text: ﻿/**
   * runlist.c - Run list handling code. Originated from the Linux-NTFS project.
   *
   * Copyright (c) 2002-2005 Anton Altaparmakov
   * Copyright (c) 2002-2005 Richard Russon
   * Copyright (c) 2002-2008 Szabolcs Szakacsits
   * Copyright (c) 2004 Yura Pakhuchiy
   * Copyright (c) 2007-2010 Jean-Pierre Andre
   *
   * 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_STDIO_H
  #include <stdio.h>
  #endif
  #ifdef HAVE_STRING_H
  #include <string.h>
  #endif
  #ifdef HAVE_STDLIB_H
  #include <stdlib.h>
  #endif
  #ifdef HAVE_ERRNO_H
  #include <errno.h>
  #endif
  
  #include "compat.h"
  #include "types.h"
  #include "volume.h"
  #include "layout.h"
  #include "debug.h"
  #include "device.h"
  #include "logging.h"
  #include "misc.h"
  
  /**
   * ntfs_rl_mm - runlist memmove
   * @base:
   * @dst:
   * @src:
   * @size:
   *
   * Description...
   *
   * Returns:
   */
  static void ntfs_rl_mm(runlist_element *base, int dst, int src, int size)
  {
  	if ((dst != src) && (size > 0))
  		memmove(base + dst, base + src, size * sizeof(*base));
  }
  
  /**
   * ntfs_rl_mc - runlist memory copy
   * @dstbase:
   * @dst:
   * @srcbase:
   * @src:
   * @size:
   *
   * Description...
   *
   * Returns:
   */
  static void ntfs_rl_mc(runlist_element *dstbase, int dst,
  		       runlist_element *srcbase, int src, int size)
  {
  	if (size > 0)
  		memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
  }
  
  /**
   * ntfs_rl_realloc - Reallocate memory for runlists
   * @rl:		original runlist
   * @old_size:	number of runlist elements in the original runlist @rl
   * @new_size:	number of runlist elements we need space for
   *
   * As the runlists grow, more memory will be required. To prevent large
   * numbers of small reallocations of memory, this function returns a 4kiB block
   * of memory.
   *
   * N.B.	If the new allocation doesn't require a different number of 4kiB
   *	blocks in memory, the function will return the original pointer.
   *
   * On success, return a pointer to the newly allocated, or recycled, memory.
   * On error, return NULL with errno set to the error code.
   */
  static runlist_element *ntfs_rl_realloc(runlist_element *rl, int old_size, 
  					int new_size)
  {
  	old_size = (old_size * sizeof(runlist_element) + 0xfff) & ~0xfff;
  	new_size = (new_size * sizeof(runlist_element) + 0xfff) & ~0xfff;
  	if (old_size == new_size)
  		return rl;
  	return realloc(rl, new_size);
  }
  
  /*
   *		Extend a runlist by some entry count
   *	The runlist may have to be reallocated
   *
   *	Returns the reallocated runlist
   *		or NULL if reallocation was not possible (with errno set)
   *		the runlist is left unchanged if the reallocation fails
   */
  
  runlist_element *ntfs_rl_extend(ntfs_attr *na, runlist_element *rl,
  			int more_entries)
  {
  	runlist_element *newrl;
  	int last;
  	int irl;
  
  	if (na->rl && rl) {
  		irl = (int)(rl - na->rl);
  		last = irl;
  		while (na->rl[last].length)
  			last++;
  		newrl = ntfs_rl_realloc(na->rl,last+1,last+more_entries+1);
  		if (!newrl) {
  			errno = ENOMEM;
  			rl = (runlist_element*)NULL;
  		} else {
  			na->rl = newrl;
  			rl = &newrl[irl];
  		}
  	} else {
  		ntfs_log_error("Cannot extend unmapped runlist");
  		errno = EIO;
  		rl = (runlist_element*)NULL;
  	}
  	return (rl);
  }
  
  /**
   * ntfs_rl_are_mergeable - test if two runlists can be joined together
   * @dst:	original runlist
   * @src:	new runlist to test for mergeability with @dst
   *
   * Test if two runlists can be joined together. For this, their VCNs and LCNs
   * must be adjacent.
   *
   * Return: TRUE   Success, the runlists can be merged.
   *	   FALSE  Failure, the runlists cannot be merged.
   */
  static BOOL ntfs_rl_are_mergeable(runlist_element *dst, runlist_element *src)
  {
  	if (!dst || !src) {
  		ntfs_log_debug("Eeek. ntfs_rl_are_mergeable() invoked with NULL "
  				"pointer!\n");
  		return FALSE;
  	}
  
  	/* We can merge unmapped regions even if they are misaligned. */
  	if ((dst->lcn == LCN_RL_NOT_MAPPED) && (src->lcn == LCN_RL_NOT_MAPPED))
  		return TRUE;
  	/* If the runs are misaligned, we cannot merge them. */
  	if ((dst->vcn + dst->length) != src->vcn)
  		return FALSE;
  	/* If both runs are non-sparse and contiguous, we can merge them. */
  	if ((dst->lcn >= 0) && (src->lcn >= 0) &&
  		((dst->lcn + dst->length) == src->lcn))
  		return TRUE;
  	/* If we are merging two holes, we can merge them. */
  	if ((dst->lcn == LCN_HOLE) && (src->lcn == LCN_HOLE))
  		return TRUE;
  	/* Cannot merge. */
  	return FALSE;
  }
  
  /**
   * __ntfs_rl_merge - merge two runlists without testing if they can be merged
   * @dst:	original, destination runlist
   * @src:	new runlist to merge with @dst
   *
   * Merge the two runlists, writing into the destination runlist @dst. The
   * caller must make sure the runlists can be merged or this will corrupt the
   * destination runlist.
   */
  static void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
  {
  	dst->length += src->length;
  }
  
  /**
   * ntfs_rl_append - append a runlist after a given element
   * @dst:	original runlist to be worked on
   * @dsize:	number of elements in @dst (including end marker)
   * @src:	runlist to be inserted into @dst
   * @ssize:	number of elements in @src (excluding end marker)
   * @loc:	append the new runlist @src after this element in @dst
   *
   * Append the runlist @src after element @loc in @dst.  Merge the right end of
   * the new runlist, if necessary. Adjust the size of the hole before the
   * appended runlist.
   *
   * On success, return a pointer to the new, combined, runlist. Note, both
   * runlists @dst and @src are deallocated before returning so you cannot use
   * the pointers for anything any more. (Strictly speaking the returned runlist
   * may be the same as @dst but this is irrelevant.)
   *
   * On error, return NULL, with errno set to the error code. Both runlists are
   * left unmodified.
   */
  static runlist_element *ntfs_rl_append(runlist_element *dst, int dsize,
  				       runlist_element *src, int ssize, int loc)
  {
  	BOOL right = FALSE;	/* Right end of @src needs merging */
  	int marker;		/* End of the inserted runs */
  
  	if (!dst || !src) {
  		ntfs_log_debug("Eeek. ntfs_rl_append() invoked with NULL "
  				"pointer!\n");
  		errno = EINVAL;
  		return NULL;
  	}
  
  	/* First, check if the right hand end needs merging. */
  	if ((loc + 1) < dsize)
  		right = ntfs_rl_are_mergeable(src + ssize - 1, dst + loc + 1);
  
  	/* Space required: @dst size + @src size, less one if we merged. */
  	dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
  	if (!dst)
  		return NULL;
  	/*
  	 * We are guaranteed to succeed from here so can start modifying the
  	 * original runlists.
  	 */
  
  	/* First, merge the right hand end, if necessary. */
  	if (right)
  		__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
  
  	/* marker - First run after the @src runs that have been inserted */
  	marker = loc + ssize + 1;
  
  	/* Move the tail of @dst out of the way, then copy in @src. */
  	ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - loc - 1 - right);
  	ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
  
  	/* Adjust the size of the preceding hole. */
  	dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
  
  	/* We may have changed the length of the file, so fix the end marker */
  	if (dst[marker].lcn == LCN_ENOENT)
  		dst[marker].vcn = dst[marker-1].vcn + dst[marker-1].length;
  
  	return dst;
  }
  
  /**
   * ntfs_rl_insert - insert a runlist into another
   * @dst:	original runlist to be worked on
   * @dsize:	number of elements in @dst (including end marker)
   * @src:	new runlist to be inserted
   * @ssize:	number of elements in @src (excluding end marker)
   * @loc:	insert the new runlist @src before this element in @dst
   *
   * Insert the runlist @src before element @loc in the runlist @dst. Merge the
   * left end of the new runlist, if necessary. Adjust the size of the hole
   * after the inserted runlist.
   *
   * On success, return a pointer to the new, combined, runlist. Note, both
   * runlists @dst and @src are deallocated before returning so you cannot use
   * the pointers for anything any more. (Strictly speaking the returned runlist
   * may be the same as @dst but this is irrelevant.)
   *
   * On error, return NULL, with errno set to the error code. Both runlists are
   * left unmodified.
   */
  static runlist_element *ntfs_rl_insert(runlist_element *dst, int dsize,
  				       runlist_element *src, int ssize, int loc)
  {
  	BOOL left = FALSE;	/* Left end of @src needs merging */
  	BOOL disc = FALSE;	/* Discontinuity between @dst and @src */
  	int marker;		/* End of the inserted runs */
  
  	if (!dst || !src) {
  		ntfs_log_debug("Eeek. ntfs_rl_insert() invoked with NULL "
  				"pointer!\n");
  		errno = EINVAL;
  		return NULL;
  	}
  
  	/* disc => Discontinuity between the end of @dst and the start of @src.
  	 *	   This means we might need to insert a "notmapped" run.
  	 */
  	if (loc == 0)
  		disc = (src[0].vcn > 0);
  	else {
  		s64 merged_length;
  
  		left = ntfs_rl_are_mergeable(dst + loc - 1, src);
  
  		merged_length = dst[loc - 1].length;
  		if (left)
  			merged_length += src->length;
  
  		disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
  	}
  
  	/* Space required: @dst size + @src size, less one if we merged, plus
  	 * one if there was a discontinuity.
  	 */
  	dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc);
  	if (!dst)
  		return NULL;
  	/*
  	 * We are guaranteed to succeed from here so can start modifying the
  	 * original runlist.
  	 */
  
  	if (left)
  		__ntfs_rl_merge(dst + loc - 1, src);
  
  	/*
  	 * marker - First run after the @src runs that have been inserted
  	 * Nominally: marker = @loc + @ssize (location + number of runs in @src)
  	 * If "left", then the first run in @src has been merged with one in @dst.
  	 * If "disc", then @dst and @src don't meet and we need an extra run to fill the gap.
  	 */
  	marker = loc + ssize - left + disc;
  
  	/* Move the tail of @dst out of the way, then copy in @src. */
  	ntfs_rl_mm(dst, marker, loc, dsize - loc);
  	ntfs_rl_mc(dst, loc + disc, src, left, ssize - left);
  
  	/* Adjust the VCN of the first run after the insertion ... */
  	dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
  	/* ... and the length. */
  	if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED)
  		dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn;
  
  	/* Writing beyond the end of the file and there's a discontinuity. */
  	if (disc) {
  		if (loc > 0) {
  			dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length;
  			dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
  		} else {
  			dst[loc].vcn = 0;
  			dst[loc].length = dst[loc + 1].vcn;
  		}
  		dst[loc].lcn = LCN_RL_NOT_MAPPED;
  	}
  	return dst;
  }
  
  /**
   * ntfs_rl_replace - overwrite a runlist element with another runlist
   * @dst:	original runlist to be worked on
   * @dsize:	number of elements in @dst (including end marker)
   * @src:	new runlist to be inserted
   * @ssize:	number of elements in @src (excluding end marker)
   * @loc:	index in runlist @dst to overwrite with @src
   *
   * Replace the runlist element @dst at @loc with @src. Merge the left and
   * right ends of the inserted runlist, if necessary.
   *
   * On success, return a pointer to the new, combined, runlist. Note, both
   * runlists @dst and @src are deallocated before returning so you cannot use
   * the pointers for anything any more. (Strictly speaking the returned runlist
   * may be the same as @dst but this is irrelevant.)
   *
   * On error, return NULL, with errno set to the error code. Both runlists are
   * left unmodified.
   */
  static runlist_element *ntfs_rl_replace(runlist_element *dst, int dsize,
  					runlist_element *src, int ssize, 
  					int loc)
  {
  	signed delta;
  	BOOL left  = FALSE;	/* Left end of @src needs merging */
  	BOOL right = FALSE;	/* Right end of @src needs merging */
  	int tail;		/* Start of tail of @dst */
  	int marker;		/* End of the inserted runs */
  
  	if (!dst || !src) {
  		ntfs_log_debug("Eeek. ntfs_rl_replace() invoked with NULL "
  				"pointer!\n");
  		errno = EINVAL;
  		return NULL;
  	}
  
  	/* First, see if the left and right ends need merging. */
  	if ((loc + 1) < dsize)
  		right = ntfs_rl_are_mergeable(src + ssize - 1, dst + loc + 1);
  	if (loc > 0)
  		left = ntfs_rl_are_mergeable(dst + loc - 1, src);
  
  	/* Allocate some space. We'll need less if the left, right, or both
  	 * ends get merged.  The -1 accounts for the run being replaced.
  	 */
  	delta = ssize - 1 - left - right;
  	if (delta > 0) {
  		dst = ntfs_rl_realloc(dst, dsize, dsize + delta);
  		if (!dst)
  			return NULL;
  	}
  	/*
  	 * We are guaranteed to succeed from here so can start modifying the
  	 * original runlists.
  	 */
  
  	/* First, merge the left and right ends, if necessary. */
  	if (right)
  		__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
  	if (left)
  		__ntfs_rl_merge(dst + loc - 1, src);
  
  	/*
  	 * tail - Offset of the tail of @dst
  	 * Nominally: @tail = @loc + 1 (location, skipping the replaced run)
  	 * If "right", then one of @dst's runs is already merged into @src.
  	 */
  	tail = loc + right + 1;
  
  	/*
  	 * marker - First run after the @src runs that have been inserted
  	 * Nominally: @marker = @loc + @ssize (location + number of runs in @src)
  	 * If "left", then the first run in @src has been merged with one in @dst.
  	 */
  	marker = loc + ssize - left;
  
  	/* Move the tail of @dst out of the way, then copy in @src. */
  	ntfs_rl_mm(dst, marker, tail, dsize - tail);
  	ntfs_rl_mc(dst, loc, src, left, ssize - left);
  
  	/* We may have changed the length of the file, so fix the end marker */
  	if (((dsize - tail) > 0) && (dst[marker].lcn == LCN_ENOENT))
  		dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
  
  	return dst;
  }
  
  /**
   * ntfs_rl_split - insert a runlist into the centre of a hole
   * @dst:	original runlist to be worked on
   * @dsize:	number of elements in @dst (including end marker)
   * @src:	new runlist to be inserted
   * @ssize:	number of elements in @src (excluding end marker)
   * @loc:	index in runlist @dst at which to split and insert @src
   *
   * Split the runlist @dst at @loc into two and insert @new in between the two
   * fragments. No merging of runlists is necessary. Adjust the size of the
   * holes either side.
   *
   * On success, return a pointer to the new, combined, runlist. Note, both
   * runlists @dst and @src are deallocated before returning so you cannot use
   * the pointers for anything any more. (Strictly speaking the returned runlist
   * may be the same as @dst but this is irrelevant.)
   *
   * On error, return NULL, with errno set to the error code. Both runlists are
   * left unmodified.
   */
  static runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
  				      runlist_element *src, int ssize, int loc)
  {
  	if (!dst || !src) {
  		ntfs_log_debug("Eeek. ntfs_rl_split() invoked with NULL pointer!\n");
  		errno = EINVAL;
  		return NULL;
  	}
  
  	/* Space required: @dst size + @src size + one new hole. */
  	dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
  	if (!dst)
  		return dst;
  	/*
  	 * We are guaranteed to succeed from here so can start modifying the
  	 * original runlists.
  	 */
  
  	/* Move the tail of @dst out of the way, then copy in @src. */
  	ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
  	ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
  
  	/* Adjust the size of the holes either size of @src. */
  	dst[loc].length		= dst[loc+1].vcn       - dst[loc].vcn;
  	dst[loc+ssize+1].vcn	= dst[loc+ssize].vcn   + dst[loc+ssize].length;
  	dst[loc+ssize+1].length	= dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
  
  	return dst;
  }
  
  
  /**
   * ntfs_runlists_merge_i - see ntfs_runlists_merge
   */
  static runlist_element *ntfs_runlists_merge_i(runlist_element *drl, 
  					      runlist_element *srl)
  {
  	int di, si;		/* Current index into @[ds]rl. */
  	int sstart;		/* First index with lcn > LCN_RL_NOT_MAPPED. */
  	int dins;		/* Index into @drl at which to insert @srl. */
  	int dend, send;		/* Last index into @[ds]rl. */
  	int dfinal, sfinal;	/* The last index into @[ds]rl with
  				   lcn >= LCN_HOLE. */
  	int marker = 0;
  	VCN marker_vcn = 0;
  
  	ntfs_log_debug("dst:\n");
  	ntfs_debug_runlist_dump(drl);
  	ntfs_log_debug("src:\n");
  	ntfs_debug_runlist_dump(srl);
  
  	/* Check for silly calling... */
  	if (!srl)
  		return drl;
  
  	/* Check for the case where the first mapping is being done now. */
  	if (!drl) {
  		drl = srl;
  		/* Complete the source runlist if necessary. */
  		if (drl[0].vcn) {
  			/* Scan to the end of the source runlist. */
  			for (dend = 0; drl[dend].length; dend++)
  				;
  			dend++;
  			drl = ntfs_rl_realloc(drl, dend, dend + 1);
  			if (!drl)
  				return drl;
  			/* Insert start element at the front of the runlist. */
  			ntfs_rl_mm(drl, 1, 0, dend);
  			drl[0].vcn = 0;
  			drl[0].lcn = LCN_RL_NOT_MAPPED;
  			drl[0].length = drl[1].vcn;
  		}
  		goto finished;
  	}
  
  	si = di = 0;
  
  	/* Skip any unmapped start element(s) in the source runlist. */
  	while (srl[si].length && srl[si].lcn < (LCN)LCN_HOLE)
  		si++;
  
  	/* Can't have an entirely unmapped source runlist. */
  	if (!srl[si].length) {
  		errno = EINVAL;
  		ntfs_log_perror("%s: unmapped source runlist", __FUNCTION__);
  		return NULL;
  	}
  
  	/* Record the starting points. */
  	sstart = si;
  
  	/*
  	 * Skip forward in @drl until we reach the position where @srl needs to
  	 * be inserted. If we reach the end of @drl, @srl just needs to be
  	 * appended to @drl.
  	 */
  	for (; drl[di].length; di++) {
  		if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
  			break;
  	}
  	dins = di;
  
  	/* Sanity check for illegal overlaps. */
  	if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
  			(srl[si].lcn >= 0)) {
  		errno = ERANGE;
  		ntfs_log_perror("Run lists overlap. Cannot merge");
  		return NULL;
  	}
  
  	/* Scan to the end of both runlists in order to know their sizes. */
  	for (send = si; srl[send].length; send++)
  		;
  	for (dend = di; drl[dend].length; dend++)
  		;
  
  	if (srl[send].lcn == (LCN)LCN_ENOENT)
  		marker_vcn = srl[marker = send].vcn;
  
  	/* Scan to the last element with lcn >= LCN_HOLE. */
  	for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
  		;
  	for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
  		;
  
  	{
  	BOOL start;
  	BOOL finish;
  	int ds = dend + 1;		/* Number of elements in drl & srl */
  	int ss = sfinal - sstart + 1;
  
  	start  = ((drl[dins].lcn <  LCN_RL_NOT_MAPPED) ||    /* End of file   */
  		  (drl[dins].vcn == srl[sstart].vcn));	     /* Start of hole */
  	finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) &&    /* End of file   */
  		 ((drl[dins].vcn + drl[dins].length) <=      /* End of hole   */
  		  (srl[send - 1].vcn + srl[send - 1].length)));
  
  	/* Or we'll lose an end marker */
  	if (finish && !drl[dins].length)
  		ss++;
  	if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
  		finish = FALSE;
  
  	ntfs_log_debug("dfinal = %i, dend = %i\n", dfinal, dend);
  	ntfs_log_debug("sstart = %i, sfinal = %i, send = %i\n", sstart, sfinal, send);
  	ntfs_log_debug("start = %i, finish = %i\n", start, finish);
  	ntfs_log_debug("ds = %i, ss = %i, dins = %i\n", ds, ss, dins);
  
  	if (start) {
  		if (finish)
  			drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
  		else
  			drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
  	} else {
  		if (finish)
  			drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
  		else
  			drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
  	}
  	if (!drl) {
  		ntfs_log_perror("Merge failed");
  		return drl;
  	}
  	free(srl);
  	if (marker) {
  		ntfs_log_debug("Triggering marker code.\n");
  		for (ds = dend; drl[ds].length; ds++)
  			;
  		/* We only need to care if @srl ended after @drl. */
  		if (drl[ds].vcn <= marker_vcn) {
  			int slots = 0;
  
  			if (drl[ds].vcn == marker_vcn) {
  				ntfs_log_debug("Old marker = %lli, replacing with "
  						"LCN_ENOENT.\n",
  						(long long)drl[ds].lcn);
  				drl[ds].lcn = (LCN)LCN_ENOENT;
  				goto finished;
  			}
  			/*
  			 * We need to create an unmapped runlist element in
  			 * @drl or extend an existing one before adding the
  			 * ENOENT terminator.
  			 */
  			if (drl[ds].lcn == (LCN)LCN_ENOENT) {
  				ds--;
  				slots = 1;
  			}
  			if (drl[ds].lcn != (LCN)LCN_RL_NOT_MAPPED) {
  				/* Add an unmapped runlist element. */
  				if (!slots) {
  					/* FIXME/TODO: We need to have the
  					 * extra memory already! (AIA)
  					 */
  					drl = ntfs_rl_realloc(drl, ds, ds + 2);
  					if (!drl)
  						goto critical_error;
  					slots = 2;
  				}
  				ds++;
  				/* Need to set vcn if it isn't set already. */
  				if (slots != 1)
  					drl[ds].vcn = drl[ds - 1].vcn +
  							drl[ds - 1].length;
  				drl[ds].lcn = (LCN)LCN_RL_NOT_MAPPED;
  				/* We now used up a slot. */
  				slots--;
  			}
  			drl[ds].length = marker_vcn - drl[ds].vcn;
  			/* Finally add the ENOENT terminator. */
  			ds++;
  			if (!slots) {
  				/* FIXME/TODO: We need to have the extra
  				 * memory already! (AIA)
  				 */
  				drl = ntfs_rl_realloc(drl, ds, ds + 1);
  				if (!drl)
  					goto critical_error;
  			}
  			drl[ds].vcn = marker_vcn;
  			drl[ds].lcn = (LCN)LCN_ENOENT;
  			drl[ds].length = (s64)0;
  		}
  	}
  	}
  
  finished:
  	/* The merge was completed successfully. */
  	ntfs_log_debug("Merged runlist:\n");
  	ntfs_debug_runlist_dump(drl);
  	return drl;
  
  critical_error:
  	/* Critical error! We cannot afford to fail here. */
  	ntfs_log_perror("libntfs: Critical error");
  	ntfs_log_debug("Forcing segmentation fault!\n");
  	marker_vcn = ((runlist*)NULL)->lcn;
  	return drl;
  }
  
  /**
   * ntfs_runlists_merge - merge two runlists into one
   * @drl:	original runlist to be worked on
   * @srl:	new runlist to be merged into @drl
   *
   * First we sanity check the two runlists @srl and @drl to make sure that they
   * are sensible and can be merged. The runlist @srl must be either after the
   * runlist @drl or completely within a hole (or unmapped region) in @drl.
   *
   * Merging of runlists is necessary in two cases:
   *   1. When attribute lists are used and a further extent is being mapped.
   *   2. When new clusters are allocated to fill a hole or extend a file.
   *
   * There are four possible ways @srl can be merged. It can:
   *	- be inserted at the beginning of a hole,
   *	- split the hole in two and be inserted between the two fragments,
   *	- be appended at the end of a hole, or it can
   *	- replace the whole hole.
   * It can also be appended to the end of the runlist, which is just a variant
   * of the insert case.
   *
   * On success, return a pointer to the new, combined, runlist. Note, both
   * runlists @drl and @srl are deallocated before returning so you cannot use
   * the pointers for anything any more. (Strictly speaking the returned runlist
   * may be the same as @dst but this is irrelevant.)
   *
   * On error, return NULL, with errno set to the error code. Both runlists are
   * left unmodified. The following error codes are defined:
   *	ENOMEM		Not enough memory to allocate runlist array.
   *	EINVAL		Invalid parameters were passed in.
   *	ERANGE		The runlists overlap and cannot be merged.
   */
  runlist_element *ntfs_runlists_merge(runlist_element *drl,
  		runlist_element *srl)
  {
  	runlist_element *rl; 
  	
  	ntfs_log_enter("Entering\n");
  	rl = ntfs_runlists_merge_i(drl, srl);
  	ntfs_log_leave("\n");
  	return rl;
  }
  
  /**
   * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
   * @vol:	ntfs volume on which the attribute resides
   * @attr:	attribute record whose mapping pairs array to decompress
   * @old_rl:	optional runlist in which to insert @attr's runlist
   *
   * Decompress the attribute @attr's mapping pairs array into a runlist. On
   * success, return the decompressed runlist.
   *
   * If @old_rl is not NULL, decompressed runlist is inserted into the
   * appropriate place in @old_rl and the resultant, combined runlist is
   * returned. The original @old_rl is deallocated.
   *
   * On error, return NULL with errno set to the error code. @old_rl is left
   * unmodified in that case.
   *
   * The following error codes are defined:
   *	ENOMEM		Not enough memory to allocate runlist array.
   *	EIO		Corrupt runlist.
   *	EINVAL		Invalid parameters were passed in.
   *	ERANGE		The two runlists overlap.
   *
   * FIXME: For now we take the conceptionally simplest approach of creating the
   * new runlist disregarding the already existing one and then splicing the
   * two into one, if that is possible (we check for overlap and discard the new
   * runlist if overlap present before returning NULL, with errno = ERANGE).
   */
  static runlist_element *ntfs_mapping_pairs_decompress_i(const ntfs_volume *vol,
  		const ATTR_RECORD *attr, runlist_element *old_rl)
  {
  	VCN vcn;		/* Current vcn. */
  	LCN lcn;		/* Current lcn. */
  	s64 deltaxcn;		/* Change in [vl]cn. */
  	runlist_element *rl;	/* The output runlist. */
  	const u8 *buf;		/* Current position in mapping pairs array. */
  	const u8 *attr_end;	/* End of attribute. */
  	int err, rlsize;	/* Size of runlist buffer. */
  	u16 rlpos;		/* Current runlist position in units of
  				   runlist_elements. */
  	u8 b;			/* Current byte offset in buf. */
  
  	ntfs_log_trace("Entering for attr 0x%x.\n",
  			(unsigned)le32_to_cpu(attr->type));
  	/* Make sure attr exists and is non-resident. */
  	if (!attr || !attr->non_resident ||
  			sle64_to_cpu(attr->lowest_vcn) < (VCN)0) {
  		errno = EINVAL;
  		return NULL;
  	}
  	/* Start at vcn = lowest_vcn and lcn 0. */
  	vcn = sle64_to_cpu(attr->lowest_vcn);
  	lcn = 0;
  	/* Get start of the mapping pairs array. */
  	buf = (const u8*)attr + le16_to_cpu(attr->mapping_pairs_offset);
  	attr_end = (const u8*)attr + le32_to_cpu(attr->length);
  	if (buf < (const u8*)attr || buf > attr_end) {
  		ntfs_log_debug("Corrupt attribute.\n");
  		errno = EIO;
  		return NULL;
  	}
  	/* Current position in runlist array. */
  	rlpos = 0;
  	/* Allocate first 4kiB block and set current runlist size to 4kiB. */
  	rlsize = 0x1000;
  	rl = ntfs_malloc(rlsize);
  	if (!rl)
  		return NULL;
  	/* Insert unmapped starting element if necessary. */
  	if (vcn) {
  		rl->vcn = (VCN)0;
  		rl->lcn = (LCN)LCN_RL_NOT_MAPPED;
  		rl->length = vcn;
  		rlpos++;
  	}
  	while (buf < attr_end && *buf) {
  		/*
  		 * Allocate more memory if needed, including space for the
  		 * not-mapped and terminator elements.
  		 */
  		if ((int)((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
  			runlist_element *rl2;
  
  			rlsize += 0x1000;
  			rl2 = realloc(rl, rlsize);
  			if (!rl2) {
  				int eo = errno;
  				free(rl);
  				errno = eo;
  				return NULL;
  			}
  			rl = rl2;
  		}
  		/* Enter the current vcn into the current runlist element. */
  		rl[rlpos].vcn = vcn;
  		/*
  		 * Get the change in vcn, i.e. the run length in clusters.
  		 * Doing it this way ensures that we signextend negative values.
  		 * A negative run length doesn't make any sense, but hey, I
  		 * didn't make up the NTFS specs and Windows NT4 treats the run
  		 * length as a signed value so that's how it is...
  		 */
  		b = *buf & 0xf;
  		if (b) {
  			if (buf + b > attr_end)
  				goto io_error;
  			for (deltaxcn = (s8)buf[b--]; b; b--)
  				deltaxcn = (deltaxcn << 8) + buf[b];
  		} else { /* The length entry is compulsory. */
  			ntfs_log_debug("Missing length entry in mapping pairs "
  					"array.\n");
  			deltaxcn = (s64)-1;
  		}
  		/*
  		 * Assume a negative length to indicate data corruption and
  		 * hence clean-up and return NULL.
  		 */
  		if (deltaxcn < 0) {
  			ntfs_log_debug("Invalid length in mapping pairs array.\n");
  			goto err_out;
  		}
  		/*
  		 * Enter the current run length into the current runlist
  		 * element.
  		 */
  		rl[rlpos].length = deltaxcn;
  		/* Increment the current vcn by the current run length. */
  		vcn += deltaxcn;
  		/*
  		 * There might be no lcn change at all, as is the case for
  		 * sparse clusters on NTFS 3.0+, in which case we set the lcn
  		 * to LCN_HOLE.
  		 */
  		if (!(*buf & 0xf0))
  			rl[rlpos].lcn = (LCN)LCN_HOLE;
  		else {
  			/* Get the lcn change which really can be negative. */
  			u8 b2 = *buf & 0xf;
  			b = b2 + ((*buf >> 4) & 0xf);
  			if (buf + b > attr_end)
  				goto io_error;
  			for (deltaxcn = (s8)buf[b--]; b > b2; b--)
  				deltaxcn = (deltaxcn << 8) + buf[b];
  			/* Change the current lcn to it's new value. */
  			lcn += deltaxcn;
  #ifdef DEBUG
  			/*
  			 * On NTFS 1.2-, apparently can have lcn == -1 to
  			 * indicate a hole. But we haven't verified ourselves
  			 * whether it is really the lcn or the deltaxcn that is
  			 * -1. So if either is found give us a message so we
  			 * can investigate it further!
  			 */
  			if (vol->major_ver < 3) {
  				if (deltaxcn == (LCN)-1)
  					ntfs_log_debug("lcn delta == -1\n");
  				if (lcn == (LCN)-1)
  					ntfs_log_debug("lcn == -1\n");
  			}
  #endif
  			/* Check lcn is not below -1. */
  			if (lcn < (LCN)-1) {
  				ntfs_log_debug("Invalid LCN < -1 in mapping pairs "
  						"array.\n");
  				goto err_out;
  			}
  			/* Enter the current lcn into the runlist element. */
  			rl[rlpos].lcn = lcn;
  		}
  		/* Get to the next runlist element. */
  		rlpos++;
  		/* Increment the buffer position to the next mapping pair. */
  		buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
  	}
  	if (buf >= attr_end)
  		goto io_error;
  	/*
  	 * If there is a highest_vcn specified, it must be equal to the final
  	 * vcn in the runlist - 1, or something has gone badly wrong.
  	 */
  	deltaxcn = sle64_to_cpu(attr->highest_vcn);
  	if (deltaxcn && vcn - 1 != deltaxcn) {
  mpa_err:
  		ntfs_log_debug("Corrupt mapping pairs array in non-resident "
  				"attribute.\n");
  		goto err_out;
  	}
  	/* Setup not mapped runlist element if this is the base extent. */
  	if (!attr->lowest_vcn) {
  		VCN max_cluster;
  
  		max_cluster = ((sle64_to_cpu(attr->allocated_size) +
  				vol->cluster_size - 1) >>
  				vol->cluster_size_bits) - 1;
  		/*
  		 * A highest_vcn of zero means this is a single extent
  		 * attribute so simply terminate the runlist with LCN_ENOENT).
  		 */
  		if (deltaxcn) {
  			/*
  			 * If there is a difference between the highest_vcn and
  			 * the highest cluster, the runlist is either corrupt
  			 * or, more likely, there are more extents following
  			 * this one.
  			 */
  			if (deltaxcn < max_cluster) {
  				ntfs_log_debug("More extents to follow; deltaxcn = "
  						"0x%llx, max_cluster = 0x%llx\n",
  						(long long)deltaxcn,
  						(long long)max_cluster);
  				rl[rlpos].vcn = vcn;
  				vcn += rl[rlpos].length = max_cluster - deltaxcn;
  				rl[rlpos].lcn = (LCN)LCN_RL_NOT_MAPPED;
  				rlpos++;
  			} else if (deltaxcn > max_cluster) {
  				ntfs_log_debug("Corrupt attribute. deltaxcn = "
  						"0x%llx, max_cluster = 0x%llx\n",
  						(long long)deltaxcn,
  						(long long)max_cluster);
  				goto mpa_err;
  			}
  		}
  		rl[rlpos].lcn = (LCN)LCN_ENOENT;
  	} else /* Not the base extent. There may be more extents to follow. */
  		rl[rlpos].lcn = (LCN)LCN_RL_NOT_MAPPED;
  
  	/* Setup terminating runlist element. */
  	rl[rlpos].vcn = vcn;
  	rl[rlpos].length = (s64)0;
  	/* If no existing runlist was specified, we are done. */
  	if (!old_rl) {
  		ntfs_log_debug("Mapping pairs array successfully decompressed:\n");
  		ntfs_debug_runlist_dump(rl);
  		return rl;
  	}
  	/* Now combine the new and old runlists checking for overlaps. */
  	old_rl = ntfs_runlists_merge(old_rl, rl);
  	if (old_rl)
  		return old_rl;
  	err = errno;
  	free(rl);
  	ntfs_log_debug("Failed to merge runlists.\n");
  	errno = err;
  	return NULL;
  io_error:
  	ntfs_log_debug("Corrupt attribute.\n");
  err_out:
  	free(rl);
  	errno = EIO;
  	return NULL;
  }
  
  runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
  		const ATTR_RECORD *attr, runlist_element *old_rl)
  {
  	runlist_element *rle; 
  	
  	ntfs_log_enter("Entering\n");
  	rle = ntfs_mapping_pairs_decompress_i(vol, attr, old_rl);
  	ntfs_log_leave("\n");
  	return rle;
  }
  
  /**
   * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
   * @rl:		runlist to use for conversion
   * @vcn:	vcn to convert
   *
   * Convert the virtual cluster number @vcn of an attribute into a logical
   * cluster number (lcn) of a device using the runlist @rl to map vcns to their
   * corresponding lcns.
   *
   * Since lcns must be >= 0, we use negative return values with special meaning:
   *
   * Return value			Meaning / Description
   * ==================================================
   *  -1 = LCN_HOLE		Hole / not allocated on disk.
   *  -2 = LCN_RL_NOT_MAPPED	This is part of the runlist which has not been
   *				inserted into the runlist yet.
   *  -3 = LCN_ENOENT		There is no such vcn in the attribute.
   *  -4 = LCN_EINVAL		Input parameter error.
   */
  LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
  {
  	int i;
  
  	if (vcn < (VCN)0)
  		return (LCN)LCN_EINVAL;
  	/*
  	 * If rl is NULL, assume that we have found an unmapped runlist. The
  	 * caller can then attempt to map it and fail appropriately if
  	 * necessary.
  	 */
  	if (!rl)
  		return (LCN)LCN_RL_NOT_MAPPED;
  
  	/* Catch out of lower bounds vcn. */
  	if (vcn < rl[0].vcn)
  		return (LCN)LCN_ENOENT;
  
  	for (i = 0; rl[i].length; i++) {
  		if (vcn < rl[i+1].vcn) {
  			if (rl[i].lcn >= (LCN)0)
  				return rl[i].lcn + (vcn - rl[i].vcn);
  			return rl[i].lcn;
  		}
  	}
  	/*
  	 * The terminator element is setup to the correct value, i.e. one of
  	 * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
  	 */
  	if (rl[i].lcn < (LCN)0)
  		return rl[i].lcn;
  	/* Just in case... We could replace this with BUG() some day. */
  	return (LCN)LCN_ENOENT;
  }
  
  /**
   * ntfs_rl_pread - gather read from disk
   * @vol:	ntfs volume to read from
   * @rl:		runlist specifying where to read the data from
   * @pos:	byte position within runlist @rl at which to begin the read
   * @count:	number of bytes to read
   * @b:		data buffer into which to read from disk
   *
   * This function will read @count bytes from the volume @vol to the data buffer
   * @b gathering the data as specified by the runlist @rl. The read begins at
   * offset @pos into the runlist @rl.
   *
   * On success, return the number of successfully read bytes. If this number is
   * lower than @count this means that the read reached end of file or that an
   * error was encountered during the read so that the read is partial. 0 means
   * nothing was read (also return 0 when @count is 0).
   *
   * On error and nothing has been read, return -1 with errno set appropriately
   * to the return code of ntfs_pread(), or to EINVAL in case of invalid
   * arguments.
   *
   * NOTE: If we encounter EOF while reading we return EIO because we assume that
   * the run list must point to valid locations within the ntfs volume.
   */
  s64 ntfs_rl_pread(const ntfs_volume *vol, const runlist_element *rl,
  		const s64 pos, s64 count, void *b)
  {
  	s64 bytes_read, to_read, ofs, total;
  	int err = EIO;
  
  	if (!vol || !rl || pos < 0 || count < 0) {
  		errno = EINVAL;
  		ntfs_log_perror("Failed to read runlist [vol: %p rl: %p "
  				"pos: %lld count: %lld]", vol, rl,
  				(long long)pos, (long long)count);
  		return -1;
  	}
  	if (!count)
  		return count;
  	/* Seek in @rl to the run containing @pos. */
  	for (ofs = 0; rl->length && (ofs + (rl->length <<
  			vol->cluster_size_bits) <= pos); rl++)
  		ofs += (rl->length << vol->cluster_size_bits);
  	/* Offset in the run at which to begin reading. */
  	ofs = pos - ofs;
  	for (total = 0LL; count; rl++, ofs = 0) {
  		if (!rl->length)
  			goto rl_err_out;
  		if (rl->lcn < (LCN)0) {
  			if (rl->lcn != (LCN)LCN_HOLE)
  				goto rl_err_out;
  			/* It is a hole. Just fill buffer @b with zeroes. */
  			to_read = min(count, (rl->length <<
  					vol->cluster_size_bits) - ofs);
  			memset(b, 0, to_read);
  			/* Update counters and proceed with next run. */
  			total += to_read;
  			count -= to_read;
  			b = (u8*)b + to_read;
  			continue;
  		}
  		/* It is a real lcn, read it from the volume. */
  		to_read = min(count, (rl->length << vol->cluster_size_bits) -
  				ofs);
  retry:
  		bytes_read = ntfs_pread(vol->dev, (rl->lcn <<
  				vol->cluster_size_bits) + ofs, to_read, b);
  		/* If everything ok, update progress counters and continue. */
  		if (bytes_read > 0) {
  			total += bytes_read;
  			count -= bytes_read;
  			b = (u8*)b + bytes_read;
  			continue;
  		}
  		/* If the syscall was interrupted, try again. */
  		if (bytes_read == (s64)-1 && errno == EINTR)
  			goto retry;
  		if (bytes_read == (s64)-1)
  			err = errno;
  		goto rl_err_out;
  	}
  	/* Finally, return the number of bytes read. */
  	return total;
  rl_err_out:
  	if (total)
  		return total;
  	errno = err;
  	return -1;
  }
  
  /**
   * ntfs_rl_pwrite - scatter write to disk
   * @vol:	ntfs volume to write to
   * @rl:		runlist entry specifying where to write the data to
   * @ofs:	offset in file for runlist element indicated in @rl
   * @pos:	byte position from runlist beginning at which to begin the write
   * @count:	number of bytes to write
   * @b:		data buffer to write to disk
   *
   * This function will write @count bytes from data buffer @b to the volume @vol
   * scattering the data as specified by the runlist @rl. The write begins at
   * offset @pos into the runlist @rl. If a run is sparse then the related buffer
   * data is ignored which means that the caller must ensure they are consistent.
   *
   * On success, return the number of successfully written bytes. If this number
   * is lower than @count this means that the write has been interrupted in
   * flight or that an error was encountered during the write so that the write
   * is partial. 0 means nothing was written (also return 0 when @count is 0).
   *
   * On error and nothing has been written, return -1 with errno set
   * appropriately to the return code of ntfs_pwrite(), or to to EINVAL in case
   * of invalid arguments.
   */
  s64 ntfs_rl_pwrite(const ntfs_volume *vol, const runlist_element *rl,
  		s64 ofs, const s64 pos, s64 count, void *b)
  {
  	s64 written, to_write, total = 0;
  	int err = EIO;
  
  	if (!vol || !rl || pos < 0 || count < 0) {
  		errno = EINVAL;
  		ntfs_log_perror("Failed to write runlist [vol: %p rl: %p "
  				"pos: %lld count: %lld]", vol, rl,
  				(long long)pos, (long long)count);
  		goto errno_set;
  	}
  	if (!count)
  		goto out;
  	/* Seek in @rl to the run containing @pos. */
  	while (rl->length && (ofs + (rl->length <<
  			vol->cluster_size_bits) <= pos)) {
  		ofs += (rl->length << vol->cluster_size_bits);
  		rl++;
  	}
  	/* Offset in the run at which to begin writing. */
  	ofs = pos - ofs;
  	for (total = 0LL; count; rl++, ofs = 0) {
  		if (!rl->length)
  			goto rl_err_out;
  		if (rl->lcn < (LCN)0) {
  
  			if (rl->lcn != (LCN)LCN_HOLE)
  				goto rl_err_out;
  			
  			to_write = min(count, (rl->length <<
  					       vol->cluster_size_bits) - ofs);
  			
  			total += to_write;
  			count -= to_write;
  			b = (u8*)b + to_write;
  			continue;
  		}
  		/* It is a real lcn, write it to the volume. */
  		to_write = min(count, (rl->length << vol->cluster_size_bits) -
  				ofs);
  retry:
  		if (!NVolReadOnly(vol))
  			written = ntfs_pwrite(vol->dev, (rl->lcn <<
  					vol->cluster_size_bits) + ofs,
  					to_write, b);
  		else
  			written = to_write;
  		/* If everything ok, update progress counters and continue. */
  		if (written > 0) {
  			total += written;
  			count -= written;
  			b = (u8*)b + written;
  			continue;
  		}
  		/* If the syscall was interrupted, try again. */
  		if (written == (s64)-1 && errno == EINTR)
  			goto retry;
  		if (written == (s64)-1)
  			err = errno;
  		goto rl_err_out;
  	}
  out:
  	return total;
  rl_err_out:
  	if (total)
  		goto out;
  	errno = err;
  errno_set:
  	total = -1;
  	goto out;
  }
  
  /**
   * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
   * @n:		number for which to get the number of bytes for
   *
   * Return the number of bytes required to store @n unambiguously as
   * a signed number.
   *
   * This is used in the context of the mapping pairs array to determine how
   * many bytes will be needed in the array to store a given logical cluster
   * number (lcn) or a specific run length.
   *
   * Return the number of bytes written. This function cannot fail.
   */
  int ntfs_get_nr_significant_bytes(const s64 n)
  {
  	u64 l;
  	int i;
  
  	l = (n < 0 ? ~n : n);
  	i = 1;
  	if (l >= 128) {
  		l >>= 7;
  		do {
  			i++;
  			l >>= 8;
  		} while (l);
  	}
  	return i;
  }
  
  /**
   * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
   * @vol:	ntfs volume (needed for the ntfs version)
   * @rl:		runlist for which to determine the size of the mapping pairs
   * @start_vcn:	vcn at which to start the mapping pairs array
   *
   * Walk the runlist @rl and calculate the size in bytes of the mapping pairs
   * array corresponding to the runlist @rl, starting at vcn @start_vcn.  This
   * for example allows us to allocate a buffer of the right size when building
   * the mapping pairs array.
   *
   * If @rl is NULL, just return 1 (for the single terminator byte).
   *
   * Return the calculated size in bytes on success.  On error, return -1 with
   * errno set to the error code.  The following error codes are defined:
   *	EINVAL	- Run list contains unmapped elements. Make sure to only pass
   *		  fully mapped runlists to this function.
   *		- @start_vcn is invalid.
   *	EIO	- The runlist is corrupt.
   */
  int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
  		const runlist_element *rl, const VCN start_vcn, int max_size)
  {
  	LCN prev_lcn;
  	int rls;
  
  	if (start_vcn < 0) {
  		ntfs_log_trace("start_vcn %lld (should be >= 0)\n",
  				(long long) start_vcn);
  		errno = EINVAL;
  		goto errno_set;
  	}
  	if (!rl) {
  		if (start_vcn) {
  			ntfs_log_trace("rl NULL, start_vcn %lld (should be > 0)\n",
  					(long long) start_vcn);
  			errno = EINVAL;
  			goto errno_set;
  		}
  		rls = 1;
  		goto out;
  	}
  	/* Skip to runlist element containing @start_vcn. */
  	while (rl->length && start_vcn >= rl[1].vcn)
  		rl++;
  	if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn) {
  		errno = EINVAL;
  		goto errno_set;
  	}
  	prev_lcn = 0;
  	/* Always need the terminating zero byte. */
  	rls = 1;
  	/* Do the first partial run if present. */
  	if (start_vcn > rl->vcn) {
  		s64 delta;
  
  		/* We know rl->length != 0 already. */
  		if (rl->length < 0 || rl->lcn < LCN_HOLE)
  			goto err_out;
  		delta = start_vcn - rl->vcn;
  		/* Header byte + length. */
  		rls += 1 + ntfs_get_nr_significant_bytes(rl->length - delta);
  		/*
  		 * If the logical cluster number (lcn) denotes a hole and we
  		 * are on NTFS 3.0+, we don't store it at all, i.e. we need
  		 * zero space. On earlier NTFS versions we just store the lcn.
  		 * Note: this assumes that on NTFS 1.2-, holes are stored with
  		 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
  		 */
  		if (rl->lcn >= 0 || vol->major_ver < 3) {
  			prev_lcn = rl->lcn;
  			if (rl->lcn >= 0)
  				prev_lcn += delta;
  			/* Change in lcn. */
  			rls += ntfs_get_nr_significant_bytes(prev_lcn);
  		}
  		/* Go to next runlist element. */
  		rl++;
  	}
  	/* Do the full runs. */
  	for (; rl->length && (rls <= max_size); rl++) {
  		if (rl->length < 0 || rl->lcn < LCN_HOLE)
  			goto err_out;
  		/* Header byte + length. */
  		rls += 1 + ntfs_get_nr_significant_bytes(rl->length);
  		/*
  		 * If the logical cluster number (lcn) denotes a hole and we
  		 * are on NTFS 3.0+, we don't store it at all, i.e. we need
  		 * zero space. On earlier NTFS versions we just store the lcn.
  		 * Note: this assumes that on NTFS 1.2-, holes are stored with
  		 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
  		 */
  		if (rl->lcn >= 0 || vol->major_ver < 3) {
  			/* Change in lcn. */
  			rls += ntfs_get_nr_significant_bytes(rl->lcn -
  					prev_lcn);
  			prev_lcn = rl->lcn;
  		}
  	}
  out:	
  	return rls;
  err_out:
  	if (rl->lcn == LCN_RL_NOT_MAPPED)
  		errno = EINVAL;
  	else
  		errno = EIO;
  errno_set:	
  	rls = -1;
  	goto out;
  }
  
  /**
   * ntfs_write_significant_bytes - write the significant bytes of a number
   * @dst:	destination buffer to write to
   * @dst_max:	pointer to last byte of destination buffer for bounds checking
   * @n:		number whose significant bytes to write
   *
   * Store in @dst, the minimum bytes of the number @n which are required to
   * identify @n unambiguously as a signed number, taking care not to exceed
   * @dest_max, the maximum position within @dst to which we are allowed to
   * write.
   *
   * This is used when building the mapping pairs array of a runlist to compress
   * a given logical cluster number (lcn) or a specific run length to the minimum
   * size possible.
   *
   * Return the number of bytes written on success. On error, i.e. the
   * destination buffer @dst is too small, return -1 with errno set ENOSPC.
   */
  int ntfs_write_significant_bytes(u8 *dst, const u8 *dst_max, const s64 n)
  {
  	s64 l = n;
  	int i;
  
  	i = 0;
  	if (dst > dst_max)
  		goto err_out;
  	*dst++ = l;
  	i++;
  	while ((l > 0x7f) || (l < -0x80)) {
  		if (dst > dst_max)
  			goto err_out;
  		l >>= 8;
  		*dst++ = l;
  		i++;
  	}
  	return i;
  err_out:
  	errno = ENOSPC;
  	return -1;
  }
  
  /**
   * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
   * @vol:	ntfs volume (needed for the ntfs version)
   * @dst:	destination buffer to which to write the mapping pairs array
   * @dst_len:	size of destination buffer @dst in bytes
   * @rl:		runlist for which to build the mapping pairs array
   * @start_vcn:	vcn at which to start the mapping pairs array
   * @stop_vcn:	first vcn outside destination buffer on success or ENOSPC error
   *
   * Create the mapping pairs array from the runlist @rl, starting at vcn
   * @start_vcn and save the array in @dst.  @dst_len is the size of @dst in
   * bytes and it should be at least equal to the value obtained by calling
   * ntfs_get_size_for_mapping_pairs().
   *
   * If @rl is NULL, just write a single terminator byte to @dst.
   *
   * On success or ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
   * the first vcn outside the destination buffer. Note that on error @dst has
   * been filled with all the mapping pairs that will fit, thus it can be treated
   * as partial success, in that a new attribute extent needs to be created or the
   * next extent has to be used and the mapping pairs build has to be continued
   * with @start_vcn set to *@stop_vcn.
   *
   * Return 0 on success.  On error, return -1 with errno set to the error code.
   * The following error codes are defined:
   *	EINVAL	- Run list contains unmapped elements. Make sure to only pass
   *		  fully mapped runlists to this function.
   *		- @start_vcn is invalid.
   *	EIO	- The runlist is corrupt.
   *	ENOSPC	- The destination buffer is too small.
   */
  int ntfs_mapping_pairs_build(const ntfs_volume *vol, u8 *dst,
  		const int dst_len, const runlist_element *rl,
  		const VCN start_vcn, runlist_element const **stop_rl)
  {
  	LCN prev_lcn;
  	u8 *dst_max, *dst_next;
  	s8 len_len, lcn_len;
  	int ret = 0;
  
  	if (start_vcn < 0)
  		goto val_err;
  	if (!rl) {
  		if (start_vcn)
  			goto val_err;
  		if (stop_rl)
  			*stop_rl = rl;
  		if (dst_len < 1)
  			goto nospc_err;
  		goto ok;
  	}
  	/* Skip to runlist element containing @start_vcn. */
  	while (rl->length && start_vcn >= rl[1].vcn)
  		rl++;
  	if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn)
  		goto val_err;
  	/*
  	 * @dst_max is used for bounds checking in
  	 * ntfs_write_significant_bytes().
  	 */
  	dst_max = dst + dst_len - 1;
  	prev_lcn = 0;
  	/* Do the first partial run if present. */
  	if (start_vcn > rl->vcn) {
  		s64 delta;
  
  		/* We know rl->length != 0 already. */
  		if (rl->length < 0 || rl->lcn < LCN_HOLE)
  			goto err_out;
  		delta = start_vcn - rl->vcn;
  		/* Write length. */
  		len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
  				rl->length - delta);
  		if (len_len < 0)
  			goto size_err;
  		/*
  		 * If the logical cluster number (lcn) denotes a hole and we
  		 * are on NTFS 3.0+, we don't store it at all, i.e. we need
  		 * zero space. On earlier NTFS versions we just write the lcn
  		 * change.  FIXME: Do we need to write the lcn change or just
  		 * the lcn in that case?  Not sure as I have never seen this
  		 * case on NT4. - We assume that we just need to write the lcn
  		 * change until someone tells us otherwise... (AIA)
  		 */
  		if (rl->lcn >= 0 || vol->major_ver < 3) {
  			prev_lcn = rl->lcn;
  			if (rl->lcn >= 0)
  				prev_lcn += delta;
  			/* Write change in lcn. */
  			lcn_len = ntfs_write_significant_bytes(dst + 1 +
  					len_len, dst_max, prev_lcn);
  			if (lcn_len < 0)
  				goto size_err;
  		} else
  			lcn_len = 0;
  		dst_next = dst + len_len + lcn_len + 1;
  		if (dst_next > dst_max)
  			goto size_err;
  		/* Update header byte. */
  		*dst = lcn_len << 4 | len_len;
  		/* Position at next mapping pairs array element. */
  		dst = dst_next;
  		/* Go to next runlist element. */
  		rl++;
  	}
  	/* Do the full runs. */
  	for (; rl->length; rl++) {
  		if (rl->length < 0 || rl->lcn < LCN_HOLE)
  			goto err_out;
  		/* Write length. */
  		len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
  				rl->length);
  		if (len_len < 0)
  			goto size_err;
  		/*
  		 * If the logical cluster number (lcn) denotes a hole and we
  		 * are on NTFS 3.0+, we don't store it at all, i.e. we need
  		 * zero space. On earlier NTFS versions we just write the lcn
  		 * change. FIXME: Do we need to write the lcn change or just
  		 * the lcn in that case? Not sure as I have never seen this
  		 * case on NT4. - We assume that we just need to write the lcn
  		 * change until someone tells us otherwise... (AIA)
  		 */
  		if (rl->lcn >= 0 || vol->major_ver < 3) {
  			/* Write change in lcn. */
  			lcn_len = ntfs_write_significant_bytes(dst + 1 +
  					len_len, dst_max, rl->lcn - prev_lcn);
  			if (lcn_len < 0)
  				goto size_err;
  			prev_lcn = rl->lcn;
  		} else
  			lcn_len = 0;
  		dst_next = dst + len_len + lcn_len + 1;
  		if (dst_next > dst_max)
  			goto size_err;
  		/* Update header byte. */
  		*dst = lcn_len << 4 | len_len;
  		/* Position at next mapping pairs array element. */
  		dst += 1 + len_len + lcn_len;
  	}
  	/* Set stop vcn. */
  	if (stop_rl)
  		*stop_rl = rl;
  ok:	
  	/* Add terminator byte. */
  	*dst = 0;
  out:
  	return ret;
  size_err:
  	/* Set stop vcn. */
  	if (stop_rl)
  		*stop_rl = rl;
  	/* Add terminator byte. */
  	*dst = 0;
  nospc_err:
  	errno = ENOSPC;
  	goto errno_set;
  val_err:
  	errno = EINVAL;
  	goto errno_set;
  err_out:
  	if (rl->lcn == LCN_RL_NOT_MAPPED)
  		errno = EINVAL;
  	else
  		errno = EIO;
  errno_set:
  	ret = -1;
  	goto out;
  }
  
  /**
   * ntfs_rl_truncate - truncate a runlist starting at a specified vcn
   * @arl:	address of runlist to truncate
   * @start_vcn:	first vcn which should be cut off
   *
   * Truncate the runlist *@arl starting at vcn @start_vcn as well as the memory
   * buffer holding the runlist.
   *
   * Return 0 on success and -1 on error with errno set to the error code.
   *
   * NOTE: @arl is the address of the runlist. We need the address so we can
   * modify the pointer to the runlist with the new, reallocated memory buffer.
   */
  int ntfs_rl_truncate(runlist **arl, const VCN start_vcn)
  {
  	runlist *rl;
  	/* BOOL is_end = FALSE; */
  
  	if (!arl || !*arl) {
  		errno = EINVAL;
  		if (!arl)
  			ntfs_log_perror("rl_truncate error: arl: %p", arl);
  		else
  			ntfs_log_perror("rl_truncate error:"
  				" arl: %p *arl: %p", arl, *arl);
  		return -1;
  	}
  	
  	rl = *arl;
  	
  	if (start_vcn < rl->vcn) {
  		errno = EINVAL;
  		ntfs_log_perror("Start_vcn lies outside front of runlist");
  		return -1;
  	}
  	
  	/* Find the starting vcn in the run list. */
  	while (rl->length) {
  		if (start_vcn < rl[1].vcn)
  			break;
  		rl++;
  	}
  	
  	if (!rl->length) {
  		errno = EIO;
  		ntfs_log_trace("Truncating already truncated runlist?\n");
  		return -1;
  	}
  	
  	/* Truncate the run. */
  	rl->length = start_vcn - rl->vcn;
  	
  	/*
  	 * If a run was partially truncated, make the following runlist
  	 * element a terminator instead of the truncated runlist
  	 * element itself.
  	 */
  	if (rl->length) {
  		++rl;
  /*
  		if (!rl->length)
  			is_end = TRUE;
  */
  		rl->vcn = start_vcn;
  		rl->length = 0;
  	}
  	rl->lcn = (LCN)LCN_ENOENT;
  	/**
  	 * Reallocate memory if necessary.
  	 * FIXME: Below code is broken, because runlist allocations must be 
  	 * a multiple of 4096. The code caused crashes and corruptions.
  	 */
  /*	
  	 if (!is_end) {
  		size_t new_size = (rl - *arl + 1) * sizeof(runlist_element);
  		rl = realloc(*arl, new_size);
  		if (rl)
  			*arl = rl;
  	}
  */
  	return 0;
  }
  
  /**
   * ntfs_rl_sparse - check whether runlist have sparse regions or not.
   * @rl:		runlist to check
   *
   * Return 1 if have, 0 if not, -1 on error with errno set to the error code.
   */
  int ntfs_rl_sparse(runlist *rl)
  {
  	runlist *rlc;
  
  	if (!rl) {
  		errno = EINVAL;
  		ntfs_log_perror("%s: ", __FUNCTION__);
  		return -1;
  	}
  
  	for (rlc = rl; rlc->length; rlc++)
  		if (rlc->lcn < 0) {
  			if (rlc->lcn != LCN_HOLE) {
  				errno = EINVAL;
  				ntfs_log_perror("%s: bad runlist", __FUNCTION__);
  				return -1;
  			}
  			return 1;
  		}
  	return 0;
  }
  
  /**
   * ntfs_rl_get_compressed_size - calculate length of non sparse regions
   * @vol:	ntfs volume (need for cluster size)
   * @rl:		runlist to calculate for
   *
   * Return compressed size or -1 on error with errno set to the error code.
   */
  s64 ntfs_rl_get_compressed_size(ntfs_volume *vol, runlist *rl)
  {
  	runlist *rlc;
  	s64 ret = 0;
  
  	if (!rl) {
  		errno = EINVAL;
  		ntfs_log_perror("%s: ", __FUNCTION__);
  		return -1;
  	}
  
  	for (rlc = rl; rlc->length; rlc++) {
  		if (rlc->lcn < 0) {
  			if (rlc->lcn != LCN_HOLE) {
  				errno = EINVAL;
  				ntfs_log_perror("%s: bad runlist", __FUNCTION__);
  				return -1;
  			}
  		} else
  			ret += rlc->length;
  	}
  	return ret << vol->cluster_size_bits;
  }
  
  
  #ifdef NTFS_TEST
  /**
   * test_rl_helper
   */
  #define MKRL(R,V,L,S)				\
  	(R)->vcn = V;				\
  	(R)->lcn = L;				\
  	(R)->length = S;
  /*
  }
  */
  /**
   * test_rl_dump_runlist - Runlist test: Display the contents of a runlist
   * @rl:
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_dump_runlist(const runlist_element *rl)
  {
  	int abbr = 0;	/* abbreviate long lists */
  	int len = 0;
  	int i;
  	const char *lcn_str[5] = { "HOLE", "NOTMAP", "ENOENT", "XXXX" };
  
  	if (!rl) {
  		printf("    Run list not present.\n");
  		return;
  	}
  
  	if (abbr)
  		for (len = 0; rl[len].length; len++) ;
  
  	printf("     VCN      LCN      len\n");
  	for (i = 0; ; i++, rl++) {
  		LCN lcn = rl->lcn;
  
  		if ((abbr) && (len > 20)) {
  			if (i == 4)
  				printf("     ...\n");
  			if ((i > 3) && (i < (len - 3)))
  				continue;
  		}
  
  		if (lcn < (LCN)0) {
  			int ind = -lcn - 1;
  
  			if (ind > -LCN_ENOENT - 1)
  				ind = 3;
  			printf("%8lld %8s %8lld\n",
  				rl->vcn, lcn_str[ind], rl->length);
  		} else
  			printf("%8lld %8lld %8lld\n",
  				rl->vcn, rl->lcn, rl->length);
  		if (!rl->length)
  			break;
  	}
  	if ((abbr) && (len > 20))
  		printf("    (%d entries)\n", len+1);
  	printf("\n");
  }
  
  /**
   * test_rl_runlists_merge - Runlist test: Merge two runlists
   * @drl:
   * @srl:
   *
   * Description...
   *
   * Returns:
   */
  static runlist_element * test_rl_runlists_merge(runlist_element *drl, runlist_element *srl)
  {
  	runlist_element *res = NULL;
  
  	printf("dst:\n");
  	test_rl_dump_runlist(drl);
  	printf("src:\n");
  	test_rl_dump_runlist(srl);
  
  	res = ntfs_runlists_merge(drl, srl);
  
  	printf("res:\n");
  	test_rl_dump_runlist(res);
  
  	return res;
  }
  
  /**
   * test_rl_read_buffer - Runlist test: Read a file containing a runlist
   * @file:
   * @buf:
   * @bufsize:
   *
   * Description...
   *
   * Returns:
   */
  static int test_rl_read_buffer(const char *file, u8 *buf, int bufsize)
  {
  	FILE *fptr;
  
  	fptr = fopen(file, "r");
  	if (!fptr) {
  		printf("open %s\n", file);
  		return 0;
  	}
  
  	if (fread(buf, bufsize, 1, fptr) == 99) {
  		printf("read %s\n", file);
  		return 0;
  	}
  
  	fclose(fptr);
  	return 1;
  }
  
  /**
   * test_rl_pure_src - Runlist test: Complicate the simple tests a little
   * @contig:
   * @multi:
   * @vcn:
   * @len:
   *
   * Description...
   *
   * Returns:
   */
  static runlist_element * test_rl_pure_src(BOOL contig, BOOL multi, int vcn, int len)
  {
  	runlist_element *result;
  	int fudge;
  
  	if (contig)
  		fudge = 0;
  	else
  		fudge = 999;
  
  	result = ntfs_malloc(4096);
  	if (!result)
  		return NULL;
  	
  	if (multi) {
  		MKRL(result+0, vcn + (0*len/4), fudge + vcn + 1000 + (0*len/4), len / 4)
  		MKRL(result+1, vcn + (1*len/4), fudge + vcn + 1000 + (1*len/4), len / 4)
  		MKRL(result+2, vcn + (2*len/4), fudge + vcn + 1000 + (2*len/4), len / 4)
  		MKRL(result+3, vcn + (3*len/4), fudge + vcn + 1000 + (3*len/4), len / 4)
  		MKRL(result+4, vcn + (4*len/4), LCN_RL_NOT_MAPPED,              0)
  	} else {
  		MKRL(result+0, vcn,       fudge + vcn + 1000, len)
  		MKRL(result+1, vcn + len, LCN_RL_NOT_MAPPED,  0)
  	}
  	return result;
  }
  
  /**
   * test_rl_pure_test - Runlist test: Perform tests using simple runlists
   * @test:
   * @contig:
   * @multi:
   * @vcn:
   * @len:
   * @file:
   * @size:
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_pure_test(int test, BOOL contig, BOOL multi, int vcn, int len, runlist_element *file, int size)
  {
  	runlist_element *src;
  	runlist_element *dst;
  	runlist_element *res;
  
  	src = test_rl_pure_src(contig, multi, vcn, len);
  	dst = ntfs_malloc(4096);
  	if (!src || !dst) {
  		printf("Test %2d ---------- FAILED! (no free memory?)\n", test);
  		return;
  	}
  
  	memcpy(dst, file, size);
  
  	printf("Test %2d ----------\n", test);
  	res = test_rl_runlists_merge(dst, src);
  
  	free(res);
  }
  
  /**
   * test_rl_pure - Runlist test: Create tests using simple runlists
   * @contig:
   * @multi:
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_pure(char *contig, char *multi)
  {
  		/* VCN,  LCN, len */
  	static runlist_element file1[] = {
  		{    0,   -1, 100 },	/* HOLE */
  		{  100, 1100, 100 },	/* DATA */
  		{  200,   -1, 100 },	/* HOLE */
  		{  300, 1300, 100 },	/* DATA */
  		{  400,   -1, 100 },	/* HOLE */
  		{  500,   -3,   0 }	/* NOENT */
  	};
  	static runlist_element file2[] = {
  		{    0, 1000, 100 },	/* DATA */
  		{  100,   -1, 100 },	/* HOLE */
  		{  200,   -3,   0 }	/* NOENT */
  	};
  	static runlist_element file3[] = {
  		{    0, 1000, 100 },	/* DATA */
  		{  100,   -3,   0 }	/* NOENT */
  	};
  	static runlist_element file4[] = {
  		{    0,   -3,   0 }	/* NOENT */
  	};
  	static runlist_element file5[] = {
  		{    0,   -2, 100 },	/* NOTMAP */
  		{  100, 1100, 100 },	/* DATA */
  		{  200,   -2, 100 },	/* NOTMAP */
  		{  300, 1300, 100 },	/* DATA */
  		{  400,   -2, 100 },	/* NOTMAP */
  		{  500,   -3,   0 }	/* NOENT */
  	};
  	static runlist_element file6[] = {
  		{    0, 1000, 100 },	/* DATA */
  		{  100,   -2, 100 },	/* NOTMAP */
  		{  200,   -3,   0 }	/* NOENT */
  	};
  	BOOL c, m;
  
  	if (strcmp(contig, "contig") == 0)
  		c = TRUE;
  	else if (strcmp(contig, "noncontig") == 0)
  		c = FALSE;
  	else {
  		printf("rl pure [contig|noncontig] [single|multi]\n");
  		return;
  	}
  	if (strcmp(multi, "multi") == 0)
  		m = TRUE;
  	else if (strcmp(multi, "single") == 0)
  		m = FALSE;
  	else {
  		printf("rl pure [contig|noncontig] [single|multi]\n");
  		return;
  	}
  
  	test_rl_pure_test(1,  c, m,   0,  40, file1, sizeof(file1));
  	test_rl_pure_test(2,  c, m,  40,  40, file1, sizeof(file1));
  	test_rl_pure_test(3,  c, m,  60,  40, file1, sizeof(file1));
  	test_rl_pure_test(4,  c, m,   0, 100, file1, sizeof(file1));
  	test_rl_pure_test(5,  c, m, 200,  40, file1, sizeof(file1));
  	test_rl_pure_test(6,  c, m, 240,  40, file1, sizeof(file1));
  	test_rl_pure_test(7,  c, m, 260,  40, file1, sizeof(file1));
  	test_rl_pure_test(8,  c, m, 200, 100, file1, sizeof(file1));
  	test_rl_pure_test(9,  c, m, 400,  40, file1, sizeof(file1));
  	test_rl_pure_test(10, c, m, 440,  40, file1, sizeof(file1));
  	test_rl_pure_test(11, c, m, 460,  40, file1, sizeof(file1));
  	test_rl_pure_test(12, c, m, 400, 100, file1, sizeof(file1));
  	test_rl_pure_test(13, c, m, 160, 100, file2, sizeof(file2));
  	test_rl_pure_test(14, c, m, 100, 140, file2, sizeof(file2));
  	test_rl_pure_test(15, c, m, 200,  40, file2, sizeof(file2));
  	test_rl_pure_test(16, c, m, 240,  40, file2, sizeof(file2));
  	test_rl_pure_test(17, c, m, 100,  40, file3, sizeof(file3));
  	test_rl_pure_test(18, c, m, 140,  40, file3, sizeof(file3));
  	test_rl_pure_test(19, c, m,   0,  40, file4, sizeof(file4));
  	test_rl_pure_test(20, c, m,  40,  40, file4, sizeof(file4));
  	test_rl_pure_test(21, c, m,   0,  40, file5, sizeof(file5));
  	test_rl_pure_test(22, c, m,  40,  40, file5, sizeof(file5));
  	test_rl_pure_test(23, c, m,  60,  40, file5, sizeof(file5));
  	test_rl_pure_test(24, c, m,   0, 100, file5, sizeof(file5));
  	test_rl_pure_test(25, c, m, 200,  40, file5, sizeof(file5));
  	test_rl_pure_test(26, c, m, 240,  40, file5, sizeof(file5));
  	test_rl_pure_test(27, c, m, 260,  40, file5, sizeof(file5));
  	test_rl_pure_test(28, c, m, 200, 100, file5, sizeof(file5));
  	test_rl_pure_test(29, c, m, 400,  40, file5, sizeof(file5));
  	test_rl_pure_test(30, c, m, 440,  40, file5, sizeof(file5));
  	test_rl_pure_test(31, c, m, 460,  40, file5, sizeof(file5));
  	test_rl_pure_test(32, c, m, 400, 100, file5, sizeof(file5));
  	test_rl_pure_test(33, c, m, 160, 100, file6, sizeof(file6));
  	test_rl_pure_test(34, c, m, 100, 140, file6, sizeof(file6));
  }
  
  /**
   * test_rl_zero - Runlist test: Merge a zero-length runlist
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_zero(void)
  {
  	runlist_element *jim = NULL;
  	runlist_element *bob = NULL;
  
  	bob = calloc(3, sizeof(runlist_element));
  	if (!bob)
  		return;
  
  	MKRL(bob+0, 10, 99, 5)
  	MKRL(bob+1, 15, LCN_RL_NOT_MAPPED, 0)
  
  	jim = test_rl_runlists_merge(jim, bob);
  	if (!jim)
  		return;
  
  	free(jim);
  }
  
  /**
   * test_rl_frag_combine - Runlist test: Perform tests using fragmented files
   * @vol:
   * @attr1:
   * @attr2:
   * @attr3:
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_frag_combine(ntfs_volume *vol, ATTR_RECORD *attr1, ATTR_RECORD *attr2, ATTR_RECORD *attr3)
  {
  	runlist_element *run1;
  	runlist_element *run2;
  	runlist_element *run3;
  
  	run1 = ntfs_mapping_pairs_decompress(vol, attr1, NULL);
  	if (!run1)
  		return;
  
  	run2 = ntfs_mapping_pairs_decompress(vol, attr2, NULL);
  	if (!run2)
  		return;
  
  	run1 = test_rl_runlists_merge(run1, run2);
  
  	run3 = ntfs_mapping_pairs_decompress(vol, attr3, NULL);
  	if (!run3)
  		return;
  
  	run1 = test_rl_runlists_merge(run1, run3);
  
  	free(run1);
  }
  
  /**
   * test_rl_frag - Runlist test: Create tests using very fragmented files
   * @test:
   *
   * Description...
   *
   * Returns:
   */
  static void test_rl_frag(char *test)
  {
  	ntfs_volume vol;
  	ATTR_RECORD *attr1 = ntfs_malloc(1024);
  	ATTR_RECORD *attr2 = ntfs_malloc(1024);
  	ATTR_RECORD *attr3 = ntfs_malloc(1024);
  
  	if (!attr1 || !attr2 || !attr3)
  		goto out;
  
  	vol.sb = NULL;
  	vol.sector_size_bits = 9;
  	vol.cluster_size = 2048;
  	vol.cluster_size_bits = 11;
  	vol.major_ver = 3;
  
  	if (!test_rl_read_buffer("runlist-data/attr1.bin", (u8*) attr1, 1024))
  		goto out;
  	if (!test_rl_read_buffer("runlist-data/attr2.bin", (u8*) attr2, 1024))
  		goto out;
  	if (!test_rl_read_buffer("runlist-data/attr3.bin", (u8*) attr3, 1024))
  		goto out;
  
  	if      (strcmp(test, "123") == 0)  test_rl_frag_combine(&vol, attr1, attr2, attr3);
  	else if (strcmp(test, "132") == 0)  test_rl_frag_combine(&vol, attr1, attr3, attr2);
  	else if (strcmp(test, "213") == 0)  test_rl_frag_combine(&vol, attr2, attr1, attr3);
  	else if (strcmp(test, "231") == 0)  test_rl_frag_combine(&vol, attr2, attr3, attr1);
  	else if (strcmp(test, "312") == 0)  test_rl_frag_combine(&vol, attr3, attr1, attr2);
  	else if (strcmp(test, "321") == 0)  test_rl_frag_combine(&vol, attr3, attr2, attr1);
  	else
  		printf("Frag: No such test '%s'\n", test);
  
  out:
  	free(attr1);
  	free(attr2);
  	free(attr3);
  }
  
  /**
   * test_rl_main - Runlist test: Program start (main)
   * @argc:
   * @argv:
   *
   * Description...
   *
   * Returns:
   */
  int test_rl_main(int argc, char *argv[])
  {
  	if      ((argc == 2) && (strcmp(argv[1], "zero") == 0)) test_rl_zero();
  	else if ((argc == 3) && (strcmp(argv[1], "frag") == 0)) test_rl_frag(argv[2]);
  	else if ((argc == 4) && (strcmp(argv[1], "pure") == 0)) test_rl_pure(argv[2], argv[3]);
  	else
  		printf("rl [zero|frag|pure] {args}\n");
  
  	return 0;
  }
  
  #endif
  
  