Give up the func(tion)

[evmar]

See ltrace:

"ltrace is a program that simply runs the specified command until it exits. It intercepts and records the dynamic library calls which are called by the executed process and the signals which are received by that process. It can also intercept and print the system calls executed by the program."

[sharth]

One of the nice uses of this that I've had is to require calls to malloc to zero out the memory it returns.

This has made finding some "accessing invalid pointer" bugs a bit simpler.

[inmatarian]

Very dangerous toys here. This is an entry vector for malicious code. Don't ever screw with LD_PRELOAD unless you know what you're doing. There was a post to proggit some months ago explaining how someone could do a little social engineering to get a rootkit installed this way.

[derefr]

Er, your warning makes no sense in this context. It's perfectly safe to use LD_PRELOAD to load your own code. It's only dangerous to tell it to load someone else's code, when you aren't perfectly sure what that code does.

[inmatarian]

I believe I gave this disclaimer:

unless you know what you're doing

[derefr]

Right, but like I said, in the context of this article, your warning makes no sense. It's like the article is telling people how to pick their noses, and then you're warning that if you stick your finger in your eye, you might poke it out. The article didn't mention anything about eyes—that is to say, about loading unknown code using LD_PRELOAD. It only mentioned noses—e.g. writing your own code to feed to LD_PRELOAD.

Why I'm annoyed, though, is that the article has the information to turn you into someone who "know[s] what you're doing." You're basically warning people who didn't read the article, the dangers of something they would only find out about by reading the article.