On Fri, Jun 15, 2012 at 12:44 PM, Even Rouault
<[email protected]> wrote:
> Selon Etienne Tourigny <[email protected]>:
>
>> All VSIFILE interfaces (/vsicurl/ , /vsigzip/ , etc.) do not work with
>> the netcdf driver.
>>
>> As the netcdf driver uses libnetcdf, I'm not sure the driver can be
>> modified to use the "large file API".
>>
>> Can someone comment on this?
>>
>> The GTiff driver support VSI, how is this done given that the driver
>> uses libgeotiff? Does the tifvsi.cpp/ file make this possible, by
>> acting as a proxy?
>
> libtiff has a TIFFClientOpen() interface where you provide pointers to
> functions
> for various stuff, including I/O functions. And libgeotiff has a similar
> XTIFFClientOpen() that just calls TIFFClientOpen() after doing some libgeotiff
> initialization.
>
>> If so, can a similar thing be done with libnetcdf?
>
> You are probably one of the best placed to answer the question ;-)
I was afraid you'd say that! I am knowledgeable with the netcdf api,
but its inner workings are still somewhat mysterious.
>
> More seriously, you need to look at the libnetcdf API to see if it offers some
> abstraction layer for its I/O, that can be customized, instead of doing
> directly
> fopen(), fread(), fwrite(), fseek(), fclose() directly all over its code. If
> not, and you want it, you'll need to hack into libnetcdf to avoid those direct
> calls to the standard library.
Quick inspection show non-customizable calls like
fd = open(path, oflags, 0);
(void) close(fd);
Netcdf-4 uses hdf5, but that also seems non-flexible:
#define HDopen(S,F,M) open(S,F,M)
This means it would probably be quite a challenge, one that should
involve quite a few people (ideally the UNIDATA folks)...
So I'm not sure it's really worth it, unfortunately - I don't have the time
thanks
Etienne
>
>>
>> thanks,
>> Etienne
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>
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