[gdal-dev] Custom raster driver startup issues

[Even Rouault]

Actually, I remember now that on Linux I've observed plugin loading 
issues specific to loading in Python when I forget to link the plugin to 
libgdal itself. This doesn't show up when loading the plugin from a GDAL 
command line utility.

Le 14/12/2023 à 22:19, Even Rouault via gdal-dev a écrit :
>
> - If you build a plugin against GDAL X.Y, you must run it against GDAL 
> X.Y, and not an earlier or later version since the C++ ABI changes 
> between feature versions (you should however be able to use a plugin, 
> built against X.Y.some_patch_version, against X.Y.another_path_version)
>
> - The error you get about specified procedure not found generally 
> indicate that your plugin links to some library that is not found in 
> the PATH / LD_LIBRARY_PATH. dlopen() / LoadLibrary() aren't super 
> verbose about the reasons. You might have to use ldd or 
> DependencyWalker to figure out the runtime linking issue.
>
> - If you use GDALRegister_X(), then your DLL must be called exactly 
> "gdal_X.dll" / "gdal_X.so"  . Or use "GDALRegisterMe()" as the 
> registration function.  GDALRegister_X or GDALRegisterMe must have C 
> export style (extern "C").
>
> - Before trying GDALOpen(), check with "gdalinfo --format X" that your 
> driver is loaded.
>
> Le 14/12/2023 à 21:52, Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS 
> AND APPLICATIONS INC] via gdal-dev a écrit :
>>
>> Hi,
>>
>> After carefully following the advice here on the lists and the Raster 
>> driver tutorial GDAL isn’t loading the driver.
>>
>> I am relying on the AutoLoadDrivers function.
>>
>> When I GDALAllRegister(), followed by a 
>> GDALOpen(“path/to/custom/raster.ext”, RA_ReadOnly);, GDAL states that 
>> the file is not recognized as a supported file format.  The 
>> application was built against the exact version of GDAL used to link 
>> the custom driver code.  GDAL 3.7.2
>>
>> I tried running an older GDAL version (3.6.3) in a python 
>> environment.  When I `from osgeo import gdal`, there are two errors 
>> that are printed.
>>
>>  1. Can’t load requested DLL – then it printed the full path and file
>>     name of the driver .dll, so it can find it!
>>  2. The specified procedure could not be found
>>
>> These look like python specific error messages to me, and probably 
>> stem from a gdal version mismatch. I’m assuming #2 is emitted in a 
>> trivial sense because the .dll could not be opened.  Curiously the 
>> error message was printed twice.  I did not expect this to work but 
>> my hope was to see a more detailed error message.
>>
>> I have exported the GDALRegister_X() function, in accordance with the 
>> documentation.  The driver code compiles cleanly and follows almost 
>> verbatim with the tutorial.
>>
>> How should I approach diagnosing the problem?
>>
>> Best,
>>
>> Jesse
>>
>>
>> _______________________________________________
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>> gdal-dev at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/gdal-dev
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