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movq
www.uninformativ.de
 (13w ago)
↳ In-reply-to » Eehhh, what the hell is going on here!?

@lyse@lyse.isobeef.org

Disclaimer: Can’t guarantee that I’m fully awake and I’m being trained at work not to use my brain anymore, so maybe this is complete bullshit. 😪🧟‍♀️

It says here that SQLite uses signed integers:

https://sqlite.org/datatype3.html

In pure bits, 1 << 63 would be 0x8000000000000000, but as a signed value, it gets interpreted as -9223372036854775808. Subtracting 1 yields -9223372036854775809 – but that doesn’t fit in 64 bits anymore. It’s possible that SQLite doesn’t want to wrap around but instead saturates? Haven’t checked. 🤔

With 62 bits, there is enough room.

With 1 << 64, I have no idea how SQLite wants to handle this, because this should immediately trigger a warning, because it doesn’t fit right away. Maybe it gets truncated to 0?

sqlite> select printf('0x%x', 2 * (1 << 64));
╭──────────────────────╮
│ printf('0x%x', 2 ... │
╞══════════════════════╡
│ 0x0                  │
╰──────────────────────╯
sqlite> select printf('0x%x', 0 - 1);
╭──────────────────────╮
│ printf('0x%x', 0 ... │
╞══════════════════════╡
│ 0xffffffffffffffff   │
╰──────────────────────╯
sqlite> select printf('0x%x', 0 - 2);
╭──────────────────────╮
│ printf('0x%x', 0 ... │
╞══════════════════════╡
│ 0xfffffffffffffffe   │
╰──────────────────────╯

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lyse
lyse.isobeef.org
 (13w ago)

Eehhh, what the hell is going on here!?

SELECT
    printf("0x%x", (1 << 63) - 2),
    printf("0x%x", (1 << 63) - 1),
    printf("0x%x",  1 << 63     ),
    printf("0x%x", (1 << 63) + 1),
    printf("0x%x", (1 << 63) + 2)

SQLite yields:

0x8000000000000000 (instead of 0x7ffffffffffffffe)
0x8000000000000000 (instead of 0x7fffffffffffffff)
0x8000000000000000 (correct)
0x8000000000000001 (correct)
0x8000000000000002 (correct)

Huh!? O_o Am I stupid? What am I missing here? Or is this actually a bug? :-?

With 62 bits, everything is spot on:

0x3ffffffffffffffe
0x3fffffffffffffff
0x4000000000000000
0x4000000000000001
0x4000000000000002

And 64 bits rather unsurprisingly also yield:

0xfffffffffffffffe
0xffffffffffffffff
0x0
0x1
0x2

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bmallred
staystrong.run
 (1y ago)

reviewing logs this morning and found i have been spammed hard by bots not respecting the robots.txt file. only noticed it because the OpenAI bot was hitting me with a lot of nonsensical requests. here is the list from last month:

i have placed some middleware to reject these for now but it is not a full proof solution.

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quark
ferengi.one
 (1y ago)

Hmm:

42 75 69 6C 64 20 77 68 61 74 20 6D 61 6B 65 73 20 79 6F 75 20 68 61 70 70 79 2E 20 4C 65 74 20 6D 69 73 65 72 61 62 6C 65 20 70 65 6F 70 6C 65 20 62 75 69 6C 64 20 74 68 65 20 72 65 73 74 2E

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