break;
568 		}
569 		/*
570 		 * Error output already done inside the function.  Note, we do
571 		 * not abort if the restart page was invalid as we might still
572 		 * find a valid one further in the file.
573 		 */
574 		if (err != EINVAL)
575 		      goto err_out;
576 		/* Continue looking. */
577 		if (!pos)
578 			pos = NTFS_BLOCK_SIZE >> 1;
579 	}
580 	if (kaddr) {
581 		free(kaddr);
582 		kaddr = NULL;
583 	}
584 	if (logfile_is_empty) {
585 		NVolSetLogFileEmpty(vol);
586 is_empty:
587 		ntfs_log_trace("Done.  ($LogFile is empty.)\n");
588 		return TRUE;
589 	}
590 	if (!rstr1_ph) {
591 		if (rstr2_ph)
592 			ntfs_log_error("BUG: rstr2_ph isn't NULL!\n");
593 		ntfs_log_error("Did not find any restart pages in "
594 			   "$LogFile and it was not empty.\n");
595 		return FALSE;
596 	}
597 	/* If both restart pages were found, use the more recent one. */
598 	if (rstr2_ph) {
599 		/*
600 		 * If the second restart area is more recent, switch to it.
601 		 * Otherwise just throw it away.
602 		 */
603 		if (rstr2_lsn > rstr1_lsn) {
604 			ntfs_log_debug("Using second restart page as it is more "
605 					"recent.\n");
606 			free(rstr1_ph);
607 			rstr1_ph = rstr2_ph;
608 			/* rstr1_lsn = rstr2_lsn; */
609 		} else {
610 			ntfs_log_debug("Using first restart page as it is more "
611 					"recent.\n");
612 			free(rstr2_ph);
613 		}
614 		rstr2_ph = NULL;
615 	}
616 	/* All consistency checks passed. */
617 	if (rp)
618 		*rp = rstr1_ph;
619 	else
620 		free(rstr1_ph);
621 	ntfs_log_trace("Done.\n");
622 	return TRUE;
623 err_out:
624 	free(kaddr);
625 	free(rstr1_ph);
626 	free(rstr2_ph);
627 	return FALSE;
628 }
629 
630 /**
631  * ntfs_is_logfile_clean - check in the journal if the volume is clean
632  * @log_na:	ntfs attribute of loaded journal $LogFile to check
633  * @rp:         copy of the current restart page
634  *
635  * Analyze the $LogFile journal and return TRUE if it indicates the volume was
636  * shutdown cleanly and FALSE if not.
637  *
638  * At present we only look at the two restart pages and ignore the log record
639  * pages.  This is a little bit crude in that there will be a very small number
640  * of cases where we think that a volume is dirty when in fact it is clean.
641  * This should only affect volumes that have not been shutdown cleanly but did
642  * not have any pending, non-check-pointed i/o, i.e. they were completely idle
643  * at least for the five seconds preceding the unclean shutdown.
644  *
645  * This function assumes that the $LogFile journal has already been consistency
646  * checked by a call to ntfs_check_logfile() and in particular if the $LogFile
647  * is empty this function requires that NVolLogFileEmpty() is true otherwise an
648  * empty volume will be reported as dirty.
649  */
650 BOOL ntfs_is_logfile_clean(ntfs_attr *log_na, RESTART_PAGE_HEADER *rp)
651 {
652 	RESTART_AREA *ra;
653 
654 	ntfs_log_trace("Entering.\n");
655 	/* An empty $LogFile must have been clean before it got emptied. */
656 	if (NVolLogFileEmpty(log_na->ni->vol)) {
657 		ntfs_log_trace("$LogFile is empty\n");
658 		return TRUE;
659 	}
660 	if (!rp) {
661 		ntfs_log_error("Restart page header is NULL\n");
662 		return FALSE;
663 	}
664 	if (!ntfs_is_rstr_record(rp->magic) &&
665 			!ntfs_is_chkd_record(rp->magic)) {
666 		ntfs_log_error("Restart page buffer is invalid\n");
667 		return FALSE;
668 	}
669 
670 	ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
671 	/*
672 	 * If the $LogFile has active clients, i.e. it is open, and we do not
673 	 * have the RESTART_VOLUME_IS_CLEAN bit set in the restart area flags,
674 	 * we assume there was an unclean shutdown.
675 	 */
676 	if (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
677 			!(ra->flags & RESTART_VOLUME_IS_CLEAN)) {
678 		ntfs_log_error("The disk contains an unclean file system (%d, "
679 			       "%d).\n", le16_to_cpu(ra->client_in_use_list),
680 			       le16_to_cpu(ra->flags));
681 		return FALSE;
682 	}
683 	/* $LogFile indicates a clean shutdown. */
684 	ntfs_log_trace("$LogFile indicates a clean shutdown\n");
685 	return TRUE;
686 }
687 
688 /**
689  * ntfs_empty_logfile - empty the contents of the $LogFile journal
690  * @na:		ntfs attribute of journal $LogFile to empty
691  *
692  * Empty the contents of the $LogFile journal @na and return 0 on success and
693  * -1 on error.
694  *
695  * This function assumes that the $LogFile journal has already been consistency
696  * checked by a call to ntfs_check_logfile() and that ntfs_is_logfile_clean()
697  * has been used to ensure that the $LogFile is clean.
698  */
699 int ntfs_empty_logfile(ntfs_attr *na)
700 {
701 	s64 pos, count;
702 	char buf[NTFS_BUF_SIZE];
703 
704 	ntfs_log_trace("Entering.\n");
705 
706 	if (NVolLogFileEmpty(na->ni->vol))
707 		return 0;
708 
709 	if (!NAttrNonResident(na)) {
710 		errno = EIO;
711 		ntfs_log_perror("Resident $LogFile $DATA attribute");
712 		return -1;
713 	}
714 
715 	memset(buf, -1, NTFS_BUF_SIZE);
716 
717 	pos = 0;
718 	while ((count = na->data_size - pos) > 0) {
719 
720 		if (count > NTFS_BUF_SIZE)
721 			count = NTFS_BUF_SIZE;
722 
723 		count = ntfs_attr_pwrite(na, pos, count, buf);
724 		if (count <= 0) {
725 			ntfs_log_perror("Failed to reset $LogFile");
726 			if (count != -1)
727 				errno = EIO;
728 			return -1;
729 		}
730 		pos += count;
731 	}
732 
733 	NVolSetLogFileEmpty(na->ni->vol);
734 
735 	return 0;
736 }
737