Possible bug in FileDataSource::DataSourceFgetc()

[larrybiehl]

Not sure of the logic in the following routine in filedatasource.cpp in degrib directory. A character is read from the grib file apparently to test whether it is at the end of the file. EOF is returned if there is an error in reading a character. But if the character read in the file is equal to EOF, the reading of valid data stops. I have a NLDAP grib file with 37 data sets in it. It stop after 9 because a character read with this routine happens to be -1. I did a check of chData to see if it was equal to EOF and set chData to 0 instead. The grib file was read correctly. I was able to access all 37 data sets. Is there a reason for chData at this point to indicate a badly formed grib file if the value return here is -1?

int FileDataSource::DataSourceFgetc()
{
    char chData;

    if( VSIFReadL( &chData, 1, 1, fp ) == 1 )
	return chData;
    else
        return EOF;
}

[warmerdam]

Hi, can you provide the file in question?

I suspect the fix is to declare "chData" as "unsigned char" but it would be easier to confirm with a file demonstrating the issue.