mirror of https://github.com/apache/poi.git
Lots more documentation on how we read in POIFS files and process the sectors/blocks and FATs. Also add a test that shows that bug #46391 is invalid
git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@933663 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Nick Burch
parent
e53e3a376e
commit
350df80600
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@ -32,10 +32,21 @@ public interface POIFSConstants
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/** Some use 4096 bytes */
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public static final int LARGER_BIG_BLOCK_SIZE = 0x1000;
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public static final int END_OF_CHAIN = -2;
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public static final int PROPERTY_SIZE = 0x0080;
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/** The highest sector number you're allowed, 0xFFFFFFFA */
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public static final int LARGEST_REGULAR_SECTOR_NUMBER = -5;
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/** Indicates the sector holds a DIFAT block (0xFFFFFFFC) */
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public static final int DIFAT_SECTOR_BLOCK = -4;
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/** Indicates the sector holds a FAT block (0xFFFFFFFD) */
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public static final int FAT_SECTOR_BLOCK = -3;
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/** Indicates the sector is the end of a chain (0xFFFFFFFE) */
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public static final int END_OF_CHAIN = -2;
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/** Indicates the sector is not used (0xFFFFFFFF) */
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public static final int UNUSED_BLOCK = -1;
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/** The first 4 bytes of an OOXML file, used in detection */
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public static final byte[] OOXML_FILE_HEADER =
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new byte[] { 0x50, 0x4b, 0x03, 0x04 };
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} // end public interface POIFSConstants;
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@ -89,17 +89,35 @@ public final class BlockAllocationTableReader {
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+ " is too high. POI maximum is " + MAX_BLOCK_COUNT + ".");
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}
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// acquire raw data blocks containing the BAT block data
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RawDataBlock blocks[] = new RawDataBlock[ block_count ];
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// We want to get the whole of the FAT table
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// To do this:
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// * Work through raw_block_list, which points to the
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// first (up to) 109 BAT blocks
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// * Jump to the XBAT offset, and read in XBATs which
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// point to more BAT blocks
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int limit = Math.min(block_count, block_array.length);
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int block_index;
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// This will hold all of the BAT blocks in order
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RawDataBlock blocks[] = new RawDataBlock[ block_count ];
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// Process the first (up to) 109 BAT blocks
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for (block_index = 0; block_index < limit; block_index++)
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{
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// Check that the sector number of the BAT block is a valid one
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int nextOffset = block_array[ block_index ];
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if(nextOffset > raw_block_list.blockCount()) {
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throw new IOException("Your file contains " + raw_block_list.blockCount() +
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" sectors, but the initial DIFAT array at index " + block_index +
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" referenced block # " + nextOffset + ". This isn't allowed and " +
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" your file is corrupt");
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}
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// Record the sector number of this BAT block
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blocks[ block_index ] =
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( RawDataBlock ) raw_block_list
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.remove(block_array[ block_index ]);
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( RawDataBlock ) raw_block_list.remove(nextOffset);
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}
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// Process additional BAT blocks via the XBATs
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if (block_index < block_count)
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{
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@ -113,6 +131,9 @@ public final class BlockAllocationTableReader {
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int max_entries_per_block = BATBlock.entriesPerXBATBlock();
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int chain_index_offset = BATBlock.getXBATChainOffset();
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// Each XBAT block contains either:
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// (maximum number of sector indexes) + index of next XBAT
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// some sector indexes + FREE sectors to max # + EndOfChain
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for (int j = 0; j < xbat_count; j++)
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{
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limit = Math.min(block_count - block_index,
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@ -139,8 +160,8 @@ public final class BlockAllocationTableReader {
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throw new IOException("Could not find all blocks");
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}
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// now that we have all of the raw data blocks, go through and
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// create the indices
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// Now that we have all of the raw data blocks which make
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// up the FAT, go through and create the indices
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setEntries(blocks, raw_block_list);
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}
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@ -79,5 +79,7 @@ public interface BlockList
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public void setBAT(final BlockAllocationTableReader bat)
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throws IOException;
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public int blockCount();
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} // end public interface BlockList
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@ -138,4 +138,21 @@ abstract class BlockListImpl implements BlockList {
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}
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_bat = bat;
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}
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/**
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* Returns the count of the number of blocks
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*/
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public int blockCount() {
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return _blocks.length;
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}
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/**
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* Returns the number of remaining blocks
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*/
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protected int remainingBlocks() {
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int c = 0;
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for(int i=0; i<_blocks.length; i++) {
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if(_blocks[i] != null) c++;
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}
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return c;
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}
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}
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@ -33,6 +33,11 @@ public interface HeaderBlockConstants
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(POIFSConstants.BIG_BLOCK_SIZE - _bat_array_offset)
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/ LittleEndianConsts.INT_SIZE;
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// Note - in Microsoft terms:
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// BAT ~= FAT
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// SBAT ~= MiniFAT
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// XBAT ~= DIFat
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// useful offsets
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public static final int _signature_offset = 0;
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public static final int _bat_count_offset = 0x2C;
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@ -22,6 +22,7 @@ import static org.apache.poi.poifs.storage.HeaderBlockConstants._bat_count_offse
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._max_bats_in_header;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._property_start_offset;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._sbat_start_offset;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._sbat_block_count_offset;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._signature;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._signature_offset;
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import static org.apache.poi.poifs.storage.HeaderBlockConstants._xbat_count_offset;
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@ -49,21 +50,37 @@ public final class HeaderBlockReader {
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*/
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private final int bigBlockSize;
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/** number of big block allocation table blocks (int) */
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/**
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* number of big block allocation table blocks (int).
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* (Number of FAT Sectors in Microsoft parlance)
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*/
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private final int _bat_count;
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/** start of the property set block (int index of the property set
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* chain's first big block)
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/**
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* Start of the property set block (int index of the property set
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* chain's first big block).
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*/
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private final int _property_start;
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/** start of the small block allocation table (int index of small
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/**
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* start of the small block allocation table (int index of small
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* block allocation table's first big block)
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*/
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private final int _sbat_start;
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/**
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* Number of small block allocation table blocks (int)
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* (Number of MiniFAT Sectors in Microsoft parlance)
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*/
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private final int _sbat_count;
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/** big block index for extension to the big block allocation table */
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/**
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* Big block index for extension to the big block allocation table
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*/
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private final int _xbat_start;
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/**
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* Number of big block allocation table blocks (int)
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* (Number of DIFAT Sectors in Microsoft parlance)
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*/
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private final int _xbat_count;
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private final byte[] _data;
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@ -132,6 +149,7 @@ public final class HeaderBlockReader {
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_bat_count = getInt(_bat_count_offset, _data);
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_property_start = getInt(_property_start_offset, _data);
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_sbat_start = getInt(_sbat_start_offset, _data);
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_sbat_count = getInt(_sbat_block_count_offset, _data);
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_xbat_start = getInt(_xbat_start_offset, _data);
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_xbat_count = getInt(_xbat_count_offset, _data);
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}
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@ -169,11 +187,14 @@ public final class HeaderBlockReader {
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}
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/**
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* @return start of small block allocation table
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* @return start of small block (MiniFAT) allocation table
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*/
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public int getSBATStart() {
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return _sbat_start;
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}
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public int getSBATCount() {
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return _sbat_count;
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}
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/**
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* @return number of BAT blocks
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@ -183,7 +204,10 @@ public final class HeaderBlockReader {
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}
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/**
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* @return BAT array
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* Returns the offsets to the first (up to) 109
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* BAT sectors.
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* Any additional BAT sectors
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* @return BAT offset array
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*/
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public int[] getBATArray() {
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int[] result = new int[ _max_bats_in_header ];
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@ -197,14 +221,14 @@ public final class HeaderBlockReader {
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}
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/**
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* @return XBAT count
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* @return XBAT (DIFAT) count
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*/
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public int getXBATCount() {
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return _xbat_count;
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}
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/**
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* @return XBAT index
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* @return XBAT (DIFAT) index
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*/
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public int getXBATIndex() {
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return _xbat_start;
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@ -112,6 +112,10 @@ public class RawDataBlock
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return _hasData;
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}
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public String toString() {
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return "RawDataBlock of size " + _data.length;
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}
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/* ********** START implementation of ListManagedBlock ********** */
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/**
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@ -149,6 +149,26 @@ public final class TestPOIFSFileSystem extends TestCase {
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}
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}
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/**
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* Check that we do the right thing when the list of which
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* sectors are BAT blocks points off the list of
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* sectors that exist in the file.
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*/
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public void testFATandDIFATsectors() throws Exception {
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POIDataSamples _samples = POIDataSamples.getPOIFSInstance();
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// Open the file up
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try {
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POIFSFileSystem fs = new POIFSFileSystem(
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_samples.openResourceAsStream("ReferencesInvalidSectors.mpp")
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);
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fail("File is corrupt and shouldn't have been opened");
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} catch(IOException e) {
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String msg = e.getMessage();
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assertTrue(msg.startsWith("Your file contains 695 sectors"));
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}
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}
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private static InputStream openSampleStream(String sampleFileName) {
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return HSSFTestDataSamples.openSampleFileStream(sampleFileName);
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}
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@ -181,4 +181,8 @@ public final class LocalRawDataBlockList extends RawDataBlockList {
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_array = _list.toArray(new RawDataBlock[ 0 ]);
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}
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}
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public int blockCount() {
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return _list.size();
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}
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}
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