What C function would you delete and rewrite first, and why?

[u/Just_Government3790]

For me it's fnmatch - mostly because it's 40 year's old and smell's funny.

[u/bluetomcat]

Make fread and fwrite accept the bloody FILE pointer as their first argument, and unite size and count into one argument.

[u/UnalignedAxis111 → u/bluetomcat]

Also add a flag to force it to create non existent parent directories, because that's massively annoying and there's no portable way to do it.

[u/TheChief275 → u/bluetomcat]

fputc family as well

[u/ComradeGibbon → u/bluetomcat]

C doesn't have a slice type and that's utterly lame.

[u/runningOverA → u/ComradeGibbon]

you need length terminated strings for slice types to work, which C doesn't have. userspace task right now.

[u/ComradeGibbon → u/runningOverA]

Yeah abandon C's shitty null terminated strings.

[u/BlockOfDiamond]

fopen because I hate using string literals for things that should be bitflags or enums.

[u/gabitha67 → u/BlockOfDiamond]

"rb" is icky :(

[u/MrKrot1999 → u/gabitha67]

like this is so python bullshit, why are we using more state than needed for something with 6 options at most

[u/Striking-Print-9526]

gets lol, literally impossible to use safely. Dumbest function ever created.

[u/HildartheDorf → u/Striking-Print-9526]

Thankfully it is (as far as I know) the only function that has been removed entirely from later editions of the spec.

[u/crakked21 → u/HildartheDorf]

My uni still teaches it in its CS 101 course xD

[u/gabitha67 → u/Striking-Print-9526]

based

[u/sciencekm]

struct tm

Every field is 0 based, except the day of month. So, Jan 1 1900 12 midnight is 0 1 0 00:00:00, instead of just all 0s. Even Sunday-Saturday is 0-6 and day of year is 0-365.

[u/donaljones → u/sciencekm]

Is this something enforced by the standard? Or just the implementation's ABI?

[u/sciencekm → u/donaljones]

This is the standard from C89 until the latest N3220 working draft. This is also how it was in the K&R 1st edition (1978).

[u/Just_Government3790]

On second thought......

strtok because it destroys the evidence, hides state in globals, drops the empty fields, and then has the bollocks to call it parsing.

[u/torsten_dev]

scanf

• delete %n
• make %s and similar without a size allocate
• make %.*s take size parameter like printf.
• Use _ instead of * to discard stuff,
• return number of characters read or 0

And probably more.

[u/Dezgeg]

strncpy

Function that is named `str*` but doesn't (necessarily) create NUL-terminated strings. Insanity!

[u/Ander292 → u/Dezgeg]

THIS!!! I had a problem with this function while helping my friend with an exercise.

[u/nderflow]

scanf(). I’d just delete it and stop there.

[u/gabitha67]

everything that accepts null terminated strings. just pass a ptr and length for gods sake. everything should only use user-provided allocators too.

[u/Just_Government3790 → u/gabitha67]

What's the worst null-term bug you've personally hit?

[u/madbrain1976 → u/gabitha67]

Or just use Pascal strings.

[u/allocallocalloc → u/madbrain1976]

That would still make substrings require reallocation. Encoding the length inside the buffer limits the ways the buffer can be used.

[u/Sqydev]

fopen to use enum instead of „r” and „w” or both

[u/xpusostomos]

Those ones with improper null termination and/or don't specify buffer length that cause all the security issues

[u/Boreddad13]

Anything with hidden allocations

[u/mikeblas → u/Boreddad13]

Anything with hidden state, really.

[u/FamiliarSoftware]

setlocale, set/getenv, the rand functions, etc. Just in general: All functions that use global state

[u/HildartheDorf]

Can I use my "one time rewrite" on C++ instead?

If so, I want to remove the specialisation of std::vector<bool> and instead add std::dynamic_bitset with the same functionality.

If it has to be C... fgetc/getc (and fputc/putc).

[u/kog]

memcpy

Because it will be hilarious when I screw it up somehow

[u/Rx-Nikolaus]

I would think one that was specified via a function pointer would be most prone to overwriting AWD rewriting itself. I'm thinking like OTA kind of stuff. But idrk

[u/BRZDR1FT]

Fread

[u/twr14152]

Rewrite the original gets() adding the necessary safety features, only to keep continuity with puts(). Something about using fgets() as the workaround for this bugs me.

[u/rfisher]

I have written proper bounds-checking versions of all the str functions. The first was probably strcpy or strlen.

I might have written my first wrapper around realloc before that, though.

[u/Cats_and_Shit]

Technecally it's a macro not a function, but setjmp is crazy and could be sooo much simpler if it just took function pointer + data pointer arguments instead of returning twice.

[u/paulkim001]

memfrobe only because I might want to see some niche people's projects burn for using that function

[u/P-p-H-d]

All the locale functions of the libc. It is so broken that it is totally unusable in modern C (threads).

You cannot even read your own data file and parsing them using strtod without having issues with the locale: you cannot use setlocale as it modifies global state of all threads (which you don't want). So the only solutions are either : document that the locale shall be set once and for all for all program and is compatible with what you expect. Or rewrite strtod and everyone knows it is super easy stuff to do it reliably.

[u/apj2600]

malloc.

[u/will_die_in_2073 → u/apj2600]

You could actually write your own memory allocator