kc3-lang/dlfcn-win32/cmake-test

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• Hash : 29c46a54
  Author :
  Date : 2019-01-29T22:38:42
  

  Fix resolving global symbols when LoadLibrary() is called after dlopen() Usage of first_automatic_object cache is wrong. This cache is filled by all loaded DLL files (either implicitly or explicitly with LoadLibrary() call) by EnumProcessModules() call at first usage of dlopen(). So dlsym() can resolve global symbols only if they were loaded prior to dlopen() call. Any future usage of LoadLibrary() does not include newly loaded DLLs into first_automatic_object cache. To fix this problem, first_automatic_object cache is fully removed and EnumProcessModules() call is issued directly in dlsym() call. As EnumProcessModules() returns all DLLs, included those which were loaded by dlopen() with RTLD_LOCAL, it may break RTLD_LOCAL support. To address this problem switch linked-list of all loaded DLLs with RTLD_GLOBAL to linked-list of all loaded DLLs with RTLD_LOCAL flag. And then skip modules from EnumProcessModules() which are in linked-list. Also in WinAPI all DLLs loaded by LoadLibrary() behaves like RTLD_GLOBAL. So above change is compatible with this behavior. There may be another problem. Before retrieving HMODULE for DLL filename (which is done by LoadLibrary()), it is not possible to detect if DLL was already loaded by RTLD_LOCAL or not. And after calling LoadLibrary() it is not possible to know if DLL was loaded either by dlsym() with RTLD_LOCAL or by LoadLibrary() (which is equivalent to RTLD_GLOBAL). To address this problem, compare number of loaded modules (counted by EnumProcessModules()) before and after LoadLibrary() called from dlsym(). If number does not change it means that DLL was already loaded. So based on this result either add or remove HMODULE from linked-list of RTLD_LOCAL modules. Added test demonstrate usage of: global = dlopen(NULL, RTLD_GLOBAL); /* global handle */ LoadLibrary("library.dll"); /* this provides function */ function = dlsym(global, "function"); /* resolve function from library.dll */

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• CMakeLists.txt

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