[GRASS-user] r.in.xyz: Could open text file ~ 2.5GB

[Michael Perdue]

On 20-Oct-06, at 8:12 AM, Glynn Clements wrote:

>
> Michael Perdue wrote:
>
>> Personally, I haven't had any LFS support problems with r.in.xyz.
>> This included scanning a text file for extents as your trying to do.
>> After the initial thread was started with respect to r.in.xyz's LFS I
>> went back and checked some of the test data sets that I have. They're
>> all beyond the 2GB limit (3.7GB is the largest i've tested so far)
>> and I haven't had any problems with the program. As far as I can see,
>> the only thing I have noticed that is different with a file beyond
>> the 2 gig size is that the progress indicator never comes up.
>
> It sounds as if the OS maps fopen() to fopen64() (or uses O_LARGEFILE
> in fopen()) regardless of the _FILE_OFFSET_BITS setting. In that case,
> the fopen() will succeed regardless of the file's size, but the call
> to fseek() will fail with EOVERFLOW.
>
> Out of curiosity, which OS is that?
>
> FWIW, this behaviour is a bad idea. If you can't reliably use
> fseek/ftell on a file, fopen is supposed to fail when you try to open
> the file, rather than succeeding then saying "ha! fooled you!" when
> you try to read the current offset. If you are modifying an existing
> file, failing half-way through (potentially leaving the file in an
> inconsistent state) is a bad thing.
>
> A correct call to fseek() shouldn't be *able* to fail on a normal file
> opened with fopen(). You shouldn't have to worry about offset
> overflows unless you use fopen64(), either literally or by using
> -D_FILE_OFFSET_BITS=64 to remap the stdio functions to their 64-bit
> equivalents.
>
> --  
> Glynn Clements <glynn at gclements.plus.com>

I'm running Mac OSX10.4.8 on a intel MacBook Pro (32bit). I'm pretty  
new to the mac OS (what can I say.... couldn't resist the sleek case  
it came in) and what your saying wouldn't surprise me at all. There  
have been a number of quirks that I've noticed about the mac, some of  
which have been driving me nuts. I'll have to do a little more  
experimentation with my linux workstation when I get it set up again.

Cheers,

Mike Perdue


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