Fix double-free when freeing ArgInfoList objects
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We previously used `StringList()` as a convenient way to print out the options of an `ArgInfoList`, however `StringList()` by default assumes that it owns the memory and should free it when the object is destroyed. This conflicted with the `ArgInfoList`'s own cleanup. This PR fixes the issue by adding an `owned` keyword argument to `StringList` and using it within the `show()` override. It also includes a test that should purposefully trigger the double-free, to prevent future regressions.
sjkelly
reviewed
Jun 28, 2022
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| SoapySDRArgInfoList_clear(s::ArgInfoList) = @GC.preserve s SoapySDRArgInfoList_clear(pointer_from_objref(s), s.length) | ||
| SoapySDRArgInfoList_clear(s::ArgInfoList) = @GC.preserve s SoapySDRArgInfoList_clear(s.ptr, s.length) |
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I am never certain on the correct use of @GC.preserve. It looks like if we omit this convenience call we can avoid it all together, like: https://github.com/JuliaTelecom/SoapySDR.jl/blame/61e3793c3fa543d7e0139956dc346d248e76fc17/src/typewrappers.jl#L73
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This line isn't changing anything about the @GC.preserve, it's instead just eliminating the slightly-confusing pointer_from_objref(s) and using the embedded pointer directly.
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Right. What I mean is that we could call SoapySDRArgInfoList_clear(s.ptr, s.length) directly in the finalizer to avoid the need for a @GC.preserve all together.
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We previously used
StringList()as a convenient way to print out theoptions of an
ArgInfoList, howeverStringList()by default assumesthat it owns the memory and should free it when the object is destroyed.
This conflicted with the
ArgInfoList's own cleanup. This PR fixes theissue by adding an
ownedkeyword argument toStringListand using itwithin the
show()override. It also includes a test that shouldpurposefully trigger the double-free, to prevent future regressions.