LayoutFile.java

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/*
 * Autopsy Forensic Browser
 * 
 * Copyright 2011 Basis Technology Corp.
 * Contact: carrier <at> sleuthkit <dot> org
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.sleuthkit.datamodel;

import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.sleuthkit.datamodel.TskData.FileKnown;
import org.sleuthkit.datamodel.TskData.TSK_DB_FILES_TYPE_ENUM;
import org.sleuthkit.datamodel.TskData.TSK_FS_ATTR_TYPE_ENUM;
import org.sleuthkit.datamodel.TskData.TSK_FS_META_TYPE_ENUM;
import org.sleuthkit.datamodel.TskData.TSK_FS_NAME_FLAG_ENUM;
import org.sleuthkit.datamodel.TskData.TSK_FS_NAME_TYPE_ENUM;

public class LayoutFile extends AbstractFile {

        private long imageHandle = -1;

        protected LayoutFile(SleuthkitCase db, long objId, String name,
                        TSK_DB_FILES_TYPE_ENUM fileType,
                        TSK_FS_NAME_TYPE_ENUM dirType, TSK_FS_META_TYPE_ENUM metaType,
                        TSK_FS_NAME_FLAG_ENUM dirFlag, short metaFlags,
                        long size, String md5Hash, FileKnown knownState, String parentPath) {
                super(db, objId, TSK_FS_ATTR_TYPE_ENUM.TSK_FS_ATTR_TYPE_DEFAULT, (short) 0, name, fileType, 0L, 0, dirType, metaType, dirFlag, metaFlags, size, 0L, 0L, 0L, 0L, (short) 0, 0, 0, md5Hash, knownState, parentPath);
                //this.size = calcSize(); //update calculated size
        }

        public int getNumParts() {
                int numParts = 0;
                try {
                        numParts = getRanges().size();
                } catch (TskCoreException ex) {
                        Logger.getLogger(LayoutFile.class.getName()).log(Level.INFO, "Error getting layout content ranges for size", ex); //NON-NLS
                }
                return numParts;
        }

        @Override
        public List<Content> getChildren() throws TskCoreException {
                return getSleuthkitCase().getAbstractFileChildren(this, TskData.TSK_DB_FILES_TYPE_ENUM.DERIVED);
        }

        @Override
        public List<Long> getChildrenIds() throws TskCoreException {
                return getSleuthkitCase().getAbstractFileChildrenIds(this, TskData.TSK_DB_FILES_TYPE_ENUM.DERIVED);
        }

        private long calcSize() {
                long calcSize = 0;
                try {
                        for (TskFileRange range : getRanges()) {
                                calcSize += range.getByteLen();
                        }
                } catch (TskCoreException ex) {
                        Logger.getLogger(LayoutFile.class.getName()).log(Level.SEVERE, "Error calculating layout file size from ranges", ex); //NON-NLS
                }
                return calcSize;
        }

        @Override
        public void close() {
                //nothing to be closed
        }

        @Override
        protected int readInt(byte[] buf, long offset, long len) throws TskCoreException {
                long offsetInThisLayoutContent = 0; // current offset in this LayoutContent
                int bytesRead = 0; // Bytes read so far

                if (imageHandle == -1) {
                        Content dataSource = getDataSource();
                        if ((dataSource != null) && (dataSource instanceof Image)) {
                                Image image = (Image) dataSource;
                                imageHandle = image.getImageHandle();
                        } else {
                                throw new TskCoreException("Data Source of LayoutFile is not Image");
                        }
                }

                for (TskFileRange range : getRanges()) {
                        if (bytesRead < len) { // we haven't read enough yet
                                if (offset < offsetInThisLayoutContent + range.getByteLen()) { // if we are in a range object we want to read from
                                        long offsetInRange = 0; // how far into the current range object to start reading
                                        if (bytesRead == 0) { // we haven't read anything yet so we want to read from the correct offset in this range object
                                                offsetInRange = offset - offsetInThisLayoutContent; // start reading from the correct offset
                                        }
                                        long offsetInImage = range.getByteStart() + offsetInRange; // how far into the image to start reading
                                        long lenToRead = Math.min(range.getByteLen() - offsetInRange, len - bytesRead); // how much we can read this time
                                        int lenRead = readImgToOffset(imageHandle, buf, bytesRead, offsetInImage, (int) lenToRead);
                                        bytesRead += lenRead;
                                        if (lenToRead != lenRead) { // If image read failed or was cut short
                                                break;
                                        }
                                }
                                offsetInThisLayoutContent += range.getByteLen();
                        } else { // we're done reading
                                break;
                        }
                }
                return bytesRead;
        }

        /*
         * Read bytes from an image into a buffer, starting at given position in buffer
         * 
         * @param imgHandle             the image to read from
         * @param buf                   the array to read into
         * @param offsetInBuf   where to start in the array
         * @param offsetInImage where to start in the image
         * @param lenToRead             how far to read in the image
         */
        private int readImgToOffset(long imgHandle, byte[] buf, int offsetInBuf, long offsetInImage, int lenToRead) throws TskCoreException {
                byte[] currentBuffer = new byte[lenToRead]; // the buffer for the current range object
                int lenRead = SleuthkitJNI.readImg(imgHandle, currentBuffer, offsetInImage, lenToRead);
                System.arraycopy(currentBuffer, 0, buf, offsetInBuf, lenToRead); // copy what we just read into the main buffer
                return lenRead;
        }

        @Override
        public <T> T accept(ContentVisitor<T> v) {
                return v.visit(this);
        }

        @Override
        public <T> T accept(SleuthkitItemVisitor<T> v) {
                return v.visit(this);
        }

        @Override
        public boolean isRoot() {
                return false;
        }

        @Override
        public String toString(boolean preserveState) {
                return super.toString(preserveState) + "LayoutFile [\t" + "]\t"; //NON-NLS
        }
}