/******************************************************************************
 *
 * 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>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

//! @cond Doxygen_Suppress

#include "cpl_port.h"
#include "cpl_vsi.h"

#include <cstring>

#if HAVE_FCNTL_H
#  include <fcntl.h>
#endif

#include <string>
#include <vector>

#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_string.h"
#include "cpl_vsi_virtual.h"

CPL_CVSID("$Id$")

#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
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
};

/************************************************************************/
/* ==================================================================== */
/*                             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);
}

#ifdef HAVE_FUZZER_FRIENDLY_ARCHIVE

/************************************************************************/
/*                           CPLmemmem()                                */
/************************************************************************/

static void* CPLmemmem(const void *haystack, size_t haystacklen,
                       const void *needle, size_t needlelen)
{
    const char* pachHaystack = reinterpret_cast<const char*>(haystack);
    if( haystacklen < needlelen )
        return nullptr;
    while( true )
    {
        const char* pachSubstrStart = reinterpret_cast<const char*>(
            memchr( pachHaystack,
                reinterpret_cast<const char*>(needle)[0], haystacklen ));
        if( pachSubstrStart == nullptr )
            return nullptr;
        if( static_cast<size_t>(pachSubstrStart - pachHaystack)
                                                + needlelen > haystacklen )
            return nullptr;
        if( memcmp( pachSubstrStart, needle, needlelen ) == 0 )
        {
            return const_cast<void*>(static_cast<const void*>(pachSubstrStart));
        }
        haystacklen -= pachSubstrStart - pachHaystack + 1;
        pachHaystack = pachSubstrStart + 1;
    }
}
#endif

/************************************************************************/
/*                       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';
                }
            }

            void* pNewFileMarker =
                CPLmemmem( m_abyBuffer + m_abyBufferIdx,
                        m_abyBufferSize - m_abyBufferIdx,
                        "***NEWFILE***:", nNewFileMarkerSize );
            if( pNewFileMarker == nullptr )
            {
                m_abyBufferIdx = m_abyBufferSize;
            }
            else
            {
                m_abyBufferIdx = static_cast<int>(
                    static_cast<const GByte*>(pNewFileMarker) - m_abyBuffer);
                // 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 )
                    {
                        osNextFileName.assign(
                            reinterpret_cast<const char*>(m_abyBuffer + nFilenameStartIdx),
                            m_abyBufferIdx - nFilenameStartIdx);
                        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.resize(osNextFileName.size() - 1);
        }
        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() override { return "/vsitar"; }
    std::vector<CPLString> GetExtensions() override;
    VSIArchiveReader* CreateReader(const char* pszTarFileName) override;

    VSIVirtualHandle *Open( const char *pszFilename,
                            const char *pszAccess,
                            bool bSetError,
                            CSLConstList /* papszOptions */ ) override;
};

/************************************************************************/
/*                          GetExtensions()                             */
/************************************************************************/

std::vector<CPLString> VSITarFilesystemHandler::GetExtensions()
{
    std::vector<CPLString> oList;
    oList.push_back(".tar.gz");
    oList.push_back(".tar");
    oList.push_back(".tgz");
    return oList;
}

/************************************************************************/
/*                           CreateReader()                             */
/************************************************************************/

VSIArchiveReader* VSITarFilesystemHandler::CreateReader(const char* pszTarFileName)
{
    CPLString osTarInFileName;

    if (VSIIsTGZ(pszTarFileName))
    {
        osTarInFileName = "/vsigzip/";
        osTarInFileName += pszTarFileName;
    }
    else
        osTarInFileName = pszTarFileName;

    VSITarReader* poReader = new VSITarReader(osTarInFileName);

    if (!poReader->IsValid())
    {
        delete poReader;
        return nullptr;
    }

    if (!poReader->GotoFirstFile())
    {
        delete poReader;
        return nullptr;
    }

    return poReader;
}

/************************************************************************/
/*                                 Open()                               */
/************************************************************************/

VSIVirtualHandle* 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;
    char* tarFilename
        = SplitFilename(pszFilename, osTarInFileName, TRUE);
    if (tarFilename == nullptr)
        return nullptr;

    VSIArchiveReader* poReader = OpenArchiveFile(tarFilename, osTarInFileName);
    if (poReader == nullptr)
    {
        CPLFree(tarFilename);
        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))
    {
        osSubFileName += "/vsigzip/";
        osSubFileName += tarFilename;
    }
    else
        osSubFileName += tarFilename;

    delete(poReader);

    CPLFree(tarFilename);
    tarFilename = nullptr;

    return reinterpret_cast<VSIVirtualHandle*>(VSIFOpenL(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

 @since GDAL 1.8.0
 */

void VSIInstallTarFileHandler(void)
{
    VSIFileManager::InstallHandler( "/vsitar/", new VSITarFilesystemHandler() );
}
