[gdal-dev] TAR POSIX support

[Even Rouault]

Fabian,

/vsitar/ has indeed no dedicated support for POSIX.1-2001 (pax)

On a very simple test with a tiny file from GDAL autotest,

tar --format=pax --create -f byte_pax.tar byte.tif

then gdalinfo /vsitar/byte_pax.tar/byte.tif works.

But I see that GDAL sees an extra text file "PaxHeaders.25680/byte.tif" which 
is the one mentionned in
https://en.wikipedia.org/wiki/Tar_(computing)#POSIX.1-2001/pax which contains 
3 timestamps with nanosecond precision.

So I suspect your particular .tar file uses specific pax extensions which are 
not UStar compatible. I didn't dig more. Would probably require an example to 
better see what's going on.

Even

> Hi list,
> 
> We have a large archive of images which are stored in POSIX TAR format
> (POSIX.1-2001 (pax)). GDAL seems to be unable to open these files (GDAL
> 2.4.0). Unfortunately, re-packing these files in GNU format (which GDAL
> seems to be happy with) is not an option.
> 
> We also tried with the latest Docker image (alpine-small-latest, GDAL
> 3.1.0dev-3c44aef0f367d0439d42f5384896fc7899317f06), but the same issue
> persists: the GNU tar is opened without issues, the POSIX one fails.
> 
> Is it confirmed that GDAL does not have support for that TAR POSIX format?
> How much effort would it be to add support for that format?
> 
> Regards,
> Fabian


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