zipcentraldirectoryentry.cpp

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/*
  Zipios -- a small C++ library that provides easy access to .zip files.
 
  Copyright (C) 2000-2007  Thomas Sondergaard
  Copyright (c) 2015-2022  Made to Order Software Corp.  All Rights Reserved
 
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
 
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#include "zipcentraldirectoryentry.hpp"
 
#include "zipios/zipiosexceptions.hpp"
#include "zipios/dosdatetime.hpp"
 
#include "zipios_common.hpp"
 
 
namespace zipios
{
 
 
 
namespace
{
 
 
uint32_t const  g_signature = 0x02014b50;
 
 
// The zip codes (values are pre-shifted)
uint16_t const   g_msdos         = 0x0000;
uint16_t const   g_amiga         = 0x0100;
uint16_t const   g_open_vms      = 0x0200;
uint16_t const   g_unix          = 0x0300;
uint16_t const   g_vm_cms        = 0x0400;
uint16_t const   g_atari_st      = 0x0500;
uint16_t const   g_os2_hpfs      = 0x0600;
uint16_t const   g_macintosh     = 0x0700;
uint16_t const   g_z_system      = 0x0800;
uint16_t const   g_cpm           = 0x0900;
uint16_t const   g_windows       = 0x0A00;
uint16_t const   g_mvs           = 0x0B00;
uint16_t const   g_vse           = 0x0C00;
uint16_t const   g_acorn_risc    = 0x0D00;
uint16_t const   g_vfat          = 0x0E00;
uint16_t const   g_alternate_vms = 0x0F00;
uint16_t const   g_beos          = 0x1000;
uint16_t const   g_tandem        = 0x1100;
uint16_t const   g_os400         = 0x1200;
uint16_t const   g_osx           = 0x1300;
 
 
struct ZipCentralDirectoryEntryHeader
{
    uint32_t        m_signature;
    uint16_t        m_writer_version;
    uint16_t        m_extract_version;
    uint16_t        m_general_purpose_bitfield;
    uint16_t        m_compress_method;
    uint32_t        m_dosdatetime;
    uint32_t        m_crc_32;
    uint32_t        m_compressed_size;
    uint32_t        m_uncompressed_size;
    uint16_t        m_filename_len;
    uint16_t        m_extra_field_len;
    uint16_t        m_file_comment_len;
    uint16_t        m_disk_num_start;
    uint16_t        m_intern_file_attr;
    uint32_t        m_extern_file_attr;
    uint32_t        m_relative_offset_location_header;
    //uint8_t       m_filename[m_filename_len];
    //uint8_t       m_extra_field[m_extra_field_len];
    //uint8_t       m_file_comment[m_file_comment_len];
};
 
 
} // no name namespace
 
 
ZipCentralDirectoryEntry::ZipCentralDirectoryEntry()
{
}
 
 
ZipCentralDirectoryEntry::ZipCentralDirectoryEntry(FileEntry const & entry)
    : ZipLocalEntry(entry)
{
}
 
 
ZipCentralDirectoryEntry::~ZipCentralDirectoryEntry()
{
}
 
 
size_t ZipCentralDirectoryEntry::getHeaderSize() const
{
    // Note that the structure is 48 bytes because of an alignment
    // and attempting to use options to avoid the alignment would
    // not be portable so we use a hard coded value (yuck!)
    return 46 /* sizeof(ZipCentralDirectoryEntryHeader) */
         + m_filename.length() + (m_is_directory ? 1 : 0)
         + m_extra_field.size()
         + m_comment.length();
}
 
 
FileEntry::pointer_t ZipCentralDirectoryEntry::clone() const
{
    return std::make_shared<ZipCentralDirectoryEntry>(*this);
}
 
 
void ZipCentralDirectoryEntry::read(std::istream & is)
{
    m_valid = false; // set back to true upon successful completion below.
 
    // verify the signature
    uint32_t signature;
    zipRead(is, signature);
    if(g_signature != signature)
    {
        is.setstate(std::ios::failbit);
        throw IOException("ZipCentralDirectoryEntry::read(): Expected Central Directory entry signature not found");
    }
 
    uint16_t writer_version(0);
    uint16_t compress_method(0);
    uint32_t dosdatetime(0);
    uint32_t compressed_size(0);
    uint32_t uncompressed_size(0);
    uint32_t rel_offset_loc_head(0);
    uint16_t filename_len(0);
    uint16_t extra_field_len(0);
    uint16_t file_comment_len(0);
    uint16_t intern_file_attr(0);
    uint32_t extern_file_attr(0);
    uint16_t disk_num_start(0);
    std::string filename;
 
    // read the header
    zipRead(is, writer_version);                    // 16
    zipRead(is, m_extract_version);                 // 16
    zipRead(is, m_general_purpose_bitfield);        // 16
    zipRead(is, compress_method);                   // 16
    zipRead(is, dosdatetime);                       // 32
    zipRead(is, m_crc_32);                          // 32
    zipRead(is, compressed_size);                   // 32
    zipRead(is, uncompressed_size);                 // 32
    zipRead(is, filename_len);                      // 16
    zipRead(is, extra_field_len);                   // 16
    zipRead(is, file_comment_len);                  // 16
    zipRead(is, disk_num_start);                    // 16
    zipRead(is, intern_file_attr);                  // 16
    zipRead(is, extern_file_attr);                  // 32
    zipRead(is, rel_offset_loc_head);               // 32
    zipRead(is, filename, filename_len);            // string
    zipRead(is, m_extra_field, extra_field_len);    // buffer
    zipRead(is, m_comment, file_comment_len);       // string
    // the FilePath() will remove the trailing slash so make sure
    // to defined the m_is_directory ahead of time!
    m_is_directory = !filename.empty() && filename.back() == g_separator;
 
    m_compress_method = static_cast<StorageMethod>(compress_method);
    DOSDateTime t;
    t.setDOSDateTime(dosdatetime);
    m_unix_time = t.getUnixTimestamp();
    m_compressed_size = compressed_size;
    m_uncompressed_size = uncompressed_size;
    m_entry_offset = rel_offset_loc_head;
    m_filename = FilePath(filename);
 
    // the zipRead() should throw if it is false...
    m_valid = true;
}
 
 
void ZipCentralDirectoryEntry::write(std::ostream & os)
{
    if(m_filename.length()  > 0x10000
    || m_extra_field.size() > 0x10000
    || m_comment.length()   > 0x10000)
    {
        throw InvalidStateException("ZipCentralDirectoryEntry::write(): file name, comment, or extra field too large to save in a Zip file.");
    }
 
// Solaris defines _ILP32 for 32 bit platforms
#if INTPTR_MAX != INT32_MAX
    if(m_compressed_size   >= 0x100000000ULL
    || m_uncompressed_size >= 0x100000000ULL
    || m_entry_offset      >= 0x100000000LL)
    {
        // This represents really large files which we do not test at this point
        throw InvalidStateException("ZipCentralDirectoryEntry::write(): The size of this file is too large to fit in a zip archive."); // LCOV_EXCL_LINE
    }
#endif
 
    // define version
    uint16_t writer_version = g_zip_format_version;
    // including the "compatibility" code
#if defined(WIN32) || defined(_WIN32) || defined(__WIN32)
    // MS-Windows
    // TBD: should we use g_msdos instead?
    writer_version |= g_windows;
#elif defined(__APPLE__) && defined(__MACH__)
    // OS/X
    writer_version |= g_osx;
#else
    // Other Unices
    writer_version |= g_unix;
#endif
 
    std::string filename(m_filename);
    if(m_is_directory)
    {
        // add a trailing separator for directories
        // (this is VERY important for zip files which do not otherwise
        // indicate that a file is a directory)
        filename += g_separator;
    }
 
    uint16_t compress_method(static_cast<uint8_t>(m_compress_method));
    if(m_compression_level == COMPRESSION_LEVEL_NONE)
    {
        compress_method = static_cast<uint8_t>(StorageMethod::STORED);
    }
 
    DOSDateTime t;
    t.setUnixTimestamp(m_unix_time);
    uint32_t dosdatetime(t.getDOSDateTime());   // type could be set to DOSDateTime::dosdatetime_t
    uint32_t compressed_size(m_compressed_size);
    uint32_t uncompressed_size(m_uncompressed_size);
    uint16_t filename_len(filename.length());
    uint16_t extra_field_len(m_extra_field.size());
    uint16_t file_comment_len(m_comment.length());
    uint16_t disk_num_start(0);
    uint16_t intern_file_attr(0);
    uint32_t extern_file_attr(m_is_directory ? 0x41FD0010 : 0x81B40000);
    uint32_t rel_offset_loc_head(m_entry_offset);
 
    zipWrite(os, g_signature);                  // 32
    zipWrite(os, writer_version);               // 16
    zipWrite(os, m_extract_version);            // 16
    zipWrite(os, m_general_purpose_bitfield);   // 16
    zipWrite(os, compress_method);              // 16
    zipWrite(os, dosdatetime);                  // 32
    zipWrite(os, m_crc_32);                     // 32
    zipWrite(os, compressed_size);              // 32
    zipWrite(os, uncompressed_size);            // 32
    zipWrite(os, filename_len);                 // 16
    zipWrite(os, extra_field_len);              // 16
    zipWrite(os, file_comment_len);             // 16
    zipWrite(os, disk_num_start);               // 16
    zipWrite(os, intern_file_attr);             // 16
    zipWrite(os, extern_file_attr);             // 32
    zipWrite(os, rel_offset_loc_head);          // 32
    zipWrite(os, filename);                     // string
    zipWrite(os, m_extra_field);                // buffer
    zipWrite(os, m_comment);                    // string
}
 
 
} // zipios namespace
 
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