WCS 1.0: WCS Exceptions raise mapscript exceptions

[fschindler]

WCS Exceptions in WCS 1.0 requests called from mapscript applications raise an exception instead of returning a proper result.

For WCS 1.1 and WCS 2.0 this is not the case, as the exception message is normally returned an can be read with the according msIO_... mapscript functions.

The following python application raises the said exception (because the coverage id is not found):

import mapscript

ows_req = mapscript.OWSRequest()
ows_req.setParameter('SERVICE','WCS')
ows_req.setParameter('REQUEST','DescribeCoverage')
ows_req.setParameter('VERSION','1.0.0')
ows_req.setParameter('COVERAGE','invalid_id')

map = mapscript.mapObj('test.map')
mapscript.msIO_installStdoutToBuffer()
dispatch_status = map.OWSDispatch(ows_req)
print mapscript.msIO_getStdoutBufferBytes()

The used map file:

MAP
  CONFIG "MS_ERRORFILE" "stderr"

  WEB
    METADATA
      "ows_onlineresource" "http://something?"
      "ows_enable_request" "*"
    END
  END 

  LAYER
    NAME "a" 
    DUMP TRUE 
    DATA "test.tif" 
    TYPE RASTER 
    METADATA
      "ows_srs" "EPSG:4326"
    END
  END
END

The exception raised:

Traceback (most recent call last):
  File "describe.py", line 13, in <module>
    dispatch_status = map.OWSDispatch(ows_req)
_mapscript.MapServerError: msWCSDescribeCoverage(): WCS server error. COVERAGE invalid_id cannot be opened / does not exist

The problem occurs in msWCSException, as the error stack is not cleared with msResetErrorList, which is done in the other WCS exception handlers.

The following patch resolves the issue:

mapwcs.c

@@ -179 +179 @@
   msIO_printf("  </ServiceException>\n");
   msIO_printf("</ServiceExceptionReport>\n");
 
+  msResetErrorList();
+
   return MS_FAILURE;
 }

[fschindler]

Patch to resolve the described problem

[schpidi]

Committed with r11980.

[schpidi]

Forgot HISTORY.txt 11981.