Re: IFS File > 2 GB -- RPG400-L

I have just started writing a program that uses C funtions to write to the
IFS. I have read where the IFS has a limit of 2 GB unless you specify Large
File type.

Do you really mean "C functions"? i.e. do you mean that you're usingfopen(), fgets(), fwrite(), fputs() etc?

Or do you mean the Unix-type APIs, open(), read(), write(), etc? TheseAPIs are not what I would call "C APIs", since they're system APIs, notpart of the ILE C runtime.

Could someone supply me with an example of how this looks in the RPGLEprogram.

If you're using open() and friends, all you need to do is pass O_LARGEFILEas one of the open flags.

There's also an open64() API, but all it does is add O_LARGEFILE to thelist of flags you've spefificed, and then call open() for you. So,there's really no reason to use it except that you can change yourExtProc() to ExtProc('open64') and have all your programs automaticallygain large file support if you recompile them.

There's are fopen64() for large files if you're using the actual C APIs,though support for that is newer than support for open64() and friends. Ibelieve (though I could be wrong) that fopen()'s large file support didn'tstart til V5R3.

The other thing you should consider is that even though the API maysupport files this large, that doesn't mean that the underlying filesystem necessarily does.

For example, in V5R3, QDLS's limit is 2gb, The "root" and QOpenSys filesystems can do up to 1TB. /QNTC is limited to 4gb, etc. So even thoughthe APIs can take 64bit values (allowing 16 exabytes!) the underlyingfilesystem has much smaller capacity.


Leif Guldbrand has handy links to the system limits on his web site:
http://www.think400.dk/downloads.htm
(Look for OS/400 max capacities and limits)

Just something to think about.