Hi, Quoting Nikolaus Rath (2016-05-29 22:11:58) > Did you write down your findings in some more detail somewhere? no, sorry. > I'd be curious why e.g. a LD_PRELOAD based wrapper would not work for all > important cases. For me "all important cases" were "compilation of all debian source packages". LD_PRELOAD based methods would not work for for source packages which make use of this mechanism already (for example during their tests). A prominent example would be src:fakechroot itself. > Or are we assuming that the application is actively trying to prevent this > (and e.g. does system calls directly on its own)? We are assuming that applications do things that they normally do during package builds. Unfortunately that includes test cases which sometimes do really weird things. Using fakechroot or proot it would definitely be possible to set up such a package building tracer that would work for 99% of the archive. By building first without tracer, then with proot (on Linux) and then with fakechroot (should the build fail with proot) and by then using reproducible builds we can even make sure that the tracer did not influence the build in any way that produces different binary packages. If test suits cannot be executed because of the tracer, they will probably fail. I did not follow-up on this 99% solution because I'm usually much less motivated if the solution is not 100% proper. And there were some tricky things to solve like what file format to make up to be able to store build logs and operation on files while at the same time maintaining the process tree that lead to writing to the build log or general file descriptor operations. And since this information becomes a lot really quickly (a yaml based representation I tested with easily reached several hundred of megabytes) it would be great if the information could be written to the output file directly instead of being stored in memory, but this then has to work even with parallel builds. There is still a sticky note about all these things on my fridge but oh if I just would have more time... XD Thanks! cheers, josch
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