Microsoft To Banish Memcpy()

kyriacos notes that Microsoft will be adding memcpy() to its list of function calls banned under its secure development lifecycle. This reader asks, "I was wondering how advanced C/C++ programmers view this move. Do you find this having a negative impact on the flexibility of the language, and do you think it will restrict the creativity of the programmer?"

Comments

No - there are plenty of safer alternatives

[MerlynEmrys67]

Just like removing printf, scanf, and most other copy/string functions. There are safe versions of memcpy that work just fine and are just as easy to use...
Lame story (Trying for flamebait here?)

Re:No - there are plenty of safer alternatives

[Anonymous Coward]

It's a psychological thing. Having a separate parameter for the size of the destination buffer forces the programmer to think about what that size is. Too often programmers call memcpy passing the size of the data that needs copying and forget to check that the destination is big enough. And that's why we see so many buffer overflows.

If you never make this mistake continue to use memcpy. I don't care and neither does Microsoft.

Re:No - there are plenty of safer alternatives

[Duhavid]

It still will not help.

If they are a sloppy enough programmer not to look at what is going on, and to ensure the size of the destination, they will be sloppy enough to use the same dratted variable in both spots, drool all over the keyboard and move on to the next sloppy bit of code.

Re:No - there are plenty of safer alternatives

[parlancex]

I know you were kidding, but I'd like to point out that the internal implementation of memcpy on many platforms will be much faster than the equivilent C using a loop for large copies, including x86/64 due to the use of architecture specific instructions designed to facilitate the operation that most compilers probably don't use even on the highest optimization levels.

Re:No - there are plenty of safer alternatives

[jd]

Whilst you are correct, if Microsoft is going to essentially replace the standard C library with one that has an incompatible API, why not just call it a new library and have done with it?

Or, better yet, if security really was the goal, develop a C-like language that was secure by design?

By simply making things awkward for people to write portable code, all they do is ensure that there are multiple code bases for projects (which increases the opportunity for error) or ensures that people won't write portably. Which is a more likely goal, given who we are talking about.

They should go one better...

[Smidge207]

...and pop up a message box asking the user to confirm they want to copy the memory, and if they press OK then they should have to enter a captcha.

Seriously though, how is it supposed to make your code safer if you pass the size you think your destination buffer is? With memcpy, that size is implicitly greater or equal to the copy size and it's the caller's responsibility to make sure this is the case. Putting bounds checking into the copy function is ridiculous if you're responsible for passing the bounds yourself, and it goes against basic good design. I'm surprised they aren't passing the source buffer size too, just to be extra safe. Also, what happened to the __restrict keyword? It's strangely absent from the memcpy_s function declaration.

=Smidge=

The wole thing is just a bunch of nonsense

[LanceUppercut]

Firstly, the specification of C anf C++ standard library is governed by the corresponding standard commitee. Microsoft has absolutely no authority to "banish" anything from neither C nor C++. They can deprecate it in their .NET code, C# etc., but it has absolutely no relevance to C and C++ languages. So, why would the author of the original question direct it to "advanced C and C++" programmers is beyond me. In general, C and C++ programmers will never know about this "interesting" development.

Secondly, the tryly unsafe and useless functions in the C standard library are the functions like "gets", which offer absolutely no protection agains buffer overflow, regardless of how careful the develoiper is. Functions like 'memcpy', on the other hand, offer sufficient protection to a qualified developer. There's absolutely no sentiment against these functions in C/C++ community and there is absolutely no possiblity of these functions to get deprecated as long as C language exists.