> The reason it is not done in C is not ignorance, it is laziness.
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.
> If it were so easy why do you think nobody has done 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.
The TL;DR on that is basically "lazy, security unconscious assholes keep shutting it down".
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.
It is easy to document mistakes in hindsight, since hindsight is 20/20.
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.
There's no need to integrate with 60 years of mission critical codebases, you're making up a problem in your head that doesn't exist.
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.
> Nothing needs to be fixed, all it takes is to stop doing the stupid thing.
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.
I don't know what to tell you. Look at the git codebase, they downright ban any usage of the strcpy family, going so far as to hide them under macros so people can't use them.
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?
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.