1HEADmaster

1 files changed, 1127 insertions, 0 deletions

diff --git a/filesystem/packfile.cpp b/filesystem/packfile.cpp
new file mode 100644
index 0000000..5190959
--- /dev/null
+++ b/filesystem/packfile.cpp
@@ -0,0 +1,1127 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose:
+//
+// $NoKeywords: $
+//===========================================================================//
+
+#include "packfile.h"
+#include "zip_utils.h"
+#include "tier0/basetypes.h"
+#include "tier1/convar.h"
+#include "tier1/lzmaDecoder.h"
+#include "tier1/utlbuffer.h"
+#include "tier1/generichash.h"
+
+ConVar fs_monitor_read_from_pack( "fs_monitor_read_from_pack", "0", 0, "0:Off, 1:Any, 2:Sync only" );
+
+// How many bytes we should decode at a time when doing pseudo-reads to seek forward in a compressed file handle,
+// (affects maximum stack allocation by a forward seek)
+#define COMPRESSED_SEEK_READ_CHUNK 1024
+
+CPackFile::CPackFile()
+{
+	m_FileLength = 0;
+	m_hPackFileHandleFS = NULL;
+	m_fs = NULL;
+	m_nBaseOffset = 0;
+	m_bIsMapPath = false;
+	m_lPackFileTime = 0L;
+	m_refCount = 0;
+	m_nOpenFiles = 0;
+	m_PackFileID = 0;
+}
+
+CPackFile::~CPackFile()
+{
+	if ( m_nOpenFiles )
+	{
+		Error( "Closing pack file with %d open files!\n", m_nOpenFiles );
+	}
+
+	if ( m_hPackFileHandleFS )
+	{
+		m_fs->FS_fclose( m_hPackFileHandleFS );
+		m_hPackFileHandleFS = NULL;
+	}
+
+	m_fs->m_ZipFiles.FindAndRemove( this );
+}
+
+int CPackFile::GetSectorSize()
+{
+	if ( m_hPackFileHandleFS )
+	{
+		return m_fs->FS_GetSectorSize( m_hPackFileHandleFS );
+	}
+#if defined( SUPPORT_PACKED_STORE )
+	else if ( m_hPackFileHandleVPK )
+	{
+		return 2048;
+	}
+#endif
+	else
+	{
+		return -1;
+	}
+}
+
+// Read a bit of the file from the pack file:
+int CZipPackFileHandle::Read( void* pBuffer, int nDestSize, int nBytes )
+{
+	// Clamp nBytes to not go past the end of the file (async is still possible due to nDestSize)
+	if ( nBytes + m_nFilePointer > m_nLength )
+	{
+		nBytes = m_nLength - m_nFilePointer;
+	}
+
+	// Seek to the given file pointer and read
+	int nBytesRead = m_pOwner->ReadFromPack( m_nIndex, pBuffer, nDestSize, nBytes, m_nBase + m_nFilePointer );
+
+	m_nFilePointer += nBytesRead;
+
+	return nBytesRead;
+}
+
+// Seek around inside the pack:
+int CZipPackFileHandle::Seek( int nOffset, int nWhence )
+{
+	if ( nWhence == SEEK_SET )
+	{
+		m_nFilePointer = nOffset;
+	}
+	else if ( nWhence == SEEK_CUR )
+	{
+		m_nFilePointer += nOffset;
+	}
+	else if ( nWhence == SEEK_END )
+	{
+		m_nFilePointer = m_nLength + nOffset;
+	}
+
+	// Clamp the file pointer to the actual bounds of the file:
+	if ( m_nFilePointer > m_nLength )
+	{
+		m_nFilePointer = m_nLength;
+	}
+
+	return m_nFilePointer;
+}
+
+//-----------------------------------------------------------------------------
+// Open a file inside of a pack file.
+//-----------------------------------------------------------------------------
+CFileHandle *CZipPackFile::OpenFile( const char *pFileName, const char *pOptions )
+{
+	int nIndex, nOriginalSize, nCompressedSize;
+	int64 nPosition;
+	unsigned short nCompressionMethod;
+
+	// find the file's location in the pack
+	if ( GetFileInfo( pFileName, nIndex, nPosition, nOriginalSize, nCompressedSize, nCompressionMethod ) )
+	{
+		m_mutex.Lock();
+#if defined( SUPPORT_PACKED_STORE )
+		if ( m_nOpenFiles == 0 && m_hPackFileHandleFS == NULL && !m_hPackFileHandleVPK )
+#else
+		if ( m_nOpenFiles == 0 && m_hPackFileHandleFS == NULL )
+#endif
+		{
+			// Try to open it as a regular file first
+			m_hPackFileHandleFS = m_fs->Trace_FOpen( m_ZipName, "rb", 0, NULL );
+
+			// !NOTE! Pack files inside of VPK not supported
+		}
+		m_nOpenFiles++;
+		m_mutex.Unlock();
+		CPackFileHandle* ph = NULL;
+		if ( nCompressionMethod == ZIP_COMPRESSION_LZMA )
+		{
+			ph = new CLZMAZipPackFileHandle( this, nPosition, nOriginalSize, nCompressedSize, nIndex );
+		}
+		else
+		{
+			AssertMsg( nCompressionMethod == ZIP_COMPRESSION_NONE, "Unsupported compression type in zip pack file" );
+			ph = new CZipPackFileHandle( this, nPosition, nOriginalSize, nIndex );
+		}
+		CFileHandle *fh = new CFileHandle( m_fs );
+		fh->m_pPackFileHandle = ph;
+		fh->m_nLength = nOriginalSize;
+
+		// The default mode for fopen is text, so require 'b' for binary
+		if ( strstr( pOptions, "b" ) == NULL )
+		{
+			fh->m_type = FT_PACK_TEXT;
+		}
+		else
+		{
+			fh->m_type = FT_PACK_BINARY;
+		}
+
+#if !defined( _RETAIL )
+		fh->SetName( pFileName );
+#endif
+		return fh;
+	}
+
+	return NULL;
+}
+
+//-----------------------------------------------------------------------------
+//	Get a directory entry from a pack's preload section
+//-----------------------------------------------------------------------------
+ZIP_PreloadDirectoryEntry* CZipPackFile::GetPreloadEntry( int nEntryIndex )
+{
+	if ( !m_pPreloadHeader )
+	{
+		return NULL;
+	}
+
+	// If this entry doesn't have a corresponding preload entry, fail.
+	if ( m_PackFiles[nEntryIndex].m_nPreloadIdx == INVALID_PRELOAD_ENTRY )
+	{
+		return NULL;
+	}
+
+	return &m_pPreloadDirectory[m_PackFiles[nEntryIndex].m_nPreloadIdx];
+}
+
+//-----------------------------------------------------------------------------
+//	Read a file from the pack
+//-----------------------------------------------------------------------------
+int CZipPackFile::ReadFromPack( int nEntryIndex, void* pBuffer, int nDestBytes, int nBytes, int64 nOffset )
+{
+	if ( nEntryIndex >= 0 )
+	{
+		if ( nBytes <= 0 )
+		{
+			return 0;
+		}
+
+		// X360TBD: This is screwy, it works because m_nBaseOffset is 0 for preload capable zips
+		// It comes into play for files out of the embedded bsp zip,
+		// this hackery is a pre-bias expecting ReadFromPack() do a symmetric post bias, yuck.
+
+		// Attempt to satisfy request from possible preload section, otherwise fall through
+		// A preload entry may be compressed
+		ZIP_PreloadDirectoryEntry *pPreloadEntry = GetPreloadEntry( nEntryIndex );
+		if ( pPreloadEntry )
+		{
+			// convert the absolute pack file position to a local file position
+			int nLocalOffset = nOffset - m_PackFiles[nEntryIndex].m_nPosition;
+			byte *pPreloadData = (byte*)m_pPreloadData + pPreloadEntry->DataOffset;
+
+			if ( CLZMA::IsCompressed( pPreloadData ) )
+			{
+				unsigned int actualSize = CLZMA::GetActualSize( pPreloadData );
+				if ( nLocalOffset + nBytes <= (int)actualSize )
+				{
+					// satisfy from compressed preload
+					if ( fs_monitor_read_from_pack.GetInt() == 1 )
+					{
+						char szName[MAX_PATH];
+						IndexToFilename( nEntryIndex, szName, sizeof( szName ) );
+						Msg( "Read From Pack: [Preload] Requested:%d, Compressed:%d, %s\n", nBytes, pPreloadEntry->Length, szName );
+					}
+
+					if ( nLocalOffset == 0 && nDestBytes >= (int)actualSize && nBytes == (int)actualSize )
+					{
+						// uncompress directly into caller's buffer
+						CLZMA::Uncompress( (unsigned char *)pPreloadData, (unsigned char *)pBuffer );
+						return nBytes;
+					}
+
+					// uncompress into temporary memory
+					CUtlMemory< byte > tempMemory;
+					tempMemory.EnsureCapacity( actualSize );
+					CLZMA::Uncompress( pPreloadData, tempMemory.Base() );
+					// copy only what caller expects
+					V_memcpy( pBuffer, (byte*)tempMemory.Base() + nLocalOffset, nBytes );
+					return nBytes;
+				}
+			}
+			else if ( nLocalOffset + nBytes <= (int)pPreloadEntry->Length )
+			{
+				// satisfy from uncompressed preload
+				if ( fs_monitor_read_from_pack.GetInt() == 1 )
+				{
+					char szName[MAX_PATH];
+					IndexToFilename( nEntryIndex, szName, sizeof( szName ) );
+					Msg( "Read From Pack: [Preload] Requested:%d, Total:%d, %s\n", nBytes, pPreloadEntry->Length, szName );
+				}
+
+				V_memcpy( pBuffer, pPreloadData + nLocalOffset, nBytes );
+				return nBytes;
+			}
+		}
+	}
+
+#if defined ( _X360 )
+	// fell through as a direct request from within the pack
+	// intercept to possible embedded section
+	if ( m_pSection )
+	{
+		// a section is a special update zip that has no files, only preload
+		// it has to be in the section
+		V_memcpy( pBuffer, (byte*)m_pSection + nOffset, nBytes );
+		return nBytes;
+	}
+#endif
+
+	// Otherwise, do the read from the pack
+	m_mutex.Lock();
+
+	if ( fs_monitor_read_from_pack.GetInt() == 1 || ( fs_monitor_read_from_pack.GetInt() == 2 && ThreadInMainThread() ) )
+	{
+		// spew info about real i/o request
+		char szName[MAX_PATH];
+		IndexToFilename( nEntryIndex, szName, sizeof( szName ) );
+		Msg( "Read From Pack: Sync I/O: Requested:%7d, Offset:0x%16.16llx, %s\n", nBytes, m_nBaseOffset + nOffset, szName );
+	}
+
+	int nBytesRead = 0;
+	// Seek to the start of the read area and perform the read: TODO: CHANGE THIS INTO A CFileHandle
+	if ( m_hPackFileHandleFS )
+	{
+		m_fs->FS_fseek( m_hPackFileHandleFS, m_nBaseOffset + nOffset, SEEK_SET );
+		nBytesRead = m_fs->FS_fread( pBuffer, nDestBytes, nBytes, m_hPackFileHandleFS );
+	}
+#if defined( SUPPORT_PACKED_STORE )
+	else
+	{
+		// We're a packfile embedded in a VPK
+		m_hPackFileHandleVPK.Seek( m_nBaseOffset + nOffset, FILESYSTEM_SEEK_HEAD );
+		nBytesRead = m_hPackFileHandleVPK.Read( pBuffer, nBytes );
+	}
+#endif
+	m_mutex.Unlock();
+
+	return nBytesRead;
+}
+
+//-----------------------------------------------------------------------------
+//	Gets size, position, and index for a file in the pack.
+//-----------------------------------------------------------------------------
+bool CZipPackFile::GetFileInfo( const char *pFileName, int &nBaseIndex, int64 &nFileOffset, int &nOriginalSize, int &nCompressedSize, unsigned short &nCompressionMethod )
+{
+	char szCleanName[MAX_FILEPATH];
+	Q_strncpy( szCleanName, pFileName, sizeof( szCleanName ) );
+#ifdef _WIN32
+	Q_strlower( szCleanName );
+#endif
+	Q_FixSlashes( szCleanName );
+
+	if ( !Q_RemoveDotSlashes( szCleanName, CORRECT_PATH_SEPARATOR, false ) )
+	{
+		return false;
+	}
+
+	CZipPackFile::CPackFileEntry lookup;
+
+	// We may get passed non-canonicalized filenames, so we need to remove the ../ from the path
+	char szFixedName[MAX_PATH] = {0};
+	V_strcpy_safe( szFixedName, pFileName );
+	V_RemoveDotSlashes( szFixedName );
+
+	lookup.m_HashName = HashStringCaselessConventional( szFixedName );
+
+	int idx = m_PackFiles.Find( lookup );
+	if ( -1 != idx  )
+	{
+		nFileOffset = m_PackFiles[idx].m_nPosition;
+		nOriginalSize = m_PackFiles[idx].m_nOriginalSize;
+		nCompressedSize = m_PackFiles[idx].m_nCompressedSize;
+		nBaseIndex = idx;
+		nCompressionMethod = m_PackFiles[idx].m_nCompressionMethod;
+		return true;
+	}
+
+	return false;
+}
+
+bool CZipPackFile::IndexToFilename( int nIndex, char *pBuffer, int nBufferSize )
+{
+	AssertMsg( nIndex >= 0 && nIndex < m_PackFiles.Count(), "Out of bounds vector access in IndexToFilename" );
+	if ( nIndex >= 0 )
+	{
+		m_fs->String( m_PackFiles[nIndex].m_hFileName, pBuffer, nBufferSize );
+		return true;
+	}
+
+	Q_strncpy( pBuffer, "unknown", nBufferSize );
+
+	return false;
+}
+
+//-----------------------------------------------------------------------------
+//	Find a file in the pack.
+//-----------------------------------------------------------------------------
+bool CZipPackFile::ContainsFile( const char *pFileName )
+{
+	int nIndex, nOriginalSize, nCompressedSize;
+	int64 nOffset;
+	unsigned short nCompressionMethod;
+	bool bFound = GetFileInfo( pFileName, nIndex, nOffset, nOriginalSize, nCompressedSize, nCompressionMethod );
+	return bFound;
+}
+
+//-----------------------------------------------------------------------------
+//	Build a list of matching files and directories given a FindFirst() style wildcard
+//-----------------------------------------------------------------------------
+void CZipPackFile::GetFileAndDirLists( const char *pRawWildCard, CUtlStringList &outDirnames, CUtlStringList &outFilenames, bool bSortedOutput )
+{
+	// See also: VPKlib function with same name.
+
+	CUtlDict<int,int> AddedDirectories; // Used to remove duplicate paths
+
+	char szWildCard[MAX_PATH] = { 0 };
+	char szWildCardPath[MAX_PATH] = { 0 };
+	char szWildCardBase[MAX_PATH] = { 0 };
+	char szWildCardExt[MAX_PATH] = { 0 };
+
+	size_t nLenWildcardPath = 0;
+	size_t nLenWildcardBase = 0;
+
+	bool bBaseWildcard = true;
+	bool bExtWildcard = true;
+
+	//
+	// Parse the wildcard string into a base and extension used for string comparisons
+	//
+	V_strncpy( szWildCard, pRawWildCard, sizeof( szWildCard ) );
+	V_FixSlashes( szWildCard, '/' );
+	V_RemoveDotSlashes( szWildCard, '/', /* bRemoveDoubleSlashes */ true );
+
+	// Workaround edge case in crappy path code. ExtractFilePath extracts a/b/ from a/b/c/ but FileBase would return the empty string.
+	size_t nLenWildCard = V_strlen( szWildCard );
+	if ( nLenWildCard && szWildCard[ nLenWildCard - 1 ] == '/' )
+	{
+		V_strncpy( szWildCardPath, szWildCard, sizeof( szWildCardPath ) );
+	}
+	else
+	{
+		V_ExtractFilePath( szWildCard, szWildCardPath, sizeof( szWildCardPath ) );
+	}
+
+	V_FileBase( szWildCard, szWildCardBase, sizeof( szWildCardBase ) );
+	bool bWildcardHasExt = !!V_strrchr( szWildCard, '.' );
+	V_ExtractFileExtension( szWildCard, szWildCardExt, sizeof( szWildCardExt ) );
+
+	// From the pattern, we now have the directory path up to the file pattern, the filename base, and the filename
+	// extension.
+
+	// We don't support partial wildcards here (foo*bar.*). This support is massively inconsistent in our codebase and
+	// there's no one point where we implement it, so rather than trying to match one of our broken implementations
+	// (windows stdio is the only one I could find that was actually right), I'm going with "you shouldn't use this API
+	// for that".
+	bBaseWildcard = ( V_strcmp( szWildCardBase, "*" ) == 0 );
+	bExtWildcard = ( V_strcmp( szWildCardExt, "*" ) == 0 );
+
+	if ( !bWildcardHasExt && bBaseWildcard )
+	{
+		// For the special case of just '*' (and not, e.g., '*.') match '*.*'
+		bExtWildcard = true;
+	}
+
+	nLenWildcardPath = V_strlen( szWildCardPath );
+	nLenWildcardBase = V_strlen( szWildCardBase );
+
+	// Generate the list of directories and files that match the wildcard
+	//
+
+	// For each candidate we attempt to walk up its path and consider the directories it represents as well (the
+	// directories in a zip only exist in that files contain them, there are no empty directories)
+	FOR_EACH_VEC( m_PackFiles, filesIdx )
+	{
+		char szCandidateName[MAX_PATH] = { 0 };
+		IndexToFilename( filesIdx, szCandidateName, sizeof( szCandidateName ));
+
+		if ( !szCandidateName[0] )
+		{
+			continue;
+		}
+
+		// Check if this file starts with the wildcard selector's path.
+		// Note that we only ensure the prefix is the same. There are no specific entries for directories in a zip, they
+		// only exist in that files in the zip reference them, so handle subdirectory matches from filenames as well.
+		CUtlDict<int,int> ConsideredDirectories; // Will have duplicate directory matches when multiple files reside in them
+		if  ( ( nLenWildcardPath && ( 0 == V_strnicmp( szCandidateName, szWildCardPath, nLenWildcardPath ) ) )
+		      || ( !nLenWildcardPath && strchr( szCandidateName, '/' ) ) )
+		{
+			// Check if we matched because of a sub-directory, e.g. a/b/*.* would match /a/b/c/d/foo (in which case we
+			// want to add /a/b/c to the matched directories list, ignoring the actual specific file)
+			char szCandidateBaseName[MAX_PATH] = { 0 };
+			bool bIsDir = false;
+			size_t nSubDirLen = 0;
+			char *pSubDirSlash = strchr( szCandidateName + nLenWildcardPath, '/' );
+			if ( pSubDirSlash )
+			{
+				// This is a subdirectory match, drop everything after it and continue with it as the filename
+				nSubDirLen = (size_t)( (ptrdiff_t)pSubDirSlash - (ptrdiff_t)( szCandidateName + nLenWildcardPath ) );
+				V_strncpy( szCandidateBaseName, szCandidateName + nLenWildcardPath, nSubDirLen + 1 );
+				bIsDir = true;
+
+				// Early out if we already considered this exact directory from another file
+				if ( ConsideredDirectories.Find( szCandidateBaseName ) != ConsideredDirectories.InvalidIndex() )
+				{
+					continue;
+				}
+
+				ConsideredDirectories.Insert( szCandidateBaseName, 0 );
+			}
+			else
+			{
+				V_strncpy( szCandidateBaseName, szCandidateName + nLenWildcardPath, sizeof( szCandidateBaseName ) );
+			}
+
+			char *pExt = strchr( szCandidateBaseName, '.' );
+			if ( pExt )
+			{
+				// Null out the . and move to point to the extension
+				*pExt = '\0';
+				pExt++;
+			}
+
+			// Determine if this file matches the wildcart (*.*, *.ext, ext.*)
+			bool bBaseMatch = false;
+			bool bExtMatch = false;
+
+			// If we have a base dir name, and we have a szWildCardBase to match against
+			if ( bBaseWildcard )
+				bBaseMatch = true;  // The base is the wildCard ("*"), so whatever we have as the base matches
+			else
+				bBaseMatch = ( 0 == V_stricmp( szCandidateBaseName, szWildCardBase ) );
+
+			// If we have an extension and we have a szWildCardExtension to mach against
+			if ( ( bExtWildcard && pExt ) || ( !pExt && !bWildcardHasExt ) )
+				bExtMatch = true;
+			else
+				bExtMatch = bWildcardHasExt && pExt && ( 0 == V_stricmp( pExt, szWildCardExt ) );
+
+			// If both parts match, then add it to the list
+			if ( bBaseMatch && bExtMatch )
+			{
+				if ( bIsDir )
+				{
+					// Pull up to the subdir we considered out of szCandidateName
+					size_t nMatchSize = nLenWildcardPath + nSubDirLen + 1;
+					char *pszFullMatch = new char[ nMatchSize ];
+					V_strncpy( pszFullMatch, szCandidateName, nMatchSize );
+					outDirnames.AddToTail( pszFullMatch );
+				}
+				else
+				{
+					size_t nMatchSize = V_strlen( szCandidateName ) + 1;
+					char *pszFullMatch = new char[ nMatchSize ];
+					V_strncpy( pszFullMatch, szCandidateName, nMatchSize );
+					outFilenames.AddToTail( pszFullMatch );
+				}
+			}
+		}
+	}
+
+	// Sort the output if requested
+	if ( bSortedOutput )
+	{
+		outDirnames.Sort( &CUtlStringList::SortFunc );
+		outFilenames.Sort( &CUtlStringList::SortFunc );
+	}
+}
+
+
+//-----------------------------------------------------------------------------
+//	Set up the preload section
+//-----------------------------------------------------------------------------
+void CZipPackFile::SetupPreloadData()
+{
+	if ( m_pPreloadHeader || !m_nPreloadSectionSize )
+	{
+		// already loaded or not available
+		return;
+	}
+
+	MEM_ALLOC_CREDIT_( "xZip" );
+
+	void *pPreload;
+#if defined ( _X360 )
+	if ( m_pSection )
+	{
+		pPreload = (byte*)m_pSection + m_nPreloadSectionOffset;
+	}
+	else
+#endif
+	{
+		pPreload = malloc( m_nPreloadSectionSize );
+		if ( !pPreload )
+		{
+			return;
+		}
+
+		if ( IsX360() )
+		{
+			// 360 XZips are always dvd aligned
+			Assert( ( m_nPreloadSectionSize % XBOX_DVD_SECTORSIZE ) == 0 );
+			Assert( ( m_nPreloadSectionOffset % XBOX_DVD_SECTORSIZE ) == 0 );
+		}
+
+		// preload data is loaded as a single unbuffered i/o operation
+		ReadFromPack( -1, pPreload, -1, m_nPreloadSectionSize, m_nPreloadSectionOffset );
+	}
+
+	// setup the header
+	m_pPreloadHeader = (ZIP_PreloadHeader *)pPreload;
+
+	// setup the preload directory
+	m_pPreloadDirectory = (ZIP_PreloadDirectoryEntry *)((byte *)m_pPreloadHeader + sizeof( ZIP_PreloadHeader ) );
+
+	// setup the remap table
+	m_pPreloadRemapTable = (unsigned short *)((byte *)m_pPreloadDirectory + m_pPreloadHeader->PreloadDirectoryEntries * sizeof( ZIP_PreloadDirectoryEntry ) );
+
+	// set the preload data base
+	m_pPreloadData = (byte *)m_pPreloadRemapTable + m_pPreloadHeader->DirectoryEntries * sizeof( unsigned short );
+}
+
+void CZipPackFile::DiscardPreloadData()
+{
+	if ( !m_pPreloadHeader )
+	{
+		// already discarded
+		return;
+	}
+
+#if defined ( _X360 )
+	// a section is an alias, the header becomes an alias, not owned memory
+	if ( !m_pSection )
+	{
+		free( m_pPreloadHeader );
+	}
+#else
+	free( m_pPreloadHeader );
+#endif
+	m_pPreloadHeader = NULL;
+}
+
+//-----------------------------------------------------------------------------
+//	Parse the zip file to build the file directory and preload section
+//-----------------------------------------------------------------------------
+bool CZipPackFile::Prepare( int64 fileLen, int64 nFileOfs )
+{
+	if ( !fileLen || fileLen < sizeof( ZIP_EndOfCentralDirRecord ) )
+	{
+		// nonsense zip
+		return false;
+	}
+
+	// Pack files are always little-endian
+	m_swap.ActivateByteSwapping( IsX360() );
+
+	m_FileLength = fileLen;
+	m_nBaseOffset = nFileOfs;
+
+	ZIP_EndOfCentralDirRecord rec = { 0 };
+
+	// Find and read the central header directory from its expected position at end of the file
+	bool bCentralDirRecord = false;
+	int64 offset = fileLen - sizeof( ZIP_EndOfCentralDirRecord );
+
+	// 360 can have an incompatible format
+	bool bCompatibleFormat = true;
+	if ( IsX360() )
+	{
+		// 360 has dependable exact zips, backup to handle possible xzip format
+		if ( offset - XZIP_COMMENT_LENGTH >= 0 )
+		{
+			offset -= XZIP_COMMENT_LENGTH;
+		}
+
+		// single i/o operation, scanning forward
+		char *pTemp = (char *)_alloca( fileLen - offset );
+		ReadFromPack( -1, pTemp, -1, fileLen - offset, offset );
+		while ( offset <= (int64)(fileLen - sizeof( ZIP_EndOfCentralDirRecord )) )
+		{
+			memcpy( &rec, pTemp, sizeof( ZIP_EndOfCentralDirRecord ) );
+			m_swap.SwapFieldsToTargetEndian( &rec );
+			if ( rec.signature == PKID( 5, 6 ) )
+			{
+				bCentralDirRecord = true;
+				if ( rec.commentLength >= 4 )
+				{
+					char *pComment = pTemp + sizeof( ZIP_EndOfCentralDirRecord );
+					if ( !V_strnicmp( pComment, "XZP2", 4 ) )
+					{
+						bCompatibleFormat = false;
+					}
+				}
+				break;
+			}
+			offset++;
+			pTemp++;
+		}
+	}
+	else
+	{
+		// scan entire file from expected location for central dir
+		for ( ; offset >= 0; offset-- )
+		{
+			ReadFromPack( -1, (void*)&rec, -1, sizeof( rec ), offset );
+			m_swap.SwapFieldsToTargetEndian( &rec );
+			if ( rec.signature == PKID( 5, 6 ) )
+			{
+				bCentralDirRecord = true;
+				break;
+			}
+		}
+	}
+	Assert( bCentralDirRecord );
+	if ( !bCentralDirRecord )
+	{
+		// no zip directory, bad zip
+		return false;
+	}
+
+	int numFilesInZip = rec.nCentralDirectoryEntries_Total;
+	if ( numFilesInZip <= 0 )
+	{
+		// empty valid zip
+		return true;
+	}
+
+	int firstFileIdx = 0;
+
+	MEM_ALLOC_CREDIT();
+
+	// read central directory into memory and parse
+	CUtlBuffer zipDirBuff( 0, rec.centralDirectorySize, 0 );
+	zipDirBuff.EnsureCapacity( rec.centralDirectorySize );
+	zipDirBuff.ActivateByteSwapping( IsX360() );
+	ReadFromPack( -1, zipDirBuff.Base(), -1, rec.centralDirectorySize, rec.startOfCentralDirOffset );
+	zipDirBuff.SeekPut( CUtlBuffer::SEEK_HEAD, rec.centralDirectorySize );
+
+	ZIP_FileHeader zipFileHeader;
+	char filename[MAX_PATH] = { 0 };
+
+	// Check for a preload section, expected to be the first file in the zip
+	zipDirBuff.GetObjects( &zipFileHeader );
+	zipDirBuff.Get( filename, Min( (size_t)zipFileHeader.fileNameLength, sizeof(filename) - 1 ) );
+	if ( !V_stricmp( filename, PRELOAD_SECTION_NAME ) )
+	{
+		m_nPreloadSectionSize = zipFileHeader.uncompressedSize;
+		m_nPreloadSectionOffset = zipFileHeader.relativeOffsetOfLocalHeader +
+						  sizeof( ZIP_LocalFileHeader ) +
+						  zipFileHeader.fileNameLength +
+						  zipFileHeader.extraFieldLength;
+		SetupPreloadData();
+
+		// Set up to extract the remaining files
+		int nextOffset = bCompatibleFormat ? zipFileHeader.extraFieldLength + zipFileHeader.fileCommentLength : 0;
+		zipDirBuff.SeekGet( CUtlBuffer::SEEK_CURRENT, nextOffset );
+		firstFileIdx = 1;
+	}
+	else
+	{
+		if ( IsX360() )
+		{
+			// all 360 zip files are expected to have preload sections
+			// only during development, maps are allowed to lack them, due to auto-conversion
+			if ( !m_bIsMapPath || g_pFullFileSystem->GetDVDMode() == DVDMODE_STRICT )
+			{
+				Warning( "ZipFile '%s' missing preload section\n", m_ZipName.String() );
+			}
+		}
+
+		// No preload section, reset buffer pointer
+		zipDirBuff.SeekGet( CUtlBuffer::SEEK_HEAD, 0 );
+	}
+
+	// Parse out central directory and determine absolute file positions of data.
+	// Supports uncompressed zip files, with or without preload sections
+	bool bSuccess = true;
+	char tmpString[MAX_PATH] = { 0 };
+
+	m_PackFiles.EnsureCapacity( numFilesInZip );
+
+	for ( int i = firstFileIdx; i < numFilesInZip; ++i )
+	{
+		CZipPackFile::CPackFileEntry lookup;
+		zipDirBuff.GetObjects( &zipFileHeader );
+
+		if ( zipFileHeader.signature != PKID( 1, 2 ) )
+		{
+			Warning( "Invalid pack file signature\n" );
+			bSuccess = false;
+			break;
+		}
+
+		if ( zipFileHeader.compressionMethod != ZIP_COMPRESSION_NONE && zipFileHeader.compressionMethod != ZIP_COMPRESSION_LZMA )
+		{
+			Warning( "Pack file uses unsupported compression method: %hi\n", zipFileHeader.compressionMethod );
+			bSuccess = false;
+			break;
+		}
+
+		Assert( zipFileHeader.fileNameLength < sizeof( tmpString ) );
+		unsigned int fileNameLen = Min( (size_t)zipFileHeader.fileNameLength, sizeof( tmpString ) - 1 );
+		zipDirBuff.Get( (void *)tmpString, fileNameLen );
+		tmpString[fileNameLen] = '\0';
+		Q_FixSlashes( tmpString );
+
+		lookup.m_hFileName = m_fs->FindOrAddFileName( tmpString );
+		lookup.m_HashName = HashStringCaselessConventional( tmpString );
+		lookup.m_nOriginalSize = zipFileHeader.uncompressedSize;
+		lookup.m_nCompressedSize = zipFileHeader.compressedSize;
+		lookup.m_nPosition = zipFileHeader.relativeOffsetOfLocalHeader +
+								sizeof( ZIP_LocalFileHeader ) +
+								zipFileHeader.fileNameLength +
+								zipFileHeader.extraFieldLength;
+		lookup.m_nCompressionMethod = zipFileHeader.compressionMethod;
+
+		// track the index to this file's possible preload directory entry
+		if ( m_pPreloadRemapTable )
+		{
+			lookup.m_nPreloadIdx = m_pPreloadRemapTable[i];
+		}
+		else
+		{
+			lookup.m_nPreloadIdx = INVALID_PRELOAD_ENTRY;
+		}
+		m_PackFiles.InsertNoSort( lookup );
+
+		int nextOffset = bCompatibleFormat ? zipFileHeader.extraFieldLength + zipFileHeader.fileCommentLength : 0;
+		zipDirBuff.SeekGet( CUtlBuffer::SEEK_CURRENT, nextOffset );
+	}
+
+	m_PackFiles.RedoSort();
+
+	return bSuccess;
+}
+
+
+//-----------------------------------------------------------------------------
+//
+//-----------------------------------------------------------------------------
+CZipPackFile::CZipPackFile( CBaseFileSystem* fs, void *pSection )
+ : m_PackFiles()
+{
+	m_fs = fs;
+	m_pPreloadDirectory = NULL;
+	m_pPreloadData = NULL;
+	m_pPreloadHeader = NULL;
+	m_pPreloadRemapTable = NULL;
+	m_nPreloadSectionOffset = 0;
+	m_nPreloadSectionSize = 0;
+
+#if defined( _X360 )
+	m_pSection = pSection;
+#endif
+}
+
+CZipPackFile::~CZipPackFile()
+{
+	DiscardPreloadData();
+}
+
+//-----------------------------------------------------------------------------
+// Purpose:
+// Input  : src1 -
+//			src2 -
+// Output : Returns true on success, false on failure.
+//-----------------------------------------------------------------------------
+bool CZipPackFile::CPackFileLessFunc::Less( CZipPackFile::CPackFileEntry const& src1, CZipPackFile::CPackFileEntry const& src2, void *pCtx )
+{
+	return ( src1.m_HashName < src2.m_HashName );
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Zip Pack file handle implementation
+//-----------------------------------------------------------------------------
+CZipPackFileHandle::CZipPackFileHandle( CZipPackFile* pOwner, int64 nBase, unsigned int nLength, unsigned int nIndex, unsigned int nFilePointer )
+{
+	m_pOwner = pOwner;
+	m_nBase = nBase;
+	m_nLength = nLength;
+	m_nIndex = nIndex;
+	m_nFilePointer = nFilePointer;
+	pOwner->AddRef();
+}
+
+CZipPackFileHandle::~CZipPackFileHandle()
+{
+	m_pOwner->m_mutex.Lock();
+	--m_pOwner->m_nOpenFiles;
+	// XXX(johns) this doesn't go here, the hell
+	if ( m_pOwner->m_nOpenFiles == 0 && m_pOwner->m_bIsMapPath )
+	{
+		if ( m_pOwner->m_hPackFileHandleFS )
+		{
+			m_pOwner->FileSystem()->Trace_FClose( m_pOwner->m_hPackFileHandleFS );
+			m_pOwner->m_hPackFileHandleFS = NULL;
+		}
+	}
+	m_pOwner->Release();
+	m_pOwner->m_mutex.Unlock();
+}
+
+void CZipPackFileHandle::SetBufferSize( int nBytes )
+{
+	if ( m_pOwner->m_hPackFileHandleFS )
+	{
+		m_pOwner->FileSystem()->FS_setbufsize( m_pOwner->m_hPackFileHandleFS, nBytes );
+	}
+}
+
+int CZipPackFileHandle::GetSectorSize()
+{
+	return m_pOwner->GetSectorSize();
+}
+
+int64 CZipPackFileHandle::AbsoluteBaseOffset()
+{
+	return m_pOwner->GetPackFileBaseOffset() + m_nBase;
+}
+
+#if defined( _DEBUG ) && !defined( OSX )
+#include <atomic>
+static std::atomic<int> sLZMAPackFileHandles( 0 );
+#endif // defined( _DEBUG ) && !defined( OSX )
+
+CLZMAZipPackFileHandle::CLZMAZipPackFileHandle( CZipPackFile* pOwner, int64 nBase, unsigned int nOriginalSize, unsigned int nCompressedSize,
+                                                unsigned int nIndex, unsigned int nFilePointer )
+	: CZipPackFileHandle( pOwner, nBase, nCompressedSize, nIndex, nFilePointer ),
+	  m_BackSeekBuffer( 0, PACKFILE_COMPRESSED_FILEHANDLE_SEEK_BUFFER ),
+	  m_ReadBuffer( 0, PACKFILE_COMPRESSED_FILEHANDLE_READ_BUFFER ),
+	  m_pLZMAStream( NULL ), m_nSeekPosition( 0 ), m_nOriginalSize( nOriginalSize )
+{
+	Reset();
+#if defined( _DEBUG ) && !defined( OSX )
+	if ( ++sLZMAPackFileHandles == PACKFILE_COMPRESSED_FILE_HANDLES_WARNING )
+	{
+		// By my count a live filehandle is currently around 270k, mostly due to the LZMA dictionary (256k) with the
+		// rest being the read/seek buffers.
+		Warning( "More than %u compressed file handles in use. "
+		         "These carry large buffers around, and can cause high memory usage\n",
+		         PACKFILE_COMPRESSED_FILE_HANDLES_WARNING );
+	}
+#endif // defined( _DEBUG ) && !defined( OSX )
+}
+
+CLZMAZipPackFileHandle::~CLZMAZipPackFileHandle()
+{
+	delete m_pLZMAStream;
+	m_pLZMAStream = NULL;
+#if defined( _DEBUG ) && !defined( OSX )
+	sLZMAPackFileHandles--;
+	Assert( sLZMAPackFileHandles >= 0 );
+#endif // defined( _DEBUG ) && !defined( OSX )
+}
+
+int CLZMAZipPackFileHandle::Read( void* pBuffer, int nDestSize, int nBytes )
+{
+	int nMaxRead = Min( Min( nDestSize, nBytes ), Size() - Tell() );
+	int nBytesRead = 0;
+
+	// If we have seeked backwards into our buffer, read from there first
+	int nBackSeek = m_BackSeekBuffer.TellPut() - m_BackSeekBuffer.TellGet();
+	Assert( nBackSeek >= 0 );
+	if ( nBackSeek > 0 )
+	{
+		int nBackSeekRead = Min( nBackSeek, nMaxRead );
+		m_BackSeekBuffer.Get( pBuffer, nBackSeekRead );
+		nBytesRead += nBackSeekRead;
+	}
+
+	// Done if nothing to read
+	if ( nMaxRead - nBytesRead <= 0 )
+	{
+		m_nSeekPosition += nBytesRead;
+		return nBytesRead;
+	}
+
+	// Read bytes not fulfilled by backbuffer
+	Assert( m_BackSeekBuffer.TellPut() == m_BackSeekBuffer.TellGet() );
+	while ( nBytesRead < nMaxRead )
+	{
+		// refill read buffer if empty
+		int nRemainingReadBuffer = FillReadBuffer();
+
+		// Consume from read buffer
+		unsigned int nCompressedBytesRead = 0;
+		unsigned int nOutputBytesWritten = 0;
+		bool bSuccess = m_pLZMAStream->Read( (unsigned char *)m_ReadBuffer.PeekGet(), nRemainingReadBuffer,
+		                                     (unsigned char *)pBuffer + nBytesRead, nMaxRead - nBytesRead,
+		                                     nCompressedBytesRead, nOutputBytesWritten );
+
+		if ( bSuccess )
+		{
+			// fixup get position
+			m_ReadBuffer.SeekGet( CUtlBuffer::SEEK_CURRENT, nCompressedBytesRead );
+
+			nBytesRead += nOutputBytesWritten;
+
+			AssertMsg( nCompressedBytesRead == (unsigned int)nRemainingReadBuffer || nBytesRead == nMaxRead,
+			           "Should have consumed the readbuffer or reached nMaxRead" );
+
+			if ( nCompressedBytesRead == 0 && nOutputBytesWritten == 0 )
+			{
+				AssertMsg( nCompressedBytesRead > 0 || nOutputBytesWritten > 0,
+				           "Stuck progress in read loop, aborting. Stream may be defunct." );
+				break;
+			}
+		}
+		else
+		{
+			Warning( "Pack file: reading from LZMA stream failed\n" );
+			break;
+		}
+	}
+
+	// Finally, store last bytes output to the backseek buffer
+
+	// If we read less than BackSeekBuffer.Size() bytes, shift the end of the old backseek buffer up
+	int nOldBackSeek = m_BackSeekBuffer.TellPut();
+	int nReuseBackSeek = Max( Min( m_BackSeekBuffer.Size() - nBytesRead, nOldBackSeek ), 0 );
+	if ( nReuseBackSeek )
+	{
+		// Shift the reused chunk to the front
+		V_memmove( m_BackSeekBuffer.Base(),
+		           (unsigned char *)m_BackSeekBuffer.Base() + m_BackSeekBuffer.TellPut() - nReuseBackSeek,
+		           nReuseBackSeek );
+	}
+
+	// Update get/put position
+	m_BackSeekBuffer.SeekPut( CUtlBuffer::SEEK_HEAD, nReuseBackSeek );
+	m_BackSeekBuffer.SeekGet( CUtlBuffer::SEEK_HEAD, nReuseBackSeek );
+
+	// Fill in remainder from what we just read
+	int nReadIntoBackSeek = Min( m_BackSeekBuffer.Size() - nReuseBackSeek, nBytesRead );
+	m_BackSeekBuffer.Put( (unsigned char *)pBuffer + nBytesRead - nReadIntoBackSeek, nReadIntoBackSeek );
+	m_BackSeekBuffer.SeekGet( CUtlBuffer::SEEK_CURRENT, nReadIntoBackSeek );
+
+	m_nSeekPosition += nBytesRead;
+	return nBytesRead;
+}
+
+int CLZMAZipPackFileHandle::Seek( int nOffset, int nWhence )
+{
+	int nNewPosition = m_nSeekPosition;
+
+	if ( nWhence == SEEK_CUR )
+	{
+		nNewPosition = m_nSeekPosition + nOffset;
+	}
+	else if ( nWhence == SEEK_END )
+	{
+		nNewPosition = Size() + nOffset;
+	}
+	else if ( nWhence == SEEK_SET )
+	{
+		nNewPosition = nOffset;
+	}
+	else
+	{
+		AssertMsg( false, "Unknown seek type" );
+	}
+
+	nNewPosition = Min( Size(), nNewPosition );
+	nNewPosition = Max( 0, nNewPosition );
+
+	if ( nNewPosition == m_nSeekPosition )
+	{
+		return nNewPosition;
+	}
+
+	// Backwards seek
+	if ( nNewPosition < m_nSeekPosition )
+	{
+		int nBackSeekAvailable = m_BackSeekBuffer.TellGet();
+		int nDesiredBackSeek = m_nSeekPosition - nNewPosition;
+
+		if ( nBackSeekAvailable >= nDesiredBackSeek )
+		{
+			// Move get backwards into backseek buffer to account for seek
+			m_BackSeekBuffer.SeekGet( CUtlBuffer::SEEK_CURRENT, -nDesiredBackSeek );
+			m_nSeekPosition = nNewPosition;
+		}
+		else
+		{
+			// Seeking backwards beyond our backseek buffer. Have to restart stream. This kills the performance.
+			Warning( "LZMA file handle: seeking backwards beyond backseek buffer size ( %u ), "
+			         "replaying read & decompression of %u bytes. Should avoid large back seeks in compressed files or "
+			         "increase backseek buffer sizing.",
+			         m_BackSeekBuffer.Size(), nNewPosition );
+
+			// Reset to beginning of underlying stream
+			Reset();
+
+			// Fall through to performing a forward seek
+		}
+	}
+
+	// Forward seek
+	if ( nNewPosition > m_nSeekPosition )
+	{
+		// Can't actually seek forward without making decode progress. Issue fake reads until we've reached our target.
+		unsigned char dummyBuffer[COMPRESSED_SEEK_READ_CHUNK];
+		while ( nNewPosition > m_nSeekPosition )
+		{
+			int nReadSize = Min( nNewPosition - m_nSeekPosition, COMPRESSED_SEEK_READ_CHUNK );
+			unsigned int nBytesRead = Read( &dummyBuffer, sizeof(dummyBuffer), nReadSize );
+			m_nSeekPosition += nBytesRead;
+			if ( !nBytesRead )
+			{
+				Warning( "LZMA file handle: failed reading forward to desired seek position\n" );
+				break;
+			}
+		}
+	}
+
+	return m_nSeekPosition;
+}
+
+int CLZMAZipPackFileHandle::Tell()
+{
+	return m_nSeekPosition;
+}
+
+int CLZMAZipPackFileHandle::Size()
+{
+	return m_nOriginalSize;
+}
+
+int CLZMAZipPackFileHandle::FillReadBuffer()
+{
+	int nRemainingReadBuffer = m_ReadBuffer.TellPut() - m_ReadBuffer.TellGet();
+	int nRemainingCompressedBytes = CZipPackFileHandle::Size() - CZipPackFileHandle::Tell();
+
+	if ( nRemainingReadBuffer > 0 || nRemainingCompressedBytes <= 0 )
+	{
+		// No action if read buffer isn't empty
+		return nRemainingReadBuffer;
+	}
+
+	// Reset empty read buffer
+	m_ReadBuffer.SeekPut( CUtlBuffer::SEEK_HEAD, 0 );
+	m_ReadBuffer.SeekGet( CUtlBuffer::SEEK_HEAD, 0 );
+	int nRefillSize = Min( nRemainingCompressedBytes, m_ReadBuffer.Size() );
+	int nRefillResult = CZipPackFileHandle::Read( m_ReadBuffer.PeekPut(), m_ReadBuffer.Size(), nRefillSize );
+	AssertMsg( nRefillSize == nRefillResult, "Don't expect to fail to read here" );
+
+	// Fixup put pointer after writing into buffer's memory
+	m_ReadBuffer.SeekPut( CUtlBuffer::SEEK_CURRENT, nRefillResult );
+
+	return nRefillResult;
+}
+
+void CLZMAZipPackFileHandle::Reset()
+{
+	// Seek underlying stream back to start
+	CZipPackFileHandle::Seek( SEEK_SET, 0 );
+
+	delete m_pLZMAStream;
+	m_pLZMAStream = new CLZMAStream();
+	m_pLZMAStream->InitZIPHeader( CZipPackFileHandle::Size(), m_nOriginalSize );
+	m_nSeekPosition = 0;
+	m_BackSeekBuffer.SeekGet( CUtlBuffer::SEEK_HEAD, 0 );
+	m_BackSeekBuffer.SeekPut( CUtlBuffer::SEEK_HEAD, 0 );
+	m_ReadBuffer.SeekGet( CUtlBuffer::SEEK_HEAD, 0 );
+	m_ReadBuffer.SeekPut( CUtlBuffer::SEEK_HEAD, 0 );
+}