🚀 go-pugleaf

In article <8804060734.AA13918@jade.berkeley.edu> SLMYQ@USU.BITNET writes:
>Here are some hints for changing the current directory in a program.
Good ideas, thanks for posting them.

>Next suggestion.  Unless you are writing a CD program, you really should
>save and restore the old current directory, so if you start a program from
Very true. Here's what I do:
At the beginning of my program, I do:

curdir = DupLock(FindTask(NULL)->pr_CurrentDir);
firstdir = CurrentDir(curdir);

So now I have firstdir available to CurrentDir to at the end of my program.
Now, since _I_ allocated curdir, I can use:

curdir = newdir;
UnLock(CurrentDir(curdir));

to move to a new directory. This is, of course, after checking that newdir
is valid and is a directory. At the end of my program I just:

UnLock(CurrentDir(firstdir));

and I'm back!

One note:
curdir = Lock("", ACCESS_READ); can be used in place of the above DupLock().

>Now if you're wondering why the current directory could possibly be zero,
>it's because of one of those weird things in AmigaDOS.  When a process is
>first created, its pr_CurrentDir is set to zero, rather than some specific
>lock.  With the BCPL commands, this zero lock "assumes" the SYS: directory.
Are you sure about this? When you 'run <programname>', the newly created
process has whatever current directory the shell it was invoked from has.
But I do believe that if you never switched directories in your original
shell, what you said above is true.


-- 
Aaron Avery (avery@puff.cs.wisc.edu)
	    ({seismo,caip,allegra,harvard,rutgers,ihnp4}!uwvax!puff!avery)