Fluxcapacitor: spoof Posix time functions | Hacker News Reader

Fluxcapacitor: spoof Posix time functions

github.com

58 pointsluu9 comments

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Reminds me about the "Subterfugue"[1] project I read about way back when.

Neat idea anyways!

[1] http://subterfugue.org/

Edit: Funnily enough, there's a "TimeWarp" example at the bottom of http://subterfugue.org/screenshot.html

Cool project! I can't think of any practical usage thought. I guess nowadays it's much easier to just spawn a VM.

For cheating in games? :)

See also libfaketime, which does all this and more besides: https://github.com/wolfcw/libfaketime

libfaketime is very cool, but I think it does something different. It focuses on, well, faking time. Fluxcapacitor makes blocking syscalls exit immediately, faking time is a necessary side effect.

For example the docs of libfaketime say:

   LD_PRELOAD=./libfaketime.so.1 FAKETIME="+1,5y x10,0" \
   /bin/bash -c 'while true; do echo $SECONDS ; sleep 1 ; done'

   For each second that the endless loop sleeps, the
   executed bash shell will think that 10 seconds have passed

While with fluxcapacitor the sleep will exit immediately, not after 1s:

  $ time ./fluxcapacitor --libpath=. -- \
         bash -c 'for i in 1 2 3 4 5 ; do sleep 1; done'
  real    0m0.279s

Especially useful for testing network protocol interactions faster than you could if you had to wait for real time to pass. Cool stuff.

Could be useful, too bad the name isn't that good.

Reminds me of the Delorean python package someone showed HN a while ago http://news.ycombinator.com/item?id=5104889.

If it's useful to you why would you care what it's called.

A library referencing a favorite movie from my childhood automatically has points for the name. On that note, it could be called the_land_before_timeofday() for all I care.

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