uk.gov.nationalarchives.droid.signatureFile.SubSequence Maven / Gradle / Ivy
/*
* � The National Archives 2005-2006. All rights reserved.
* See Licence.txt for full licence details.
*
* Developed by:
* Tessella Support Services plc
* 3 Vineyard Chambers
* Abingdon, OX14 3PX
* United Kingdom
* http://www.tessella.com
*
* Tessella/NPD/4305
* PRONOM 4
*
* $Id: SubSequence.java,v 1.8 2006/03/13 15:15:29 linb Exp $
*
* $Logger: SubSequence.java,v $
* Revision 1.8 2006/03/13 15:15:29 linb
* Changed copyright holder from Crown Copyright to The National Archives.
* Added reference to licence.txt
* Changed dates to 2005-2006
*
* Revision 1.7 2006/02/13 10:29:40 gaur
* Fixed bug in searching a short file for a byte sequence at a large offset from BOF
*
* Revision 1.6 2006/02/13 09:26:16 gaur
* Fixed bug in searching files from EOF, after first STS round
*
* Revision 1.5 2006/02/09 15:04:37 gaur
* Corrected formatting
*
* Revision 1.4 2006/02/07 17:16:23 linb
* - Change fileReader to ByteReader in formal parameters of methods
* - use new static constructors
* - Add detection of if a filePath is a URL or not
*
* Revision 1.3 2006/02/07 11:30:04 gaur
* Added support for endianness of signature
*
*
* $History: SubSequence.java $
*
* ***************** Version 6 *****************
* User: Walm Date: 29/09/05 Time: 9:16
* Updated in $/PRONOM4/FFIT_SOURCE/signatureFile
* Bug fix in response to JIRA issue PRON-29.
* changed startPosInFile to an array + some changes to the way start
* position options are dealt with.
*
* ***************** Version 5 *****************
* User: Walm Date: 17/05/05 Time: 12:47
* Updated in $/PRONOM4/FFIT_SOURCE/signatureFile
* added more error trapping
*
* ***************** Version 4 *****************
* User: Walm Date: 5/04/05 Time: 18:08
* Updated in $/PRONOM4/FFIT_SOURCE/signatureFile
* review headers
*
*/
package uk.gov.nationalarchives.droid.signatureFile;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import uk.gov.nationalarchives.droid.base.MessageDisplay;
import uk.gov.nationalarchives.droid.base.SimpleElement;
import uk.gov.nationalarchives.droid.binFileReader.ByteReader;
/**
* holds a subsequence for a byte sequence also contains most of the logic for
* identifying files
*
* @author Martin Waller
* @version 4.0.0
*/
public class SubSequence extends SimpleElement {
private String reference;
private int parentSignature;
private boolean bigEndian = true;
private ByteSequence parentByteSequence;
int position;
int minSeqOffset = 0;
int maxSeqOffset = 0;
int minFragLength;
String sequence;
// shiftFunction shift;
long[] shiftFunction = new long[256];
List leftFragments = new ArrayList();
List rightFragments = new ArrayList();
byte[] byteSequence;
List> orderedLeftFragments = new ArrayList>();
List> orderedRightFragments = new ArrayList>();
static boolean showProgress = false;
/* setters */
public void addLeftFragment(final LeftFragment lf) {
this.leftFragments.add(lf);
}
public void addRightFragment(final RightFragment lf) {
this.rightFragments.add(lf);
}
public byte getByte(final int theIndex) {
return this.byteSequence[theIndex];
}
public ByteSequence getByteSequence() {
return this.parentByteSequence;
}
public SideFragment getFragment(final boolean leftFrag,
final int thePosition, final int theIndex) {
if (leftFrag) {
return (SideFragment) ((ArrayList) this.orderedLeftFragments
.get(thePosition - 1)).get(theIndex);
} else {
return (SideFragment) ((ArrayList) this.orderedRightFragments
.get(thePosition - 1)).get(theIndex);
}
}
public List getLeftFragments() {
return this.leftFragments;
}
public int getMaxSeqOffset() {
return this.maxSeqOffset;
}
public int getMinFragLength() {
return this.minFragLength;
}
public int getMinSeqOffset() {
return this.minSeqOffset;
}
public int getNumAlternativeFragments(final boolean leftFrag,
final int thePosition) {
if (leftFrag) {
return ((ArrayList) this.orderedLeftFragments
.get(thePosition - 1)).size();
} else {
return ((ArrayList) this.orderedRightFragments
.get(thePosition - 1)).size();
}
}
public int getNumBytes() {
return this.byteSequence.length;
}
/* getters */
public int getNumFragmentPositions(final boolean leftFrag) {
if (leftFrag) {
return this.orderedLeftFragments.size();
} else {
return this.orderedRightFragments.size();
}
}
/**
* Get the id of the internal signature that this sequence belongs to
*
* @return
*/
public int getParentSignature() {
return this.parentSignature;
}
public int getPosition() {
return this.position;
}
public LeftFragment getRawLeftFragment(final int theIndex) {
return this.leftFragments.get(theIndex);
}
public RightFragment getRawRightFragment(final int theIndex) {
return this.rightFragments.get(theIndex);
}
public List getRightFragments() {
return this.rightFragments;
}
public String getSequence() {
return this.sequence;
}
public long getShift(final byte theByteValue) {
// this.ShiftFunction is a long[256] array
return this.shiftFunction[theByteValue + 128];
}
public boolean isBigEndian() {
return this.bigEndian;
}
/**
* is this a BOF sub squence If this subsequence does not match the we can
* reject the entire signature
*
* @return boolean
*/
public boolean isBOF() {
return (this.reference.equalsIgnoreCase("BOFoffset") && (this.position == 1));
}
/**
* is this a EOF sub squence If this subsequence does not match the we can
* reject the entire signature
*
* @return boolean
*/
public boolean isEOF() {
return (this.reference.equalsIgnoreCase("EOFoffset") && (this.position == 1));
}
/**
* Searches for this subsequence after the current file marker position in
* the file. Moves the file marker to the end of this subsequence.
*
* @param targetFile
* the binary file to be identified
* @param reverseOrder
* true if file is being searched from right to left
* @param bigEndian
* True iff our parent signature is big-endian
*/
public boolean isFoundAfterFileMarker(final ByteReader targetFile,
final boolean reverseOrder, final boolean bigEndian) {
final long fileSize = targetFile.getNumBytes() - 1;
final int searchDirection = reverseOrder ? -1 : 1;
// get the current file marker
long startPosInFile = targetFile.getFileMarker();
// Add the minimum offset before start of sequence and update the file
// marker accordingly
startPosInFile = startPosInFile
+ (searchDirection * getMinSeqOffset());
if (fileSize < startPosInFile - 1) {
// We're looking for a sequence of bytes at an offset which is
// longer than the file itself
return false;
}
targetFile.setFileMarker(startPosInFile);
// start searching for main sequence after the minimum length of the
// relevant fragments
startPosInFile = startPosInFile
+ (searchDirection * getMinFragLength());
final int numSeqBytes = getNumBytes();
boolean subSeqFound = false;
boolean missMatchFound = false;
final int byteLoopStart = reverseOrder ? numSeqBytes - 1 : 0;
final int byteLoopEnd = reverseOrder ? 0 : numSeqBytes - 1;
try {
while (!subSeqFound) {
// compare sequence with file contents directly at fileMarker
// position
missMatchFound = false;
// Start by checking the last byte in the window on the file.
// If this byte is different from the last byte in the
// subsequence,
// Then we may shift the window according to the value of this
// byte.
// In practice, this saves us from unnecessarily checking file
// bytes to calculate the shift.
final byte lastByte = targetFile.getByte(startPosInFile
+ byteLoopEnd);
if (this.byteSequence[byteLoopEnd] != lastByte) {
startPosInFile += (this.shiftFunction[128 + lastByte] - 1);
if ((startPosInFile < 0L) || (startPosInFile > fileSize)) {
break;
}
} else {
// If the last bytes don't match, then check the rest.
for (int iByte = byteLoopStart; (!missMatchFound)
&& (iByte <= numSeqBytes - 1) && (iByte >= 0); iByte += searchDirection) {
missMatchFound = (this.byteSequence[iByte] != targetFile
.getByte(startPosInFile + iByte
- byteLoopStart));
}
if (!missMatchFound) { // subsequence was found at position
// fileMarker in the file
// Now search for fragments between original fileMarker
// and startPosInFile
if (reverseOrder) {
final long[] rightFragEndArray = bytePosForRightFragments(
targetFile, startPosInFile + 1,
targetFile.getFileMarker(), 1, 0,
bigEndian);
if (rightFragEndArray.length == 0) {
missMatchFound = true;
} else {
long leftFragEnd;
final long[] leftFragEndArray = bytePosForLeftFragments(
targetFile, 0, startPosInFile
- numSeqBytes, -1, 0,
bigEndian);
if (leftFragEndArray.length == 0) {
missMatchFound = true;
} else {
leftFragEnd = leftFragEndArray[0];
targetFile
.setFileMarker(leftFragEnd - 1L);
subSeqFound = true;
}
}
} else { // search is in forward direction
final long[] leftFragEndArray = bytePosForLeftFragments(
targetFile, targetFile.getFileMarker(),
startPosInFile - 1L, -1, 0, bigEndian);
if (leftFragEndArray.length == 0) {
missMatchFound = true;
} else {
long rightFragEnd;
final long[] rightFragEndArray = bytePosForRightFragments(
targetFile, startPosInFile
+ numSeqBytes, targetFile
.getNumBytes() - 1L, 1, 0,
bigEndian);
if (rightFragEndArray.length == 0) {
missMatchFound = true;
} else {
rightFragEnd = rightFragEndArray[0];
targetFile
.setFileMarker(rightFragEnd + 1L);
subSeqFound = true;
}
}
}
}
if (missMatchFound) {
// If a mismatch is found, then shift the window by a
// shift calculated from the value
// of the file byte occuring one place after the window
// position.
startPosInFile += this.shiftFunction[128 + targetFile
.getByte(startPosInFile
+ (searchDirection * numSeqBytes))];
if ((startPosInFile < 0L)
|| (startPosInFile > fileSize)) {
break;
}
}
}
}
} catch (final IndexOutOfBoundsException e) {
// This only happens when the end of the file is reached.
// This exception is allowed to be thrown to avoid repeatedly
// checking if the index is valid
// and to hence improve the performace of DROID
}
return subSeqFound;
}
/**
* Searches for this subsequence at the start of the current file. Moves the
* file marker to the end of this subsequence.
*
* @param targetFile
* the binary file to be identified
* @param reverseOrder
* true if file is being searched from right to left
* @param bigEndian
* True iff our parent signature is big-endian
*/
public boolean isFoundAtStartOfFile(final ByteReader targetFile,
final boolean reverseOrder, final boolean bigEndian) {
try {
final int searchDirection = reverseOrder ? -1 : 1;
int minSeqOffset = getMinSeqOffset();
int maxSeqOffset = getMaxSeqOffset();
// Get any indirect offset
if (this.reference.startsWith("Indirect")) {
try {
final int indirectOffset = getIndirectOffset(targetFile);
minSeqOffset += indirectOffset;
maxSeqOffset += indirectOffset;
} catch (final Exception e) {
// If an exception is thrown, we can assume that the file
// did not match the indirect offset
// eg. the indirect offset found could be too large to be
// held in an int type
return false;
}
}
long[] startPosInFile = new long[1];
startPosInFile[0] = reverseOrder ? targetFile.getNumBytes()
- minSeqOffset - 1 : minSeqOffset;
boolean subseqFound = true;
boolean leftFrag = true;
if (reverseOrder) {
leftFrag = false;
}
// match intial fragment
if (reverseOrder) {
startPosInFile = bytePosForRightFragments(targetFile, 0,
startPosInFile[0], -1, (maxSeqOffset - minSeqOffset),
bigEndian);
} else {
startPosInFile = bytePosForLeftFragments(targetFile,
startPosInFile[0], targetFile.getNumBytes() - 1, 1,
(maxSeqOffset - minSeqOffset), bigEndian);
}
int numOptions = startPosInFile.length;
if (numOptions == 0) {
subseqFound = false;
} else {
for (int i = 0; i < numOptions; i++) {
startPosInFile[i] += searchDirection;
}
}
// match main sequence
if (subseqFound) {
// move startPosInFile according to min offset of last fragment
// looked at
int minOffset = 0;
int maxOffset = 0;
if (getNumFragmentPositions(leftFrag) > 0) {
minOffset = getFragment(leftFrag, 1, 0).getMinOffset();
maxOffset = getFragment(leftFrag, 1, 0).getMaxOffset();
for (int i = 0; i < numOptions; i++) {
startPosInFile[i] += (minOffset * searchDirection);
}
}
// add new possible values for startPosInFile to allow for
// difference between maxOffset and minOffset
final int offsetRange = maxOffset - minOffset;
if (offsetRange > 0) {
final long[] newStartPosInFile = new long[numOptions
* (offsetRange + 1)];
for (int i = 0; i <= offsetRange; i++) {
for (int j = 0; j < numOptions; j++) {
newStartPosInFile[j + i * numOptions] = startPosInFile[j]
+ (i * searchDirection);
}
}
Arrays.sort(newStartPosInFile);
int newNumOptions = 1;
for (int i = 1; i < numOptions * (offsetRange + 1); i++) {
if (newStartPosInFile[i] > newStartPosInFile[newNumOptions - 1]) {
newStartPosInFile[newNumOptions] = newStartPosInFile[i];
newNumOptions++;
}
}
// now copy these back to the startPosInFile array (sorted
// in searchDirection)
numOptions = newNumOptions;
if (searchDirection > 1) {
System.arraycopy(newStartPosInFile, 0,
startPosInFile, 0, numOptions);
} else {
// reverse order copy
for (int i = 0; i < numOptions; i++) {
startPosInFile[i] = newStartPosInFile[numOptions
- 1 - i];
}
}
}
// check that the end of the file is not going to be reached
final int numSeqBytes = getNumBytes();
final long numBytesInFile = targetFile.getNumBytes();
if (reverseOrder) {
// cutoff if startPosInFile is too close to start of file
for (int i = 0; i < numOptions; i++) {
if (startPosInFile[i] < (numSeqBytes - 1L)) {
numOptions = i;
}
}
} else {
// cutoff if startPosInFile is too close to end of file
for (int i = 0; i < numOptions; i++) {
if (startPosInFile[i] > (numBytesInFile - numSeqBytes)) {
numOptions = i;
}
}
}
for (int iOption = 0; iOption < numOptions; iOption++) {
// compare sequence with file contents directly at
// fileMarker position
final int byteLoopStart = reverseOrder ? numSeqBytes - 1
: 0;
long tempFileMarker = startPosInFile[iOption];
boolean provSeqMatch = true;
// check whether the file and signature sequences match
for (int iByte = byteLoopStart; (provSeqMatch)
&& (iByte <= numSeqBytes - 1) && (iByte >= 0); iByte += searchDirection) {
provSeqMatch = (this.byteSequence[iByte] == targetFile
.getByte(tempFileMarker));
tempFileMarker += searchDirection;
}
if (!provSeqMatch) {
// no match
startPosInFile[iOption] = -2L;
} else {
// success: a match was found - update the
// startPosInFile
startPosInFile[iOption] = tempFileMarker;
}
}
// check the startPosInFile array: remove -2 values, reorder and
// remove duplicates
Arrays.sort(startPosInFile, 0, numOptions);
int newNumOptions = 0;
final long[] newStartPosInFile = new long[numOptions];
if (numOptions > 0) {
if (startPosInFile[0] >= -1L) {
newStartPosInFile[0] = startPosInFile[0];
newNumOptions = 1;
}
}
for (int i = 1; i < numOptions; i++) {
if (startPosInFile[i] > startPosInFile[i - 1]) {
newStartPosInFile[newNumOptions] = startPosInFile[i];
newNumOptions++;
}
}
if (newNumOptions == 0) {
subseqFound = false;
} else {
numOptions = newNumOptions;
if (searchDirection < 0) {
// for right to left search direction, reorder in
// reverse
for (int iOption = 0; iOption < numOptions; iOption++) {
startPosInFile[iOption] = newStartPosInFile[numOptions
- 1 - iOption];
}
} else {
// for left to right search direction, copy over as is
System.arraycopy(newStartPosInFile, 0,
startPosInFile, 0, numOptions);
}
}
}
// match remaining sequence fragment
long newValueStartPosInFile = 0L;
if (subseqFound) {
long[] newArrayStartPosInFile;
if (reverseOrder) {
int i = 0;
subseqFound = false;
while ((i < numOptions) && !subseqFound) {
newArrayStartPosInFile = bytePosForLeftFragments(
targetFile, 0L, startPosInFile[i], -1, 0,
bigEndian);
if (newArrayStartPosInFile.length == 0) {
subseqFound = false;
} else {
subseqFound = true;
newValueStartPosInFile = newArrayStartPosInFile[0] - 1L; // take
// away
// -1???
}
i++;
}
} else {
int i = 0;
subseqFound = false;
while ((i < numOptions) && !subseqFound) {
newArrayStartPosInFile = bytePosForRightFragments(
targetFile, startPosInFile[i], targetFile
.getNumBytes() - 1L, 1, 0, bigEndian);
if (newArrayStartPosInFile.length == 0) {
subseqFound = false;
} else {
subseqFound = true;
newValueStartPosInFile = newArrayStartPosInFile[0] + 1L; // take
// away
// +1????
}
i++;
}
}
}
// update the file marker
if (subseqFound) {
targetFile.setFileMarker(newValueStartPosInFile);
}
return subseqFound;
} catch (final IndexOutOfBoundsException e) {
// If an indirect offset points to a place that is after the end of
// the file,
// Then this exception is thrown and it can be assumed that the
// signature is not compliant
return false;
}
}
/**
* Re-orders the left and right sequence fragments in increasing position
* order this method must be after the signature file has been parsed and
* before running any file identifications
*/
public void prepareSeqFragments() {
/* Left fragments */
// Determine the number of fragment subsequences there are
int numFrags = 0;
for (int i = 0; i < this.leftFragments.size(); i++) {
final int currentPosition = getRawLeftFragment(i).getPosition();
if (currentPosition > numFrags) {
numFrags = currentPosition;
}
}
// initialise all necessary fragment lists (one for each position)
for (int i = 0; i < numFrags; i++) { // loop through fragment positions
final List alternativeFragments = new ArrayList();
this.orderedLeftFragments.add(alternativeFragments);
}
// Add fragments to new structure
for (int i = 0; i < this.leftFragments.size(); i++) { // loop through
// all fragments
final int currentPosition = getRawLeftFragment(i).getPosition();
this.orderedLeftFragments.get(currentPosition - 1).add(
getRawLeftFragment(i));
}
// clear out unecessary info
this.leftFragments = null;
/* Right fragments */
// Determine the number of fragment subsequences there are
numFrags = 0;
for (int i = 0; i < this.rightFragments.size(); i++) {
final int currentPosition = getRawRightFragment(i).getPosition();
if (currentPosition > numFrags) {
numFrags = currentPosition;
}
}
// initialise all necessary fragment lists (one for each position)
for (int i = 0; i < numFrags; i++) { // loop through fragment positions
final List alternativeFragments = new ArrayList();
this.orderedRightFragments.add(alternativeFragments);
}
// Add fragments to new structure
for (int i = 0; i < this.rightFragments.size(); i++) { // loop through
// all fragments
final int currentPosition = getRawRightFragment(i).getPosition();
this.orderedRightFragments.get(currentPosition - 1).add(
getRawRightFragment(i));
}
// clear out unecessary info
this.rightFragments = null;
}
@Override
public void setAttributeValue(final String name, final String value) {
if (name.equals("Position")) {
setPosition(Integer.parseInt(value));
} else if (name.equals("SubSeqMinOffset")) {
setMinSeqOffset(Integer.parseInt(value));
} else if (name.equals("SubSeqMaxOffset")) {
setMaxSeqOffset(Integer.parseInt(value));
} else if (name.equals("MinFragLength")) {
setMinFragLength(Integer.parseInt(value));
} else {
MessageDisplay.unknownAttributeWarning(name, getElementName());
}
}
public void setBigEndian(final boolean bigEndian) {
this.bigEndian = bigEndian;
}
public void setByteSequence(final ByteSequence byteSequence) {
this.parentByteSequence = byteSequence;
}
public void setDefaultShift(final String theValue) {
for (int i = 0; i < 256; i++) {
this.shiftFunction[i] = Long.parseLong(theValue);
}
}
public void setMaxSeqOffset(final int theOffset) {
this.maxSeqOffset = theOffset;
if (this.maxSeqOffset < this.minSeqOffset) {
this.maxSeqOffset = this.minSeqOffset;
}
}
public void setMinFragLength(final int theLength) {
this.minFragLength = theLength;
}
public void setMinSeqOffset(final int theOffset) {
this.minSeqOffset = theOffset;
if (this.maxSeqOffset < this.minSeqOffset) {
this.maxSeqOffset = this.minSeqOffset;
}
}
public void setParentSignature(final int parentSignature) {
this.parentSignature = parentSignature;
}
public void setPosition(final int position) {
this.position = position;
}
public void setReference(final String reference) {
this.reference = reference;
}
public void setSequence(final String seq) {
this.sequence = seq;
final int seqLength = seq.length() / 2;
if (2 * seqLength != seq.length()) {
System.out
.println("A problem - sequence of odd length was found: "
+ seq);
}
this.byteSequence = new byte[seqLength];
for (int i = 0; i < seqLength; i++) {
final int byteVal = Integer.parseInt(seq.substring(2 * i,
2 * (i + 1)), 16);
this.byteSequence[i] = (byteVal > Byte.MAX_VALUE) ? (byte) (byteVal - 256)
: (byte) byteVal;
}
}
public void setShift(final Shift theShift) {
final int theShiftByte = theShift.getShiftByte();
if ((theShiftByte >= 0) && (theShiftByte < 128)) {
this.shiftFunction[theShiftByte + 128] = theShift.getShiftValue();
} else if ((theShiftByte >= 128) && (theShiftByte < 256)) {
this.shiftFunction[theShiftByte - 128] = theShift.getShiftValue();
}
}
@Override
public String toString() {
return this.position + " seq=<" + this.sequence + ">" + "LLL"
+ this.orderedLeftFragments + "LLL" + "RRR"
+ this.orderedRightFragments + "RRR";
}
/**
* Searches for the left fragments of this subsequence between the given
* byte positions in the file. Either returns the last byte taken up by the
* identified sequences or returns -2 if no match was found
*
* @param targetFile
* the binary file to be identified
* @param leftBytePos
* left-most byte position of allowed search window on file
* @param rightBytePos
* right-most byte position of allowed search window on file
* @param searchDirection
* 1 for a left to right search, -1 for right to left
* @param offsetRange
* range of possible start positions in the direction of
* searchDirection
* @param bigEndian
* True iff our parent signature is big-endian
*/
private long[] bytePosForLeftFragments(final ByteReader targetFile,
final long leftBytePos, final long rightBytePos,
final int searchDirection, final int offsetRange,
final boolean bigEndian) {
final boolean leftFrag = true;
long startPos = rightBytePos;
int posLoopStart = 1;
final int numFragPos = getNumFragmentPositions(leftFrag);
if (searchDirection == 1) {
startPos = leftBytePos;
posLoopStart = numFragPos;
}
// now set up the array so that it can potentially hold all
// possibilities
int totalNumOptions = offsetRange + 1;
for (int iFragPos = 1; iFragPos <= numFragPos; iFragPos++) {
totalNumOptions = totalNumOptions
* getNumAlternativeFragments(leftFrag, iFragPos);
}
final long[] markerPos = new long[totalNumOptions];
for (int iOffset = 0; iOffset <= offsetRange; iOffset++) {
markerPos[iOffset] = startPos + iOffset * searchDirection;
}
int numOptions = 1 + offsetRange;
boolean seqNotFound = false;
for (int iFragPos = posLoopStart; (!seqNotFound)
&& (iFragPos <= numFragPos) && (iFragPos >= 1); iFragPos -= searchDirection) {
final int numAltFrags = getNumAlternativeFragments(leftFrag,
iFragPos);
final long[] tempEndPos = new long[numAltFrags * numOptions]; // array
// to
// store
// possible
// end
// positions
// after
// this
// fragment
// position
// has
// been
// examined
int numEndPos = 0;
for (int iOption = 0; iOption < numOptions; iOption++) {
// will now look for all matching alternative sequence at the
// current end positions
for (int iAlt = 0; iAlt < numAltFrags; iAlt++) {
long tempFragEnd;
if (searchDirection == 1) {
tempFragEnd = endBytePosForSeqFrag(targetFile,
markerPos[iOption], rightBytePos, true,
searchDirection, iFragPos, iAlt, bigEndian);
} else {
tempFragEnd = endBytePosForSeqFrag(targetFile,
leftBytePos, markerPos[iOption], true,
searchDirection, iFragPos, iAlt, bigEndian);
}
if (tempFragEnd > -1L) { // amatch has been found
tempEndPos[numEndPos] = tempFragEnd + searchDirection;
numEndPos += 1;
}
}
}
if (numEndPos == 0) {
seqNotFound = true;
} else {
numOptions = 0;
for (int iOption = 0; iOption < numEndPos; iOption++) {
// eliminate any repeated end positions
boolean addEndPos = true;
for (int iMarker = 0; iMarker < numOptions; iMarker++) {
if (markerPos[iMarker] == tempEndPos[iOption]) {
addEndPos = false;
break;
}
}
if (addEndPos) {
markerPos[numOptions] = tempEndPos[iOption];
numOptions++;
}
}
}
}
// prepare array to be returned
if (seqNotFound) {
// no possible positions found, return 0 length array
final long[] outArray = new long[0];
return outArray;
} else {
// return ordered array of possibilities
final long[] outArray = new long[numOptions];
// convert values to negative temporarily so that reverse sort order
// can be obtained for a right to left search direction
if (searchDirection < 0) {
for (int iOption = 0; iOption < numOptions; iOption++) {
markerPos[iOption] = -markerPos[iOption];
}
}
// sort the values in the array
Arrays.sort(markerPos, 0, numOptions);
// convert values back to positive now that a reverse sort order has
// been obtained
if (searchDirection < 0) {
for (int iOption = 0; iOption < numOptions; iOption++) {
markerPos[iOption] = -markerPos[iOption];
}
}
// copy to a new array which has precisely the correct length
System.arraycopy(markerPos, 0, outArray, 0, numOptions);
// correct the value
for (int iOption = 0; iOption < numOptions; iOption++) {
outArray[iOption] -= searchDirection;
}
return outArray;
}
}
/**
* Searches for the right fragments of this subsequence between the given
* byte positions in the file. Either returns the last byte taken up by the
* identified sequences or returns -2 if no match was found
*
* @param targetFile
* the binary file to be identified
* @param leftBytePos
* left-most byte position of allowed search window on file
* @param rightBytePos
* right-most byte position of allowed search window on file
* @param searchDirection
* 1 for a left to right search, -1 for right to left
* @param offsetRange
* range of possible start positions in the direction of
* searchDirection
* @param bigEndian
* True iff our parent signature is big-endian
*/
private long[] bytePosForRightFragments(final ByteReader targetFile,
final long leftBytePos, final long rightBytePos,
final int searchDirection, final int offsetRange,
final boolean bigEndian) {
final boolean leftFrag = false;
long startPos = leftBytePos;
int posLoopStart = 1;
final int numFragPos = getNumFragmentPositions(leftFrag);
if (searchDirection == -1) {
startPos = rightBytePos;
posLoopStart = numFragPos;
}
// now set up the array so that it can potentially hold all
// possibilities
int totalNumOptions = offsetRange + 1;
for (int iFragPos = 1; iFragPos <= numFragPos; iFragPos++) {
totalNumOptions = totalNumOptions
* getNumAlternativeFragments(leftFrag, iFragPos);
}
final long[] markerPos = new long[totalNumOptions];
for (int iOffset = 0; iOffset <= offsetRange; iOffset++) {
markerPos[iOffset] = startPos + iOffset * searchDirection;
}
int numOptions = 1 + offsetRange;
boolean seqNotFound = false;
for (int iFragPos = posLoopStart; (!seqNotFound)
&& (iFragPos <= numFragPos) && (iFragPos >= 1); iFragPos += searchDirection) {
final int numAltFrags = getNumAlternativeFragments(leftFrag,
iFragPos);
final long[] tempEndPos = new long[numAltFrags * numOptions]; // array
// to
// store
// possible
// end
// positions
// after
// this
// fragment
// position
// has
// been
// examined
int numEndPos = 0;
for (int iOption = 0; iOption < numOptions; iOption++) {
// will now look for all matching alternative sequence at the
// current end positions
for (int iAlt = 0; iAlt < numAltFrags; iAlt++) {
long tempFragEnd;
if (searchDirection == -1) {
tempFragEnd = endBytePosForSeqFrag(targetFile,
leftBytePos, markerPos[iOption], false,
searchDirection, iFragPos, iAlt, bigEndian);
} else {
tempFragEnd = endBytePosForSeqFrag(targetFile,
markerPos[iOption], rightBytePos, false,
searchDirection, iFragPos, iAlt, bigEndian);
}
if (tempFragEnd > -1) { // amatch has been found
tempEndPos[numEndPos] = tempFragEnd + searchDirection;
numEndPos += 1;
}
}
}
if (numEndPos == 0) {
seqNotFound = true;
} else {
numOptions = 0;
for (int iOption = 0; iOption < numEndPos; iOption++) {
// eliminate any repeated end positions
boolean addEndPos = true;
for (int iMarker = 0; iMarker < numOptions; iMarker++) {
if (markerPos[iMarker] == tempEndPos[iOption]) {
addEndPos = false;
break;
}
}
if (addEndPos) {
markerPos[numOptions] = tempEndPos[iOption];
numOptions++;
}
}
}
}
// prepare array to be returned
if (seqNotFound) {
// no possible positions found, return 0 length array
final long[] outArray = new long[0];
return outArray;
} else {
// return ordered array of possibilities
final long[] outArray = new long[numOptions];
// convert values to negative temporarily so that reverse sort order
// can be obtained for a right to left search direction
if (searchDirection < 0) {
for (int iOption = 0; iOption < numOptions; iOption++) {
markerPos[iOption] = -markerPos[iOption];
}
}
// sort the values in the array
Arrays.sort(markerPos, 0, numOptions);
// convert values back to positive now that a reverse sort order has
// been obtained
if (searchDirection < 0) {
for (int iOption = 0; iOption < numOptions; iOption++) {
markerPos[iOption] = -markerPos[iOption];
}
}
// copy to a new array which has precisely the correct length
System.arraycopy(markerPos, 0, outArray, 0, numOptions);
// correct the value
for (int iOption = 0; iOption < numOptions; iOption++) {
outArray[iOption] -= searchDirection;
}
return outArray;
}
}
/**
* searches for the specified fragment sequence between the leftmost and
* rightmost byte positions that are given. returns the end position of the
* found sequence or -1 if it is not found
*
* @param targetFile
* The file that is being reviewed for identification
* @param leftEndBytePos
* leftmost position in file at which to search
* @param rightEndBytePos
* rightmost postion in file at which to search
* @param leftFrag
* flag to indicate whether looking at left or right fragments
* @param searchDirection
* direction in which search is carried out (1 for left to right,
* -1 for right to left)
* @param fragPos
* position of left/right sequence fragment to use
* @param fragIndex
* index of fragment within the position (where alternatives
* exist)
* @param bigEndian
* True iff out parent signature is big-endian
*/
private long endBytePosForSeqFrag(final ByteReader targetFile,
final long leftEndBytePos, final long rightEndBytePos,
final boolean leftFrag, final int searchDirection,
final int fragPos, final int fragIndex, final boolean bigEndian) {
long startPosInFile;
long lastStartPosInFile;
long endPosInFile = -1L;
final long searchDirectionL = searchDirection;
int numBytes;
int minOffset;
int maxOffset;
// read in values
numBytes = getFragment(leftFrag, fragPos, fragIndex).getNumBytes();
if (leftFrag && (searchDirection == -1)) {
minOffset = getFragment(leftFrag, fragPos, fragIndex)
.getMinOffset();
maxOffset = getFragment(leftFrag, fragPos, fragIndex)
.getMaxOffset();
} else if (!leftFrag && (searchDirection == 1)) {
minOffset = getFragment(leftFrag, fragPos, fragIndex)
.getMinOffset();
maxOffset = getFragment(leftFrag, fragPos, fragIndex)
.getMaxOffset();
} else if (fragPos < getNumFragmentPositions(leftFrag)) {
minOffset = getFragment(leftFrag, fragPos + 1, 0).getMinOffset();
maxOffset = getFragment(leftFrag, fragPos + 1, 0).getMaxOffset();
} else {
minOffset = 0;
maxOffset = 0;
}
// set up start and end positions for searches taking into account min
// and max offsets
if (searchDirection == -1) {
startPosInFile = rightEndBytePos - minOffset;
final long lastStartPosInFile1 = leftEndBytePos + numBytes - 1L;
final long lastStartPosInFile2 = rightEndBytePos - maxOffset;
lastStartPosInFile = (lastStartPosInFile1 < lastStartPosInFile2) ? lastStartPosInFile2
: lastStartPosInFile1;
} else {
startPosInFile = leftEndBytePos + minOffset;
final long lastStartPosInFile1 = rightEndBytePos - numBytes + 1L;
final long lastStartPosInFile2 = leftEndBytePos + maxOffset;
lastStartPosInFile = (lastStartPosInFile1 < lastStartPosInFile2) ? lastStartPosInFile1
: lastStartPosInFile2;
}
// keep searching until either the sequence fragment is found or until
// the end of the search area has been reached.
// compare sequence with file contents directly at fileMarker position
boolean subSeqFound = false;
while ((!subSeqFound)
&& ((searchDirectionL)
* (lastStartPosInFile - startPosInFile) >= 0L)) {
boolean missMatchFound = false;
if (searchDirection == -1) {
} else {
}
final SideFragment fragment = getFragment(leftFrag, fragPos,
fragIndex);
long tempFileMarker = startPosInFile;
for (int i = (searchDirection == 1) ? 0 : fragment
.getNumByteSeqSpecifiers() - 1; !missMatchFound
&& (0 <= i) && (i < fragment.getNumByteSeqSpecifiers()); i += searchDirection) {
missMatchFound = !fragment.getByteSeqSpecifier(i)
.matchesByteSequence(targetFile, tempFileMarker,
searchDirection, bigEndian);
if (!missMatchFound) {
tempFileMarker += searchDirection
* fragment.getByteSeqSpecifier(i).getNumBytes();
}
}
if (!missMatchFound) { // subsequence fragment was found in the file
subSeqFound = true;
endPosInFile = tempFileMarker - searchDirectionL;
} else {
startPosInFile += searchDirectionL;
}
}
return endPosInFile; // this is -1 unless subSeqFound = true
}
/**
* Interpret the bytes in a file as an offset.
*
* The next indirectOffsetLength() bytes after
* indirectOffsetLocation() are interpreted as an offset
* according to the endianness of the byte sequence.
*
* @param targetFile
* @return
*/
private int getIndirectOffset(final ByteReader targetFile) {
int offset = 0;
long power = 1;
long offsetLocation = getByteSequence().getIndirectOffsetLocation();
if (getByteSequence().getReference().endsWith("EOFoffset")) {
offsetLocation = targetFile.getNumBytes() - offsetLocation - 1;
}
final int offsetLength = getByteSequence().getIndirectOffsetLength();
// In the case of indirect BOF or indirect EOF bytesequences,
// We need to get read the file to get the offset.
if (isBigEndian()) {
for (int i = offsetLength - 1; i > -1; i--) {
final Byte fileByte = targetFile.getByte(offsetLocation + i);
int byteValue = fileByte.intValue();
byteValue = (byteValue >= 0) ? byteValue : byteValue + 256;
offset += power * byteValue;
power *= 256;
}
} else {
for (int i = 0; i < offsetLength; i++) {
final Byte fileByte = targetFile.getByte(offsetLocation + i);
int byteValue = fileByte.intValue();
byteValue = (byteValue >= 0) ? byteValue : byteValue + 256;
offset += power * byteValue;
power *= 256;
}
}
return offset;
}
}
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