zipfile.cxx

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you 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 .
 */
 
#include "zipexcptn.hxx"
#include <zipfile.hxx>
#include <global.hxx>
#include <types.hxx>
#include <stream_helper.hxx>
 
#include <malloc.h>
#include <algorithm>
#include <memory>
 
#include <string.h>
 
#include <o3tl/safeint.hxx>
 
#include <zlib.h>
 
namespace
{
 
struct LocalFileHeader
{
    unsigned short min_version;
    unsigned short general_flag;
    unsigned short compression;
    unsigned short lastmod_time;
    unsigned short lastmod_date;
    unsigned crc32;
    unsigned compressed_size;
    unsigned uncompressed_size;
    unsigned short filename_size;
    unsigned short extra_field_size;
    std::string filename;
    std::string extra_field;
    LocalFileHeader()
        : min_version(0), general_flag(0), compression(0), lastmod_time(0), lastmod_date(0),
          crc32(0), compressed_size(0), uncompressed_size(0), filename_size(0), extra_field_size(0),
          filename(), extra_field() {}
};
 
struct CentralDirectoryEntry
{
    unsigned short creator_version;
    unsigned short min_version;
    unsigned short general_flag;
    unsigned short compression;
    unsigned short lastmod_time;
    unsigned short lastmod_date;
    unsigned crc32;
    unsigned compressed_size;
    unsigned uncompressed_size;
    unsigned short filename_size;
    unsigned short extra_field_size;
    unsigned short file_comment_size;
    unsigned short disk_num;
    unsigned short internal_attr;
    unsigned external_attr;
    unsigned offset;
    std::string filename;
    std::string extra_field;
    std::string file_comment;
    CentralDirectoryEntry()
        : creator_version(0), min_version(0), general_flag(0), compression(0), lastmod_time(0),
          lastmod_date(0), crc32(0), compressed_size(0), uncompressed_size(0), filename_size(0),
          extra_field_size(0), file_comment_size(0), disk_num(0), internal_attr(0),
          external_attr(0), offset(0), filename(), extra_field(), file_comment() {}
};
 
struct CentralDirectoryEnd
{
    unsigned short disk_num;
    unsigned short cdir_disk;
    unsigned short disk_entries;
    unsigned short cdir_entries;
    unsigned cdir_size;
    unsigned cdir_offset;
    unsigned short comment_size;
    std::string comment;
    CentralDirectoryEnd()
        : disk_num(0), cdir_disk(0), disk_entries(0), cdir_entries(0),
          cdir_size(0), cdir_offset(0), comment_size(0), comment() {}
};
 
#define CDIR_ENTRY_SIG 0x02014b50
#define LOC_FILE_HEADER_SIG 0x04034b50
#define CDIR_END_SIG 0x06054b50
 
// This little lot performs in a truly appalling way without
// buffering eg. on an IStream.
 
unsigned short readShort(StreamInterface *stream)
{
    if (!stream || stream->stell() == -1)
        throw IOException(-1);
    unsigned short tmpBuf;
    unsigned long numBytesRead = stream->sread(
        reinterpret_cast<unsigned char *>( &tmpBuf ), 2);
    if (numBytesRead != 2)
        throw IOException(-1);
    return tmpBuf;
}
 
unsigned readInt(StreamInterface *stream)
{
    if (!stream || stream->stell() == -1)
        throw IOException(-1);
    unsigned tmpBuf;
    unsigned long numBytesRead = stream->sread(
        reinterpret_cast<unsigned char *>( &tmpBuf ), 4);
    if (numBytesRead != 4)
        throw IOException(-1);
    return tmpBuf;
}
 
std::string readString(StreamInterface *stream, unsigned long size)
{
    if (!stream || stream->stell() == -1)
        throw IOException(-1);
    auto tmp = std::make_unique<unsigned char[]>(size);
    unsigned long numBytesRead = stream->sread(tmp.get(), size);
    if (numBytesRead != size)
    {
        throw IOException(-1);
    }
 
    std::string aStr(reinterpret_cast<char *>(tmp.get()), size);
    return aStr;
}
 
bool readCentralDirectoryEnd(StreamInterface *stream, CentralDirectoryEnd &end)
{
    try
    {
        unsigned signature = readInt(stream);
        if (signature != CDIR_END_SIG)
            return false;
 
        end.disk_num = readShort(stream);
        end.cdir_disk = readShort(stream);
        end.disk_entries = readShort(stream);
        end.cdir_entries = readShort(stream);
        end.cdir_size = readInt(stream);
        end.cdir_offset = readInt(stream);
        end.comment_size = readShort(stream);
        end.comment.assign(readString(stream, end.comment_size));
    }
    catch (...)
    {
        return false;
    }
    return true;
}
 
bool readCentralDirectoryEntry(StreamInterface *stream, CentralDirectoryEntry &entry)
{
    try
    {
        unsigned signature = readInt(stream);
        if (signature != CDIR_ENTRY_SIG)
            return false;
 
        entry.creator_version = readShort(stream);
        entry.min_version = readShort(stream);
        entry.general_flag = readShort(stream);
        entry.compression = readShort(stream);
        entry.lastmod_time = readShort(stream);
        entry.lastmod_date = readShort(stream);
        entry.crc32 = readInt(stream);
        entry.compressed_size = readInt(stream);
        entry.uncompressed_size = readInt(stream);
        entry.filename_size = readShort(stream);
        entry.extra_field_size = readShort(stream);
        entry.file_comment_size = readShort(stream);
        entry.disk_num = readShort(stream);
        entry.internal_attr = readShort(stream);
        entry.external_attr = readInt(stream);
        entry.offset = readInt(stream);
        entry.filename.assign(readString(stream, entry.filename_size));
        entry.extra_field.assign(readString(stream, entry.extra_field_size));
        entry.file_comment.assign(readString(stream, entry.file_comment_size));
    }
    catch (...)
    {
        return false;
    }
    return true;
}
 
bool readLocalFileHeader(StreamInterface *stream, LocalFileHeader &header)
{
    try
    {
        unsigned signature = readInt(stream);
        if (signature != LOC_FILE_HEADER_SIG)
            return false;
 
        header.min_version = readShort(stream);
        header.general_flag = readShort(stream);
        header.compression = readShort(stream);
        header.lastmod_time = readShort(stream);
        header.lastmod_date = readShort(stream);
        header.crc32 = readInt(stream);
        header.compressed_size = readInt(stream);
        header.uncompressed_size = readInt(stream);
        header.filename_size = readShort(stream);
        header.extra_field_size = readShort(stream);
        header.filename.assign(readString(stream, header.filename_size));
        header.extra_field.assign(readString(stream, header.extra_field_size));
    }
    catch (...)
    {
        return false;
    }
    return true;
}
 
bool areHeadersConsistent(const LocalFileHeader &header, const CentralDirectoryEntry &entry)
{
    if (header.min_version != entry.min_version)
        return false;
    if (header.general_flag != entry.general_flag)
        return false;
    if (header.compression != entry.compression)
        return false;
    if (!(header.general_flag & 0x08))
    {
        if (header.crc32 != entry.crc32)
            return false;
        if (header.compressed_size != entry.compressed_size)
            return false;
        if (header.uncompressed_size != entry.uncompressed_size)
            return false;
    }
    return true;
}
 
#define BLOCK_SIZE 0x800
 
bool findSignatureAtOffset(StreamInterface *stream, unsigned long nOffset)
{
    // read in reasonably sized chunk, and read more, to get overlapping sigs
    unsigned char aBuffer[ BLOCK_SIZE + 4 ];
 
    stream->sseek(nOffset, SEEK_SET);
 
    unsigned long nBytesRead = stream->sread(aBuffer, sizeof(aBuffer));
 
    for (long n = nBytesRead - 4; n >= 0; n--)
    {
        if (aBuffer[n  ] == 0x50 && aBuffer[n+1] == 0x4b &&
            aBuffer[n+2] == 0x05 && aBuffer[n+3] == 0x06)
        { // a palpable hit ...
            stream->sseek(nOffset + n, SEEK_SET);
            return true;
        }
    }
 
    return false;
}
 
bool findCentralDirectoryEnd(StreamInterface *stream)
{
    if (!stream)
        return false;
 
    stream->sseek(0,SEEK_END);
 
    long nLength = stream->stell();
    if (nLength == -1)
        return false;
 
    try
    {
        for (long nOffset = nLength - BLOCK_SIZE - 4;
             nOffset > 0; nOffset -= BLOCK_SIZE)
        {
            if (findSignatureAtOffset(stream, nOffset))
                return true;
        }
        return findSignatureAtOffset(stream, 0);
    }
    catch (...)
    {
        return false;
    }
}
 
bool isZipStream(StreamInterface *stream)
{
    if (!findCentralDirectoryEnd(stream))
        return false;
    CentralDirectoryEnd end;
    if (!readCentralDirectoryEnd(stream, end))
        return false;
    stream->sseek(end.cdir_offset, SEEK_SET);
    CentralDirectoryEntry entry;
    if (!readCentralDirectoryEntry(stream, entry))
        return false;
    stream->sseek(entry.offset, SEEK_SET);
    LocalFileHeader header;
    if (!readLocalFileHeader(stream, header))
        return false;
    if (!areHeadersConsistent(header, entry))
        return false;
    return true;
}
 
} // anonymous namespace
 
namespace internal
{
 
namespace {
 
/* for case in-sensitive string comparison */
struct stricmp
{
    explicit stricmp(const std::string &str) : str_(str)
    {}
 
    bool operator() (const std::string &other)
    {
        return (0 == _stricmp(str_.c_str(), other.c_str()));
    }
 
    std::string str_;
};
 
}
 
} // namespace internal
 
bool ZipFile::IsZipFile(const Filepath_t& /*FileName*/)
{
    return true;
}
 
bool ZipFile::IsZipFile(void* /*stream*/)
{
    return true;
}
 
 
bool ZipFile::IsValidZipFileVersionNumber(const Filepath_t& /*FileName*/)
{
    return true;
}
 
bool ZipFile::IsValidZipFileVersionNumber(void* /* stream*/)
{
    return true;
}
 
 
ZipFile::ZipFile(const Filepath_t &FileName) :
    m_pStream(nullptr),
    m_bShouldFree(true)
{
    m_pStream = new FileStream(FileName.c_str());
    if (!isZipStream(m_pStream))
    {
        delete m_pStream;
        m_pStream = nullptr;
    }
}
 
ZipFile::ZipFile(StreamInterface *stream) :
    m_pStream(stream),
    m_bShouldFree(false)
{
    if (!isZipStream(stream))
        m_pStream = nullptr;
}
 
 
ZipFile::~ZipFile()
{
    if (m_pStream && m_bShouldFree)
        delete m_pStream;
}
 
void ZipFile::GetUncompressedContent(
    const std::string &ContentName, /*inout*/ ZipContentBuffer_t &ContentBuffer)
{
    if (!findCentralDirectoryEnd(m_pStream))
        return;
    CentralDirectoryEnd end;
    if (!readCentralDirectoryEnd(m_pStream, end))
        return;
    m_pStream->sseek(end.cdir_offset, SEEK_SET);
    CentralDirectoryEntry entry;
    while (m_pStream->stell() != -1 && o3tl::make_unsigned(m_pStream->stell()) < end.cdir_offset + end.cdir_size)
    {
        if (!readCentralDirectoryEntry(m_pStream, entry))
            return;
        if (ContentName.length() == entry.filename_size && !_stricmp(entry.filename.c_str(), ContentName.c_str()))
            break;
    }
    if (ContentName.length() != entry.filename_size)
        return;
    if (_stricmp(entry.filename.c_str(), ContentName.c_str()))
        return;
    m_pStream->sseek(entry.offset, SEEK_SET);
    LocalFileHeader header;
    if (!readLocalFileHeader(m_pStream, header))
        return;
    if (!areHeadersConsistent(header, entry))
        return;
    ContentBuffer.clear();
    ContentBuffer = ZipContentBuffer_t(entry.uncompressed_size);
    if (!entry.compression)
        m_pStream->sread(reinterpret_cast<unsigned char *>(ContentBuffer.data()), entry.uncompressed_size);
    else
    {
        int ret;
        z_stream strm;
 
        /* allocate inflate state */
        strm.zalloc = Z_NULL;
        strm.zfree = Z_NULL;
        strm.opaque = Z_NULL;
        strm.avail_in = 0;
        strm.next_in = Z_NULL;
        ret = inflateInit2(&strm,-MAX_WBITS);
        if (ret != Z_OK)
            return;
 
        std::vector<unsigned char> tmpBuffer(entry.compressed_size);
        if (entry.compressed_size != m_pStream->sread(tmpBuffer.data(), entry.compressed_size))
            return;
 
        strm.avail_in = entry.compressed_size;
        strm.next_in = reinterpret_cast<Bytef *>(tmpBuffer.data());
 
        strm.avail_out = entry.uncompressed_size;
        strm.next_out = reinterpret_cast<Bytef *>(ContentBuffer.data());
        ret = inflate(&strm, Z_FINISH);
        switch (ret)
        {
        case Z_NEED_DICT:
        case Z_DATA_ERROR:
        case Z_MEM_ERROR:
            (void)inflateEnd(&strm);
            ContentBuffer.clear();
            return;
        }
        (void)inflateEnd(&strm);
    }
}
 
ZipFile::DirectoryPtr_t ZipFile::GetDirectory() const
{
    DirectoryPtr_t dir(new Directory_t());
    if (!findCentralDirectoryEnd(m_pStream))
        return dir;
    CentralDirectoryEnd end;
    if (!readCentralDirectoryEnd(m_pStream, end))
        return dir;
    m_pStream->sseek(end.cdir_offset, SEEK_SET);
    CentralDirectoryEntry entry;
    while (m_pStream->stell() != -1 && o3tl::make_unsigned(m_pStream->stell()) < end.cdir_offset + end.cdir_size)
    {
        if (!readCentralDirectoryEntry(m_pStream, entry))
            return dir;
        if (entry.filename_size)
            dir->push_back(entry.filename);
    }
    return dir;
}
 
bool ZipFile::HasContent(const std::string &ContentName) const
{
    //#i34314# we need to compare package content names
    //case in-sensitive as it is not defined that such
    //names must be handled case sensitive
    DirectoryPtr_t dir = GetDirectory();
 
    return std::any_of(dir->begin(), dir->end(), internal::stricmp(ContentName));
}
 
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */