[GRASS-dev] Re: [BULK] grass-dev Digest, Vol 30, Issue 9

[Laura Toma]

I remember we replaced  the fseek() with an fseeko()  because we ran  
into a bug where we were trying to seek to a large offset (in  
r.terracost).

No objection to removing the 2 includes, given that it still compiles  
w/o them  on other platforms.

-Laura


On Oct 6, 2008, at 9:18 PM, grass-dev-request at lists.osgeo.org wrote:

> Message: 4
> Date: Tue, 7 Oct 2008 00:12:10 +0100 (BST)
> From: Paul Kelly <paul-grass at stjohnspoint.co.uk>
> Subject: Re: [GRASS-dev] fseeko() in libiostream
> To: Andrew Danner <adanner at cs.swarthmore.edu>
> Cc: grass-dev at lists.osgeo.org
> Message-ID: <Pine.LNX.4.62.0810070005140.2785 at vortex.ukshells.co.uk>
> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>
> On Mon, 6 Oct 2008, Andrew Danner wrote:
>
>> fseek is not the same as fseeko.
>>
>> int fseek(FILE *stream, long offset, int whence);
>>
>> int fseeko(FILE *stream, off_t offset, int whence);
>>
>> If large file support is enabled, fseeko will convert off_t to a  
>> 64 bit type
>> even on a 32-bit OS. I'm not sure if long will be 64 bit on a 64- 
>> bit OS for
>> fseek.
>>
>> r.in.xyz may work with large files using plain old fseek as long  
>> as r.in.xyz
>> doesn't make long seeks. ami_stream.h could potentially make long  
>> seeks
>> (e.g., skip the first 8GB of a 30GB file), though in practice, I'm  
>> not sure
>> that code that uses ami_stream (r.terraflow) actually uses this  
>> kind of
>> fseek. Still the interface is designed to potentially use long  
>> seeks and I
>> would be reluctant to simply replace fseeko with fseek in  
>> ami_stream.h.
>>
>> you may to add a #define to check the compiler type and use fseek  
>> only if
>> fseeko does not exist.
>
> Right - I was vaguely aware of some configure checks for fseeko()  
> but as
> ami_stream.h was the only file in GRASS using fseeko() I wasn't  
> sure if it
> had been made redundant by something else. But looking closely at
> include/config.h, I see that we can conditionalise fseeko() on
> #ifdef HAVE_LARGEFILES. After doing that, on Windows fseeko() is  
> redefined
> to fseeko64() and all then works well.
>
> A couple of further Windows compile errors in lib/iostream though:
>
> sh-2.04$ make
> c++ -I/c/grass/grass7/dist.i686-pc-mingw32/include -I/c/grass/extra/ 
> include -O2 -s -I/c/grass/extra/include  -D_FILE_OFFSET_BITS=64 - 
> DPACKAGE=\""grasslibs"\"   -I/c/grass/grass7/dist.i686-pc-mingw32/ 
> include -o OBJ.i686-pc-mingw32/mm_utils.o -c mm_utils.cc
> mm_utils.cc:38:22: sys/mman.h: No such file or directory
> make: *** [OBJ.i686-pc-mingw32/mm_utils.o] Error 1
>
> sh-2.04$ make
> c++ -I/c/grass/grass7/dist.i686-pc-mingw32/include -I/c/grass/extra/ 
> include -O2 -s -I/c/grass/extra/include  -D_FILE_OFFSET_BITS=64 - 
> DPACKAGE=\""grasslibs"\"   -I/c/grass/grass7/dist.i686-pc-mingw32/ 
> include -o OBJ.i686-pc-mingw32/mm_utils.o -c mm_utils.cc
> c++ -I/c/grass/grass7/dist.i686-pc-mingw32/include -I/c/grass/extra/ 
> include -O2 -s -I/c/grass/extra/include  -D_FILE_OFFSET_BITS=64 - 
> DPACKAGE=\""grasslibs"\"   -I/c/grass/grass7/dist.i686-pc-mingw32/ 
> include -o OBJ.i686-pc-mingw32/rtimer.o -c rtimer.cc
> rtimer.cc:38:26: sys/resource.h: No such file or directory
> make: *** [OBJ.i686-pc-mingw32/rtimer.o] Error 1
>
> In the two respective cases I commented out the #includes for sys/ 
> mman.h
> and sys/resource.h and everything compiled fine. r.terraflow  
> compiles fine
> too. So I'll simply remove those two #includes unless there's any
> objection?
>
> Thanks for the feedback,
>
> Paul
>
>

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