Of course not. C has been around since the dawn of UNIX and the majority of important libraries at the OS level are written in it.
Compatibility with such a vast amount of code is a lot more important than anything else.
If it were so easy why do you think nobody has done it?
> Ignoring the also obvious solution of just keeping a null terminator around
That's not very useful for the general case. If your code relies on the extra metadata (length, size) being correct and you're passing that null-terminated buffer around to libraries outside your code, it won't be correct since nothing else is aware of it.
People have done it, there are plenty strbuf implementations to go around. Even the kernel has seq_buf. How you handle string manipulation internally in your codebase does not matter for compatibility with existing libraries.
> That's not very useful for the general case. If your code relies on the extra metadata (length, size) being correct and you're passing that null-terminated buffer around to libraries outside your code, it won't be correct since nothing else is aware of it.
You can safely pass the char* buffer inside a std::string to any C library with no conversion. You're making up issues in your head. Don't excuse incompetence.
Precisely!
Why plenty and why is none of them the standard in C?
Dennies Ritchie strongly suggested C should add fat pointers all the way back in 1990. Other people have pointed out the issues with zero terminated strings and arrays decaying into pointers (and the ways to deal with them even with backwards compatibility constraints) for years.
One of the most prominent was Walter Bright's article on "C's Biggest Mistake" back in 2009 and he was a C/C++ commercial compiler developer.
There is no excuse.
It is very easy to write your own one-off secure string handling library. This is a common assignment in intro to C programming classes.
So why isn't it standard in C already?
You offer a theory that there is a gang of "security unconscious assholes [who] keep shutting it down". This gang is so well organized that they have managed to block an easy improvement for many many decades for unknown reasons. That's a pretty wild theory.
Or Occam's razor suggests a different answer: It's actually difficult.
No, not the writing code part, that's easy. It's the seamlessly integrating with ~60 years of mission critical codebases part that's hard.
Nothing needs to be fixed, all it takes is to stop doing the stupid thing.
It does not take a "coordinated gang" to shut down C standard proposals, them getting shut down is the default.
You seem to be neither familiar with the nature of the problem or the struggle that is getting anything passed through ISO standardization. I don't mean to belittle you by saying this, I just hope to make you understand that you are assuming things that are simply not based in reality.
It doesn't even need to be in the standard btw. Just write your own. It's a few lines of code. As you say, a beginner exercise. Yet there is code written after the year 2000 that still uses the strxcpy family. Long after the issues have been known and what the solution is.
"Backwards compatibility" is a total red herring. C++ has the solution right there in its standard library. A backwards compatible string buffer implementation.
Well we'll just agree to disagree I suppose, as I'm equally convinced that you're not grasping what the problem actually is.
All I can say is that if this were as easy to fix as you assert and "all it takes is to stop doing the stupid thing" and we both agree that writing code for the better thing is super easy, then consider why it has not been possible to fix in the C universe.
Banning them outright is not possible in old codebases before the internet got really popular and people were pointing out how bad these functions were, but they sure could stop using them in any new code written in that codebase. That's what code review is for.
Any C code written after 2010 has absolutely no excuse to use these functions. They are inefficient, unsafe and more annoying to use than a strbuf implementation that takes half an hour to write.
So why have people continued to use them?
Option a) they were already there, the codebase is over 30 years old, and replacing the code entirely would be too much work. This is a valid reason.
Option b) ignorance, they don't know how to write a strbuf type. This one is downright impossible, any C dev knows how to do it, and like I said, literally every other language does it the same way.
Option c) laziness. This is for me the only real reason. As awful as these functions are, they're in the stdlib. You still see people saying "simple usages of strncpy are fine". They are not fine.
If you can think of an option d) I'd love to know, because I honestly can't think of anything else. Note that interfacing with existing 30 year old codebases does not count, as how you internally manipulate strings has no bearing on that, all you need to ensure is the 0 terminator at the end.
You get a mutable char* from the old function. You shove it in a struct strbuf {size_t capacity, size_t length, char* data}. Done.
You get a constant char* from the old function. You call strlen followed by malloc and memcpy into a new buffer for the strbuf. Or if you don't need to actually mutate the string, you store it in a non-zero terminated struct strview {size_t length; char* data}.
So what is the challenge here? Why is usage of strcpy not banned in any codebase less than 20 years old?
If this was a mitigation, it would solve all problems with nul-terminated strings i.e. do strict and error-checked conversions to nul-terminated strings at all boundaries to the program, and then nul-terminated strings and len-specified strings are equivalently dangerous (or safe, depending on your perspective).
The problem is precisely that unsanitised input makes its way into the application, bypassing any checks.
That's very different from needing to be on your toes with every usage of the strxcpy family.
I agree: having a datatype beats sanitising input (I think there's a popular essay somewhere about parsing input vs sanitising input which makes pretty much the same point as you do), but it's still only partially correct.
To get to fully correct you don't need a new string type, you need developers to recognise that the fields "Full Name" and "Email address" and "Phone number", while all being stored as strings, are actually different types and to handle them as such by making those types incompatible so that a `string_copy` function must produce a compilation failure when the destination is "EmailAddressType" and the source is "FullNameType".
Developers in C can, right now, do that with only a few minutes of extra typing effort. Adding a "proper" string type is still going to result in someone, somewhere, parsing a uint8_t from a string into a uint64_t, and then (after some computation) reversing that (now overflowing) uint64_t back into a uint8_t.
If you're doing the right thing and creating types because "Parse, Don't Validate", a better string type doesn't bring any benefits. If you're doing the wrong thing and validating inputs, then you're going to miss one anyway, no matter the underlying string type.
Of course, but that's my point - C already gives you the ability to fix the incorrect typing problem, using the existing foundational `str*` functions.
A team who is not using the compiler's ability to warn when mixing types are still going to mix types when there is a safe strbuf_t type.
The problem with the `str*` functions can be fixed today without modifying the language or it's stdlib.
Most C programmers don't do it (myself included). I think that, in one sense, you are correct in that removing the existing string representation (and functions for them) and replacing them with len+data representation for strings will fix some problems.
Trouble is, a lot of useful tokenising/parsing/etc string problems are not possible in a len+data representation (each strtok() type function, for example, needs to make a copy of what it returns) so programmers are just going to do their best to bypass them.
Having programmers trained to create new string types using existing C is just easier, because then you solve the whole 'mixing types' problem even when looking at replacements for things like `strtok`.
Or ... maybe I'm completely off-base and the reason that programmers don't create different types for string-stored data is because it is too much work in current C-as-we-know-it.
Every other language with mutable strings, including C++, does it like that. It is obvious. The reason it is not done in C is not ignorance, it is laziness.
> Which you then can't pass to any other library. String management is very easy to solve within the boundaries of your own code. But you'll need to interact with existing code as well.
Ignoring the also obvious solution of just keeping a null terminator around (see: C++ std::string), you should only worry about it at the boundary with the other library.
Same as converting from utf-8 to utf-16 to talk to the Windows API for example.