Allow IPv6 address entry in tools>ping - Loosens valid character check

[tomato/davidwu.git] / release / src / router / ntfs-3g / libntfs-3g / logfile.c

/**
 * logfile.c - NTFS journal handling. Originated from the Linux-NTFS project.
 *
 * Copyright (c) 2002-2005 Anton Altaparmakov
 * Copyright (c) 2005 Yura Pakhuchiy
 * Copyright (c) 2005-2009 Szabolcs Szakacsits
 *
 * This program/include file 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/include file 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 (in the main directory of the NTFS-3G
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#include "attrib.h"
#include "debug.h"
#include "logfile.h"
#include "volume.h"
#include "mst.h"
#include "logging.h"
#include "misc.h"

/**
 * ntfs_check_restart_page_header - check the page header for consistency
 * @rp:         restart page header to check
 * @pos:        position in logfile at which the restart page header resides
 *
 * Check the restart page header @rp for consistency and return TRUE if it is
 * consistent and FALSE otherwise.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 */
static BOOL ntfs_check_restart_page_header(RESTART_PAGE_HEADER *rp, s64 pos)
{
        u32 logfile_system_page_size, logfile_log_page_size;
        u16 ra_ofs, usa_count, usa_ofs, usa_end = 0;
        BOOL have_usa = TRUE;

        ntfs_log_trace("Entering.\n");
        /*
         * If the system or log page sizes are smaller than the ntfs block size
         * or either is not a power of 2 we cannot handle this log file.
         */
        logfile_system_page_size = le32_to_cpu(rp->system_page_size);
        logfile_log_page_size = le32_to_cpu(rp->log_page_size);
        if (logfile_system_page_size < NTFS_BLOCK_SIZE ||
                        logfile_log_page_size < NTFS_BLOCK_SIZE ||
                        logfile_system_page_size &
                        (logfile_system_page_size - 1) ||
                        logfile_log_page_size & (logfile_log_page_size - 1)) {
                ntfs_log_error("$LogFile uses unsupported page size.\n");
                return FALSE;
        }
        /*
         * We must be either at !pos (1st restart page) or at pos = system page
         * size (2nd restart page).
         */
        if (pos && pos != logfile_system_page_size) {
                ntfs_log_error("Found restart area in incorrect "
                                "position in $LogFile.\n");
                return FALSE;
        }
        /*
         * We only know how to handle version 1.1 and 2.0, though
         * version 2.0 is probably related to cached metadata in
         * Windows 8, and we will refuse to mount.
         * Nevertheless, do all the relevant checks before rejecting.
         */
        if (((rp->major_ver != const_cpu_to_le16(1))
                         || (rp->minor_ver != const_cpu_to_le16(1)))
           && ((rp->major_ver != const_cpu_to_le16(2))
                         || (rp->minor_ver != const_cpu_to_le16(0)))) {
                ntfs_log_error("$LogFile version %i.%i is not "
                                "supported.\n   (This driver supports version "
                                "1.1 and 2.0 only.)\n",
                                        (int)sle16_to_cpu(rp->major_ver),
                                        (int)sle16_to_cpu(rp->minor_ver));
                return FALSE;
        }
        /*
         * If chkdsk has been run the restart page may not be protected by an
         * update sequence array.
         */
        if (ntfs_is_chkd_record(rp->magic) && !le16_to_cpu(rp->usa_count)) {
                have_usa = FALSE;
                goto skip_usa_checks;
        }
        /* Verify the size of the update sequence array. */
        usa_count = 1 + (logfile_system_page_size >> NTFS_BLOCK_SIZE_BITS);
        if (usa_count != le16_to_cpu(rp->usa_count)) {
                ntfs_log_error("$LogFile restart page specifies "
                                "inconsistent update sequence array count.\n");
                return FALSE;
        }
        /* Verify the position of the update sequence array. */
        usa_ofs = le16_to_cpu(rp->usa_ofs);
        usa_end = usa_ofs + usa_count * sizeof(u16);
        if (usa_ofs < sizeof(RESTART_PAGE_HEADER) ||
                        usa_end > NTFS_BLOCK_SIZE - sizeof(u16)) {
                ntfs_log_error("$LogFile restart page specifies "
                                "inconsistent update sequence array offset.\n");
                return FALSE;
        }
skip_usa_checks:
        /*
         * Verify the position of the restart area.  It must be:
         *      - aligned to 8-byte boundary,
         *      - after the update sequence array, and
         *      - within the system page size.
         */
        ra_ofs = le16_to_cpu(rp->restart_area_offset);
        if (ra_ofs & 7 || (have_usa ? ra_ofs < usa_end :
                        ra_ofs < sizeof(RESTART_PAGE_HEADER)) ||
                        ra_ofs > logfile_system_page_size) {
                ntfs_log_error("$LogFile restart page specifies "
                                "inconsistent restart area offset.\n");
                return FALSE;
        }
        /*
         * Only restart pages modified by chkdsk are allowed to have chkdsk_lsn
         * set.
         */
        if (!ntfs_is_chkd_record(rp->magic) && sle64_to_cpu(rp->chkdsk_lsn)) {
                ntfs_log_error("$LogFile restart page is not modified "
                                "by chkdsk but a chkdsk LSN is specified.\n");
                return FALSE;
        }
        ntfs_log_trace("Done.\n");
        return TRUE;
}

/**
 * ntfs_check_restart_area - check the restart area for consistency
 * @rp:         restart page whose restart area to check
 *
 * Check the restart area of the restart page @rp for consistency and return
 * TRUE if it is consistent and FALSE otherwise.
 *
 * This function assumes that the restart page header has already been
 * consistency checked.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 */
static BOOL ntfs_check_restart_area(RESTART_PAGE_HEADER *rp)
{
        u64 file_size;
        RESTART_AREA *ra;
        u16 ra_ofs, ra_len, ca_ofs;
        u8 fs_bits;

        ntfs_log_trace("Entering.\n");
        ra_ofs = le16_to_cpu(rp->restart_area_offset);
        ra = (RESTART_AREA*)((u8*)rp + ra_ofs);
        /*
         * Everything before ra->file_size must be before the first word
         * protected by an update sequence number.  This ensures that it is
         * safe to access ra->client_array_offset.
         */
        if (ra_ofs + offsetof(RESTART_AREA, file_size) >
                        NTFS_BLOCK_SIZE - sizeof(u16)) {
                ntfs_log_error("$LogFile restart area specifies "
                                "inconsistent file offset.\n");
                return FALSE;
        }
        /*
         * Now that we can access ra->client_array_offset, make sure everything
         * up to the log client array is before the first word protected by an
         * update sequence number.  This ensures we can access all of the
         * restart area elements safely.  Also, the client array offset must be
         * aligned to an 8-byte boundary.
         */
        ca_ofs = le16_to_cpu(ra->client_array_offset);
        if (((ca_ofs + 7) & ~7) != ca_ofs ||
                        ra_ofs + ca_ofs > (u16)(NTFS_BLOCK_SIZE -
                        sizeof(u16))) {
                ntfs_log_error("$LogFile restart area specifies "
                                "inconsistent client array offset.\n");
                return FALSE;
        }
        /*
         * The restart area must end within the system page size both when
         * calculated manually and as specified by ra->restart_area_length.
         * Also, the calculated length must not exceed the specified length.
         */
        ra_len = ca_ofs + le16_to_cpu(ra->log_clients) *
                        sizeof(LOG_CLIENT_RECORD);
        if ((u32)(ra_ofs + ra_len) > le32_to_cpu(rp->system_page_size) ||
                        (u32)(ra_ofs + le16_to_cpu(ra->restart_area_length)) >
                        le32_to_cpu(rp->system_page_size) ||
                        ra_len > le16_to_cpu(ra->restart_area_length)) {
                ntfs_log_error("$LogFile restart area is out of bounds "
                                "of the system page size specified by the "
                                "restart page header and/or the specified "
                                "restart area length is inconsistent.\n");
                return FALSE;
        }
        /*
         * The ra->client_free_list and ra->client_in_use_list must be either
         * LOGFILE_NO_CLIENT or less than ra->log_clients or they are
         * overflowing the client array.
         */
        if ((ra->client_free_list != LOGFILE_NO_CLIENT &&
                        le16_to_cpu(ra->client_free_list) >=
                        le16_to_cpu(ra->log_clients)) ||
                        (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
                        le16_to_cpu(ra->client_in_use_list) >=
                        le16_to_cpu(ra->log_clients))) {
                ntfs_log_error("$LogFile restart area specifies "
                                "overflowing client free and/or in use lists.\n");
                return FALSE;
        }
        /*
         * Check ra->seq_number_bits against ra->file_size for consistency.
         * We cannot just use ffs() because the file size is not a power of 2.
         */
        file_size = (u64)sle64_to_cpu(ra->file_size);
        fs_bits = 0;
        while (file_size) {
                file_size >>= 1;
                fs_bits++;
        }
        if (le32_to_cpu(ra->seq_number_bits) != (u32)(67 - fs_bits)) {
                ntfs_log_error("$LogFile restart area specifies "
                                "inconsistent sequence number bits.\n");
                return FALSE;
        }
        /* The log record header length must be a multiple of 8. */
        if (((le16_to_cpu(ra->log_record_header_length) + 7) & ~7) !=
                        le16_to_cpu(ra->log_record_header_length)) {
                ntfs_log_error("$LogFile restart area specifies "
                                "inconsistent log record header length.\n");
                return FALSE;
        }
        /* Ditto for the log page data offset. */
        if (((le16_to_cpu(ra->log_page_data_offset) + 7) & ~7) !=
                        le16_to_cpu(ra->log_page_data_offset)) {
                ntfs_log_error("$LogFile restart area specifies "
                                "inconsistent log page data offset.\n");
                return FALSE;
        }
        ntfs_log_trace("Done.\n");
        return TRUE;
}

/**
 * ntfs_check_log_client_array - check the log client array for consistency
 * @rp:         restart page whose log client array to check
 *
 * Check the log client array of the restart page @rp for consistency and
 * return TRUE if it is consistent and FALSE otherwise.
 *
 * This function assumes that the restart page header and the restart area have
 * already been consistency checked.
 *
 * Unlike ntfs_check_restart_page_header() and ntfs_check_restart_area(), this
 * function needs @rp->system_page_size bytes in @rp, i.e. it requires the full
 * restart page and the page must be multi sector transfer deprotected.
 */
static BOOL ntfs_check_log_client_array(RESTART_PAGE_HEADER *rp)
{
        RESTART_AREA *ra;
        LOG_CLIENT_RECORD *ca, *cr;
        u16 nr_clients, idx;
        BOOL in_free_list, idx_is_first;

        ntfs_log_trace("Entering.\n");
        ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
        ca = (LOG_CLIENT_RECORD*)((u8*)ra +
                        le16_to_cpu(ra->client_array_offset));
        /*
         * Check the ra->client_free_list first and then check the
         * ra->client_in_use_list.  Check each of the log client records in
         * each of the lists and check that the array does not overflow the
         * ra->log_clients value.  Also keep track of the number of records
         * visited as there cannot be more than ra->log_clients records and
         * that way we detect eventual loops in within a list.
         */
        nr_clients = le16_to_cpu(ra->log_clients);
        idx = le16_to_cpu(ra->client_free_list);
        in_free_list = TRUE;
check_list:
        for (idx_is_first = TRUE; idx != LOGFILE_NO_CLIENT_CPU; nr_clients--,
                        idx = le16_to_cpu(cr->next_client)) {
                if (!nr_clients || idx >= le16_to_cpu(ra->log_clients))
                        goto err_out;
                /* Set @cr to the current log client record. */
                cr = ca + idx;
                /* The first log client record must not have a prev_client. */
                if (idx_is_first) {
                        if (cr->prev_client != LOGFILE_NO_CLIENT)
                                goto err_out;
                        idx_is_first = FALSE;
                }
        }
        /* Switch to and check the in use list if we just did the free list. */
        if (in_free_list) {
                in_free_list = FALSE;
                idx = le16_to_cpu(ra->client_in_use_list);
                goto check_list;
        }
        ntfs_log_trace("Done.\n");
        return TRUE;
err_out:
        ntfs_log_error("$LogFile log client array is corrupt.\n");
        return FALSE;
}

/**
 * ntfs_check_and_load_restart_page - check the restart page for consistency
 * @log_na:     opened ntfs attribute for journal $LogFile
 * @rp:         restart page to check
 * @pos:        position in @log_na at which the restart page resides
 * @wrp:       [OUT] copy of the multi sector transfer deprotected restart page
 * @lsn:       [OUT] set to the current logfile lsn on success
 *
 * Check the restart page @rp for consistency and return 0 if it is consistent
 * and errno otherwise.  The restart page may have been modified by chkdsk in
 * which case its magic is CHKD instead of RSTR.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 *
 * If @wrp is not NULL, on success, *@wrp will point to a buffer containing a
 * copy of the complete multi sector transfer deprotected page.  On failure,
 * *@wrp is undefined.
 *
 * Similarly, if @lsn is not NULL, on success *@lsn will be set to the current
 * logfile lsn according to this restart page.  On failure, *@lsn is undefined.
 *
 * The following error codes are defined:
 *     EINVAL - The restart page is inconsistent.
 *     ENOMEM - Not enough memory to load the restart page.
 *     EIO    - Failed to reading from $LogFile.
 */
static int ntfs_check_and_load_restart_page(ntfs_attr *log_na,
                RESTART_PAGE_HEADER *rp, s64 pos, RESTART_PAGE_HEADER **wrp,
                LSN *lsn)
{
        RESTART_AREA *ra;
        RESTART_PAGE_HEADER *trp;
        int err;

        ntfs_log_trace("Entering.\n");
        /* Check the restart page header for consistency. */
        if (!ntfs_check_restart_page_header(rp, pos)) {
                /* Error output already done inside the function. */
                return EINVAL;
        }
        /* Check the restart area for consistency. */
        if (!ntfs_check_restart_area(rp)) {
                /* Error output already done inside the function. */
                return EINVAL;
        }
        ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
        /*
         * Allocate a buffer to store the whole restart page so we can multi
         * sector transfer deprotect it.
         */
        trp = ntfs_malloc(le32_to_cpu(rp->system_page_size));
        if (!trp)
                return errno;
        /*
         * Read the whole of the restart page into the buffer.  If it fits
         * completely inside @rp, just copy it from there.  Otherwise read it
         * from disk.
         */
        if (le32_to_cpu(rp->system_page_size) <= NTFS_BLOCK_SIZE)
                memcpy(trp, rp, le32_to_cpu(rp->system_page_size));
        else if (ntfs_attr_pread(log_na, pos,
                        le32_to_cpu(rp->system_page_size), trp) !=
                        le32_to_cpu(rp->system_page_size)) {
                err = errno;
                ntfs_log_error("Failed to read whole restart page into the "
                                "buffer.\n");
                if (err != ENOMEM)
                        err = EIO;
                goto err_out;
        }
        /*
         * Perform the multi sector transfer deprotection on the buffer if the
         * restart page is protected.
         */
        if ((!ntfs_is_chkd_record(trp->magic) || le16_to_cpu(trp->usa_count))
                        && ntfs_mst_post_read_fixup((NTFS_RECORD*)trp,
                        le32_to_cpu(rp->system_page_size))) {
                /*
                 * A multi sector tranfer error was detected.  We only need to
                 * abort if the restart page contents exceed the multi sector
                 * transfer fixup of the first sector.
                 */
                if (le16_to_cpu(rp->restart_area_offset) +
                                le16_to_cpu(ra->restart_area_length) >
                                NTFS_BLOCK_SIZE - (int)sizeof(u16)) {
                        ntfs_log_error("Multi sector transfer error "
                                   "detected in $LogFile restart page.\n");
                        err = EINVAL;
                        goto err_out;
                }
        }
        /*
         * If the restart page is modified by chkdsk or there are no active
         * logfile clients, the logfile is consistent.  Otherwise, need to
         * check the log client records for consistency, too.
         */
        err = 0;
        if (ntfs_is_rstr_record(rp->magic) &&
                        ra->client_in_use_list != LOGFILE_NO_CLIENT) {
                if (!ntfs_check_log_client_array(trp)) {
                        err = EINVAL;
                        goto err_out;
                }
        }
        if (lsn) {
                if (ntfs_is_rstr_record(rp->magic))
                        *lsn = sle64_to_cpu(ra->current_lsn);
                else /* if (ntfs_is_chkd_record(rp->magic)) */
                        *lsn = sle64_to_cpu(rp->chkdsk_lsn);
        }
        ntfs_log_trace("Done.\n");
        if (wrp)
                *wrp = trp;
        else {
err_out:
                free(trp);
        }
        return err;
}

/**
 * ntfs_check_logfile - check in the journal if the volume is consistent
 * @log_na:     ntfs attribute of loaded journal $LogFile to check
 * @rp:         [OUT] on success this is a copy of the current restart page
 *
 * Check the $LogFile journal for consistency and return TRUE if it is
 * consistent and FALSE if not.  On success, the current restart page is
 * returned in *@rp.  Caller must call ntfs_free(*@rp) when finished with it.
 *
 * At present we only check the two restart pages and ignore the log record
 * pages.
 *
 * Note that the MstProtected flag is not set on the $LogFile inode and hence
 * when reading pages they are not deprotected.  This is because we do not know
 * if the $LogFile was created on a system with a different page size to ours
 * yet and mst deprotection would fail if our page size is smaller.
 */
BOOL ntfs_check_logfile(ntfs_attr *log_na, RESTART_PAGE_HEADER **rp)
{
        s64 size, pos;
        LSN rstr1_lsn, rstr2_lsn;
        ntfs_volume *vol = log_na->ni->vol;
        u8 *kaddr = NULL;
        RESTART_PAGE_HEADER *rstr1_ph = NULL;
        RESTART_PAGE_HEADER *rstr2_ph = NULL;
        int log_page_size, err;
        BOOL logfile_is_empty = TRUE;
        u8 log_page_bits;

        ntfs_log_trace("Entering.\n");
        /* An empty $LogFile must have been clean before it got emptied. */
        if (NVolLogFileEmpty(vol))
                goto is_empty;
        size = log_na->data_size;
        /* Make sure the file doesn't exceed the maximum allowed size. */
        if (size > (s64)MaxLogFileSize)
                size = MaxLogFileSize;
        log_page_size = DefaultLogPageSize;
        /*
         * Use generic_ffs() instead of ffs() to enable the compiler to
         * optimize log_page_size and log_page_bits into constants.
         */
        log_page_bits = ffs(log_page_size) - 1;
        size &= ~(log_page_size - 1);

        /*
         * Ensure the log file is big enough to store at least the two restart
         * pages and the minimum number of log record pages.
         */
        if (size < log_page_size * 2 || (size - log_page_size * 2) >>
                        log_page_bits < MinLogRecordPages) {
                ntfs_log_error("$LogFile is too small.\n");
                return FALSE;
        }
        /* Allocate memory for restart page. */
        kaddr = ntfs_malloc(NTFS_BLOCK_SIZE);
        if (!kaddr)
                return FALSE;
        /*
         * Read through the file looking for a restart page.  Since the restart
         * page header is at the beginning of a page we only need to search at
         * what could be the beginning of a page (for each page size) rather
         * than scanning the whole file byte by byte.  If all potential places
         * contain empty and uninitialized records, the log file can be assumed
         * to be empty.
         */
        for (pos = 0; pos < size; pos <<= 1) {
                /*
                 * Read first NTFS_BLOCK_SIZE bytes of potential restart page.
                 */
                if (ntfs_attr_pread(log_na, pos, NTFS_BLOCK_SIZE, kaddr) !=
                                NTFS_BLOCK_SIZE) {
                        ntfs_log_error("Failed to read first NTFS_BLOCK_SIZE "
                                        "bytes of potential restart page.\n");
                        goto err_out;
                }

                /*
                 * A non-empty block means the logfile is not empty while an
                 * empty block after a non-empty block has been encountered
                 * means we are done.
                 */
                if (!ntfs_is_empty_recordp((le32*)kaddr))
                        logfile_is_empty = FALSE;
                else if (!logfile_is_empty)
                        break;
                /*
                 * A log record page means there cannot be a restart page after
                 * this so no need to continue searching.
                 */
                if (ntfs_is_rcrd_recordp((le32*)kaddr))
                        break;
                /* If not a (modified by chkdsk) restart page, continue. */
                if (!ntfs_is_rstr_recordp((le32*)kaddr) &&
                                !ntfs_is_chkd_recordp((le32*)kaddr)) {
                        if (!pos)
                                pos = NTFS_BLOCK_SIZE >> 1;
                        continue;
                }
                /*
                 * Check the (modified by chkdsk) restart page for consistency
                 * and get a copy of the complete multi sector transfer
                 * deprotected restart page.
                 */
                err = ntfs_check_and_load_restart_page(log_na,
                                (RESTART_PAGE_HEADER*)kaddr, pos,
                                !rstr1_ph ? &rstr1_ph : &rstr2_ph,
                                !rstr1_ph ? &rstr1_lsn : &rstr2_lsn);
                if (!err) {
                        /*
                         * If we have now found the first (modified by chkdsk)
                         * restart page, continue looking for the second one.
                         */
                        if (!pos) {
                                pos = NTFS_BLOCK_SIZE >> 1;
                                continue;
                        }
                        /*
                         * We have now found the second (modified by chkdsk)
                         * restart page, so we can stop looking.
                         */
                        break;
                }
                /*
                 * Error output already done inside the function.  Note, we do
                 * not abort if the restart page was invalid as we might still
                 * find a valid one further in the file.
                 */
                if (err != EINVAL)
                      goto err_out;
                /* Continue looking. */
                if (!pos)
                        pos = NTFS_BLOCK_SIZE >> 1;
        }
        if (kaddr) {
                free(kaddr);
                kaddr = NULL;
        }
        if (logfile_is_empty) {
                NVolSetLogFileEmpty(vol);
is_empty:
                ntfs_log_trace("Done.  ($LogFile is empty.)\n");
                return TRUE;
        }
        if (!rstr1_ph) {
                if (rstr2_ph)
                        ntfs_log_error("BUG: rstr2_ph isn't NULL!\n");
                ntfs_log_error("Did not find any restart pages in "
                           "$LogFile and it was not empty.\n");
                return FALSE;
        }
        /* If both restart pages were found, use the more recent one. */
        if (rstr2_ph) {
                /*
                 * If the second restart area is more recent, switch to it.
                 * Otherwise just throw it away.
                 */
                if (rstr2_lsn > rstr1_lsn) {
                        ntfs_log_debug("Using second restart page as it is more "
                                        "recent.\n");
                        free(rstr1_ph);
                        rstr1_ph = rstr2_ph;
                        /* rstr1_lsn = rstr2_lsn; */
                } else {
                        ntfs_log_debug("Using first restart page as it is more "
                                        "recent.\n");
                        free(rstr2_ph);
                }
                rstr2_ph = NULL;
        }
        /* All consistency checks passed. */
        if (rp)
                *rp = rstr1_ph;
        else
                free(rstr1_ph);
        ntfs_log_trace("Done.\n");
        return TRUE;
err_out:
        free(kaddr);
        free(rstr1_ph);
        free(rstr2_ph);
        return FALSE;
}

/**
 * ntfs_is_logfile_clean - check in the journal if the volume is clean
 * @log_na:     ntfs attribute of loaded journal $LogFile to check
 * @rp:         copy of the current restart page
 *
 * Analyze the $LogFile journal and return TRUE if it indicates the volume was
 * shutdown cleanly and FALSE if not.
 *
 * At present we only look at the two restart pages and ignore the log record
 * pages.  This is a little bit crude in that there will be a very small number
 * of cases where we think that a volume is dirty when in fact it is clean.
 * This should only affect volumes that have not been shutdown cleanly but did
 * not have any pending, non-check-pointed i/o, i.e. they were completely idle
 * at least for the five seconds preceding the unclean shutdown.
 *
 * This function assumes that the $LogFile journal has already been consistency
 * checked by a call to ntfs_check_logfile() and in particular if the $LogFile
 * is empty this function requires that NVolLogFileEmpty() is true otherwise an
 * empty volume will be reported as dirty.
 */
BOOL ntfs_is_logfile_clean(ntfs_attr *log_na, RESTART_PAGE_HEADER *rp)
{
        RESTART_AREA *ra;

        ntfs_log_trace("Entering.\n");
        /* An empty $LogFile must have been clean before it got emptied. */
        if (NVolLogFileEmpty(log_na->ni->vol)) {
                ntfs_log_trace("$LogFile is empty\n");
                return TRUE;
        }
        if (!rp) {
                ntfs_log_error("Restart page header is NULL\n");
                return FALSE;
        }
        if (!ntfs_is_rstr_record(rp->magic) &&
                        !ntfs_is_chkd_record(rp->magic)) {
                ntfs_log_error("Restart page buffer is invalid\n");
                return FALSE;
        }

        ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
        /*
         * If the $LogFile has active clients, i.e. it is open, and we do not
         * have the RESTART_VOLUME_IS_CLEAN bit set in the restart area flags,
         * we assume there was an unclean shutdown.
         */
        if (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
                        !(ra->flags & RESTART_VOLUME_IS_CLEAN)) {
                ntfs_log_error("The disk contains an unclean file system (%d, "
                               "%d).\n", le16_to_cpu(ra->client_in_use_list),
                               le16_to_cpu(ra->flags));
                return FALSE;
        }
        /* $LogFile indicates a clean shutdown. */
        ntfs_log_trace("$LogFile indicates a clean shutdown\n");
        return TRUE;
}

/**
 * ntfs_empty_logfile - empty the contents of the $LogFile journal
 * @na:         ntfs attribute of journal $LogFile to empty
 *
 * Empty the contents of the $LogFile journal @na and return 0 on success and
 * -1 on error.
 *
 * This function assumes that the $LogFile journal has already been consistency
 * checked by a call to ntfs_check_logfile() and that ntfs_is_logfile_clean()
 * has been used to ensure that the $LogFile is clean.
 */
int ntfs_empty_logfile(ntfs_attr *na)
{
        s64 pos, count;
        char buf[NTFS_BUF_SIZE];

        ntfs_log_trace("Entering.\n");
        
        if (NVolLogFileEmpty(na->ni->vol))
                return 0;

        if (!NAttrNonResident(na)) {
                errno = EIO;
                ntfs_log_perror("Resident $LogFile $DATA attribute");
                return -1;
        }

        memset(buf, -1, NTFS_BUF_SIZE);

        pos = 0;
        while ((count = na->data_size - pos) > 0) {
                
                if (count > NTFS_BUF_SIZE)
                        count = NTFS_BUF_SIZE;

                count = ntfs_attr_pwrite(na, pos, count, buf);
                if (count <= 0) {
                        ntfs_log_perror("Failed to reset $LogFile");
                        if (count != -1)
                                errno = EIO;
                        return -1;
                }
                pos += count;
        }

        NVolSetLogFileEmpty(na->ni->vol);
        
        return 0;
}