OGR GML reader fails if file has UTF-8 BOM prefix

[rogerjames99]

The function OGRGMLDataSource::Open in ogrgmldatasource.cpp fails is the GML file has a UTF-8 encoded UNICODE BOM (Byte order mark) at the start of the file. This is valid UTF-8 encoding (see RFC 3629 section 6) and should be allowed. Xerces properly handles this sequence. The code below is a modification to this function to allow for this.

It may be better to remove the "Test Open" functionality altogether and just let Xerces worry about correctly formed xml.

int OGRGMLDataSource::Open( const char * pszNewName, int bTestOpen )

{

FILE *fp; char szHeader[1000];

/* -------------------------------------------------------------------- */ /* Open the source file. */ /* -------------------------------------------------------------------- */

fp = VSIFOpen( pszNewName, "r" ); if( fp == NULL ) {

if( !bTestOpen )

CPLError( CE_Failure, CPLE_OpenFailed,

"Failed to open GML file `%s'.", pszNewName );

return FALSE;

}

/* -------------------------------------------------------------------- */ /* If we aren't sure it is GML, load a header chunk and check */ /* for signs it is GML */ /* -------------------------------------------------------------------- */

if( bTestOpen ) {

char *szPtr = szHeader;

VSIFRead( szHeader, 1, sizeof(szHeader), fp ); szHeader[sizeof(szHeader)-1] = '\0';

/* -------------------------------------------------------------------- */ /* Check for a UTF-8 BOM and skip if found */ /* -------------------------------------------------------------------- */

if (((unsigned char)szPtr[0] == 0xEF) && ((unsigned char)szPtr[1] == 0xBB) && ((unsigned char)szPtr[2] == 0xBF))

szPtr += 3;

if( szPtr[0] != '<'

strstr(szPtr,"opengis.net/gml") == NULL )

{

VSIFClose( fp ); return FALSE;

}

}