VRT XML in xml:VRT metadata recurses

[warmerdam]

#!/usr/bin/env python

import sys

from osgeo import gdal


def auto_wrap(src_filename):
    ds = gdal.Open(src_filename)
    vrt_ds = gdal.GetDriverByName('VRT').CreateCopy('/vsimem/x.vrt', ds)
    print vrt_ds.GetMetadata('xml:VRT')[0]


if __name__ == '__main__':
    print auto_wrap(sys.argv[1])

Gives the following. Note the entire extra copy of the VRT XML within the xml:VRT domain. This appears to be because the VRTDataset::GetMetadata() method inserts it's xml:VRT results into the metadata cache. So this gets populated when GetMetadata() is first called (in CreateCopy()), and then later requests result in this problem. I'd suggest GetMetadata() not cache the result in the parent object, but generate generate it on each call (I'm not sure if this complicates the lifetime for the returned string list).

<VRTDataset rasterXSize="512" rasterYSize="512">
  <SRS>PROJCS["NAD27 / UTM zone 11N",GEOGCS["NAD27",DATUM["North_American_Datum_1927",SPHEROID["Clarke 1866",6378206.4,294.9786982138982,AUTHORITY["EPSG","7008"]],AUTHORITY["EPSG","6267"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4267"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-117],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","26711"]]</SRS>
  <GeoTransform>  4.4072000000000000e+05,  6.0000000000000000e+01,  0.0000000000000000e+00,  3.7513200000000000e+06,  0.0000000000000000e+00, -6.0000000000000000e+01</GeoTransform>
  <Metadata>
    <MDI key="AREA_OR_POINT">Area</MDI>
    <MDI key="COLORSPACE">GREYSCALE</MDI>
    <MDI key="COMPRESSION_RATE_TARGET">4</MDI>
    <MDI key="VERSION">1</MDI>
  </Metadata>
  <Metadata domain="xml:VRT" format="xml">
    <VRTDataset rasterXSize="512" rasterYSize="512">
      <SRS>PROJCS["NAD27 / UTM zone 11N",GEOGCS["NAD27",DATUM["North_American_Datum_1927",SPHEROID["Clarke 1866",6378206.4,294.9786982138982,AUTHORITY["EPSG","7008"]],AUTHORITY["EPSG","6267"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4267"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-117],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","26711"]]</SRS>
      <GeoTransform>4.4072000000000000e+05,  6.0000000000000000e+01,  0.0000000000000000e+00,  3.7513200000000000e+06,  0.0000000000000000e+00, -6.0000000000000000e+01</GeoTransform>
      <Metadata>
        <MDI key="AREA_OR_POINT">Area</MDI>
        <MDI key="COLORSPACE">GREYSCALE</MDI>
        <MDI key="COMPRESSION_RATE_TARGET">4</MDI>
        <MDI key="VERSION">1</MDI>
      </Metadata>
      <VRTRasterBand dataType="Byte" band="1">
        <Description>Grayscale</Description>
        <ColorInterp>Gray</ColorInterp>
        <SimpleSource>
          <SourceFilename relativeToVRT="0">utm.tif</SourceFilename>
          <SourceBand>1</SourceBand>
          <SourceProperties RasterXSize="512" RasterYSize="512" DataType="Byte" BlockXSize="512" BlockYSize="16" />
          <SrcRect xOff="0" yOff="0" xSize="512" ySize="512" />
          <DstRect xOff="0" yOff="0" xSize="512" ySize="512" />
        </SimpleSource>
      </VRTRasterBand>
    </VRTDataset>
  </Metadata>
  <VRTRasterBand dataType="Byte" band="1">
    <Description>Grayscale</Description>
    <ColorInterp>Gray</ColorInterp>
    <SimpleSource>
      <SourceFilename relativeToVRT="0">utm.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <SourceProperties RasterXSize="512" RasterYSize="512" DataType="Byte" BlockXSize="512" BlockYSize="16" />
      <SrcRect xOff="0" yOff="0" xSize="512" ySize="512" />
      <DstRect xOff="0" yOff="0" xSize="512" ySize="512" />
    </SimpleSource>
  </VRTRasterBand>
</VRTDataset>

[Even Rouault]

In 37069:

VRT: avoid recursion in xml:VRT metadata (fixes #6767)

[Even Rouault]

Note: not appropriate as such for backport as it has a potential ABI impact