Re: [Compilercache-general] oh boy...

[Mike A. H. <mh...@re...>]

On Wed, 31 Oct 2001, Erik Thiele wrote:

>i got a problem that drives me nuts.
>
>it's all about temporary files creation in bash scripts.
>compilercache needs to do two things.
>
>1) create a temporary file that is maximally fast
>
>2) create a temporary file in the cache directory that can be renamed
>to the real entry by a single atomic "rename" system call. (i.e. mv
>needn't copy) this is important because otherwise other users of your
>cache will get half-ready (i.e. wrong) .o files.
>
>debian has the nicest fix for this task. it's the "tempfile"
>program. unfortunately it is not installed in other distributions like
>redhat, or even other unixes.

I do not know if debian has mktemp or not, but the standard way 
in Red Hat Linux and most other RPM based distro's is to use 
mktemp.

TEMPFILE=$(mktemp "/tmp/somefile.XXXXXX")

>in compilercache-1.0.9 i was using
>
>FASTTMPFILE=/tmp/compilercache_$$
>
>which is a VERY severe security hole since other users could install
>link files there and manipulate the temporary files of other users...

Correct, and we are constantly tracking down these horrible 
security problems too.  ;o(


>there exists a "mktemp" program which is not portable to HP-UX at least.

Yep, that is what we use.


>ok. i NEED the functionality (especially the --directory parameter) of
>debian "tempfile".

mktemp -d

>either it is there or not. if not, i must include a tempfile
>program in the compilercache distribution and tell the user he
>must install it. but where to ??? /bin is not an option for
>non-root users. so the user must put it somewhere in his path
>and set the PATH variable accordingly in the .compilercacherc
>config file. but where will he put it ? in the compilercache
>bin dir?

mktemp sources are very very small, I'd just include it in its 
entirety, and by default install it into the compilercache dir.


>and who writes the tempfile program? maybe a perl script? i wrote one,
>(without the --directory functionality) but it is very slow:
>
>use File::Temp qw/tempfile/;
>($fh,$filename)=tempfile();
>print $filename."\n";
>
>and by the way.... the current 1.0.10 version fixes this problem in a
>somehow funny way. you just set your own private temporary directory
>and all problems are gone away.

With mktemp being open source and written in C, it would be a 
better choice.  Any perl script or other script is going to 
defeat a lot of the purpose of compilercache, which is speed.

Hope this helps.



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