I have a C++ application that I wrote. Due to the special nature of this program, it is not intended to be invoked directly by the user, but instead there is a Perl script which does some important pre-processing for calling the C++ application.


Is there a way that I can have the C++ application check that it was called by this Perl script? (I googled and didn't find an answer). Currently I do a cheap trick where the Perl script sends an undocumented command line argument to the application, and the application will refuse to run unless it has been given that argument (so a user can technically still invoke the application directly). Thanks in advance.

Hmmm, that's a tough problem...if Perl spawns new programs as child processes, maybe you could have the program find its parent process with the entries in /proc, then make sure that the command line of the parent process (in /proc/[process_num]/stat) has 'perl' (or whatever the name of the executable is) in it? Sort of a nasty hack, but I guess it's more secure than relying on the command line option remaining undocumented. It won't work, however, if processes spawned by Perl have only init as a parent.

Why not use a semaphore? Have your Perl app "touch" some file and your app check for that file's existence. You could even check the the "creation time" for the file was reasonably close to that of the start of the C app.

It doesn't spawn it as a new child process (the invocations of the application also need to run on a distributed computing cluster). I wanted to avoid a Linux-specific solution to the problem, because the app is designed to be portable.

This Perl script may execute the application multiple times in one run through the script, and it also does some amount of computation before the program is run (parses configuration files).




Thanks for the suggestions. I just wanted to make sure there wasn't some easy method for doing this that I wasn't aware of. Since it doesn't sound like there is an easy solution, I think my curent method will do the job.

Well, you could still use a file to pass a "token" to the C program (generated by some cryptic process) which the C program needs to "match" before it would run. Something as simple as an XOR with a key might work to discourage casual use of the code. Yes, "touch" is *NIX specific, but files are not.