[gdal-dev] Zip files and VISFileFromMemBuffer()

[Sean Gillies]

Thanks for confirming that I was on the right trail, Even! I got it figured
out: I was naively trying to open the /vsizip/vsimem/ file in update mode.

In case you're interested, my new Python usage is like this:

with open(path_zip_file, 'rb') as f:
    with MemoryFile(f) as memfile:
        with memfile.open('white-gemini-iv.vrt') as dataset:
            assert dataset.count == 3

https://github.com/mapbox/rasterio/pull/972/files#diff-d3388b510bd97235e4741b8417cc41e9R148


On Tue, Jan 31, 2017 at 5:42 PM, Even Rouault <even.rouault at spatialys.com>
wrote:

> On mardi 31 janvier 2017 17:33:23 CET Sean Gillies wrote:
>
> > Hey all,
>
> >
>
> > The tests in
>
> > https://svn.osgeo.org/gdal/branches/1.9/autotest/gcore/vsizip.py show
> how
>
> > to create a zip archive in memory and create directories and files within
>
> > it. I'm looking for a shortcut.
>
> >
>
> > Given a sequence of bytes representing an existing zip file that
> contains a
>
> > TIFF and a VRT (referencing the TIFF), is it possible to make a VSI file
>
> > from this buffer (using VISFileFromMemBuffer()) and then access the VRT
>
> > using a path like /vsizip/vsimem/archive.zip/example.vrt protocol?
>
>
>
> Hi Sean,
>
>
>
> That sounds like you tested it and something went wrong ? Perhaps check
> the path to the source in the VRT and the value of the relativeToVRT
> attribute.
>
>
>
> Your above strategy does work for me:
>
>
>
> $ gdal_translate byte.tif byte.vrt -of VRT
>
> Input file size is 20, 20
>
>
>
> $ zip byte.tif.zip byte.tif byte.vrt
>
> adding: byte.tif (deflated 96%)
>
> adding: byte.vrt (deflated 53%)
>
>
>
> $ python
>
> >>> from osgeo import gdal
>
> >>> data = open('byte.tif.zip', 'rb').read()
>
> >>> gdal.FileFromMemBuffer('/vsimem/archive.zip', data)
>
> >>> ds = gdal.Open('/vsizip/vsimem/archive.zip/byte.vrt')
>
> >>> ds.GetRasterBand(1).Checksum()
>
> 4672
>
>
>
>
>
> Even
>
>
>
>
>
> --
>
> Spatialys - Geospatial professional services
>
> http://www.spatialys.com
>



-- 
Sean Gillies
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