Hacker News: dmitrygr

New comment by dmitrygr in "Bun support is now limited and deprecated"

dmitrygr — Sat, 23 May 2026 02:44:43 +0000

Do you also install pre-alpha revisions of operating systems on your main work pc? No, you do not. Why? Because of the "foreseeable compatibility and security issues".

"Well, why don't you install and only then resolve issues if you have those difficulties?" most comments here are asking, in effect

Cause you're sane, that's why!

Same here. yt-dlp does not owe it to anyone to beta test things. Maybe this bun rewrite will be the best thing since sex, and maybe it won't be. Not wanting to alpha test someone else's shit is sane. And the bugs (if any) would go to yt-dlp, forcing them to debug someone else's alpha software. This is a sane response.

New comment by dmitrygr in "AI is just unauthorised plagiarism at a bigger scale"

dmitrygr — Thu, 21 May 2026 15:35:18 +0000

Prior to the invention of copyright, it was not very cheap or easy to make a faithful copy of something. Books had to be type set by hand, before the printing press they had to be copied by hand. Photography of good enough quality to reproduce a painting is very very recent. So is ability to record a play well enough to enjoy it like you are there later.

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 13:41:45 +0000

Which is ok since it is UB to deref

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 13:41:31 +0000

No cause that requires initial alignment.

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 07:50:07 +0000

Without memcpy there is no guarantee that that line produces an invalid pointer

I don’t see what spec part would prohibit that cast from validly compiling to

   BIC r3, r0, #3

Spec only guaranteed round-trip through char* of properly aligned for type pointers. This doesn’t break that.

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 07:48:07 +0000

For signed. Unsigned overflow was defined for a while now.

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 07:44:39 +0000

I do not see there a promise that the cast will produce an invalid pointer, nor anything prohibiting the compiler from rounding the pointer down, thus producing a valid one. “Converted” does not require bit copy. I don’t see how this interpretation is against any section of the spec.

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 07:12:08 +0000

Fun story: even the latest C spec doesn’t require CHAR_BIT == 8, but it does now codify 2s complement int representation. (IIRC)

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 07:03:52 +0000

That cast is valid. Spec does not guarantee same bit sequence for resulting pointer and source pointer. But as the cast is explicitly allowed, it is not UB. Compiler is free to round the pointer down. Or up. Or even sideways. All ok. Dereferencing it — indeed not ok. But the cast is explicitly allowed and not UB.

Pointer casts changing pointer bit sequences is common on weird platforms (eg: some TI DSPs, PIC, and aarch64+PAC). And it is valid as per spec. Pointer assignment is not required to be the same as memcpy-ing the pointer unto a pointer to another type.

You misunderstood the spec. No promises are made that that cast copies the pointer bit for bit (and thus creates an invalid pointer). Therefore, your objection to invalid pointers is null and void. :)

New comment by dmitrygr in "Everything in C is undefined behavior"

dmitrygr — Wed, 20 May 2026 06:41:32 +0000

I stoped reading about here:

    > bool parse_packet(const uint8_t* bytes) {
    >   const int* magic_intp = (const int*)bytes;   // UB!

Author, if you are reading this, please cite the spec section explaining that this is UB. Dereferencing the produced pointer may be UB, but casting itself is not, since uint8_t is ~ char and char* can be cast to and from any type.

you might try to argue that uint8_t is not necessarily char, and while it is true that implementations of C can exist where CHAR_BIT > 8, but those do not have uint8_t defined (as per spec), so if you have uint8_t, then it is "unsigned char", which makes this cast perfectly safe and defined as far as i can tell. Of course CHAR_BIT is required to be >= 8, so if it is not >8, it is exactly 8. (In any case, whether uint8_t is literally a typedef of unsigned char is implementation-defined and not actually relevant to whether the cast itself is valid -- it is)

New comment by dmitrygr in "I’ve built a virtual museum with nearly every operating system you can think of"

dmitrygr — Tue, 19 May 2026 23:42:01 +0000

posted above.

New comment by dmitrygr in "I’ve built a virtual museum with nearly every operating system you can think of"

dmitrygr — Tue, 19 May 2026 23:41:20 +0000

magnet:?xt=urn:btih:24badf9996920185291b39f209cd820aa87fda0d&dn=virtual_os_museum-2026.05.19-full.zip&ws=http%3a%2f%2fdownloads.virtualosmuseum.org%2fvirtual_os_museum-2026.05.19-full.zip&ws=https%3a%2f%2fdownloads.virtualosmuseum.org%2fvirtual_os_museum-2026.05.19-full.zip

seeding now. please seed too :)

New comment by dmitrygr in "I’ve built a virtual museum with nearly every operating system you can think of"

dmitrygr — Tue, 19 May 2026 20:51:59 +0000

#16, 115/120GB

and it is not resuming ...

      2026-05-19 16:23:03 ERROR 522: .

#23, 118.5/120GB and going again

New comment by dmitrygr in "I’ve built a virtual museum with nearly every operating system you can think of"

dmitrygr — Tue, 19 May 2026 18:49:12 +0000

If my download ever finishes i'll spin up a torrent.

So far on retry/resume #12, 97.3/120GB done (i am live updating this comment as long as i can)

New comment by dmitrygr in "Mini Shai-Hulud Strikes Again: 314 npm Packages Compromised"

dmitrygr — Tue, 19 May 2026 15:35:01 +0000

Libc still unaffected. Write native code. Your users will thank you

New comment by dmitrygr in "Hosting a website on an 8-bit microcontroller"

dmitrygr — Mon, 18 May 2026 21:33:37 +0000

ENC28J60 + PIC18 was a typical demo microchip gave out doing precisely this 20 years ago

New comment by dmitrygr in "Native all the way, until you need text"

dmitrygr — Mon, 18 May 2026 01:13:32 +0000

> You go to the dark side. And you are amazed.

And your users hate you and look for alternatives.

New comment by dmitrygr in "Japan Team Successfully Test Engine for Mach 5 Aircraft, Eyeing 2HR Trip to US"

dmitrygr — Mon, 18 May 2026 01:04:26 +0000

If you believe Boom, let me know if you'd be interested in a bet. I'll take the "not gonna happen" side of that for any amount.

New comment by dmitrygr in "WinCE64 – Windows CE 2.11 for N64"

dmitrygr — Fri, 15 May 2026 21:57:34 +0000

yes, but it was rather choosy with the rest of the hardware

New comment by dmitrygr in "WinCE64 – Windows CE 2.11 for N64"

dmitrygr — Fri, 15 May 2026 21:56:44 +0000

probably cause it is just CE 2.11?

either you have seen it and seeing it again is pointless, or you do not know what CE is, and the headline means nothing to you