RE: tip required to transfer large data from User Space to IFS - stop press

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

Hi Ian,

> BUT, one of them seems not to make a reference to IFS mode in the open(). I
> need to find out why on Thursday, but its looking increasingly likely its
> the IFS mode that I am getting wrong.

Whenever you specify O_CREAT the API will assume that you've passed a
mode.  If you haven't, the API will use whatever happens to be in memory
at the spot where the mode parameter would've been...  most of the time,
you'll get zeroes, which means that nobody has authority to the file, but
other times you might get random numbers.

The moral of the story is, ALWAYS pass a Mode if you specify O_CREAT.

In another message you asked "what's a umask?"

Well, a Mode specifies bits that get turned on in the permissions...
there's one bit for each permission (owner read, owner write, owner exec,
group read, group write, group exec, public read, public write, public
exec.)

A UMask specifies bits in the mode that are TURNED OFF before a file is
created.  That way, each user can specify something like "never give
public access to files that I create" or "never give the public write
access, but give him read access"  stuff like that.

I've never seen anyone use a umask on the iSeries -- only on Unix systems
-- but I know that it's there, lurking, waiting for someone to use
improperly :)  hehehe