make: evaluation of symbolic link with ../ fails

[Julian Stacey]

I found some unexpected behaviour within make on 6.2-RELEASE,
Not sure if it's a bug, or proper behaviour. Comment please ?

Make seems to be being too clever, evaluating where it
think the CWD (current working directory) is, whereas I think
it should better let the external per line shell discover for itself.
Make fails to realise that because of  symbolic links, it is not
acceptable to shorten
	cd /site/home/jhs/pics/.. ; rdist
to
	cd /site/home/jhs ; rdist

How I discovered the behaviour:
	I keep my data split in 2: 
		Some small enough to back up to a USB stick, eg:
			/usra/home/jhs/._/txt/	
		& some bulky eg:
			/usra/jhs/xtra/pics
	using symbolic links eg
		/site/home	-> /usra/home
		~/.HOME		-> /site/home/jhs/._
		~/txt		-> .HOME/txt
		~/pics		-> .HOME/pics
		~/._/pics	-> xtra/pics
		~/._/xtra/pics	-> /usra/jhs/xtra/pics

	Some links are more complex than shown, for reasons
	beyond scope of this posting, but it's all been working fine
	for 8 years & I've had patches to 2.2.8 onward
	kernels to increase the allowed traversal count for sym
	links etc
	http://berklix.com/~jhs/src/bsd/fixes/FreeBSD/src/gen/sys/sys/param.h.REL=ALL.diff

It's been fine while I manually ran:
	cd ; rdist `hostname -s`
	cd ~/xtra/LN  ; rdist xtra	# LN -> /usra/jhs/xtra
The make behaviour was noticed when I embeded those lines in a Makefile.

Here's some to try yourself:
# Warning cant use eg ~/pics/../Distfile
bug1:
	-cd ~/txt/.. && pwd
	@#	/usr/home/jhs
	-cd ~/txt/.. && /bin/pwd
	@#	/usra/home/jhs
	-cd ~/txt && cd .. && /bin/pwd
	@#	/usra/home/jhs
	-cd ~/._/txt/.. && /bin/pwd
	@#	/usra/home/jhs/._
bug2:
	cd ~/pics && pwd
	@#	/usr/home/jhs/pics
	cd ~/pics/.. && pwd
	@#	/usr/home/jhs
	cd ~/pics && /bin/pwd
	@#	/usra/jhs/xtra/pics
	cd ~/pics/.. && /bin/pwd
	@#	/usra/home/jhs

See from results marked @#, make is evaluating eg
	cd ~/txt/.. ; rdist
as if it's equivalent to 
	cd ~; rdist
& it's Not equivalent,
if I do eg:
	cd ~/pics/.. ; rdist 
rdist6 runs using the Distfile in my ~/Distfile, rather than different
/usra/jhs/xtra/Distfile.

I can cludge round this make behaviour, eg by in Makefile avoiding the ../ in
	cd ~/xtra/pics/.. && rdist -f /usra/jhs/xtra/Distfile pics
but seems make is trying to be too clever, & failing, & make would be better
if it did less.

(BTW, to avoid distracting answers: I know make invokes a seperate
shell per line, that's not the issue, also not the issue is /usr/obj/
or which external interactive shell I use).

Julian
--
Julian Stacey. Munich Consultant: BSD Unix Linux. http://berklix.com
        Ihr Rauch=mein allergischer Kopfschmerz. Dump cigs 4 snuff.