A number of languages have open() functions that are generalized by default; they open more than plain files, sometimes far more. Such functions are dangerous bear traps lying in wait for the unwary and insufficiently paranoid, because what the programmer thinks is a simple file open may be something very different and more dangerous. In turn, this means that all an attacker needs to do is find some way to supply a 'file name' that your program will try to open.

There's two core problems: the generality is implicit, not explicit, and it is in what you use for a common case that neither needs nor wants the generality. This means that the full potential of what the code can do is not immediately obvious when you read (or write) ' open(filename) ', and that you will be writing it a lot. Adding to the problem is that this is a hard mistake to notice. Your code works; it just has extra 'features' that you don't actually want.

(Even if there is a way to be explicit, people are lazy and sooner or later someone is going to use the implicit way when they shouldn't have.)

As you may have gathered, I don't particularly like such open() s; I feel that they are a prime example of an error-prone interface.