New Video about Dynamic Loading

Video: https://youtu.be/VO6gMLtQOKM

Code: https://github.com/simonracz/dynamic-loading

This is mostly for C and C++ devs, although I briefly mention other languages as well.

It's about the dlopen(), dlsym().. APIs and their many use cases.

#linux #C #C++ #dlopen #linker #dynamic #loading #java #android #live #streaming

I am trying to figure out why can one update a .dylib file to a #symlink of a locally built file in a #MacOS #App and there is no error related to #signature check on #Apple #MacOS while running..

In this case the culprit #application is #Thunderbird and most probably is doing #dlopen of that changed dylib.

I thought #GateKeeper will stop this. #security #verification

The difference is due to the behavior of #dlopen when given a null pointer for the first argument.

Linux: "If filename is NULL, then the returned handle is for the main program."

https://man7.org/linux/man-pages/man3/dlopen.3.html

I've been looking at the behavior of #dlopen on #Linux and #macOS in relation to `ctypes.pythonapi._handle`.

On Linux, this returns a specific handle to look up symbols in the Python executable via `dlsym` even when statically linked to libpython.

On macOS, this returns RTLD_DEFAULT, which can be a bit slow since this searches all mach-o images.