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jacereda / fsatrace

Filesystem access tracer
ISC License
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Quantifying fsatrace's coverage #36

Open samth opened 4 years ago

samth commented 4 years ago

For a paper we're writing about Rattle (which uses fsatrace) we'd like to quantify in some way how much of the filesystem API fsatrace covers. Right now, it looks like 25 functions are overridden on Linux, which is my estimate just by grepping for R(. Is that accurate? Is there a way to tell how many relevant functions glibc provides? Or anything else in this neighborhood?

cc @ndmitchell @spall

jacereda commented 4 years ago

Grepping for R( won't do it, since there're some #ifdefs and some bare calls to resolv. I guess you can invoke a preprocessor pass via gcc -E and count the resolv( occurrences (subtract 1 for the definition itself).

As to figuring out the glibc functions, no idea. I picked that set using nm, looking at the weak symbols in the library and trying to figure out which ones were relevant. But I guess there must be some documentation.

Please, share the results, I might have missed a bunch of hooks.

samth commented 4 years ago

I ended up looking manually, and counting the calls to resolv etc. I have been unable to find anything that mentions xlstat at all, so my documentation search was pretty fruitless.