/******************************************************************************

 *

 * Project:  CPL - Common Portability Library

 * Purpose:  Implement VSI large file api for tar files (.tar).

 * Author:   Even Rouault, even.rouault at spatialys.com

 *

 ******************************************************************************

 * Copyright (c) 2010-2014, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

 ****************************************************************************/

//! @cond Doxygen_Suppress

#include "cpl_port.h"

#include "cpl_vsi.h"

#include <cstring>

#include <fcntl.h>

#include <memory>

#include <string>

#include <string_view>

#include <vector>

#include "cpl_conv.h"

#include "cpl_error.h"

#include "cpl_string.h"

#include "cpl_vsi_virtual.h"

#if (defined(DEBUG) || defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)) &&   \

    !defined(HAVE_FUZZER_FRIENDLY_ARCHIVE)

/* This is a completely custom archive format that is rather inefficient */

/* but supports random insertions or deletions, since it doesn't record */

/* explicit file size or rely on files starting on a particular boundary */

#define HAVE_FUZZER_FRIENDLY_ARCHIVE 1

#endif

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

constexpr int HALF_BUFFER_SIZE = 1024;

constexpr int BUFFER_SIZE = 2 * HALF_BUFFER_SIZE;

#endif

/************************************************************************/

/* ==================================================================== */

/*                       VSITarEntryFileOffset                          */

/* ==================================================================== */

/************************************************************************/

class VSITarEntryFileOffset final : public VSIArchiveEntryFileOffset

{

  public:

    GUIntBig m_nOffset = 0;

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    GUIntBig m_nFileSize = 0;

    CPLString m_osFileName{};

#endif

    explicit VSITarEntryFileOffset(GUIntBig nOffset) : m_nOffset(nOffset)

    {

    }

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    VSITarEntryFileOffset(GUIntBig nOffset, GUIntBig nFileSize,

                          const CPLString &osFileName)

        : m_nOffset(nOffset), m_nFileSize(nFileSize), m_osFileName(osFileName)

    {

    }

#endif

    ~VSITarEntryFileOffset() override;

};

VSITarEntryFileOffset::~VSITarEntryFileOffset() = default;

/************************************************************************/

/* ==================================================================== */

/*                             VSITarReader                             */

/* ==================================================================== */

/************************************************************************/

class VSITarReader final : public VSIArchiveReader

{

  private:

    CPL_DISALLOW_COPY_ASSIGN(VSITarReader)

    VSILFILE *fp = nullptr;

    GUIntBig nCurOffset = 0;

    GUIntBig nNextFileSize = 0;

    CPLString osNextFileName{};

    GIntBig nModifiedTime = 0;

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    bool m_bIsFuzzerFriendly = false;

    GByte m_abyBuffer[BUFFER_SIZE + 1] = {};

    int m_abyBufferIdx = 0;

    int m_abyBufferSize = 0;

    GUIntBig m_nCurOffsetOld = 0;

#endif

  public:

    explicit VSITarReader(const char *pszTarFileName);

    ~VSITarReader() override;

    int IsValid()

    {

        return fp != nullptr;

    }

    int GotoFirstFile() override;

    int GotoNextFile() override;

    VSIArchiveEntryFileOffset *GetFileOffset() override;

    GUIntBig GetFileSize() override

    {

        return nNextFileSize;

    }

    CPLString GetFileName() override

    {

        return osNextFileName;

    }

    GIntBig GetModifiedTime() override

    {

        return nModifiedTime;

    }

    int GotoFileOffset(VSIArchiveEntryFileOffset *pOffset) override;

};

/************************************************************************/

/*                               VSIIsTGZ()                             */

/************************************************************************/

static bool VSIIsTGZ(const char *pszFilename)

{

    return (

        !STARTS_WITH_CI(pszFilename, "/vsigzip/") &&

        ((strlen(pszFilename) > 4 &&

          STARTS_WITH_CI(pszFilename + strlen(pszFilename) - 4, ".tgz")) ||

         (strlen(pszFilename) > 7 &&

          STARTS_WITH_CI(pszFilename + strlen(pszFilename) - 7, ".tar.gz"))));

}

/************************************************************************/

/*                           VSITarReader()                             */

/************************************************************************/

// TODO(schwehr): What is this ***NEWFILE*** thing?

// And make it a symbolic constant.

VSITarReader::VSITarReader(const char *pszTarFileName)

    : fp(VSIFOpenL(pszTarFileName, "rb"))

{

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    if (fp != nullptr)

    {

        GByte abySignature[24] = {};

        m_bIsFuzzerFriendly =

            (VSIFReadL(abySignature, 1, 24, fp) == 24) &&

            (memcmp(abySignature, "FUZZER_FRIENDLY_ARCHIVE\n", 24) == 0 ||

             memcmp(abySignature, "***NEWFILE***:", strlen("***NEWFILE***:")) ==

                 0);

        CPL_IGNORE_RET_VAL(VSIFSeekL(fp, 0, SEEK_SET));

    }

#endif

}

/************************************************************************/

/*                          ~VSITarReader()                             */

/************************************************************************/

VSITarReader::~VSITarReader()

{

    if (fp)

        CPL_IGNORE_RET_VAL(VSIFCloseL(fp));

}

/************************************************************************/

/*                          GetFileOffset()                             */

/************************************************************************/

VSIArchiveEntryFileOffset *VSITarReader::GetFileOffset()

{

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    if (m_bIsFuzzerFriendly)

    {

        return new VSITarEntryFileOffset(nCurOffset, nNextFileSize,

                                         osNextFileName);

    }

#endif

    return new VSITarEntryFileOffset(nCurOffset);

}

/************************************************************************/

/*                       IsNumericFieldTerminator()                     */

/************************************************************************/

static bool IsNumericFieldTerminator(GByte byVal)

{

    // See https://github.com/Keruspe/tar-parser.rs/blob/master/tar.specs#L202

    return byVal == '\0' || byVal == ' ';

}

/************************************************************************/

/*                           GotoNextFile()                             */

/************************************************************************/

int VSITarReader::GotoNextFile()

{

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    if (m_bIsFuzzerFriendly)

    {

        const int nNewFileMarkerSize =

            static_cast<int>(strlen("***NEWFILE***:"));

        while (true)

        {

            if (m_abyBufferIdx >= m_abyBufferSize)

            {

                if (m_abyBufferSize == 0)

                {

                    m_abyBufferSize = static_cast<int>(

                        VSIFReadL(m_abyBuffer, 1, BUFFER_SIZE, fp));

                    if (m_abyBufferSize == 0)

                        return FALSE;

                    m_abyBuffer[m_abyBufferSize] = '\0';

                }

                else

                {

                    if (m_abyBufferSize < BUFFER_SIZE)

                    {

                        if (nCurOffset > 0 && nCurOffset != m_nCurOffsetOld)

                        {

                            nNextFileSize = VSIFTellL(fp);

                            if (nNextFileSize >= nCurOffset)

                            {

                                nNextFileSize -= nCurOffset;

                                m_nCurOffsetOld = nCurOffset;

                                return TRUE;

                            }

                        }

                        return FALSE;

                    }

                    memcpy(m_abyBuffer, m_abyBuffer + HALF_BUFFER_SIZE,

                           HALF_BUFFER_SIZE);

                    m_abyBufferSize = static_cast<int>(

                        VSIFReadL(m_abyBuffer + HALF_BUFFER_SIZE, 1,

                                  HALF_BUFFER_SIZE, fp));

                    if (m_abyBufferSize == 0)

                        return FALSE;

                    m_abyBufferIdx = 0;

                    m_abyBufferSize += HALF_BUFFER_SIZE;

                    m_abyBuffer[m_abyBufferSize] = '\0';

                }

            }

            std::string_view abyBuffer(reinterpret_cast<char *>(m_abyBuffer),

                                       m_abyBufferSize);

            const auto posNewFile = abyBuffer.find(

                std::string_view("***NEWFILE***:", nNewFileMarkerSize),

                m_abyBufferIdx);

            if (posNewFile == std::string::npos)

            {

                m_abyBufferIdx = m_abyBufferSize;

            }

            else

            {

                m_abyBufferIdx = static_cast<int>(posNewFile);

                // 2: space for at least one-char filename and '\n'

                if (m_abyBufferIdx < m_abyBufferSize - (nNewFileMarkerSize + 2))

                {

                    if (nCurOffset > 0 && nCurOffset != m_nCurOffsetOld)

                    {

                        nNextFileSize = VSIFTellL(fp);

                        nNextFileSize -= m_abyBufferSize;

                        nNextFileSize += m_abyBufferIdx;

                        if (nNextFileSize >= nCurOffset)

                        {

                            nNextFileSize -= nCurOffset;

                            m_nCurOffsetOld = nCurOffset;

                            return TRUE;

                        }

                    }

                    m_abyBufferIdx += nNewFileMarkerSize;

                    const int nFilenameStartIdx = m_abyBufferIdx;

                    for (; m_abyBufferIdx < m_abyBufferSize &&

                           m_abyBuffer[m_abyBufferIdx] != '\n';

                         ++m_abyBufferIdx)

                    {

                        // Do nothing.

                    }

                    if (m_abyBufferIdx < m_abyBufferSize)

                    {

                        const char *pszFilename =

                            reinterpret_cast<const char *>(m_abyBuffer +

                                                           nFilenameStartIdx);

                        osNextFileName.assign(

                            pszFilename,

                            CPLStrnlen(pszFilename,

                                       m_abyBufferIdx - nFilenameStartIdx));

                        if (osNextFileName.empty() || osNextFileName == "." ||

                            osNextFileName.find("..") != std::string::npos ||

                            osNextFileName.find("//") != std::string::npos ||

                            osNextFileName.find("\\\\") != std::string::npos)

                        {

                            CPLError(CE_Failure, CPLE_AppDefined,

                                     "Invalid filename");

                            return false;

                        }

                        nCurOffset = VSIFTellL(fp);

                        nCurOffset -= m_abyBufferSize;

                        nCurOffset += m_abyBufferIdx + 1;

                    }

                }

                else

                {

                    m_abyBufferIdx = m_abyBufferSize;

                }

            }

        }

    }

#endif

    osNextFileName.clear();

    while (true)

    {

        GByte abyHeader[512] = {};

        if (VSIFReadL(abyHeader, 512, 1, fp) != 1)

            return FALSE;

        if (!(abyHeader[100] == 0x80 ||

              IsNumericFieldTerminator(

                  abyHeader[107])) || /* start/end of filemode */

            !(abyHeader[108] == 0x80 ||

              IsNumericFieldTerminator(

                  abyHeader[115])) || /* start/end of owner ID */

            !(abyHeader[116] == 0x80 ||

              IsNumericFieldTerminator(

                  abyHeader[123])) || /* start/end of group ID */

            !IsNumericFieldTerminator(abyHeader[135]) || /* end of file size */

            !IsNumericFieldTerminator(abyHeader[147]))   /* end of mtime */

        {

            return FALSE;

        }

        if (!(abyHeader[124] == ' ' ||

              (abyHeader[124] >= '0' && abyHeader[124] <= '7')))

            return FALSE;

        if (osNextFileName.empty())

        {

            osNextFileName.assign(

                reinterpret_cast<const char *>(abyHeader),

                CPLStrnlen(reinterpret_cast<const char *>(abyHeader), 100));

        }

        nNextFileSize = 0;

        for (int i = 0; i < 11; i++)

        {

            if (abyHeader[124 + i] != ' ')

            {

                if (nNextFileSize > static_cast<GUIntBig>(GINTBIG_MAX / 8) ||

                    abyHeader[124 + i] < '0' || abyHeader[124 + i] >= '8')

                {

                    CPLError(CE_Failure, CPLE_AppDefined,

                             "Invalid file size for %s",

                             osNextFileName.c_str());

                    return FALSE;

                }

                nNextFileSize = nNextFileSize * 8 + (abyHeader[124 + i] - '0');

            }

        }

        if (nNextFileSize > GINTBIG_MAX)

        {

            CPLError(CE_Failure, CPLE_AppDefined, "Invalid file size for %s",

                     osNextFileName.c_str());

            return FALSE;

        }

        nModifiedTime = 0;

        for (int i = 0; i < 11; i++)

        {

            if (abyHeader[136 + i] != ' ')

            {

                if (nModifiedTime > GINTBIG_MAX / 8 ||

                    abyHeader[136 + i] < '0' || abyHeader[136 + i] >= '8' ||

                    nModifiedTime * 8 >

                        GINTBIG_MAX - (abyHeader[136 + i] - '0'))

                {

                    CPLError(CE_Failure, CPLE_AppDefined,

                             "Invalid mtime for %s", osNextFileName.c_str());

                    return FALSE;

                }

                nModifiedTime = nModifiedTime * 8 + (abyHeader[136 + i] - '0');

            }

        }

        if (abyHeader[156] == 'L' && nNextFileSize > 0 && nNextFileSize < 32768)

        {

            // If this is a large filename record, then read the filename

            osNextFileName.clear();

            osNextFileName.resize(

                static_cast<size_t>(((nNextFileSize + 511) / 512) * 512));

            if (VSIFReadL(&osNextFileName[0], osNextFileName.size(), 1, fp) !=

                1)

                return FALSE;

            osNextFileName.resize(static_cast<size_t>(nNextFileSize));

            if (osNextFileName.back() == '\0')

                osNextFileName.pop_back();

        }

        else

        {

            // Is it a ustar extension ?

            // Cf https://en.wikipedia.org/wiki/Tar_(computing)#UStar_format

            if (memcmp(abyHeader + 257, "ustar\0", 6) == 0 &&

                abyHeader[345] != '\0')

            {

                std::string osFilenamePrefix;

                osFilenamePrefix.assign(

                    reinterpret_cast<const char *>(abyHeader + 345),

                    CPLStrnlen(reinterpret_cast<const char *>(abyHeader + 345),

                               155));

                osNextFileName = osFilenamePrefix + '/' + osNextFileName;

            }

            break;

        }

    }

    nCurOffset = VSIFTellL(fp);

    const GUIntBig nBytesToSkip = ((nNextFileSize + 511) / 512) * 512;

    if (nBytesToSkip > (~(static_cast<GUIntBig>(0))) - nCurOffset)

    {

        CPLError(CE_Failure, CPLE_AppDefined, "Bad .tar structure");

        return FALSE;

    }

    if (VSIFSeekL(fp, nBytesToSkip, SEEK_CUR) < 0)

        return FALSE;

    return TRUE;

}

/************************************************************************/

/*                          GotoFirstFile()                             */

/************************************************************************/

int VSITarReader::GotoFirstFile()

{

    if (VSIFSeekL(fp, 0, SEEK_SET) < 0)

        return FALSE;

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    m_abyBufferIdx = 0;

    m_abyBufferSize = 0;

    nCurOffset = 0;

    m_nCurOffsetOld = 0;

    osNextFileName = "";

    nNextFileSize = 0;

#endif

    return GotoNextFile();

}

/************************************************************************/

/*                         GotoFileOffset()                             */

/************************************************************************/

int VSITarReader::GotoFileOffset(VSIArchiveEntryFileOffset *pOffset)

{

    VSITarEntryFileOffset *pTarEntryOffset =

        static_cast<VSITarEntryFileOffset *>(pOffset);

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

    if (m_bIsFuzzerFriendly)

    {

        if (VSIFSeekL(fp,

                      pTarEntryOffset->m_nOffset + pTarEntryOffset->m_nFileSize,

                      SEEK_SET) < 0)

            return FALSE;

        m_abyBufferIdx = 0;

        m_abyBufferSize = 0;

        nCurOffset = pTarEntryOffset->m_nOffset;

        m_nCurOffsetOld = pTarEntryOffset->m_nOffset;

        osNextFileName = pTarEntryOffset->m_osFileName;

        nNextFileSize = pTarEntryOffset->m_nFileSize;

        return TRUE;

    }

#endif

    if (pTarEntryOffset->m_nOffset < 512 ||

        VSIFSeekL(fp, pTarEntryOffset->m_nOffset - 512, SEEK_SET) < 0)

        return FALSE;

    return GotoNextFile();

}

/************************************************************************/

/* ==================================================================== */

/*                        VSITarFilesystemHandler                      */

/* ==================================================================== */

/************************************************************************/

class VSITarFilesystemHandler final : public VSIArchiveFilesystemHandler

{

  public:

    const char *GetPrefix() const override

    {

        return "/vsitar";

    }

    std::vector<CPLString> GetExtensions() const override;

    std::unique_ptr<VSIArchiveReader>

    CreateReader(const char *pszTarFileName) override;

    VSIVirtualHandleUniquePtr Open(const char *pszFilename,

                                   const char *pszAccess, bool bSetError,

                                   CSLConstList /* papszOptions */) override;

};

/************************************************************************/

/*                          GetExtensions()                             */

/************************************************************************/

std::vector<CPLString> VSITarFilesystemHandler::GetExtensions() const

{

    std::vector<CPLString> oList;

    oList.push_back(".tar.gz");

    oList.push_back(".tar");

    oList.push_back(".tgz");

    return oList;

}

/************************************************************************/

/*                           CreateReader()                             */

/************************************************************************/

std::unique_ptr<VSIArchiveReader>

VSITarFilesystemHandler::CreateReader(const char *pszTarFileName)

{

    CPLString osTarInFileName;

    if (VSIIsTGZ(pszTarFileName))

    {

        osTarInFileName = "/vsigzip/";

        osTarInFileName += pszTarFileName;

    }

    else

        osTarInFileName = pszTarFileName;

    auto poReader = std::make_unique<VSITarReader>(osTarInFileName);

    if (!poReader->IsValid() || !poReader->GotoFirstFile())

    {

        return nullptr;

    }

    return poReader;

}

/************************************************************************/

/*                                 Open()                               */

/************************************************************************/

VSIVirtualHandleUniquePtr

VSITarFilesystemHandler::Open(const char *pszFilename, const char *pszAccess,

                              bool bSetError, CSLConstList /* papszOptions */)

{

    if (strchr(pszAccess, 'w') != nullptr || strchr(pszAccess, '+') != nullptr)

    {

        CPLError(CE_Failure, CPLE_AppDefined,

                 "Only read-only mode is supported for /vsitar");

        return nullptr;

    }

    CPLString osTarInFileName;

    std::unique_ptr<char, VSIFreeReleaser> tarFilename(

        SplitFilename(pszFilename, osTarInFileName, true, bSetError));

    if (tarFilename == nullptr)

        return nullptr;

    auto poReader = OpenArchiveFile(tarFilename.get(), osTarInFileName);

    if (poReader == nullptr)

    {

        return nullptr;

    }

    CPLString osSubFileName("/vsisubfile/");

    VSITarEntryFileOffset *pOffset =

        reinterpret_cast<VSITarEntryFileOffset *>(poReader->GetFileOffset());

    osSubFileName += CPLString().Printf(CPL_FRMT_GUIB, pOffset->m_nOffset);

    osSubFileName += "_";

    osSubFileName += CPLString().Printf(CPL_FRMT_GUIB, poReader->GetFileSize());

    osSubFileName += ",";

    delete pOffset;

    if (VSIIsTGZ(tarFilename.get()))

    {

        osSubFileName += "/vsigzip/";

        osSubFileName += tarFilename.get();

    }

    else

        osSubFileName += tarFilename.get();

    return VSIFilesystemHandler::OpenStatic(osSubFileName, "rb");

}

//! @endcond

/************************************************************************/

/*                    VSIInstallTarFileHandler()                        */

/************************************************************************/

/*!

 \brief Install /vsitar/ file system handler.

 A special file handler is installed that allows reading on-the-fly in TAR

 (regular .tar, or compressed .tar.gz/.tgz) archives.

 All portions of the file system underneath the base path "/vsitar/" will be

 handled by this driver.

 \verbatim embed:rst

 See :ref:`/vsitar/ documentation <vsitar>`

 \endverbatim

 */

void VSIInstallTarFileHandler(void)

{

    VSIFileManager::InstallHandler("/vsitar/", new VSITarFilesystemHandler());

}