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dartposixdynamic-linkingffistat

stat method not found in libc.so.6

Using Dart FFI I'm trying to dynamically load the linux/posix 'stat' function.

I've assumed that the function is in the libc.so.6 library but when I attempt to load it I get the error:

Invalid argument(s): Failed to lookup symbol (/lib/x86_64-linux-gnu/libc.so.6: undefined symbol: stat)

I'm successfully loading other functions from the libc.so.6 library so my dynamic loading technique is working correctly.

I have two theories:

  1. stat is a macro for xstat and as such stat no longer exists.
  2. stat is in another library that I've not been able to groc.

Ideally I want to use stat rather than xstat as I need this code to also work on osx which as far as I can tell doesn't support xstat. Help?

Solution

  • I have two theories:

    There is no need to theorize: you can just look:

    echo "#include <sys/stat.h>" | gcc -xc - -E -dD | less
nm -AD /lib/x86_64-linux/gnu/*.so* | grep ' stat$'

    will tell you everything you need to know (your first theory is correct).

    I want to use stat rather than xstat

    You can't: it doesn't exist (when using GLIBC).

    I need this code to also work on osx which as far as I can tell doesn't support xstat.

    Your code can detect the platform it's running on and adjust. This is the price of using non-portable mechanisms, such as FFI.