[1]: https://nee.lv/2021/02/28/How-I-cut-GTA-Online-loading-times...
It's a bit of extra code, yes. Not necessarily all that much, but some. On average it is only slightly more expensive than null termination, and considered as a proportion of the size of the strings themselves it's hardly anything. It's probably better than the strings getting hard-limited to 0-255, though, which was quite frequently a user-visible quirk.
I’m not sure why this was - the source base was so old it might have had its origins in Pascal struct behaviour.
I should have sent them a nice fruit basket to commemorate the occasion.
unfortunately as time goes by, the linux api surface gets larger and more convoluted. so there's going to be some coverage you're just never going to get.
but in the abstract, definitely. linux is so bloated at this point that its not clear that it can ever be 'made safe'.
But at the same time, I think blaming the software was kind of a cop out. Devs were in a hurry and simply didnt respect the rules. Given todays software engineer at large. Nerfing programming languages so they cant destroy things might not be a bad idea. But AI will nerf everything.
Why do you assume that AI is gonna nerf everything?
And sentinel value terminations make a lot of sense when you have punch cards and fixed length records that you need to carve into pieces.
Nobody expected any decisions they were making in the 1960s and 1970s to have any bearing on computing a half-century later. They all expected to have their mistakes long papered over by smarter people at some point.
But we ALL make the mistake of underestimating inertia.
This is, and continues to be, an incredibly useful feature that makes C and C structs immensely useful concepts. Part of that does need an invalid value[1]. NULL is convenient for this and although there are some very weird JavaScript-trinity-meme-style consequences for this[2], it's such a useful concept that basically all languages that have the ability to construct pointers have a null pointer[3].
The alternative world looks like everyone inventing their own invalid values. Invalid, non-null, pointers are typically MUCH worse than null pointers for debuggability and security. If you unintentionally read/write/execute memory at 0x0 (by far the most common value for NULL), most operating systems will trap this, whereas may not necessarily if 0x12345678 is your invalid value.
[1]: Stuff like IA64 had NaT bits which were effectively an extra bit for what I assume to be this sorta thing. The problem with this is that it costs an extra bit. I don't really know much about IA64, but presumably [NaT 1] + [don't care] would be your null pointers here. I think?
[2]: Really what the standard, in my opinion, should have done is probably not make use of the null pointer UB for many different functions. A lot of compilers took the UB surrounding that to make incredibly dubious "optimizations" that broke stuff with zero actual performance benefit whatsoever
[3]: Yes, even Rust. Although some (again in my opinion) unfortunate design decisions made it so that C-Rust FFI isn't zero cost because of how it treats spans/slices
C pretends types exist with you, but once bytes hit the road, it's all real-life and segmentation faults.
The subdivision issue is a good perspective, but i would argue the performance impact of cloning substrings is dwarfed by the redundant full string reads to find length.
The limitations were brutal. Initially you could only have 255 bytes in a string. The length of a string and the size of the allocation are now separate and you may need to think about that unused memory in your design. The problem now doubles with the introduction of UTF-8. Your string size is in bytes and you need to track characters separately.
If you want to create an array of strings you either need to specify the length of all strings and accept the memory overhead or have an array of pointers to strings. If you use an array of pointers you may end up choosing to use the 'nil' value as a sentinel that means "end of list." So we're right back where we started.
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Because someone decided to downvote this HN has limited the speed at which I can reply. This site is tragic and I'm fully done with it now. You can spread propaganda and poorly sourced zeitgeist and be among friends but if you try to have a genuine conversation about programming languages you are made to be unwelcome immediately. Screw this.
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> No other data structure works like this.
The linked list.
> You can't mess this up in an array
C happily decomposes arrays into pointers. You can erase your length information from the type. This was an intentional decision.
> Strings are the only data structure that assume there will be a NULL at end.
Which is why almost every string API has a version that allows you to specify the maximum length. The fact that you can use a NUL doesn't mean you have to. Which is why the concept of "sentinel values" is broadly used in many types of applications you haven't considered here.
No worse than C strings then.
That isn't really a problem.
The problem with null-terminated strings is specifically what happens when you reach the end of the allocated array and there ISN'T a NULL character.
Every string function is designed to keep going until it finds the NULL character, so if a hacker gets rid of the NULL character, he can exploit pretty much any standard string manipulation function being used elsewhere in the program to manipulate whatever memory comes AFTER the string data structure.
No other data structure works like this. You can't mess this up in an array, because no function that manipulates arrays is just going to keep going until there is a null. That would be stupid because it would require users of the function to add a NULL to the end of their arrays before passing it to the function, so instead we just pass the size of the array to everything. Strings are the only data structure that assume there will be a NULL at end.
By the way, I read once that if you use UTF-32 every code point will be 4 bytes, constantly, but even then a single code point isn't necessarily a single character. Text is just complicated.
See, AI was trained on existing data - on all that existing C code out there (sure, and also on all the papers and articles saying what was wrong with that C code). Those bugs are in the training data, and often not marked as bugs. So when AI generates C code, is it going to avoid making the mistakes that human code made? No, it's going to generate the kind of code it was trained on. How could it be otherwise?
That's not going to nerf anything.
In C most data structures work like this, you keep going until you find NUL (character) or NULL (pointer). E.g. Strings, array of pointers, linked lists, etc. Of course you can add length to most of those, but it isn't the canonical/traditional way of doing things.
The null in a linked list is the null in the .next field, right? That's the way you would implemented linked lists independent of language. It's not the .value that is null.
A string is an array of characters (well, for characters representable in one byte at least) that has a specific value to represent the end of string.
It would be like if Int::MAX was reduced by 1 to make space for an Int:NUL constant that represented the end of an integer array. Or if you were creating your own ENUM, let's say for NORTH, SOUTH, EAST, WEST, and you added a fifth enumeration called Direction.NUL for use in arrays.
There is a huge gap between developer expectation "it's pointing at something known" and hard reality confirmed by zillions of CVE. That's the reason optionality is prevalent in modern languages and type checkers (python, typescript), nowdays even Java has sane non-nullable types.
I wouldn't call "cause of bugs and security issues" "no cost".
> it's quite rare for a pointer in C to have the ability to be NULL
As a C programmer for more than 25 years, that is the exact opposite of my experience.
In practice really 4 because "indeterminate" is a reasonable error condition you'd like to know about.
And it keeps increasing anyway: e.g. not set has subcategories: not set due to lack of user input, not set because we're loading state from the backend etc.
NULL is the first expression of that basic problem: it's definitely not enough to eliminate NULL because the first thing which happens is your non pointer default value takes it's place.
NULL in C just doesn’t belong at the end of a string. But IMO having a “there is no value here” designation is not a bad thing.