0ad/source/lib/file/archive/archive_zip.cpp

/**
 * =========================================================================
 * File        : archive_zip.cpp
 * Project     : 0 A.D.
 * Description : archive backend for Zip files.
 * =========================================================================
 */

// license: GPL; see lib/license.txt

#include "precompiled.h"
#include "archive_zip.h"

#include <time.h>
#include <limits>

#include "lib/bits.h"
#include "lib/byte_order.h"
#include "lib/fat_time.h"
#include "lib/path_util.h"
#include "lib/allocators/pool.h"
#include "lib/sysdep/cpu.h"		// cpu_memcpy
#include "archive.h"
#include "codec_zlib.h"
#include "stream.h"
#include "lib/file/filesystem.h"
#include "lib/file/posix/fs_posix.h"
#include "lib/file/posix/io_posix.h"
#include "lib/file/io/io_manager.h"


//-----------------------------------------------------------------------------
// Zip file data structures and signatures
//-----------------------------------------------------------------------------

enum ZipMethod
{
	ZIP_METHOD_NONE    = 0,
	ZIP_METHOD_DEFLATE = 8
};

enum ZipFlags
{
	// indicates ZipEntry.ofs points to a "local file header" instead of
	// the file data. a fixup routine is called when reading the file;
	// it skips past the LFH and clears this flag.
	// this is somewhat of a hack, but vital to archive open performance.
	// without it, we'd have to scan through the entire archive file,
	// which can take *seconds*.
	// (we cannot use the information in CDFH, because its 'extra' field
	// has been observed to differ from that of the LFH)
	// since we read the LFH right before the rest of the file, the block
	// cache will absorb the IO cost.
	NEEDS_LFH_FIXUP = 1
};

// all relevant LFH/CDFH fields not covered by FileInfo
struct ZipEntry
{
	ZipEntry()
	{
	}

	ZipEntry(off_t ofs, off_t csize, u32 checksum, u16 method, u16 flags)
	{
		this->ofs = ofs;
		this->csize = csize;
		this->checksum = checksum;
		this->method = method;
		this->flags = flags;
	}

	off_t ofs;
	off_t csize;

	u32 checksum;
	u16 method;
	u16 flags;
};


static const u32 cdfh_magic = FOURCC_LE('P','K','\1','\2');
static const u32  lfh_magic = FOURCC_LE('P','K','\3','\4');
static const u32 ecdr_magic = FOURCC_LE('P','K','\5','\6');

#pragma pack(push, 1)

class LFH
{
public:
	void Init(const FileInfo& fileInfo, const ZipEntry& zipEntry, const char* pathname, size_t pathnameLength)
	{
		m_magic     = lfh_magic;
		m_x1        = to_le16(0);
		m_flags     = to_le16(0);
		m_method    = to_le16(u16_from_larger(zipEntry.method));
		m_fat_mtime = to_le32(FAT_from_time_t(fileInfo.MTime()));
		m_crc       = to_le32(zipEntry.checksum);
		m_csize     = to_le32(u32_from_larger(zipEntry.csize));
		m_usize     = to_le32(u32_from_larger(fileInfo.Size()));
		m_fn_len    = to_le16(u16_from_larger((uint)pathnameLength));
		m_e_len     = to_le16(0);

		cpu_memcpy((char*)this + sizeof(LFH), pathname, pathnameLength);
	}

	size_t Size() const
	{
		debug_assert(m_magic == lfh_magic);
		const size_t fn_len = read_le16(&m_fn_len);
		const size_t  e_len = read_le16(&m_e_len);
		// note: LFH doesn't have a comment field!

		return sizeof(LFH) + fn_len + e_len;
	}

private:
	u32 m_magic;
	u16 m_x1;			// version needed
	u16 m_flags;
	u16 m_method;
	u32 m_fat_mtime;	// last modified time (DOS FAT format)
	u32 m_crc;
	u32 m_csize;
	u32 m_usize;
	u16 m_fn_len;
	u16 m_e_len;
};

cassert(sizeof(LFH) == 30);


class CDFH
{
public:
	void Init(const FileInfo& fileInfo, const ZipEntry& zipEntry, const char* pathname, size_t pathnameLength, size_t slack)
	{
		m_magic     = cdfh_magic;
		m_x1        = to_le32(0);
		m_flags     = to_le16(0);
		m_method    = to_le16(u16_from_larger(zipEntry.method));
		m_fat_mtime = to_le32(FAT_from_time_t(fileInfo.MTime()));
		m_crc       = to_le32(zipEntry.checksum);
		m_csize     = to_le32(u32_from_larger(zipEntry.csize));
		m_usize     = to_le32(u32_from_larger(fileInfo.Size()));
		m_fn_len    = to_le16(u16_from_larger((uint)pathnameLength));
		m_e_len     = to_le16(0);
		m_c_len     = to_le16(u16_from_larger((uint)slack));
		m_x2        = to_le32(0);
		m_x3        = to_le32(0);
		m_lfh_ofs   = to_le32(zipEntry.ofs);

		cpu_memcpy((char*)this + sizeof(CDFH), pathname, pathnameLength);
	}

	void Decompose(FileInfo& fileInfo, ZipEntry& zipEntry, const char*& pathname, size_t& cdfhSize) const
	{
		const u16 zipMethod = read_le16(&m_method);
		const u32 fat_mtime = read_le32(&m_fat_mtime);
		const u32 crc       = read_le32(&m_crc);
		const u32 csize     = read_le32(&m_csize);
		const u32 usize     = read_le32(&m_usize);
		const u16 fn_len    = read_le16(&m_fn_len);
		const u16 e_len     = read_le16(&m_e_len);
		const u16 c_len     = read_le16(&m_c_len);
		const u32 lfh_ofs   = read_le32(&m_lfh_ofs);

		// get 0-terminated copy of pathname
		const char* fn = (const char*)this + sizeof(CDFH); // not 0-terminated!
		char buf[PATH_MAX];	// path_Pool()->UniqueCopy requires a 0-terminated string
		cpu_memcpy(buf, fn, fn_len*sizeof(char));
		buf[fn_len] = '\0';
		pathname = path_Pool()->UniqueCopy(buf);

		fileInfo = FileInfo(path_name_only(pathname), (off_t)usize, time_t_from_FAT(fat_mtime));
		zipEntry = ZipEntry((off_t)lfh_ofs, (off_t)csize, crc, zipMethod, NEEDS_LFH_FIXUP);

		cdfhSize = sizeof(CDFH) + fn_len + e_len + c_len;
	}

private:
	u32 m_magic;
	u32 m_x1;			// versions
	u16 m_flags;
	u16 m_method;
	u32 m_fat_mtime;	// last modified time (DOS FAT format)
	u32 m_crc;
	u32 m_csize;
	u32 m_usize;
	u16 m_fn_len;
	u16 m_e_len;
	u16 m_c_len;
	u32 m_x2;			// spanning
	u32 m_x3;			// attributes
	u32 m_lfh_ofs;
};

cassert(sizeof(CDFH) == 46);


class ECDR
{
public:
	void Init(uint cd_numEntries, off_t cd_ofs, size_t cd_size)
	{
		m_magic         = ecdr_magic;
		memset(m_x1, 0, sizeof(m_x1));
		m_cd_numEntries = to_le16(u16_from_larger(cd_numEntries));
		m_cd_size       = to_le32(u32_from_larger(cd_size));
		m_cd_ofs        = to_le32(u32_from_larger(cd_ofs));
		m_comment_len   = to_le16(0);
	}

	void Decompose(uint& cd_numEntries, off_t& cd_ofs, size_t& cd_size) const
	{
		cd_numEntries = (uint)read_le16(&m_cd_numEntries);
		cd_ofs    = (off_t)read_le32(&m_cd_ofs);
		cd_size  = (size_t)read_le32(&m_cd_size);
	}

private:
	u32 m_magic;
	u8 m_x1[6];	// multiple-disk support
	u16 m_cd_numEntries;
	u32 m_cd_size;
	u32 m_cd_ofs;
	u16 m_comment_len;
};

cassert(sizeof(ECDR) == 22);

#pragma pack(pop)


//-----------------------------------------------------------------------------

/**
 * scan buffer for a Zip file record.
 *
 * @param start position within buffer
 * @param magic signature of record
 * @param recordSize size of record (including signature)
 * @return pointer to record within buffer or 0 if not found.
 **/
static const u8* zip_FindRecord(const u8* buf, size_t size, const u8* start, u32 magic, size_t recordSize)
{
	// (don't use <start> as the counter - otherwise we can't tell if
	// scanning within the buffer was necessary.)
	for(const u8* p = start; p <= buf+size-recordSize; p++)
	{
		// found it
		if(*(u32*)p == magic)
		{
			debug_assert(p == start);	// otherwise, the archive is a bit broken
			return p;
		}
	}

	// passed EOF, didn't find it.
	// note: do not warn - this happens in the initial ECDR search at
	// EOF if the archive contains a comment field.
	return 0;
}


// search for ECDR in the last <maxScanSize> bytes of the file.
// if found, fill <dst_ecdr> with a copy of the (little-endian) ECDR and
// return INFO::OK, otherwise IO error or ERR::CORRUPTED.
static LibError zip_ReadECDR(const File_Posix& file, off_t fileSize, IoBuf& buf, size_t maxScanSize, uint& cd_numEntries, off_t& cd_ofs, size_t& cd_size)
{
	// don't scan more than the entire file
	const size_t scanSize = std::min(maxScanSize, (size_t)fileSize);

	// read desired chunk of file into memory
	const off_t ofs = fileSize - (off_t)scanSize;
	RETURN_ERR(io_Read(file, ofs, buf, scanSize));

	// look for ECDR in buffer
	const u8* start = (const u8*)buf.get();
	const ECDR* ecdr = (const ECDR*)zip_FindRecord(start, scanSize, start, ecdr_magic, sizeof(ECDR));
	if(!ecdr)
		WARN_RETURN(INFO::CANNOT_HANDLE);

	ecdr->Decompose(cd_numEntries, cd_ofs, cd_size);
	return INFO::OK;
}


static LibError zip_LocateCentralDirectory(const File_Posix& file, off_t fileSize, off_t& cd_ofs, uint& cd_numEntries, size_t& cd_size)
{
	const size_t maxScanSize = 66000u;	// see below
	IoBuf buf = io_buf_Allocate(maxScanSize);

	// expected case: ECDR at EOF; no file comment
	LibError ret = zip_ReadECDR(file, fileSize, buf, sizeof(ECDR), cd_numEntries, cd_ofs, cd_size);
	if(ret == INFO::OK)
		return INFO::OK;
	// worst case: ECDR precedes 64 KiB of file comment
	ret = zip_ReadECDR(file, fileSize, buf, maxScanSize, cd_numEntries, cd_ofs, cd_size);
	if(ret == INFO::OK)
		return INFO::OK;

	// both ECDR scans failed - this is not a valid Zip file.
	RETURN_ERR(io_Read(file, 0, buf, sizeof(LFH)));
	// the Zip file has an LFH but lacks an ECDR. this can happen if
	// the user hard-exits while an archive is being written.
	// notes:
	// - return ERR::CORRUPTED so VFS will not include this file.
	// - we could work around this by scanning all LFHs, but won't bother
	//   because it'd be slow.
	// - do not warn - the corrupt archive will be deleted on next
	//   successful archive builder run anyway.
	if(zip_FindRecord(buf.get(), sizeof(LFH), buf.get(), lfh_magic, sizeof(LFH)))
		return ERR::CORRUPTED;	// NOWARN
	// totally bogus
	else
		WARN_RETURN(ERR::ARCHIVE_UNKNOWN_FORMAT);
}


//-----------------------------------------------------------------------------
// ArchiveReader_Zip
//-----------------------------------------------------------------------------

static Filesystem_Posix fsPosix;

class ArchiveReader_Zip : public IArchiveReader
{
public:
	ArchiveReader_Zip(const char* pathname)
	{
		m_file.Open(pathname, 'r');
		
		FileInfo fileInfo;
		fsPosix.GetFileInfo(pathname, fileInfo);
		m_fileSize = fileInfo.Size();
		debug_assert(m_fileSize >= sizeof(LFH)+sizeof(CDFH)+sizeof(ECDR));
	}

	virtual LibError ReadEntries(ArchiveEntryCallback cb, uintptr_t cbData)
	{
		// locate and read Central Directory
		off_t cd_ofs; uint cd_numEntries; size_t cd_size;
		RETURN_ERR(zip_LocateCentralDirectory(m_file, m_fileSize, cd_ofs, cd_numEntries, cd_size));
		IoBuf buf = io_buf_Allocate(cd_size);
		RETURN_ERR(io_Read(m_file, cd_ofs, buf, cd_size));
		const u8* cd = (const u8*)buf.get();

		m_entries.reserve(cd_numEntries);

		// iterate over Central Directory
		const u8* pos = cd;
		for(uint i = 0; i < cd_numEntries; i++)
		{
			// scan for next CDFH
			CDFH* cdfh = (CDFH*)zip_FindRecord(cd, cd_size, pos, cdfh_magic, sizeof(CDFH));
			if(!cdfh)
				WARN_RETURN(ERR::CORRUPTED);

			FileInfo fileInfo;
			ZipEntry zipEntry;
			const char* pathname;
			size_t cdfhSize;
			cdfh->Decompose(fileInfo, zipEntry, pathname, cdfhSize);

			m_entries.push_back(zipEntry);
			cb(pathname, fileInfo, (ArchiveEntry*)&m_entries.back(), cbData);

			pos += cdfhSize;
		}

		return INFO::OK;
	}

	virtual unsigned Precedence() const
	{
		return 2u;
	}

	virtual char LocationCode() const
	{
		return 'A';
	}

	virtual LibError Load(const char* UNUSED(name), const void* location, u8* fileContents, size_t size) const
	{
		ZipEntry* zipEntry = (ZipEntry*)location;

		if((zipEntry->flags & NEEDS_LFH_FIXUP) != 0)
		{
			FixupEntry(*zipEntry);
			zipEntry->flags &= ~NEEDS_LFH_FIXUP;
		}

		boost::shared_ptr<ICodec> codec;
		switch(zipEntry->method)
		{
		case ZIP_METHOD_NONE:
			codec = CreateCodec_ZLibNone();
			break;
		case ZIP_METHOD_DEFLATE:
			codec = CreateDecompressor_ZLibDeflate();
			break;
		default:
			WARN_RETURN(ERR::ARCHIVE_UNKNOWN_METHOD);
		}

		Stream stream(codec);
		stream.SetOutputBuffer(fileContents, size);
		RETURN_ERR(io_Read(m_file, zipEntry->ofs, IO_BUF_TEMP, zipEntry->csize, FeedStream, (uintptr_t)&stream));
		RETURN_ERR(stream.Finish());
		debug_assert(zipEntry->checksum == stream.Checksum());

		return INFO::OK;
	}

	virtual LibError Store(const char* UNUSED(name), const void* UNUSED(location), const u8* UNUSED(fileContents), size_t UNUSED(size)) const
	{
		return ERR::NOT_SUPPORTED;
	}

private:
	struct LFH_Copier
	{
		u8* lfh_dst;
		size_t lfh_bytes_remaining;
	};

	// this code grabs an LFH struct from file block(s) that are
	// passed to the callback. usually, one call copies the whole thing,
	// but the LFH may straddle a block boundary.
	//
	// rationale: this allows using temp buffers for zip_fixup_lfh,
	// which avoids involving the file buffer manager and thus
	// avoids cluttering the trace and cache contents.
	static LibError lfh_copier_cb(uintptr_t cbData, const u8* block, size_t size, size_t& bytesProcessed)
	{
		LFH_Copier* p = (LFH_Copier*)cbData;

		debug_assert(size <= p->lfh_bytes_remaining);
		cpu_memcpy(p->lfh_dst, block, size);
		p->lfh_dst += size;
		p->lfh_bytes_remaining -= size;

		bytesProcessed = size;
		return INFO::CB_CONTINUE;
	}

	/**
	 * fix up zipEntry's offset within the archive.
	 * called by archive_LoadFile iff NEEDS_LFH_FIXUP is set.
	 * side effects: adjusts zipEntry.ofs.
	 *
	 * ensures <ent.ofs> points to the actual file contents; it is initially
	 * the offset of the LFH. we cannot use CDFH filename and extra field
	 * lengths to skip past LFH since that may not mirror CDFH (has happened).
	 *
	 * this is called at file-open time instead of while mounting to
	 * reduce seeks: since reading the file will typically follow, the
	 * block cache entirely absorbs the IO cost.
	 **/
	void FixupEntry(ZipEntry& zipEntry) const
	{
		// performance note: this ends up reading one file block, which is
		// only in the block cache if the file starts in the same block as a
		// previously read file (i.e. both are small).
		LFH lfh;
		LFH_Copier params = { (u8*)&lfh, sizeof(LFH) };
		THROW_ERR(io_Read(m_file, zipEntry.ofs, IO_BUF_TEMP, sizeof(LFH), lfh_copier_cb, (uintptr_t)&params));

		zipEntry.ofs += (off_t)lfh.Size();
	}

	File_Posix m_file;
	off_t m_fileSize;
	std::vector<ZipEntry> m_entries;
};


boost::shared_ptr<IArchiveReader> CreateArchiveReader_Zip(const char* archivePathname)
{
	return PIArchiveReader(new ArchiveReader_Zip(archivePathname));
}


//-----------------------------------------------------------------------------
// ArchiveWriterZip
//-----------------------------------------------------------------------------

static bool IsFileTypeIncompressible(const char* extension)
{
	// file extensions that we don't want to compress
	static const char* incompressibleExtensions[] =
	{
		"zip", "rar",
		"jpg", "jpeg", "png", 
		"ogg", "mp3"
	};

	for(uint i = 0; i < ARRAY_SIZE(incompressibleExtensions); i++)
	{
		if(!strcasecmp(extension, incompressibleExtensions[i]))
			return true;
	}

	return false;
}


class ArchiveWriter_Zip : public IArchiveWriter
{
public:
	ArchiveWriter_Zip(const char* archivePathname)
		: m_fileSize(0)
		, m_numEntries(0)
	{
		THROW_ERR(m_file.Open(archivePathname, 'w'));
		THROW_ERR(pool_create(&m_cdfhPool, 10*MiB, 0));
	}

	~ArchiveWriter_Zip()
	{
		const size_t cd_size = m_cdfhPool.da.pos;

		// append an ECDR to the CDFH list (this allows us to
		// write out both to the archive file in one burst)
		ECDR* ecdr = (ECDR*)pool_alloc(&m_cdfhPool, sizeof(ECDR));
		if(ecdr)
		{
			ecdr->Init(m_numEntries, m_fileSize, cd_size);
			io_Write(m_file, m_fileSize, m_cdfhPool.da.base, cd_size+sizeof(ECDR));
		}

		(void)pool_destroy(&m_cdfhPool);
	}

	LibError AddFile(const char* pathname)
	{
		FileInfo fileInfo;
		RETURN_ERR(fsPosix.GetFileInfo(pathname, fileInfo));
		const off_t usize = fileInfo.Size();
		// skip 0-length files.
		// rationale: zip.cpp needs to determine whether a CDFH entry is
		// a file or directory (the latter are written by some programs but
		// not needed - they'd only pollute the file table).
		// it looks like checking for usize=csize=0 is the safest way -
		// relying on file attributes (which are system-dependent!) is
		// even less safe.
		// we thus skip 0-length files to avoid confusing them with directories.
		if(!usize)
			return INFO::SKIPPED;

		File_Posix file;
		RETURN_ERR(file.Open(pathname, 'r'));

		// choose method and the corresponding codec
		ZipMethod zipMethod;
		PICodec codec;
		if(IsFileTypeIncompressible(pathname))
		{
			zipMethod = ZIP_METHOD_NONE;
			codec = CreateCodec_ZLibNone();
		}
		else
		{
			zipMethod = ZIP_METHOD_DEFLATE;
			codec = CreateCompressor_ZLibDeflate();
		}

		// allocate memory
		const size_t pathnameLength = strlen(pathname);
		const size_t csizeMax = codec.get()->MaxOutputSize(usize);
		IoBuf buf = io_buf_Allocate(sizeof(LFH) + pathnameLength + csizeMax);

		// read and compress file contents
		size_t csize; u32 checksum;
		{
			u8* cdata = (u8*)buf.get() + sizeof(LFH) + pathnameLength;
			Stream stream(codec);
			stream.SetOutputBuffer(cdata, csizeMax);
			RETURN_ERR(io_Read(file, 0, IO_BUF_TEMP, usize, FeedStream, (uintptr_t)&stream));
			RETURN_ERR(stream.Finish());
			csize = stream.OutSize();
			checksum = stream.Checksum();
		}

		ZipEntry zipEntry(m_fileSize, (off_t)csize, checksum, zipMethod, 0);

		// build LFH
		{
			LFH* lfh = (LFH*)buf.get();
			lfh->Init(fileInfo, zipEntry, pathname, pathnameLength);
		}

		// write to LFH, pathname and cdata to file
		const size_t packageSize = sizeof(LFH) + pathnameLength + csize;
		RETURN_ERR(io_Write(m_file, m_fileSize, buf, packageSize));
		m_fileSize += (off_t)packageSize;

		// append a CDFH to the central directory (in memory)
		// .. note: pool_alloc may round size up for padding purposes.
		const size_t prev_pos = m_cdfhPool.da.pos;
		const size_t cdfhSize = sizeof(CDFH) + pathnameLength;
		CDFH* cdfh = (CDFH*)pool_alloc(&m_cdfhPool, cdfhSize);
		if(!cdfh)
			WARN_RETURN(ERR::NO_MEM);
		const size_t slack = m_cdfhPool.da.pos - prev_pos - cdfhSize;
		cdfh->Init(fileInfo, zipEntry, pathname, pathnameLength, slack);

		m_numEntries++;

		return INFO::OK;
	}

private:
	File_Posix m_file;
	off_t m_fileSize;

	Pool m_cdfhPool;
	uint m_numEntries;
};

PIArchiveWriter CreateArchiveWriter_Zip(const char* archivePathname)
{
	return PIArchiveWriter(new ArchiveWriter_Zip(archivePathname));
}