/******************************************************************************
 *
 * Project:  OpenGIS Simple Features Reference Implementation
 * Author:   Even Rouault, <even dot rouault at mines dash paris dot org>
 * Purpose:  OSM XML and OSM PBF parser
 *
 ******************************************************************************
 * Copyright (c) 2012-2013, Even Rouault <even dot rouault at mines-paris dot org>
 *
 * 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.
 ****************************************************************************/

#include "osm_parser.h"
#include "gpb.h"

#include <climits>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <exception>
#include <string>
#include <vector>

#include "cpl_config.h"
#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_multiproc.h"
#include "cpl_string.h"
#include "cpl_vsi.h"
#include "cpl_worker_thread_pool.h"


#ifdef HAVE_EXPAT
#include "ogr_expat.h"
#endif

CPL_CVSID("$Id: osm_parser.cpp 492e798bc6ac5f2aadcd051228c3c2cb7d774c40 2019-03-23 14:03:24 +0100 Even Rouault $")

// The buffer that are passed to GPB decoding are extended with 0's
// to be sure that we will be able to read a single 64bit value without
// doing checks for each byte.
constexpr int EXTRA_BYTES = 1;

#ifdef HAVE_EXPAT
constexpr int XML_BUFSIZE = 64 * 1024;
#endif

// Per OSM PBF spec
constexpr unsigned int MAX_BLOB_HEADER_SIZE = 64 * 1024;

// Per OSM PBF spec (usually much smaller !)
constexpr unsigned int MAX_BLOB_SIZE = 64 * 1024 * 1024;

// GDAL implementation limits
constexpr unsigned int MAX_ACC_BLOB_SIZE = 50 * 1024 * 1024;
constexpr unsigned int MAX_ACC_UNCOMPRESSED_SIZE = 100 * 1024 * 1024;
constexpr int N_MAX_JOBS = 1024;

#if defined(__GNUC__)
#define CPL_NO_INLINE __attribute__ ((noinline))
#else
#define CPL_NO_INLINE
#endif

class OSMParsingException: public std::exception
{
        std::string m_osMessage;
    public:
        explicit OSMParsingException(int nLine): m_osMessage(
            CPLSPrintf("Parsing error occurred at line %d", nLine)) {}

        const char* what() const noexcept override
                                        { return m_osMessage.c_str(); }
};

#define THROW_OSM_PARSING_EXCEPTION throw OSMParsingException(__LINE__)


/************************************************************************/
/*                            INIT_INFO()                               */
/************************************************************************/

static void INIT_INFO( OSMInfo *sInfo )
{
    sInfo->ts.nTimeStamp = 0;
    sInfo->nChangeset = 0;
    sInfo->nVersion = 0;
    sInfo->nUID = 0;
    sInfo->bTimeStampIsStr = false;
    sInfo->pszUserSID = nullptr;
}

/************************************************************************/
/*                            _OSMContext                               */
/************************************************************************/

typedef struct
{
    const GByte *pabySrc;
    size_t       nSrcSize;
    GByte       *pabyDstBase;
    size_t       nDstOffset;
    size_t       nDstSize;
    bool         bStatus;
} DecompressionJob;

struct _OSMContext
{
    char          *pszStrBuf;
    int           *panStrOff;
    unsigned int   nStrCount;
    unsigned int   nStrAllocated;

    OSMNode       *pasNodes;
    unsigned int   nNodesAllocated;

    OSMTag        *pasTags;
    unsigned int   nTagsAllocated;

    OSMMember     *pasMembers;
    unsigned int   nMembersAllocated;

    GIntBig       *panNodeRefs;
    unsigned int   nNodeRefsAllocated;

    int            nGranularity;
    int            nDateGranularity;
    GIntBig        nLatOffset;
    GIntBig        nLonOffset;

    // concatenated protocol buffer messages BLOB_OSMDATA, or single BLOB_OSMHEADER
    GByte         *pabyBlob;
    unsigned int   nBlobSizeAllocated;
    unsigned int   nBlobOffset;
    unsigned int   nBlobSize;

    GByte         *pabyBlobHeader; // MAX_BLOB_HEADER_SIZE+EXTRA_BYTES large

    CPLWorkerThreadPool* poWTP;

    GByte         *pabyUncompressed;
    unsigned int   nUncompressedAllocated;
    unsigned int   nTotalUncompressedSize;

    DecompressionJob asJobs[N_MAX_JOBS];
    int              nJobs;
    int              iNextJob;

#ifdef HAVE_EXPAT
    XML_Parser     hXMLParser;
    bool           bEOF;
    bool           bStopParsing;
    bool           bHasFoundFeature;
    int            nWithoutEventCounter;
    int            nDataHandlerCounter;

    unsigned int   nStrLength;
    unsigned int   nTags;

    bool           bInNode;
    bool           bInWay;
    bool           bInRelation;

    OSMWay         sWay;
    OSMRelation    sRelation;

    bool           bTryToFetchBounds;
#endif

    VSILFILE      *fp;

    bool           bPBF;

    double         dfLeft;
    double         dfRight;
    double         dfTop;
    double         dfBottom;

    GUIntBig        nBytesRead;

    NotifyNodesFunc     pfnNotifyNodes;
    NotifyWayFunc       pfnNotifyWay;
    NotifyRelationFunc  pfnNotifyRelation;
    NotifyBoundsFunc    pfnNotifyBounds;
    void               *user_data;
};

/************************************************************************/
/*                          ReadBlobHeader()                            */
/************************************************************************/

constexpr int BLOBHEADER_IDX_TYPE = 1;
constexpr int BLOBHEADER_IDX_INDEXDATA = 2;
constexpr int BLOBHEADER_IDX_DATASIZE = 3;

typedef enum
{
    BLOB_UNKNOWN,
    BLOB_OSMHEADER,
    BLOB_OSMDATA
} BlobType;

static
bool ReadBlobHeader( const GByte* pabyData, const GByte* pabyDataLimit,
                     unsigned int* pnBlobSize, BlobType* peBlobType )
{
    *pnBlobSize = 0;
    *peBlobType = BLOB_UNKNOWN;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(BLOBHEADER_IDX_TYPE, WT_DATA) )
            {
                unsigned int nDataLength = 0;
                READ_SIZE(pabyData, pabyDataLimit, nDataLength);

                if( nDataLength == 7 && memcmp(pabyData, "OSMData", 7) == 0 )
                {
                    *peBlobType = BLOB_OSMDATA;
                }
                else if( nDataLength == 9 && memcmp(pabyData, "OSMHeader", 9) == 0 )
                {
                    *peBlobType = BLOB_OSMHEADER;
                }

                pabyData += nDataLength;
            }
            else if( nKey == MAKE_KEY(BLOBHEADER_IDX_INDEXDATA, WT_DATA) )
            {
                // Ignored if found.
                unsigned int nDataLength = 0;
                READ_SIZE(pabyData, pabyDataLimit, nDataLength);
                pabyData += nDataLength;
            }
            else if( nKey == MAKE_KEY(BLOBHEADER_IDX_DATASIZE, WT_VARINT) )
            {
                unsigned int nBlobSize = 0;
                READ_VARUINT32(pabyData, pabyDataLimit, nBlobSize);
                // printf("nBlobSize = %d\n", nBlobSize);
                *pnBlobSize = nBlobSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          ReadHeaderBBox()                            */
/************************************************************************/

constexpr int HEADERBBOX_IDX_LEFT = 1;
constexpr int HEADERBBOX_IDX_RIGHT = 2;
constexpr int HEADERBBOX_IDX_TOP = 3;
constexpr int HEADERBBOX_IDX_BOTTOM = 4;

static
bool ReadHeaderBBox( const GByte* pabyData, const GByte* pabyDataLimit,
                     OSMContext* psCtxt )
{
    psCtxt->dfLeft = 0.0;
    psCtxt->dfRight = 0.0;
    psCtxt->dfTop = 0.0;
    psCtxt->dfBottom = 0.0;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(HEADERBBOX_IDX_LEFT, WT_VARINT) )
            {
                GIntBig nLeft = 0;
                READ_VARSINT64(pabyData, pabyDataLimit, nLeft);
                psCtxt->dfLeft = nLeft * 1e-9;
            }
            else if( nKey == MAKE_KEY(HEADERBBOX_IDX_RIGHT, WT_VARINT) )
            {
                GIntBig nRight = 0;
                READ_VARSINT64(pabyData, pabyDataLimit, nRight);
                psCtxt->dfRight = nRight * 1e-9;
            }
            else if( nKey == MAKE_KEY(HEADERBBOX_IDX_TOP, WT_VARINT) )
            {
                GIntBig nTop = 0;
                READ_VARSINT64(pabyData, pabyDataLimit, nTop);
                psCtxt->dfTop = nTop * 1e-9;
            }
            else if( nKey == MAKE_KEY(HEADERBBOX_IDX_BOTTOM, WT_VARINT) )
            {
                GIntBig nBottom = 0;
                READ_VARSINT64(pabyData, pabyDataLimit, nBottom);
                psCtxt->dfBottom = nBottom * 1e-9;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        psCtxt->pfnNotifyBounds(psCtxt->dfLeft, psCtxt->dfBottom,
                                psCtxt->dfRight, psCtxt->dfTop,
                                psCtxt, psCtxt->user_data);

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          ReadOSMHeader()                             */
/************************************************************************/

constexpr int OSMHEADER_IDX_BBOX              = 1;
constexpr int OSMHEADER_IDX_REQUIRED_FEATURES = 4;
constexpr int OSMHEADER_IDX_OPTIONAL_FEATURES = 5;
constexpr int OSMHEADER_IDX_WRITING_PROGRAM   = 16;
constexpr int OSMHEADER_IDX_SOURCE            = 17;

/* Ignored */
constexpr int OSMHEADER_IDX_OSMOSIS_REPLICATION_TIMESTAMP  = 32;
constexpr int OSMHEADER_IDX_OSMOSIS_REPLICATION_SEQ_NUMBER = 33;
constexpr int OSMHEADER_IDX_OSMOSIS_REPLICATION_BASE_URL   = 34;

static
bool ReadOSMHeader( const GByte* pabyData, const GByte* pabyDataLimit,
                    OSMContext* psCtxt )
{
    char* pszTxt = nullptr;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(OSMHEADER_IDX_BBOX, WT_DATA) )
            {
                unsigned int nBBOXSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nBBOXSize);

                if( !ReadHeaderBBox(pabyData, pabyData + nBBOXSize, psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nBBOXSize;
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_REQUIRED_FEATURES, WT_DATA) )
            {
                READ_TEXT(pabyData, pabyDataLimit, pszTxt);
                // printf("OSMHEADER_IDX_REQUIRED_FEATURES = %s\n", pszTxt)
                if( !(strcmp(pszTxt, "OsmSchema-V0.6") == 0 ||
                    strcmp(pszTxt, "DenseNodes") == 0) )
                {
                    CPLError(CE_Failure, CPLE_NotSupported,
                            "Error: unsupported required feature : %s",
                            pszTxt);
                    VSIFree(pszTxt);
                    THROW_OSM_PARSING_EXCEPTION;
                }
                VSIFree(pszTxt);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_OPTIONAL_FEATURES, WT_DATA) )
            {
                READ_TEXT(pabyData, pabyDataLimit, pszTxt);
                // printf("OSMHEADER_IDX_OPTIONAL_FEATURES = %s\n", pszTxt);
                VSIFree(pszTxt);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_WRITING_PROGRAM, WT_DATA) )
            {
                READ_TEXT(pabyData, pabyDataLimit, pszTxt);
                // printf("OSMHEADER_IDX_WRITING_PROGRAM = %s\n", pszTxt);
                VSIFree(pszTxt);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_SOURCE, WT_DATA) )
            {
                READ_TEXT(pabyData, pabyDataLimit, pszTxt);
                // printf("OSMHEADER_IDX_SOURCE = %s\n", pszTxt);
                VSIFree(pszTxt);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_OSMOSIS_REPLICATION_TIMESTAMP,
                                    WT_VARINT) )
            {
                SKIP_VARINT(pabyData, pabyDataLimit);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_OSMOSIS_REPLICATION_SEQ_NUMBER,
                                    WT_VARINT) )
            {
                SKIP_VARINT(pabyData, pabyDataLimit);
            }
            else if( nKey == MAKE_KEY(OSMHEADER_IDX_OSMOSIS_REPLICATION_BASE_URL,
                                    WT_DATA) )
            {
                READ_TEXT(pabyData, pabyDataLimit, pszTxt);
                /* printf("OSMHEADER_IDX_OSMOSIS_REPLICATION_BASE_URL = %s\n", pszTxt); */
                VSIFree(pszTxt);
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                         ReadStringTable()                            */
/************************************************************************/

constexpr int READSTRINGTABLE_IDX_STRING = 1;

static
bool ReadStringTable( const GByte* pabyData, const GByte* pabyDataLimit,
                      OSMContext* psCtxt )
{
    char* pszStrBuf = (char*)pabyData;

    unsigned int nStrCount = 0;
    int* panStrOff = psCtxt->panStrOff;

    psCtxt->pszStrBuf = pszStrBuf;

    try
    {
        if( (unsigned int)(pabyDataLimit - pabyData) > psCtxt->nStrAllocated )
        {
            psCtxt->nStrAllocated = std::max(psCtxt->nStrAllocated * 2,
                                            (unsigned int)(pabyDataLimit - pabyData));
            int* panStrOffNew = (int*) VSI_REALLOC_VERBOSE(
                panStrOff, psCtxt->nStrAllocated * sizeof(int));
            if( panStrOffNew == nullptr )
                THROW_OSM_PARSING_EXCEPTION;
            panStrOff = panStrOffNew;
        }

        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            while (nKey == MAKE_KEY(READSTRINGTABLE_IDX_STRING, WT_DATA))
            {
                unsigned int nDataLength = 0;
                READ_SIZE(pabyData, pabyDataLimit, nDataLength);

                panStrOff[nStrCount ++] = static_cast<int>(pabyData - (GByte*)pszStrBuf);
                GByte* pbSaved = const_cast<GByte*>(&pabyData[nDataLength]);

                pabyData += nDataLength;

                if( pabyData < pabyDataLimit )
                {
                    READ_FIELD_KEY(nKey);
                    *pbSaved = 0;
                    /* printf("string[%d] = %s\n", nStrCount-1, pbSaved - nDataLength); */
                }
                else
                {
                    *pbSaved = 0;
                    /* printf("string[%d] = %s\n", nStrCount-1, pbSaved - nDataLength); */
                    break;
                }
            }

            if( pabyData < pabyDataLimit )
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        psCtxt->panStrOff = panStrOff;
        psCtxt->nStrCount = nStrCount;

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        psCtxt->panStrOff = panStrOff;
        psCtxt->nStrCount = nStrCount;
        return false;
    }
}

/************************************************************************/
/*                     AddWithOverflowAccepted()                        */
/************************************************************************/

CPL_NOSANITIZE_UNSIGNED_INT_OVERFLOW
static GIntBig AddWithOverflowAccepted(GIntBig a, GIntBig b)
{
    // Assumes complement-to-two signed integer representation and that
    // the compiler will safely cast a negative number to unsigned and a
    // big unsigned to negative integer.
    return static_cast<GIntBig>(
                        static_cast<GUIntBig>(a) + static_cast<GUIntBig>(b));
}

CPL_NOSANITIZE_UNSIGNED_INT_OVERFLOW
static int AddWithOverflowAccepted(int a, int b)
{
    // Assumes complement-to-two signed integer representation and that
    // the compiler will safely cast a negative number to unsigned and a
    // big unsigned to negative integer.
    return static_cast<int>(
                        static_cast<unsigned>(a) + static_cast<unsigned>(b));
}

CPL_NOSANITIZE_UNSIGNED_INT_OVERFLOW
static unsigned AddWithOverflowAccepted(unsigned a, int b)
{
    // Assumes complement-to-two signed integer representation and that
    // the compiler will safely cast a negative number to unsigned.
    return a + static_cast<unsigned>(b);
}

/************************************************************************/
/*                         ReadDenseNodes()                             */
/************************************************************************/

constexpr int DENSEINFO_IDX_VERSION   = 1;
constexpr int DENSEINFO_IDX_TIMESTAMP = 2;
constexpr int DENSEINFO_IDX_CHANGESET = 3;
constexpr int DENSEINFO_IDX_UID       = 4;
constexpr int DENSEINFO_IDX_USER_SID  = 5;
constexpr int DENSEINFO_IDX_VISIBLE   = 6;

constexpr int DENSENODES_IDX_ID        = 1;
constexpr int DENSENODES_IDX_DENSEINFO = 5;
constexpr int DENSENODES_IDX_LAT       = 8;
constexpr int DENSENODES_IDX_LON       = 9;
constexpr int DENSENODES_IDX_KEYVALS   = 10;

static
bool ReadDenseNodes( const GByte* pabyData, const GByte* pabyDataLimit,
                     OSMContext* psCtxt )
{
    const GByte* pabyDataIDs = nullptr;
    const GByte* pabyDataIDsLimit = nullptr;
    const GByte* pabyDataLat = nullptr;
    const GByte* pabyDataLon = nullptr;
    const GByte* apabyData[DENSEINFO_IDX_VISIBLE] = {nullptr, nullptr, nullptr,
                                               nullptr, nullptr, nullptr};
    const GByte* pabyDataKeyVal = nullptr;
    unsigned int nMaxTags = 0;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(DENSENODES_IDX_ID, WT_DATA) )
            {
                unsigned int nSize = 0;

                if( pabyDataIDs != nullptr )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nNodesAllocated )
                {
                    psCtxt->nNodesAllocated = std::max(psCtxt->nNodesAllocated * 2,
                                                    nSize);
                    OSMNode* pasNodesNew = (OSMNode*) VSI_REALLOC_VERBOSE(
                        psCtxt->pasNodes, psCtxt->nNodesAllocated * sizeof(OSMNode));
                    if( pasNodesNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasNodes = pasNodesNew;
                }

                pabyDataIDs = pabyData;
                pabyDataIDsLimit = pabyData + nSize;
                pabyData += nSize;
            }
            else if( nKey == MAKE_KEY(DENSENODES_IDX_DENSEINFO, WT_DATA) )
            {
                unsigned int nSize = 0;

                READ_SIZE(pabyData, pabyDataLimit, nSize);

                /* Inline reading of DenseInfo structure */

                const GByte* pabyDataNewLimit = pabyData + nSize;
                while(pabyData < pabyDataNewLimit)
                {
                    READ_FIELD_KEY(nKey);

                    const int nFieldNumber = GET_FIELDNUMBER(nKey);
                    if( GET_WIRETYPE(nKey) == WT_DATA &&
                        nFieldNumber >= DENSEINFO_IDX_VERSION &&
                        nFieldNumber <= DENSEINFO_IDX_VISIBLE )
                    {
                        if( apabyData[nFieldNumber - 1] != nullptr) THROW_OSM_PARSING_EXCEPTION;
                        READ_SIZE(pabyData, pabyDataNewLimit, nSize);

                        apabyData[nFieldNumber - 1] = pabyData;
                        pabyData += nSize;
                    }
                    else
                    {
                        SKIP_UNKNOWN_FIELD(pabyData, pabyDataNewLimit, TRUE);
                    }
                }

                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(DENSENODES_IDX_LAT, WT_DATA) )
            {
                if( pabyDataLat != nullptr )
                    THROW_OSM_PARSING_EXCEPTION;
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);
                pabyDataLat = pabyData;
                pabyData += nSize;
            }
            else if( nKey == MAKE_KEY(DENSENODES_IDX_LON, WT_DATA) )
            {
                if( pabyDataLon != nullptr )
                    THROW_OSM_PARSING_EXCEPTION;
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);
                pabyDataLon = pabyData;
                pabyData += nSize;
            }
            else if( nKey == MAKE_KEY(DENSENODES_IDX_KEYVALS, WT_DATA) )
            {
                if( pabyDataKeyVal != nullptr )
                    THROW_OSM_PARSING_EXCEPTION;
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                pabyDataKeyVal = pabyData;
                nMaxTags = nSize / 2;

                if( nMaxTags > psCtxt->nTagsAllocated )
                {

                    psCtxt->nTagsAllocated = std::max(
                        psCtxt->nTagsAllocated * 2, nMaxTags);
                    OSMTag* pasTagsNew = (OSMTag*) VSI_REALLOC_VERBOSE(
                        psCtxt->pasTags,
                        psCtxt->nTagsAllocated * sizeof(OSMTag));
                    if( pasTagsNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasTags = pasTagsNew;
                }

                pabyData += nSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        if( pabyData != pabyDataLimit )
            THROW_OSM_PARSING_EXCEPTION;

        if( pabyDataIDs != nullptr && pabyDataLat != nullptr &&
            pabyDataLon != nullptr )
        {
            const GByte* pabyDataVersion = apabyData[DENSEINFO_IDX_VERSION - 1];
            const GByte* pabyDataTimeStamp = apabyData[DENSEINFO_IDX_TIMESTAMP - 1];
            const GByte* pabyDataChangeset = apabyData[DENSEINFO_IDX_CHANGESET - 1];
            const GByte* pabyDataUID = apabyData[DENSEINFO_IDX_UID - 1];
            const GByte* pabyDataUserSID = apabyData[DENSEINFO_IDX_USER_SID - 1];
            /* GByte* pabyDataVisible = apabyData[DENSEINFO_IDX_VISIBLE - 1]; */

            GIntBig nID = 0;
            GIntBig nLat = 0;
            GIntBig nLon = 0;
            GIntBig nTimeStamp = 0;
            GIntBig nChangeset = 0;
            int nUID = 0;
            unsigned int nUserSID = 0;
            int nTags = 0;
            int nNodes = 0;

            const char* pszStrBuf = psCtxt->pszStrBuf;
            int* panStrOff = psCtxt->panStrOff;
            const unsigned int nStrCount = psCtxt->nStrCount;
            OSMTag* pasTags = psCtxt->pasTags;
            OSMNode* pasNodes = psCtxt->pasNodes;

            int nVersion = 0;
            /* int nVisible = 1; */

            while(pabyDataIDs < pabyDataIDsLimit)
            {
                GIntBig nDelta1, nDelta2;
                int nKVIndexStart = nTags;

                READ_VARSINT64_NOCHECK(pabyDataIDs, pabyDataIDsLimit, nDelta1);
                READ_VARSINT64(pabyDataLat, pabyDataLimit, nDelta2);
                nID = AddWithOverflowAccepted(nID, nDelta1);
                nLat = AddWithOverflowAccepted(nLat, nDelta2);

                READ_VARSINT64(pabyDataLon, pabyDataLimit, nDelta1);
                nLon = AddWithOverflowAccepted(nLon, nDelta1);

                if( pabyDataTimeStamp )
                {
                    READ_VARSINT64(pabyDataTimeStamp, pabyDataLimit, nDelta2);
                    nTimeStamp = AddWithOverflowAccepted(nTimeStamp, nDelta2);
                }
                if( pabyDataChangeset )
                {
                    READ_VARSINT64(pabyDataChangeset, pabyDataLimit, nDelta1);
                    nChangeset = AddWithOverflowAccepted(nChangeset, nDelta1);
                }
                if( pabyDataVersion )
                {
                    READ_VARINT32(pabyDataVersion, pabyDataLimit, nVersion);
                }
                if( pabyDataUID )
                {
                    int nDeltaUID = 0;
                    READ_VARSINT32(pabyDataUID, pabyDataLimit, nDeltaUID);
                    nUID = AddWithOverflowAccepted(nUID, nDeltaUID);
                }
                if( pabyDataUserSID )
                {
                    int nDeltaUserSID = 0;
                    READ_VARSINT32(pabyDataUserSID, pabyDataLimit, nDeltaUserSID);
                    nUserSID = AddWithOverflowAccepted(nUserSID, nDeltaUserSID);
                    if( nUserSID >= nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;
                }
                /* if( pabyDataVisible )
                    READ_VARINT32(pabyDataVisible, pabyDataLimit, nVisible); */

                if( pabyDataKeyVal != nullptr && pasTags != nullptr )
                {
                    while( static_cast<unsigned>(nTags) < nMaxTags )
                    {
                        unsigned int nKey, nVal;
                        READ_VARUINT32(pabyDataKeyVal, pabyDataLimit, nKey);
                        if( nKey == 0 )
                            break;
                        if( nKey >= nStrCount )
                            THROW_OSM_PARSING_EXCEPTION;

                        READ_VARUINT32(pabyDataKeyVal, pabyDataLimit, nVal);
                        if( nVal >= nStrCount )
                            THROW_OSM_PARSING_EXCEPTION;

                        pasTags[nTags].pszK = pszStrBuf + panStrOff[nKey];
                        pasTags[nTags].pszV = pszStrBuf + panStrOff[nVal];
                        nTags ++;

                        /* printf("nKey = %d, nVal = %d\n", nKey, nVal); */
                    }
                }

                if( pasTags != nullptr && nTags > nKVIndexStart )
                    pasNodes[nNodes].pasTags = pasTags + nKVIndexStart;
                else
                    pasNodes[nNodes].pasTags = nullptr;
                pasNodes[nNodes].nTags = nTags - nKVIndexStart;

                pasNodes[nNodes].nID = nID;
                pasNodes[nNodes].dfLat = .000000001 * (psCtxt->nLatOffset + ((double)psCtxt->nGranularity * nLat));
                pasNodes[nNodes].dfLon = .000000001 * (psCtxt->nLonOffset + ((double)psCtxt->nGranularity * nLon));
                if( pasNodes[nNodes].dfLon < -180 || pasNodes[nNodes].dfLon > 180 ||
                    pasNodes[nNodes].dfLat < -90 || pasNodes[nNodes].dfLat > 90 )
                    THROW_OSM_PARSING_EXCEPTION;
                pasNodes[nNodes].sInfo.bTimeStampIsStr = false;
                pasNodes[nNodes].sInfo.ts.nTimeStamp = nTimeStamp;
                pasNodes[nNodes].sInfo.nChangeset = nChangeset;
                pasNodes[nNodes].sInfo.nVersion = nVersion;
                pasNodes[nNodes].sInfo.nUID = nUID;
                if( nUserSID >= nStrCount )
                    pasNodes[nNodes].sInfo.pszUserSID = "";
                else
                    pasNodes[nNodes].sInfo.pszUserSID = pszStrBuf + panStrOff[nUserSID];
                /* pasNodes[nNodes].sInfo.nVisible = nVisible; */
                nNodes ++;
                /* printf("nLat = " CPL_FRMT_GIB "\n", nLat); printf("nLon = " CPL_FRMT_GIB "\n", nLon); */
            }

            psCtxt->pfnNotifyNodes(nNodes, pasNodes, psCtxt, psCtxt->user_data);

            if(pabyDataIDs != pabyDataIDsLimit)
                THROW_OSM_PARSING_EXCEPTION;
        }

        return true;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                           ReadOSMInfo()                              */
/************************************************************************/

constexpr int INFO_IDX_VERSION   = 1;
constexpr int INFO_IDX_TIMESTAMP = 2;
constexpr int INFO_IDX_CHANGESET = 3;
constexpr int INFO_IDX_UID       = 4;
constexpr int INFO_IDX_USER_SID  = 5;
constexpr int INFO_IDX_VISIBLE   = 6;

static
bool ReadOSMInfo( const GByte* pabyData, const GByte* pabyDataLimit,
                  OSMInfo* psInfo, OSMContext* psContext ) CPL_NO_INLINE;

static
bool ReadOSMInfo( const GByte* pabyData, const GByte* pabyDataLimit,
                  OSMInfo* psInfo, OSMContext* psContext )
{
    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(INFO_IDX_VERSION, WT_VARINT) )
            {
                READ_VARINT32(pabyData, pabyDataLimit, psInfo->nVersion);
            }
            else if( nKey == MAKE_KEY(INFO_IDX_TIMESTAMP, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, psInfo->ts.nTimeStamp);
            }
            else if( nKey == MAKE_KEY(INFO_IDX_CHANGESET, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, psInfo->nChangeset);
            }
            else if( nKey == MAKE_KEY(INFO_IDX_UID, WT_VARINT) )
            {
                READ_VARINT32(pabyData, pabyDataLimit, psInfo->nUID);
            }
            else if( nKey == MAKE_KEY(INFO_IDX_USER_SID, WT_VARINT) )
            {
                unsigned int nUserSID = 0;
                READ_VARUINT32(pabyData, pabyDataLimit, nUserSID);
                if( nUserSID < psContext->nStrCount)
                    psInfo->pszUserSID = psContext->pszStrBuf +
                                        psContext->panStrOff[nUserSID];
            }
            else if( nKey == MAKE_KEY(INFO_IDX_VISIBLE, WT_VARINT) )
            {
                SKIP_VARINT(pabyData, pabyDataLimit);
                // int nVisible = 0;
                // READ_VARINT32(pabyData, pabyDataLimit, /*psInfo->*/nVisible);
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                             ReadNode()                               */
/************************************************************************/

/* From https://github.com/openstreetmap/osmosis/blob/master/osmosis-osm-binary/src/main/protobuf/osmformat.proto */
/* The one advertized in http://wiki.openstreetmap.org/wiki/PBF_Format and */
/* used previously seem wrong/old-dated */

constexpr int NODE_IDX_ID   = 1;
constexpr int NODE_IDX_LAT  = 8;
constexpr int NODE_IDX_LON  = 9;
constexpr int NODE_IDX_KEYS = 2;
constexpr int NODE_IDX_VALS = 3;
constexpr int NODE_IDX_INFO = 4;

static
bool ReadNode( const GByte* pabyData, const GByte* pabyDataLimit,
               OSMContext* psCtxt )
{
    OSMNode sNode;

    sNode.nID = 0;
    sNode.dfLat = 0.0;
    sNode.dfLon = 0.0;
    INIT_INFO(&(sNode.sInfo));
    sNode.nTags = 0;
    sNode.pasTags = nullptr;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(NODE_IDX_ID, WT_VARINT) )
            {
                READ_VARSINT64_NOCHECK(pabyData, pabyDataLimit, sNode.nID);
            }
            else if( nKey == MAKE_KEY(NODE_IDX_LAT, WT_VARINT) )
            {
                GIntBig nLat = 0;
                READ_VARSINT64_NOCHECK(pabyData, pabyDataLimit, nLat);
                sNode.dfLat =
                    0.000000001 * (psCtxt->nLatOffset +
                                ((double)psCtxt->nGranularity * nLat));
            }
            else if( nKey == MAKE_KEY(NODE_IDX_LON, WT_VARINT) )
            {
                GIntBig nLon = 0;
                READ_VARSINT64_NOCHECK(pabyData, pabyDataLimit, nLon);
                sNode.dfLon =
                    0.000000001 * (psCtxt->nLonOffset +
                                ((double)psCtxt->nGranularity * nLon));
            }
            else if( nKey == MAKE_KEY(NODE_IDX_KEYS, WT_DATA) )
            {
                unsigned int nSize = 0;
                const GByte* pabyDataNewLimit = nullptr;
                if( sNode.nTags != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nTagsAllocated )
                {
                    psCtxt->nTagsAllocated = std::max(
                        psCtxt->nTagsAllocated * 2, nSize);
                    OSMTag* pasTagsNew = (OSMTag*) VSI_REALLOC_VERBOSE(
                        psCtxt->pasTags,
                        psCtxt->nTagsAllocated * sizeof(OSMTag));
                    if( pasTagsNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasTags = pasTagsNew;
                }

                pabyDataNewLimit = pabyData + nSize;
                while (pabyData < pabyDataNewLimit)
                {
                    unsigned int nKey2 = 0;
                    READ_VARUINT32(pabyData, pabyDataNewLimit, nKey2);

                    if( nKey2 >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[sNode.nTags].pszK = psCtxt->pszStrBuf +
                                                psCtxt->panStrOff[nKey2];
                    psCtxt->pasTags[sNode.nTags].pszV = "";
                    sNode.nTags ++;
                }
                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(NODE_IDX_VALS, WT_DATA) )
            {
                unsigned int nIter = 0;
                if( sNode.nTags == 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                // unsigned int nSize = 0;
                // READ_VARUINT32(pabyData, pabyDataLimit, nSize);
                SKIP_VARINT(pabyData, pabyDataLimit);

                for( ; nIter < sNode.nTags; nIter++)
                {
                    unsigned int nVal = 0;
                    READ_VARUINT32(pabyData, pabyDataLimit, nVal);

                    if( nVal >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[nIter].pszV = psCtxt->pszStrBuf +
                                                psCtxt->panStrOff[nVal];
                }
            }
            else if( nKey == MAKE_KEY(NODE_IDX_INFO, WT_DATA) )
            {
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( !ReadOSMInfo(pabyData, pabyDataLimit + nSize,
                                &sNode.sInfo, psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        if( sNode.dfLon < -180 || sNode.dfLon > 180 ||
            sNode.dfLat < -90 || sNode.dfLat > 90 )
            THROW_OSM_PARSING_EXCEPTION;

        if( pabyData != pabyDataLimit )
            THROW_OSM_PARSING_EXCEPTION;

        if( sNode.nTags )
            sNode.pasTags = psCtxt->pasTags;
        else
            sNode.pasTags = nullptr;
        psCtxt->pfnNotifyNodes(1, &sNode, psCtxt, psCtxt->user_data);

        return true;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                              ReadWay()                               */
/************************************************************************/

constexpr int WAY_IDX_ID   = 1;
constexpr int WAY_IDX_KEYS = 2;
constexpr int WAY_IDX_VALS = 3;
constexpr int WAY_IDX_INFO = 4;
constexpr int WAY_IDX_REFS = 8;

static
bool ReadWay( const GByte* pabyData, const GByte* pabyDataLimit,
              OSMContext* psCtxt )
{
    OSMWay sWay;
    sWay.nID = 0;
    INIT_INFO(&(sWay.sInfo));
    sWay.nTags = 0;
    sWay.nRefs = 0;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(WAY_IDX_ID, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, sWay.nID);
            }
            else if( nKey == MAKE_KEY(WAY_IDX_KEYS, WT_DATA) )
            {
                unsigned int nSize = 0;
                const GByte* pabyDataNewLimit = nullptr;
                if( sWay.nTags != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nTagsAllocated )
                {
                    psCtxt->nTagsAllocated = std::max(
                        psCtxt->nTagsAllocated * 2, nSize);
                    OSMTag* pasTagsNew = (OSMTag*) VSI_REALLOC_VERBOSE(
                        psCtxt->pasTags,
                        psCtxt->nTagsAllocated * sizeof(OSMTag));
                    if( pasTagsNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasTags = pasTagsNew;
                }

                pabyDataNewLimit = pabyData + nSize;
                while (pabyData < pabyDataNewLimit)
                {
                    unsigned int nKey2 = 0;
                    READ_VARUINT32(pabyData, pabyDataNewLimit, nKey2);

                    if( nKey2 >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[sWay.nTags].pszK = psCtxt->pszStrBuf +
                                                    psCtxt->panStrOff[nKey2];
                    psCtxt->pasTags[sWay.nTags].pszV = "";
                    sWay.nTags ++;
                }
                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(WAY_IDX_VALS, WT_DATA) )
            {
                unsigned int nIter = 0;
                if( sWay.nTags == 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                // unsigned int nSize = 0;
                // READ_VARUINT32(pabyData, pabyDataLimit, nSize);
                SKIP_VARINT(pabyData, pabyDataLimit);

                for(; nIter < sWay.nTags; nIter ++)
                {
                    unsigned int nVal = 0;
                    READ_VARUINT32(pabyData, pabyDataLimit, nVal);

                    if( nVal >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[nIter].pszV = psCtxt->pszStrBuf +
                                                psCtxt->panStrOff[nVal];
                }
            }
            else if( nKey == MAKE_KEY(WAY_IDX_INFO, WT_DATA) )
            {
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( !ReadOSMInfo(pabyData, pabyData + nSize, &sWay.sInfo, psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;
            }
            else if( nKey == MAKE_KEY(WAY_IDX_REFS, WT_DATA) )
            {
                GIntBig nRefVal = 0;
                unsigned int nSize = 0;
                const GByte* pabyDataNewLimit = nullptr;
                if( sWay.nRefs != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nNodeRefsAllocated )
                {
                    psCtxt->nNodeRefsAllocated =
                        std::max(psCtxt->nNodeRefsAllocated * 2, nSize);
                    GIntBig* panNodeRefsNew = (GIntBig*) VSI_REALLOC_VERBOSE(
                            psCtxt->panNodeRefs,
                            psCtxt->nNodeRefsAllocated * sizeof(GIntBig));
                    if( panNodeRefsNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->panNodeRefs = panNodeRefsNew;
                }

                pabyDataNewLimit = pabyData + nSize;
                while (pabyData < pabyDataNewLimit)
                {
                    GIntBig nDeltaRef = 0;
                    READ_VARSINT64_NOCHECK(pabyData, pabyDataNewLimit, nDeltaRef);
                    nRefVal = AddWithOverflowAccepted(nRefVal, nDeltaRef);

                    psCtxt->panNodeRefs[sWay.nRefs ++] = nRefVal;
                }

                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        if( pabyData != pabyDataLimit )
            THROW_OSM_PARSING_EXCEPTION;

        if( sWay.nTags )
            sWay.pasTags = psCtxt->pasTags;
        else
            sWay.pasTags = nullptr;
        sWay.panNodeRefs = psCtxt->panNodeRefs;

        psCtxt->pfnNotifyWay(&sWay, psCtxt, psCtxt->user_data);

        return true;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                            ReadRelation()                            */
/************************************************************************/

constexpr int RELATION_IDX_ID        = 1;
constexpr int RELATION_IDX_KEYS      = 2;
constexpr int RELATION_IDX_VALS      = 3;
constexpr int RELATION_IDX_INFO      = 4;
constexpr int RELATION_IDX_ROLES_SID = 8;
constexpr int RELATION_IDX_MEMIDS    = 9;
constexpr int RELATION_IDX_TYPES     = 10;

static
bool ReadRelation( const GByte* pabyData, const GByte* pabyDataLimit,
                   OSMContext* psCtxt )
{
    OSMRelation sRelation;
    sRelation.nID = 0;
    INIT_INFO(&(sRelation.sInfo));
    sRelation.nTags = 0;
    sRelation.nMembers = 0;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(RELATION_IDX_ID, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, sRelation.nID);
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_KEYS, WT_DATA) )
            {
                unsigned int nSize = 0;
                const GByte* pabyDataNewLimit = nullptr;
                if( sRelation.nTags != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nTagsAllocated )
                {
                    psCtxt->nTagsAllocated = std::max(
                        psCtxt->nTagsAllocated * 2, nSize);
                    OSMTag* pasTagsNew = (OSMTag*) VSI_REALLOC_VERBOSE(
                        psCtxt->pasTags,
                        psCtxt->nTagsAllocated * sizeof(OSMTag));
                    if( pasTagsNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasTags = pasTagsNew;
                }

                pabyDataNewLimit = pabyData + nSize;
                while (pabyData < pabyDataNewLimit)
                {
                    unsigned int nKey2 = 0;
                    READ_VARUINT32(pabyData, pabyDataNewLimit, nKey2);

                    if( nKey2 >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[sRelation.nTags].pszK =
                        psCtxt->pszStrBuf + psCtxt->panStrOff[nKey2];
                    psCtxt->pasTags[sRelation.nTags].pszV = "";
                    sRelation.nTags ++;
                }
                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_VALS, WT_DATA) )
            {
                unsigned int nIter = 0;
                if( sRelation.nTags == 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                // unsigned int nSize = 0;
                // READ_VARUINT32(pabyData, pabyDataLimit, nSize);
                SKIP_VARINT(pabyData, pabyDataLimit);

                for(; nIter < sRelation.nTags; nIter ++)
                {
                    unsigned int nVal = 0;
                    READ_VARUINT32(pabyData, pabyDataLimit, nVal);

                    if( nVal >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasTags[nIter].pszV = psCtxt->pszStrBuf +
                                                psCtxt->panStrOff[nVal];
                }
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_INFO, WT_DATA) )
            {
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( !ReadOSMInfo(pabyData, pabyData + nSize,
                                &sRelation.sInfo, psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_ROLES_SID, WT_DATA) )
            {
                unsigned int nSize = 0;
                const GByte* pabyDataNewLimit = nullptr;
                if( sRelation.nMembers != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( nSize > psCtxt->nMembersAllocated )
                {
                    psCtxt->nMembersAllocated =
                        std::max(psCtxt->nMembersAllocated * 2, nSize);
                    OSMMember* pasMembersNew = (OSMMember*) VSI_REALLOC_VERBOSE(
                            psCtxt->pasMembers,
                            psCtxt->nMembersAllocated * sizeof(OSMMember));
                    if( pasMembersNew == nullptr )
                        THROW_OSM_PARSING_EXCEPTION;
                    psCtxt->pasMembers = pasMembersNew;
                }

                pabyDataNewLimit = pabyData + nSize;
                while (pabyData < pabyDataNewLimit)
                {
                    unsigned int nRoleSID = 0;
                    READ_VARUINT32(pabyData, pabyDataNewLimit, nRoleSID);
                    if( nRoleSID >= psCtxt->nStrCount )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasMembers[sRelation.nMembers].pszRole =
                        psCtxt->pszStrBuf + psCtxt->panStrOff[nRoleSID];
                    psCtxt->pasMembers[sRelation.nMembers].nID = 0;
                    psCtxt->pasMembers[sRelation.nMembers].eType = MEMBER_NODE;
                    sRelation.nMembers ++;
                }

                if( pabyData != pabyDataNewLimit )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_MEMIDS, WT_DATA) )
            {
                unsigned int nIter = 0;
                GIntBig nMemID = 0;
                if( sRelation.nMembers == 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                // unsigned int nSize = 0;
                // READ_VARUINT32(pabyData, pabyDataLimit, nSize);
                SKIP_VARINT(pabyData, pabyDataLimit);

                for(; nIter < sRelation.nMembers; nIter++)
                {
                    GIntBig nDeltaMemID = 0;
                    READ_VARSINT64(pabyData, pabyDataLimit, nDeltaMemID);
                    nMemID = AddWithOverflowAccepted(nMemID, nDeltaMemID);

                    psCtxt->pasMembers[nIter].nID = nMemID;
                }
            }
            else if( nKey == MAKE_KEY(RELATION_IDX_TYPES, WT_DATA) )
            {
                unsigned int nIter = 0;
                if( sRelation.nMembers == 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);
                if( nSize != sRelation.nMembers )
                    THROW_OSM_PARSING_EXCEPTION;

                for(; nIter < sRelation.nMembers; nIter++)
                {
                    unsigned int nType = pabyData[nIter];
                    if( nType > MEMBER_RELATION )
                        THROW_OSM_PARSING_EXCEPTION;

                    psCtxt->pasMembers[nIter].eType = (OSMMemberType) nType;
                }
                pabyData += nSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }
        /* printf("<ReadRelation\n"); */

        if( pabyData != pabyDataLimit )
            THROW_OSM_PARSING_EXCEPTION;

        if( sRelation.nTags )
            sRelation.pasTags = psCtxt->pasTags;
        else
            sRelation.pasTags = nullptr;

        sRelation.pasMembers = psCtxt->pasMembers;

        psCtxt->pfnNotifyRelation(&sRelation, psCtxt, psCtxt->user_data);

        return true;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          ReadPrimitiveGroup()                        */
/************************************************************************/

constexpr int PRIMITIVEGROUP_IDX_NODES = 1;
// constexpr int PRIMITIVEGROUP_IDX_DENSE = 2;
// constexpr int PRIMITIVEGROUP_IDX_WAYS = 3;
constexpr int PRIMITIVEGROUP_IDX_RELATIONS = 4;
// constexpr int PRIMITIVEGROUP_IDX_CHANGESETS = 5;

typedef bool (*PrimitiveFuncType)( const GByte* pabyData,
                                   const GByte* pabyDataLimit,
                                   OSMContext* psCtxt );

static const PrimitiveFuncType apfnPrimitives[] =
{
    ReadNode,
    ReadDenseNodes,
    ReadWay,
    ReadRelation
};

static
bool ReadPrimitiveGroup( const GByte* pabyData, const GByte* pabyDataLimit,
                         OSMContext* psCtxt )
{
    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            const int nFieldNumber = GET_FIELDNUMBER(nKey) - 1;
            if( GET_WIRETYPE(nKey) == WT_DATA &&
                nFieldNumber >= PRIMITIVEGROUP_IDX_NODES - 1 &&
                nFieldNumber <= PRIMITIVEGROUP_IDX_RELATIONS - 1 )
            {
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( !apfnPrimitives[nFieldNumber](pabyData, pabyData + nSize,
                                                psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          ReadPrimitiveBlock()                        */
/************************************************************************/

constexpr int PRIMITIVEBLOCK_IDX_STRINGTABLE      = 1;
constexpr int PRIMITIVEBLOCK_IDX_PRIMITIVEGROUP   = 2;
constexpr int PRIMITIVEBLOCK_IDX_GRANULARITY      = 17;
constexpr int PRIMITIVEBLOCK_IDX_DATE_GRANULARITY = 18;
constexpr int PRIMITIVEBLOCK_IDX_LAT_OFFSET       = 19;
constexpr int PRIMITIVEBLOCK_IDX_LON_OFFSET       = 20;

static
bool ReadPrimitiveBlock( const GByte* pabyData, const GByte* pabyDataLimit,
                         OSMContext* psCtxt )
{
    const GByte* pabyDataSave = pabyData;

    psCtxt->pszStrBuf = nullptr;
    psCtxt->nStrCount = 0;
    psCtxt->nGranularity = 100;
    psCtxt->nDateGranularity = 1000;
    psCtxt->nLatOffset = 0;
    psCtxt->nLonOffset = 0;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_GRANULARITY, WT_VARINT) )
            {
                READ_VARINT32(pabyData, pabyDataLimit, psCtxt->nGranularity);
                if( psCtxt->nGranularity <= 0 )
                    THROW_OSM_PARSING_EXCEPTION;
            }
            else if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_DATE_GRANULARITY,
                                    WT_VARINT) )
            {
                READ_VARINT32(pabyData, pabyDataLimit, psCtxt->nDateGranularity);
            }
            else if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_LAT_OFFSET, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, psCtxt->nLatOffset);
            }
            else if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_LON_OFFSET, WT_VARINT) )
            {
                READ_VARINT64(pabyData, pabyDataLimit, psCtxt->nLonOffset);
            }
            else
            {
                SKIP_UNKNOWN_FIELD_INLINE(pabyData, pabyDataLimit, FALSE);
            }
        }

        if( pabyData != pabyDataLimit )
            THROW_OSM_PARSING_EXCEPTION;

        pabyData = pabyDataSave;
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_STRINGTABLE, WT_DATA) )
            {
                GByte bSaveAfterByte = 0;
                GByte* pbSaveAfterByte = nullptr;
                if( psCtxt->nStrCount != 0 )
                    THROW_OSM_PARSING_EXCEPTION;
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                // Dirty little trick:
                // ReadStringTable() will over-write the byte after the
                // StringTable message with a NUL character, so we backup
                // it to be able to restore it just before issuing the next
                // READ_FIELD_KEY. Then we will re-NUL it to have valid
                // NUL terminated strings.
                // This trick enable us to keep the strings where there are
                // in RAM.
                pbSaveAfterByte = const_cast<GByte*>(pabyData + nSize);
                bSaveAfterByte = *pbSaveAfterByte;

                if( !ReadStringTable(pabyData, pabyData + nSize, psCtxt) )
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;

                *pbSaveAfterByte = bSaveAfterByte;
                if( pabyData == pabyDataLimit )
                    break;

                READ_FIELD_KEY(nKey);
                *pbSaveAfterByte = 0;

                if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_STRINGTABLE, WT_DATA) )
                    THROW_OSM_PARSING_EXCEPTION;

                /* Yes we go on ! */
            }

            if( nKey == MAKE_KEY(PRIMITIVEBLOCK_IDX_PRIMITIVEGROUP, WT_DATA) )
            {
                unsigned int nSize = 0;
                READ_SIZE(pabyData, pabyDataLimit, nSize);

                if( !ReadPrimitiveGroup(pabyData, pabyData + nSize, psCtxt))
                    THROW_OSM_PARSING_EXCEPTION;

                pabyData += nSize;
            }
            else
            {
                SKIP_UNKNOWN_FIELD_INLINE(pabyData, pabyDataLimit, FALSE);
            }
        }

        return pabyData == pabyDataLimit;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          DecompressFunction()                        */
/************************************************************************/

static void DecompressFunction(void* pDataIn)
{
    DecompressionJob* psJob = static_cast<DecompressionJob*>(pDataIn);
    psJob->bStatus =
        CPLZLibInflate( psJob->pabySrc, psJob->nSrcSize,
                        psJob->pabyDstBase + psJob->nDstOffset,
                        psJob->nDstSize, nullptr) != nullptr;
}

/************************************************************************/
/*                      RunDecompressionJobs()                          */
/************************************************************************/

static bool RunDecompressionJobs(OSMContext* psCtxt)
{
    psCtxt->nTotalUncompressedSize = 0;

    GByte* pabyDstBase = psCtxt->pabyUncompressed;
    std::vector<void*> ahJobs;
    for( int i = 0; i < psCtxt->nJobs; i++ )
    {
        psCtxt->asJobs[i].pabyDstBase = pabyDstBase;
        if( psCtxt->poWTP )
            ahJobs.push_back(&psCtxt->asJobs[i]);
        else
            DecompressFunction(&psCtxt->asJobs[i]);
    }
    if( psCtxt->poWTP )
    {
        psCtxt->poWTP->SubmitJobs(DecompressFunction, ahJobs);
        psCtxt->poWTP->WaitCompletion();
    }

    bool bRet = true;
    for( int i = 0; bRet && i < psCtxt->nJobs; i++ )
    {
        bRet &= psCtxt->asJobs[i].bStatus;
    }
    return bRet;
}

/************************************************************************/
/*                          ProcessSingleBlob()                         */
/************************************************************************/

static bool ProcessSingleBlob(OSMContext* psCtxt,
                           DecompressionJob& sJob, BlobType eType)
{
    if( eType == BLOB_OSMHEADER )
    {
        return ReadOSMHeader(
            sJob.pabyDstBase + sJob.nDstOffset,
            sJob.pabyDstBase + sJob.nDstOffset + sJob.nDstSize,
            psCtxt);
    }
    else
    {
        CPLAssert( eType == BLOB_OSMDATA );
        return ReadPrimitiveBlock(
            sJob.pabyDstBase + sJob.nDstOffset,
            sJob.pabyDstBase + sJob.nDstOffset + sJob.nDstSize,
            psCtxt);
    }
}

/************************************************************************/
/*                   RunDecompressionJobsAndProcessAll()                */
/************************************************************************/

static bool RunDecompressionJobsAndProcessAll(OSMContext* psCtxt,
                                              BlobType eType)
{
    if( !RunDecompressionJobs(psCtxt) )
    {
        return false;
    }
    for( int i = 0; i < psCtxt->nJobs; i++ )
    {
        if( !ProcessSingleBlob(psCtxt, psCtxt->asJobs[i], eType) )
        {
            return false;
        }
    }
    psCtxt->iNextJob = 0;
    psCtxt->nJobs = 0;
    return true;
}

/************************************************************************/
/*                              ReadBlob()                              */
/************************************************************************/

constexpr int BLOB_IDX_RAW       = 1;
constexpr int BLOB_IDX_RAW_SIZE  = 2;
constexpr int BLOB_IDX_ZLIB_DATA = 3;

static
bool ReadBlob( OSMContext* psCtxt, BlobType eType )
{
    unsigned int nUncompressedSize = 0;
    bool bRet = true;
    const GByte* pabyData = psCtxt->pabyBlob + psCtxt->nBlobOffset;
    const GByte* pabyLastCheckpointData = pabyData;
    const GByte* pabyDataLimit = psCtxt->pabyBlob + psCtxt->nBlobSize;

    try
    {
        while(pabyData < pabyDataLimit)
        {
            int nKey = 0;
            READ_FIELD_KEY(nKey);

            if( nKey == MAKE_KEY(BLOB_IDX_RAW, WT_DATA) )
            {
                if( psCtxt->nJobs > 0 &&
                    !RunDecompressionJobsAndProcessAll(psCtxt, eType) )
                {
                    THROW_OSM_PARSING_EXCEPTION;
                }

                unsigned int nDataLength = 0;
                READ_SIZE(pabyData, pabyDataLimit, nDataLength);
                if( nDataLength > MAX_BLOB_SIZE ) THROW_OSM_PARSING_EXCEPTION;

                // printf("raw data size = %d\n", nDataLength);

                if( eType == BLOB_OSMHEADER )
                {
                    bRet = ReadOSMHeader(pabyData, pabyData + nDataLength, psCtxt);
                }
                else if( eType == BLOB_OSMDATA )
                {
                    bRet = ReadPrimitiveBlock(pabyData, pabyData + nDataLength,
                                            psCtxt);
                }

                pabyData += nDataLength;
            }
            else if( nKey == MAKE_KEY(BLOB_IDX_RAW_SIZE, WT_VARINT) )
            {
                READ_VARUINT32(pabyData, pabyDataLimit, nUncompressedSize);
                // printf("nUncompressedSize = %d\n", nUncompressedSize);
            }
            else if( nKey == MAKE_KEY(BLOB_IDX_ZLIB_DATA, WT_DATA) )
            {
                unsigned int nZlibCompressedSize = 0;
                READ_VARUINT32(pabyData, pabyDataLimit, nZlibCompressedSize);
                if( CHECK_OOB && nZlibCompressedSize >
                        psCtxt->nBlobSize - psCtxt->nBlobOffset)
                {
                    THROW_OSM_PARSING_EXCEPTION;
                }

                // printf("nZlibCompressedSize = %d\n", nZlibCompressedSize);

                if( nUncompressedSize != 0 )
                {
                    if( nUncompressedSize / 100 > nZlibCompressedSize )
                    {
                        // Too prevent excessive memory allocations
                        CPLError(CE_Failure, CPLE_AppDefined,
                                    "Excessive uncompressed vs compressed ratio");
                        THROW_OSM_PARSING_EXCEPTION;
                    }
                    if( psCtxt->nJobs > 0 &&
                        (psCtxt->nTotalUncompressedSize >
                                    UINT_MAX - nUncompressedSize ||
                        psCtxt->nTotalUncompressedSize +
                                nUncompressedSize > MAX_ACC_UNCOMPRESSED_SIZE) )
                    {
                        pabyData = pabyLastCheckpointData;
                        break;
                    }
                    unsigned nSizeNeeded = psCtxt->nTotalUncompressedSize +
                                        nUncompressedSize;
                    if( nSizeNeeded > psCtxt->nUncompressedAllocated )
                    {

                        GByte* pabyUncompressedNew = nullptr;
                        if( psCtxt->nUncompressedAllocated <=
                                UINT_MAX - psCtxt->nUncompressedAllocated / 3 &&
                            psCtxt->nUncompressedAllocated +
                                psCtxt->nUncompressedAllocated / 3 <
                                    MAX_ACC_UNCOMPRESSED_SIZE )
                        {
                            psCtxt->nUncompressedAllocated =
                                std::max(psCtxt->nUncompressedAllocated +
                                                psCtxt->nUncompressedAllocated / 3,
                                        nSizeNeeded);
                        }
                        else
                        {
                            psCtxt->nUncompressedAllocated = nSizeNeeded;
                        }
                        if( psCtxt->nUncompressedAllocated > UINT_MAX - EXTRA_BYTES )
                            THROW_OSM_PARSING_EXCEPTION;
                        pabyUncompressedNew =
                            (GByte*)VSI_REALLOC_VERBOSE(psCtxt->pabyUncompressed,
                                    psCtxt->nUncompressedAllocated + EXTRA_BYTES);
                        if( pabyUncompressedNew == nullptr )
                            THROW_OSM_PARSING_EXCEPTION;
                        psCtxt->pabyUncompressed = pabyUncompressedNew;
                    }
                    memset(psCtxt->pabyUncompressed + nSizeNeeded, 0, EXTRA_BYTES);

                    psCtxt->asJobs[psCtxt->nJobs].pabySrc = pabyData;
                    psCtxt->asJobs[psCtxt->nJobs].nSrcSize = nZlibCompressedSize;
                    psCtxt->asJobs[psCtxt->nJobs].nDstOffset =
                                                    psCtxt->nTotalUncompressedSize;
                    psCtxt->asJobs[psCtxt->nJobs].nDstSize = nUncompressedSize;
                    psCtxt->nJobs ++;
                    if( psCtxt->poWTP == nullptr || eType != BLOB_OSMDATA )
                    {
                        if( !RunDecompressionJobsAndProcessAll(psCtxt, eType) )
                        {
                            THROW_OSM_PARSING_EXCEPTION;
                        }
                    }
                    else
                    {
                        // Make sure that uncompressed blobs are separated by
                        // EXTRA_BYTES in the case where in the future we would
                        // implement parallel decoding of them (not sure if that's
                        // doable)
                        psCtxt->nTotalUncompressedSize +=
                                                nUncompressedSize + EXTRA_BYTES;
                    }
                }

                nUncompressedSize = 0;
                pabyData += nZlibCompressedSize;
                pabyLastCheckpointData = pabyData;
                if( psCtxt->nJobs == N_MAX_JOBS )
                    break;
            }
            else
            {
                SKIP_UNKNOWN_FIELD(pabyData, pabyDataLimit, TRUE);
            }
        }

        if( psCtxt->nJobs > 0 )
        {
            if( !RunDecompressionJobs(psCtxt) )
            {
                THROW_OSM_PARSING_EXCEPTION;
            }
            // Just process one blob at a time
            if( !ProcessSingleBlob(psCtxt, psCtxt->asJobs[0], eType) )
            {
                THROW_OSM_PARSING_EXCEPTION;
            }
            psCtxt->iNextJob = 1;
        }

        psCtxt->nBlobOffset = static_cast<unsigned>(pabyData - psCtxt->pabyBlob);
        return bRet;
    }
    catch( const std::exception& e )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "%s", e.what());
        return false;
    }
}

/************************************************************************/
/*                          OSM_ProcessBlock()                          */
/************************************************************************/

static OSMRetCode PBF_ProcessBlock(OSMContext* psCtxt)
{
    // Process any remaining queued jobs one by one
    if (psCtxt->iNextJob < psCtxt->nJobs)
    {
        if( !(ProcessSingleBlob(psCtxt,
                                psCtxt->asJobs[psCtxt->iNextJob],
                                BLOB_OSMDATA)) )
        {
            return OSM_ERROR;
        }
        psCtxt->iNextJob ++;
        return OSM_OK;
    }
    psCtxt->iNextJob = 0;
    psCtxt->nJobs = 0;

    // Make sure to finish parsing the last concatenated blocks
    if( psCtxt->nBlobOffset < psCtxt->nBlobSize )
    {
        return ReadBlob(psCtxt, BLOB_OSMDATA) ? OSM_OK : OSM_ERROR;
    }
    psCtxt->nBlobOffset = 0;
    psCtxt->nBlobSize = 0;

    bool nRet = false;
    int nBlobCount = 0;
    OSMRetCode eRetCode = OSM_OK;
    unsigned int nBlobSizeAcc = 0;
    BlobType eType = BLOB_UNKNOWN;
    while( true )
    {
        GByte abyHeaderSize[4];
        unsigned int nBlobSize = 0;

        if( VSIFReadL(abyHeaderSize, 4, 1, psCtxt->fp) != 1 )
        {
            eRetCode = OSM_EOF;
            break;
        }
        const unsigned int nHeaderSize =
            (static_cast<unsigned int>(abyHeaderSize[0]) << 24) |
            (abyHeaderSize[1] << 16) |
            (abyHeaderSize[2] << 8) | abyHeaderSize[3];

        psCtxt->nBytesRead += 4;

        /* printf("nHeaderSize = %d\n", nHeaderSize); */
        if( nHeaderSize > MAX_BLOB_HEADER_SIZE )
        {
            eRetCode = OSM_ERROR;
            break;
        }
        if( VSIFReadL(psCtxt->pabyBlobHeader, 1, nHeaderSize, psCtxt->fp) !=
                                                                nHeaderSize )
        {
            eRetCode = OSM_ERROR;
            break;
        }

        psCtxt->nBytesRead += nHeaderSize;

        memset(psCtxt->pabyBlobHeader + nHeaderSize, 0, EXTRA_BYTES);
        nRet = ReadBlobHeader(psCtxt->pabyBlobHeader, 
                              psCtxt->pabyBlobHeader + nHeaderSize,
                              &nBlobSize, &eType);
        if( !nRet || eType == BLOB_UNKNOWN )
        {
            eRetCode = OSM_ERROR;
            break;
        }

        // Limit in OSM PBF spec
        if( nBlobSize > MAX_BLOB_SIZE )
        {
            eRetCode = OSM_ERROR;
            break;
        }
        if( nBlobSize + nBlobSizeAcc > psCtxt->nBlobSizeAllocated )
        {
            psCtxt->nBlobSizeAllocated =
                std::max(std::min(MAX_ACC_BLOB_SIZE,
                                  psCtxt->nBlobSizeAllocated * 2),
                         nBlobSize + nBlobSizeAcc);
            GByte* pabyBlobNew = static_cast<GByte *>(
                VSI_REALLOC_VERBOSE(psCtxt->pabyBlob,
                                    psCtxt->nBlobSizeAllocated + EXTRA_BYTES));
            if( pabyBlobNew == nullptr )
            {
                eRetCode = OSM_ERROR;
                break;
            }
            psCtxt->pabyBlob = pabyBlobNew;
        }
        // Given how Protocol buffer work, we can merge sevaral buffers
        // by just appending them to the previous ones.
        if( VSIFReadL(psCtxt->pabyBlob + nBlobSizeAcc, 1,
                      nBlobSize, psCtxt->fp) != nBlobSize )
        {
            eRetCode = OSM_ERROR;
            break;
        }
        psCtxt->nBytesRead += nBlobSize;
        nBlobSizeAcc += nBlobSize;
        memset(psCtxt->pabyBlob + nBlobSizeAcc, 0, EXTRA_BYTES);

        nBlobCount ++;

        if( eType == BLOB_OSMDATA && psCtxt->poWTP != nullptr )
        {
            // Accumulate BLOB_OSMDATA until we reach either the maximum
            // number of jobs or a threshold in bytes
            if( nBlobCount == N_MAX_JOBS || nBlobSizeAcc > MAX_ACC_BLOB_SIZE )
            {
                break;
            }
        }
        else
        {
            break;
        }
    }

    if( nBlobCount > 0 )
    {
        psCtxt->nBlobOffset = 0;
        psCtxt->nBlobSize = nBlobSizeAcc;
        nRet = ReadBlob(psCtxt, eType);
        if( nRet )
        {
            if( eRetCode == OSM_EOF &&
                (psCtxt->iNextJob < psCtxt->nJobs ||
                 psCtxt->nBlobOffset < psCtxt->nBlobSize) )
            {
                eRetCode = OSM_OK;
            }
            CPLAssert( psCtxt->iNextJob == psCtxt->nJobs ||
                       eType == BLOB_OSMDATA );
        }
        else
        {
            eRetCode = OSM_ERROR;
        }
    }

    return eRetCode;
}

/************************************************************************/
/*                        EmptyNotifyNodesFunc()                        */
/************************************************************************/

static void EmptyNotifyNodesFunc( unsigned int /* nNodes */,
                                  OSMNode* /* pasNodes */,
                                  OSMContext* /* psCtxt */,
                                  void* /* user_data */ )
{}

/************************************************************************/
/*                         EmptyNotifyWayFunc()                         */
/************************************************************************/

static void EmptyNotifyWayFunc( OSMWay* /* psWay */,
                                OSMContext* /* psCtxt */,
                                void* /* user_data */ )
{}

/************************************************************************/
/*                       EmptyNotifyRelationFunc()                      */
/************************************************************************/

static void EmptyNotifyRelationFunc( OSMRelation* /* psRelation */,
                                     OSMContext* /* psCtxt */,
                                     void* /* user_data */ )
{}

/************************************************************************/
/*                         EmptyNotifyBoundsFunc()                      */
/************************************************************************/

static void EmptyNotifyBoundsFunc( double /* dfXMin */,
                                   double /* dfYMin */,
                                   double /* dfXMax */,
                                   double /* dfYMax */,
                                   OSMContext* /*psCtxt */,
                                   void * /* user_data */)
{}

#ifdef HAVE_EXPAT

/************************************************************************/
/*                          OSM_AddString()                             */
/************************************************************************/

static const char* OSM_AddString(OSMContext* psCtxt, const char* pszStr)
{
    int nLen = (int)strlen(pszStr);
    if( psCtxt->nStrLength + nLen + 1 > psCtxt->nStrAllocated )
    {
        CPLError(CE_Failure, CPLE_AppDefined, "String buffer too small");
        return "";
    }
    char* pszRet = psCtxt->pszStrBuf + psCtxt->nStrLength;
    memcpy(pszRet, pszStr, nLen);
    pszRet[nLen] = '\0';
    psCtxt->nStrLength += nLen + 1;
    return pszRet;
}

/************************************************************************/
/*                            OSM_Atoi64()                              */
/************************************************************************/

static GIntBig OSM_Atoi64( const char *pszString )
{

#if defined(__MSVCRT__) || (defined(WIN32) && defined(_MSC_VER))
    const GIntBig iValue = (GIntBig)_atoi64( pszString );
# elif HAVE_ATOLL
    const GIntBig iValue = atoll( pszString );
#else
    const GIntBig iValue = atol( pszString );
#endif

    return iValue;
}

/************************************************************************/
/*                      OSM_XML_startElementCbk()                       */
/************************************************************************/

static void XMLCALL OSM_XML_startElementCbk( void *pUserData,
                                             const char *pszName,
                                             const char **ppszAttr)
{
    OSMContext* psCtxt = (OSMContext*) pUserData;
    const char** ppszIter = ppszAttr;

    if( psCtxt->bStopParsing ) return;

    psCtxt->nWithoutEventCounter = 0;

    if( psCtxt->bTryToFetchBounds )
    {
        if( strcmp(pszName, "bounds") == 0 ||
            strcmp(pszName, "bound") == 0 /* osmosis uses bound */ )
        {
            int nCountCoords = 0;

            psCtxt->bTryToFetchBounds = false;

            if( ppszIter )
            {
                while( ppszIter[0] != nullptr )
                {
                    if( strcmp(ppszIter[0], "minlon") == 0 )
                    {
                        psCtxt->dfLeft = CPLAtof( ppszIter[1] );
                        nCountCoords ++;
                    }
                    else if( strcmp(ppszIter[0], "minlat") == 0 )
                    {
                        psCtxt->dfBottom = CPLAtof( ppszIter[1] );
                        nCountCoords ++;
                    }
                    else if( strcmp(ppszIter[0], "maxlon") == 0 )
                    {
                        psCtxt->dfRight = CPLAtof( ppszIter[1] );
                        nCountCoords ++;
                    }
                    else if( strcmp(ppszIter[0], "maxlat") == 0 )
                    {
                        psCtxt->dfTop = CPLAtof( ppszIter[1] );
                        nCountCoords ++;
                    }
                    else if( strcmp(ppszIter[0], "box") == 0  /* osmosis uses box */ )
                    {
                        char** papszTokens = CSLTokenizeString2( ppszIter[1], ",", 0 );
                        if( CSLCount(papszTokens) == 4 )
                        {
                            psCtxt->dfBottom = CPLAtof( papszTokens[0] );
                            psCtxt->dfLeft = CPLAtof( papszTokens[1] );
                            psCtxt->dfTop = CPLAtof( papszTokens[2] );
                            psCtxt->dfRight = CPLAtof( papszTokens[3] );
                            nCountCoords = 4;
                        }
                        CSLDestroy(papszTokens);
                    }
                    ppszIter += 2;
                }
            }

            if( nCountCoords == 4 )
            {
                psCtxt->pfnNotifyBounds(psCtxt->dfLeft, psCtxt->dfBottom,
                                        psCtxt->dfRight, psCtxt->dfTop,
                                        psCtxt, psCtxt->user_data);
            }
        }
    }

    if( !psCtxt->bInNode && !psCtxt->bInWay && !psCtxt->bInRelation &&
        strcmp(pszName, "node") == 0 )
    {
        psCtxt->bInNode = true;
        psCtxt->bTryToFetchBounds = false;

        psCtxt->nStrLength = 0;
        psCtxt->pszStrBuf[0] = '\0';
        psCtxt->nTags = 0;

        memset( &(psCtxt->pasNodes[0]), 0, sizeof(OSMNode) );
        psCtxt->pasNodes[0].sInfo.pszUserSID = "";

        if( ppszIter )
        {
            while( ppszIter[0] != nullptr )
            {
                if( strcmp(ppszIter[0], "id") == 0 )
                {
                    psCtxt->pasNodes[0].nID = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "lat") == 0 )
                {
                    psCtxt->pasNodes[0].dfLat = CPLAtof( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "lon") == 0 )
                {
                    psCtxt->pasNodes[0].dfLon = CPLAtof( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "version") == 0 )
                {
                    psCtxt->pasNodes[0].sInfo.nVersion = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "changeset") == 0 )
                {
                    psCtxt->pasNodes[0].sInfo.nChangeset = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "user") == 0 )
                {
                    psCtxt->pasNodes[0].sInfo.pszUserSID = OSM_AddString(psCtxt, ppszIter[1]);
                }
                else if( strcmp(ppszIter[0], "uid") == 0 )
                {
                    psCtxt->pasNodes[0].sInfo.nUID = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "timestamp") == 0 )
                {
                    psCtxt->pasNodes[0].sInfo.ts.pszTimeStamp = OSM_AddString(psCtxt, ppszIter[1]);
                    psCtxt->pasNodes[0].sInfo.bTimeStampIsStr = true;
                }
                ppszIter += 2;
            }
        }
    }

    else if( !psCtxt->bInNode && !psCtxt->bInWay && !psCtxt->bInRelation &&
             strcmp(pszName, "way") == 0 )
    {
        psCtxt->bInWay = true;

        psCtxt->nStrLength = 0;
        psCtxt->pszStrBuf[0] = '\0';
        psCtxt->nTags = 0;

        memset( &(psCtxt->sWay), 0, sizeof(OSMWay) );
        psCtxt->sWay.sInfo.pszUserSID = "";

        if( ppszIter )
        {
            while( ppszIter[0] != nullptr )
            {
                if( strcmp(ppszIter[0], "id") == 0 )
                {
                    psCtxt->sWay.nID = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "version") == 0 )
                {
                    psCtxt->sWay.sInfo.nVersion = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "changeset") == 0 )
                {
                    psCtxt->sWay.sInfo.nChangeset = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "user") == 0 )
                {
                    psCtxt->sWay.sInfo.pszUserSID = OSM_AddString(psCtxt, ppszIter[1]);
                }
                else if( strcmp(ppszIter[0], "uid") == 0 )
                {
                    psCtxt->sWay.sInfo.nUID = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "timestamp") == 0 )
                {
                    psCtxt->sWay.sInfo.ts.pszTimeStamp = OSM_AddString(psCtxt, ppszIter[1]);
                    psCtxt->sWay.sInfo.bTimeStampIsStr = true;
                }
                ppszIter += 2;
            }
        }
    }

    else if( !psCtxt->bInNode && !psCtxt->bInWay && !psCtxt->bInRelation &&
             strcmp(pszName, "relation") == 0 )
    {
        psCtxt->bInRelation = true;

        psCtxt->nStrLength = 0;
        psCtxt->pszStrBuf[0] = '\0';
        psCtxt->nTags = 0;

        memset( &(psCtxt->sRelation), 0, sizeof(OSMRelation) );
        psCtxt->sRelation.sInfo.pszUserSID = "";

        if( ppszIter )
        {
            while( ppszIter[0] != nullptr )
            {
                if( strcmp(ppszIter[0], "id") == 0 )
                {
                    psCtxt->sRelation.nID = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "version") == 0 )
                {
                    psCtxt->sRelation.sInfo.nVersion = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "changeset") == 0 )
                {
                    psCtxt->sRelation.sInfo.nChangeset = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "user") == 0 )
                {
                    psCtxt->sRelation.sInfo.pszUserSID = OSM_AddString(psCtxt, ppszIter[1]);
                }
                else if( strcmp(ppszIter[0], "uid") == 0 )
                {
                    psCtxt->sRelation.sInfo.nUID = atoi( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "timestamp") == 0 )
                {
                    psCtxt->sRelation.sInfo.ts.pszTimeStamp = OSM_AddString(psCtxt, ppszIter[1]);
                    psCtxt->sRelation.sInfo.bTimeStampIsStr = true;
                }
                ppszIter += 2;
            }
        }
    }

    else if( psCtxt->bInWay &&
             strcmp(pszName, "nd") == 0 )
    {
        if( ppszAttr != nullptr && ppszAttr[0] != nullptr &&
            strcmp(ppszAttr[0], "ref") == 0 )
        {
            if( psCtxt->sWay.nRefs < psCtxt->nNodeRefsAllocated )
            {
                psCtxt->panNodeRefs[psCtxt->sWay.nRefs] = OSM_Atoi64( ppszAttr[1] );
                psCtxt->sWay.nRefs ++;
            }
            else
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "Too many nodes referenced in way " CPL_FRMT_GIB,
                         psCtxt->sWay.nID);
            }
        }
    }

    else if( psCtxt->bInRelation &&
             strcmp(pszName, "member") == 0 )
    {
        /* 300 is the recommended value, but there are files with more than 2000 so we should be able */
        /* to realloc over that value */
        if( psCtxt->sRelation.nMembers >= psCtxt->nMembersAllocated )
        {
            int nMembersAllocated =
                std::max(psCtxt->nMembersAllocated * 2, psCtxt->sRelation.nMembers + 1);
            OSMMember* pasMembersNew = (OSMMember*) VSI_REALLOC_VERBOSE(
                    psCtxt->pasMembers,
                    nMembersAllocated * sizeof(OSMMember));
            if( pasMembersNew == nullptr )
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                        "Cannot allocate enough memory to store members of relation " CPL_FRMT_GIB,
                        psCtxt->sRelation.nID);
                return;
            }
            psCtxt->nMembersAllocated = nMembersAllocated;
            psCtxt->pasMembers = pasMembersNew;
        }

        OSMMember* psMember = &(psCtxt->pasMembers[psCtxt->sRelation.nMembers]);
        psCtxt->sRelation.nMembers ++;

        psMember->nID = 0;
        psMember->pszRole = "";
        psMember->eType = MEMBER_NODE;

        if( ppszIter )
        {
            while( ppszIter[0] != nullptr )
            {
                if( strcmp(ppszIter[0], "ref") == 0 )
                {
                    psMember->nID = OSM_Atoi64( ppszIter[1] );
                }
                else if( strcmp(ppszIter[0], "type") == 0 )
                {
                    if( strcmp( ppszIter[1], "node") == 0 )
                        psMember->eType = MEMBER_NODE;
                    else if( strcmp( ppszIter[1], "way") == 0 )
                        psMember->eType = MEMBER_WAY;
                    else if( strcmp( ppszIter[1], "relation") == 0 )
                        psMember->eType = MEMBER_RELATION;
                }
                else if( strcmp(ppszIter[0], "role") == 0 )
                {
                    psMember->pszRole = OSM_AddString(psCtxt, ppszIter[1]);
                }
                ppszIter += 2;
            }
        }
    }
    else if( (psCtxt->bInNode || psCtxt->bInWay || psCtxt->bInRelation) &&
             strcmp(pszName, "tag") == 0 )
    {
        if( psCtxt->nTags == psCtxt->nTagsAllocated )
        {
            psCtxt->nTagsAllocated =
                psCtxt->nTagsAllocated * 2;
            OSMTag* pasTagsNew = (OSMTag*) VSI_REALLOC_VERBOSE(
                psCtxt->pasTags,
                psCtxt->nTagsAllocated * sizeof(OSMTag));
            if( pasTagsNew == nullptr )
            {
                if( psCtxt->bInNode )
                    CPLError(CE_Failure, CPLE_AppDefined,
                            "Too many tags in node " CPL_FRMT_GIB,
                            psCtxt->pasNodes[0].nID);
                else if( psCtxt->bInWay )
                    CPLError(CE_Failure, CPLE_AppDefined,
                            "Too many tags in way " CPL_FRMT_GIB,
                            psCtxt->sWay.nID);
                else if( psCtxt->bInRelation )
                    CPLError(CE_Failure, CPLE_AppDefined,
                            "Too many tags in relation " CPL_FRMT_GIB,
                            psCtxt->sRelation.nID);
                return;
            }
            psCtxt->pasTags = pasTagsNew;
        }

        OSMTag* psTag = &(psCtxt->pasTags[psCtxt->nTags]);
        psCtxt->nTags ++;

        psTag->pszK = "";
        psTag->pszV = "";

        if( ppszIter )
        {
            while( ppszIter[0] != nullptr )
            {
                if( ppszIter[0][0] == 'k' )
                {
                    psTag->pszK = OSM_AddString(psCtxt, ppszIter[1]);
                }
                else if( ppszIter[0][0] == 'v' )
                {
                    psTag->pszV = OSM_AddString(psCtxt, ppszIter[1]);
                }
                ppszIter += 2;
            }
        }
    }
}

/************************************************************************/
/*                       OSM_XML_endElementCbk()                        */
/************************************************************************/

static void XMLCALL OSM_XML_endElementCbk( void *pUserData,
                                           const char *pszName )
{
    OSMContext* psCtxt = (OSMContext*) pUserData;

    if( psCtxt->bStopParsing ) return;

    psCtxt->nWithoutEventCounter = 0;

    if( psCtxt->bInNode && strcmp(pszName, "node") == 0 )
    {
        if( psCtxt->pasNodes[0].dfLon < -180 || psCtxt->pasNodes[0].dfLon > 180 ||
            psCtxt->pasNodes[0].dfLat < -90 || psCtxt->pasNodes[0].dfLat > 90 )
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Invalid lon=%f lat=%f",
                     psCtxt->pasNodes[0].dfLon,
                     psCtxt->pasNodes[0].dfLat);
        }
        else
        {
            psCtxt->pasNodes[0].nTags = psCtxt->nTags;
            psCtxt->pasNodes[0].pasTags = psCtxt->pasTags;

            psCtxt->pfnNotifyNodes(1, psCtxt->pasNodes, psCtxt, psCtxt->user_data);

            psCtxt->bHasFoundFeature = true;
        }
        psCtxt->bInNode = false;
    }

    else
    if( psCtxt->bInWay && strcmp(pszName, "way") == 0 )
    {
        psCtxt->sWay.nTags = psCtxt->nTags;
        psCtxt->sWay.pasTags = psCtxt->pasTags;

        psCtxt->sWay.panNodeRefs = psCtxt->panNodeRefs;

        psCtxt->pfnNotifyWay(&(psCtxt->sWay), psCtxt, psCtxt->user_data);

        psCtxt->bHasFoundFeature = true;

        psCtxt->bInWay = false;
    }

    else
    if( psCtxt->bInRelation && strcmp(pszName, "relation") == 0 )
    {
        psCtxt->sRelation.nTags = psCtxt->nTags;
        psCtxt->sRelation.pasTags = psCtxt->pasTags;

        psCtxt->sRelation.pasMembers = psCtxt->pasMembers;

        psCtxt->pfnNotifyRelation(&(psCtxt->sRelation), psCtxt, psCtxt->user_data);

        psCtxt->bHasFoundFeature = true;

        psCtxt->bInRelation = false;
    }
}
/************************************************************************/
/*                           dataHandlerCbk()                           */
/************************************************************************/

static void XMLCALL OSM_XML_dataHandlerCbk( void *pUserData,
                                            const char * /* data */,
                                            int /* nLen */)
{
    OSMContext* psCtxt = static_cast<OSMContext *>(pUserData);

    if( psCtxt->bStopParsing ) return;

    psCtxt->nWithoutEventCounter = 0;

    psCtxt->nDataHandlerCounter ++;
    if( psCtxt->nDataHandlerCounter >= XML_BUFSIZE )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "File probably corrupted (million laugh pattern)");
        XML_StopParser(psCtxt->hXMLParser, XML_FALSE);
        psCtxt->bStopParsing = true;
        return;
    }
}

/************************************************************************/
/*                          XML_ProcessBlock()                          */
/************************************************************************/

static OSMRetCode XML_ProcessBlock(OSMContext* psCtxt)
{
    if( psCtxt->bEOF )
        return OSM_EOF;
    if( psCtxt->bStopParsing )
        return OSM_ERROR;

    psCtxt->bHasFoundFeature = false;
    psCtxt->nWithoutEventCounter = 0;

    do
    {
        psCtxt->nDataHandlerCounter = 0;

        const unsigned int nLen =
            (unsigned int)VSIFReadL( psCtxt->pabyBlob, 1,
                                     XML_BUFSIZE, psCtxt->fp );

        psCtxt->nBytesRead += nLen;

        psCtxt->bEOF = CPL_TO_BOOL(VSIFEofL(psCtxt->fp));
        const int eErr =
            XML_Parse(psCtxt->hXMLParser, (const char*) psCtxt->pabyBlob,
                      nLen, psCtxt->bEOF );

        if( eErr == XML_STATUS_ERROR )
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of OSM file failed : %s "
                     "at line %d, column %d",
                     XML_ErrorString(XML_GetErrorCode(psCtxt->hXMLParser)),
                     (int)XML_GetCurrentLineNumber(psCtxt->hXMLParser),
                     (int)XML_GetCurrentColumnNumber(psCtxt->hXMLParser));
            psCtxt->bStopParsing = true;
        }
        psCtxt->nWithoutEventCounter ++;
    } while (!psCtxt->bEOF && !psCtxt->bStopParsing &&
             !psCtxt->bHasFoundFeature &&
             psCtxt->nWithoutEventCounter < 10);

    if( psCtxt->nWithoutEventCounter == 10 )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        psCtxt->bStopParsing = true;
    }

    return psCtxt->bStopParsing ? OSM_ERROR : psCtxt->bEOF ? OSM_EOF : OSM_OK;
}

#endif

/************************************************************************/
/*                              OSM_Open()                              */
/************************************************************************/

OSMContext* OSM_Open( const char* pszFilename,
                      NotifyNodesFunc pfnNotifyNodes,
                      NotifyWayFunc pfnNotifyWay,
                      NotifyRelationFunc pfnNotifyRelation,
                      NotifyBoundsFunc pfnNotifyBounds,
                      void* user_data )
{

    VSILFILE* fp = VSIFOpenL(pszFilename, "rb");
    if( fp == nullptr )
        return nullptr;

    GByte abyHeader[1024];
    int nRead = static_cast<int>(
        VSIFReadL(abyHeader, 1, sizeof(abyHeader)-1, fp));
    abyHeader[nRead] = '\0';

    bool bPBF = false;

    if( strstr((const char*)abyHeader, "<osm") != nullptr )
    {
        /* OSM XML */
#ifndef HAVE_EXPAT
        CPLError(CE_Failure, CPLE_AppDefined,
                 "OSM XML detected, but Expat parser not available");
        VSIFCloseL(fp);
        return nullptr;
#endif
    }
    else
    {
        const int nLimitI = nRead - static_cast<int>(strlen("OSMHeader"));
        for( int i = 0; i < nLimitI; i++)
        {
            if( memcmp(abyHeader + i, "OSMHeader", strlen("OSMHeader") ) == 0 )
            {
                bPBF = true;
                break;
            }
        }
        if( !bPBF )
        {
            VSIFCloseL(fp);
            return nullptr;
        }
    }

    VSIFSeekL(fp, 0, SEEK_SET);

    OSMContext* psCtxt = static_cast<OSMContext *>(
        VSI_MALLOC_VERBOSE(sizeof(OSMContext)) );
    if( psCtxt == nullptr )
    {
        VSIFCloseL(fp);
        return nullptr;
    }
    memset(psCtxt, 0, sizeof(OSMContext));
    psCtxt->bPBF = bPBF;
    psCtxt->fp = fp;
    psCtxt->pfnNotifyNodes = pfnNotifyNodes;
    if( pfnNotifyNodes == nullptr )
        psCtxt->pfnNotifyNodes = EmptyNotifyNodesFunc;
    psCtxt->pfnNotifyWay = pfnNotifyWay;
    if( pfnNotifyWay == nullptr )
        psCtxt->pfnNotifyWay = EmptyNotifyWayFunc;
    psCtxt->pfnNotifyRelation = pfnNotifyRelation;
    if( pfnNotifyRelation == nullptr )
        psCtxt->pfnNotifyRelation = EmptyNotifyRelationFunc;
    psCtxt->pfnNotifyBounds = pfnNotifyBounds;
    if( pfnNotifyBounds == nullptr )
        psCtxt->pfnNotifyBounds = EmptyNotifyBoundsFunc;
    psCtxt->user_data = user_data;

    if( bPBF )
    {
        psCtxt->nBlobSizeAllocated = 64 * 1024 + EXTRA_BYTES;
    }
#ifdef HAVE_EXPAT
    else
    {
        psCtxt->nBlobSizeAllocated = XML_BUFSIZE;

        psCtxt->nStrAllocated = 1024*1024;
        psCtxt->pszStrBuf = (char*) VSI_MALLOC_VERBOSE(psCtxt->nStrAllocated);
        if( psCtxt->pszStrBuf )
            psCtxt->pszStrBuf[0] = '\0';

        psCtxt->hXMLParser = OGRCreateExpatXMLParser();
        XML_SetUserData(psCtxt->hXMLParser, psCtxt);
        XML_SetElementHandler(psCtxt->hXMLParser,
                              OSM_XML_startElementCbk,
                              OSM_XML_endElementCbk);
        XML_SetCharacterDataHandler(psCtxt->hXMLParser, OSM_XML_dataHandlerCbk);

        psCtxt->bTryToFetchBounds = true;

        psCtxt->nNodesAllocated = 1;
        psCtxt->pasNodes = (OSMNode*) VSI_MALLOC_VERBOSE(sizeof(OSMNode) * psCtxt->nNodesAllocated);

        psCtxt->nTagsAllocated = 256;
        psCtxt->pasTags = (OSMTag*) VSI_MALLOC_VERBOSE(sizeof(OSMTag) * psCtxt->nTagsAllocated);

        /* 300 is the recommended value, but there are files with more than 2000 so we should be able */
        /* to realloc over that value */
        psCtxt->nMembersAllocated = 2000;
        psCtxt->pasMembers = (OSMMember*) VSI_MALLOC_VERBOSE(sizeof(OSMMember) * psCtxt->nMembersAllocated);

        psCtxt->nNodeRefsAllocated = 10000;
        psCtxt->panNodeRefs = (GIntBig*) VSI_MALLOC_VERBOSE(sizeof(GIntBig) * psCtxt->nNodeRefsAllocated);

        if( psCtxt->pszStrBuf == nullptr ||
            psCtxt->pasNodes == nullptr ||
            psCtxt->pasTags == nullptr ||
            psCtxt->pasMembers == nullptr ||
            psCtxt->panNodeRefs == nullptr )
        {
            OSM_Close(psCtxt);
            return nullptr;
        }
    }
#endif

    psCtxt->pabyBlob = (GByte*)VSI_MALLOC_VERBOSE(psCtxt->nBlobSizeAllocated);
    if( psCtxt->pabyBlob == nullptr )
    {
        OSM_Close(psCtxt);
        return nullptr;
    }
    psCtxt->pabyBlobHeader =
            (GByte*)VSI_MALLOC_VERBOSE(MAX_BLOB_HEADER_SIZE+EXTRA_BYTES);
    if( psCtxt->pabyBlobHeader == nullptr )
    {
        OSM_Close(psCtxt);
        return nullptr;
    }
    const char* pszNumThreads =
                CPLGetConfigOption("GDAL_NUM_THREADS", "ALL_CPUS");
    int nNumCPUs = CPLGetNumCPUs();
    if( pszNumThreads && !EQUAL(pszNumThreads, "ALL_CPUS") )
        nNumCPUs = std::max(0, std::min(2 * nNumCPUs, atoi(pszNumThreads)));
    if( nNumCPUs > 1 )
    {
        psCtxt->poWTP = new CPLWorkerThreadPool();
        // coverity[tainted_data]
        if( !psCtxt->poWTP->Setup(nNumCPUs , nullptr, nullptr) )
        {
            delete psCtxt->poWTP;
            psCtxt->poWTP = nullptr;
        }
    }

    return psCtxt;
}

/************************************************************************/
/*                              OSM_Close()                             */
/************************************************************************/

void OSM_Close(OSMContext* psCtxt)
{
    if( psCtxt == nullptr )
        return;

#ifdef HAVE_EXPAT
    if( !psCtxt->bPBF )
    {
        if( psCtxt->hXMLParser )
            XML_ParserFree(psCtxt->hXMLParser);

        CPLFree(psCtxt->pszStrBuf); /* only for XML case ! */
    }
#endif

    VSIFree(psCtxt->pabyBlob);
    VSIFree(psCtxt->pabyBlobHeader);
    VSIFree(psCtxt->pabyUncompressed);
    VSIFree(psCtxt->panStrOff);
    VSIFree(psCtxt->pasNodes);
    VSIFree(psCtxt->pasTags);
    VSIFree(psCtxt->pasMembers);
    VSIFree(psCtxt->panNodeRefs);
    delete psCtxt->poWTP;

    VSIFCloseL(psCtxt->fp);
    VSIFree(psCtxt);
}
/************************************************************************/
/*                          OSM_ResetReading()                          */
/************************************************************************/

void OSM_ResetReading( OSMContext* psCtxt )
{
    VSIFSeekL(psCtxt->fp, 0, SEEK_SET);

    psCtxt->nBytesRead = 0;
    psCtxt->nJobs = 0;
    psCtxt->iNextJob = 0;
    psCtxt->nBlobOffset = 0;
    psCtxt->nBlobSize = 0;
    psCtxt->nTotalUncompressedSize = 0;

#ifdef HAVE_EXPAT
    if( !psCtxt->bPBF )
    {
        XML_ParserFree(psCtxt->hXMLParser);
        psCtxt->hXMLParser = OGRCreateExpatXMLParser();
        XML_SetUserData(psCtxt->hXMLParser, psCtxt);
        XML_SetElementHandler(psCtxt->hXMLParser,
                              OSM_XML_startElementCbk,
                              OSM_XML_endElementCbk);
        XML_SetCharacterDataHandler(psCtxt->hXMLParser, OSM_XML_dataHandlerCbk);
        psCtxt->bEOF = false;
        psCtxt->bStopParsing = false;
        psCtxt->nStrLength = 0;
        psCtxt->pszStrBuf[0] = '\0';
        psCtxt->nTags = 0;

        psCtxt->bTryToFetchBounds = true;
        psCtxt->bInNode = false;
        psCtxt->bInWay = false;
        psCtxt->bInRelation = false;
    }
#endif
}

/************************************************************************/
/*                          OSM_ProcessBlock()                          */
/************************************************************************/

OSMRetCode OSM_ProcessBlock( OSMContext* psCtxt )
{
#ifdef HAVE_EXPAT
    if( psCtxt->bPBF )
        return PBF_ProcessBlock(psCtxt);
    else
        return XML_ProcessBlock(psCtxt);
#else
    return PBF_ProcessBlock(psCtxt);
#endif
}

/************************************************************************/
/*                          OSM_GetBytesRead()                          */
/************************************************************************/

GUIntBig OSM_GetBytesRead( OSMContext* psCtxt )
{
    return psCtxt->nBytesRead;
}
