ECRG: error in base34 decoding and in Windows filename handling

[Even Rouault]

Reported by Damian Dixon

I have a couple of ECRG fixes that I would like to push back.

The check is slightly wrong for the base34 change. '=' signs are required in two places.

static GIntBig GetFromBase34(const char* pszVal, int nMaxSize)
{
    int i;
    GIntBig nFrameNumber = 0;
    for(i=0;i<nMaxSize;i++)
    {
        char ch = pszVal[i];
        if (ch == '\0')
            break;
        int chVal;
        if (ch >= 'A' && ch <= 'Z')
            ch += 'a' - 'A';
        /* i and o letters are excluded, */
        if (ch >= '0' && ch <= '9')
            chVal = ch - '0';
        else if (ch >= 'a' && ch <= 'h')
            chVal = ch - 'a' + 10;
        else if (ch >= 'j' && ch <= 'n')
            chVal = ch - 'a' + 10 - 1;
        else if (ch >= 'p' && ch <= 'z')
            chVal = ch - 'a' + 10 - 2;
        else
        {
            CPLDebug("ECRG", "Invalid base34 value : %s", pszVal);
            break;
        }
        nFrameNumber = nFrameNumber * 34 + chVal;
    }

    return nFrameNumber;
}


If we try and read data from say 'D:' on Windows then the path becomes invalid:

GDALDataset *ECRGTOCDataset::Open( GDALOpenInfo * poOpenInfo )
{
....

        if( nTokens == 3 )
            osFilename = papszTokens[2];
        else if( nTokens == 4 )
        {
            if( strlen(papszTokens[2]) == 1 &&
                (papszTokens[3][0] == '\\' ||
                 papszTokens[3][0] == '/') )
            {
                osFilename = papszTokens[2];
                osFilename += ":";
    // envitia
                osFilename += papszTokens[3];
    // envitia end
            }
            else
            {
                osScale = papszTokens[2];
                osFilename = papszTokens[3];
            }
        }
        else if( nTokens == 5 &&
               strlen(papszTokens[3]) == 1 &&
                (papszTokens[4][0] == '\\' ||
                 papszTokens[4][0] == '/') )
        {
            osScale = papszTokens[2];
            osFilename = papszTokens[3];
            osFilename += ":";
    // envitia
            osFilename += papszTokens[4];
    // envitia end
        }

[Even Rouault]

trunk r32231, branches/2.0 r32232, branches/1.11 r32233 "ECRG: fix base34 decoding and Windows filename handling (patch by Damian Dixon, #6271)"