logfile.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

	}
	/*
	 * 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, log_page_mask, 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;
	log_page_mask = log_page_size - 1;
	/*
	 * 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 = malloc(NTFS_BLOCK_SIZE);
	if (!kaddr) {
		ntfs_log_error("Not enough memory.\n");
		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 $LogFile must have been clean before it got emptied. */
	if (NVolLogFileEmpty(log_na->ni->vol)) {
		ntfs_log_trace("Done.  ($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.  This is "
			   "probably a bug in that the $LogFile should "
			   "have been consistency checked before calling "
			   "this function.\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_debug("Done.  $LogFile indicates a dirty shutdown.\n");
		return FALSE;
	}
	/* $LogFile indicates a clean shutdown. */
	ntfs_log_trace("Done.  $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, progress *prog, int progidx)
{
	s64 len, pos, count;
	char *buf = NULL;
	int err;

	ntfs_log_trace("Entering.\n");
	buf = malloc(NTFS_BUF_SIZE);
	if (buf == NULL)
	  {
	    err = ENOMEM;
	    goto io_error_exit;
	  }
	if (NVolLogFileEmpty(na->ni->vol))
		goto done;

	/* The $DATA attribute of the $LogFile has to be non-resident. */
	if (!NAttrNonResident(na)) {
		err = EIO;
		ntfs_log_debug("$LogFile $DATA attribute is resident!?!\n");
		goto io_error_exit;
	}

	/* Get length of $LogFile contents. */
	len = na->data_size;
	if (!len) {
		ntfs_log_debug("$LogFile has zero length, no disk write "
				"needed.\n");
		free(buf);
		return 0;
	}

	/* Read $LogFile until its end. We do this as a check for correct
	   length thus making sure we are decompressing the mapping pairs
	   array correctly and hence writing below is safe as well. */
	pos = 0;
	while ((count = ntfs_attr_pread(na, pos, NTFS_BUF_SIZE, buf)) > 0)
	  {
		if (prog)
			progress_update(prog, progidx, pos, (len * 3));
		pos += count;
	  }

	if (count == -1 || pos != len) {
		err = errno;
		ntfs_log_debug("Amount of $LogFile data read does not "
				"correspond to expected length!\n");
		if (count != -1)
			err = EIO;
		goto io_error_exit;
	}

	/* Fill the buffer with 0xff's. */
	memset(buf, -1, NTFS_BUF_SIZE);

	/* Set the $DATA attribute. */
	pos = 0;
	while ((count = len - pos) > 0) {
		if (count > NTFS_BUF_SIZE)
			count = NTFS_BUF_SIZE;

		if ((count = ntfs_attr_pwrite(na, pos, count, buf)) <= 0) {
			err = errno;
			ntfs_log_debug("Failed to set the $LogFile attribute "
					"value.\n");
			if (count != -1)
				err = EIO;
			goto io_error_exit;
		}
		if (prog)
			progress_update(prog, progidx, (len + (pos * 2)),
					(len * 3));
		pos += count;
	}

	/* Set the flag so we do not have to do it again on remount. */
	NVolSetLogFileEmpty(na->ni->vol);
done:
	ntfs_log_trace("Done.\n");
	free(buf);
	return 0;
io_error_exit:
	ntfs_attr_close(na);
	ntfs_inode_close(na->ni);
	errno = err;
	free(buf);
	return -1;
}