MImilkshakes·Oct 11, 2023
there's labrea which is pretty dusty: https://github.com/dustin/labrea
you could probably achieve something similar with bpf today.
In Open-source network emulators and simulatorsdustin
labrea
C2010–2023
dustin / labrea
labrea
Scripting other people's programs.
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4Mentions
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108GitHub stars
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Scripting other people's programs.
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Observed mentions: 2010-11-13 20:23:19 UTC to 2023-10-11 11:29:35 UTC.
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| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2010 | 2010-01-01 00:00:00 UTC | 2011-01-01 00:00:00 UTC | 2 | 0 | 2 |
| 2011 | 2011-01-01 00:00:00 UTC | 2012-01-01 00:00:00 UTC | 1 | 1 | 0 |
| 2012 | 2012-01-01 00:00:00 UTC | 2013-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2013 | 2013-01-01 00:00:00 UTC | 2014-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2014 | 2014-01-01 00:00:00 UTC | 2015-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2015 | 2015-01-01 00:00:00 UTC | 2016-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2016 | 2016-01-01 00:00:00 UTC | 2017-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2022 | 2022-01-01 00:00:00 UTC | 2023-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 1 | 0 | 1 |
What Hacker News says
4 sourcesLabrea - Scripting other people's programs
2 points · Open discussionRegarding function pointer arrays, I'm doing something in labrea (http://github.com/dustin/labrea) where I need to make what is effectively an FFI call from C to C where I know the number of arguments, and their types, but I have them in the form of an array of unions.
For example, if I need to call read, it's basically an invocation of a function with a 4 byte, 8 byte, and then 4 byte argument (on a 64-bit system). I have a union argument type that represents 32-bit and 64-bit parameter types at the same time. I make a call like this:
rv = abstractInvoke(&fun, args);
which, depending on arity of fun, invokes something like this (auto-generated):
rv = abstractInvoke(fun, args[0], args[1], args[2]);
That three-arg function looks roughly like this (calling my argument type ``a_t'' to abbreviate):
a_t abstractInvoke(struct ft
Read the rest
ype *fun, a_t a0, a_t a1, a_t a2) {
static a_t (*allfuns[])(const void*, a_t a0, a_t a1, a_t a2) = {
invoke_3_4_444, // 0
invoke_3_8_444, // 1
invoke_3_4_448, // 2
invoke_3_8_448, // 3
invoke_3_4_484, // 4
invoke_3_8_484, // 5
// [...]
invoke_3_8_888, // 15
};
return allfuns[fun->offset](fun->orig, a0, a1, a2);
}
I generate all of the functions by arity and types and then compute an array offset of them ahead of time (so read has an offset of 5 since it returns an 8 byte value and its arguments take a 4 byte, 8 byte, and then 4 byte value).
Without this trick, I'd have to use very non-portable assembler to do the same invocation (OK, I'd use libffi or dyncall's already prepackaged very non-portable assembler, which I may end up with anyway) to make this function call.
VMs running on my box might not get a lot of CPU time, but will still get good IO performance.
It's going a bit beyond just simple performance, too. For example, I can add logging of reads on client network file descriptors like this:
https://github.com/dustin/labrea/blob/master/examples/lognet...
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