Crash if two USD versions coexist

[wingfiring]

Description of Issue

We have an application A consumed library B two years ago, which introduced USD build C dylibs dependence, this module name is libusd_ms.dylib.

Currently, we also used USD 3p as library D in application A, we build it from source codes and renamed the module name to libusd_msx.dylib.

By renaming module we can avoid compile issues and running issue if USD version is mostly compatible. But currently we upgraded USD D to 23.11, it's not compatible with library B's USD C version 22.xx. So it leads to a crash when startup application A.

The root causes is USD wrote many initial/destroy functions address in __DATA, pxrctor/pxrdtor sections. USD build C would be loaded first in our case, then get a function lists via iterating all sections named 'pxrctor' from all loaded modules( via function _dyld_register_func_for_add_image), and then call each of them. In one word, intialized. After that, while loading USD build D, the initialization process would also get a function lists in the same way, and theh lists would also contains the functions lists collected from USD build C. Again, all functions would be called, including those from USD build C. That means those functions from USD build C would be called twice. And it leads to crash in our case.

The related codes are in /pxr/base/arch/attributes.h, /pxr/base/arch/attributes.cpp.

In order to fix this issue, we renamed this two __DATA names if allow USD C and USD D coexist temporarily. We also created a internal fix to allow user to specify a suffix to the section name via build-args .
 

Steps to Reproduce

1. build two different version monolithic USD
2. build the following code to generate an executable, with command clang++ -o load -O2 -g a.cpp -std=c++17 -ldl

#include <dlfcn.h>
#include <iostream>
#include <vector>

int main(int argc, char** argv){
    std::vector<void*> handles;
    for (int i = 1; i < argc; ++i){
        auto file = argv[i];
        std::cout << "dlopen: " << file << "\n";
        auto h = dlopen(argv[i], RTLD_NOW|RTLD_GLOBAL);
        if (!h)
            std::cout << "Error: " << dlerror();
        handles.push_back(h);
    }

    for(auto h : handles)
        dlclose(h);
}

3. DYLD_LIBRARY_PATH=PATH1:PATH2 ./load path_to_usd1 path_to_usd2

System Information (OS, Hardware)

OS: MacOS 13.3.1
Xcode: 14.3.1 (14E300c)
Hardware: Apple M1 Pro 2021, 32 GB Memory

Package Versions

23.11, 22.xx

Build Flags

python3 build_scripts/build_usd.py --no-python --no-imaging --build-monolithic --build-variant debug

[jesschimein]

Filed as internal issue #USD-9055

[wingfiring]

PR-2908 has been created for this issue.

[nvmkuruc]

@jesschimein It seems like this was fixed by 319d589

Should we close?

[jesschimein]

Yes, thank you for flagging! Fixed by 319d589