empty PATH, LD_LOAD_PATH default

[Reini Urban]

Reini Urban schrieb:
> I have a minor compatibility problem.
> 
> In Linux and other unices it is valid to start a process with an empty 
> path because the LD_LOAD_PATH is correctly set to resolve the path for 
> dynamic libraries.
> I have this situation in perl TAINT-checked environments.
> Our dll loader cannot handle LD_LOAD_PATH because in the case of linked 
> shared libs we don't have our own loader, besides doing the dynamic dlopen.
> 
> So in linux et al. it is valid to do:
> $ PATH= ./someprog-with-dependent-so
> because linux has LD_LOAD_PATH and paths from /etc/ld.so.conf
> while under cygwin it will fail.
> 
> Is there some fast way in the environment handling of the startup from 
> cygwin processes before CreateProcess with a cygwin binary to detect an 
> empty PATH, to mimic the behaviour of
>   LD_LOAD_PATH=/usr/bin:$SYSTEMROOT/System32
> Setting PATH to "/usr/bin/:$SYSTEMROOT:$SYSTEMROOT/System32"
> to resolve the dll's to please the kernel loader.

$SYSTEMROOT:$SYSTEMROOT/System32 is not needed, since native windows 
loads an exe with dll dependencies in $SYSTEMROOT/System32 and empty 
PATH correctly. Some CreateProcess magic.
So only some similar /usr/bin magic is required.

> Or is this a stupid idea? It would make process slower I assume if we 
> want to detect the dependency of shared libs in processes to be created.
> 
> I do not know how the situation of an empty PATH in cygwin
> should be handled.
> cygcheck does write "WARNING: PATH is not set at all!"
> Currently the process fails to start, which seems logic, but is a bit 
> incompatible.

-- 
Reini Urban
http://phpwiki.org/  http://murbreak.at/
http://helsinki.at/  http://spacemovie.mur.at/

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