[OpenGL] Use elfhacks to load real OpenGL functions

src/gl/inject.cpp

@@ -186,10 +186,10 @@ void* get_proc_address(const char* name) {
 void* get_glx_proc_address(const char* name) {
     if (!gl.Load()) {
         // Force load libGL then. If it still doesn't find it, get_proc_address should quit the program
-        void *handle = dlopen("libGL.so.1", RTLD_GLOBAL | RTLD_LAZY | RTLD_DEEPBIND);
+        void *handle = real_dlopen("libGL.so.1", RTLD_LAZY);
         if (!handle)
             std::cerr << "MANGOHUD: couldn't find libGL.so.1" << std::endl;
-        gl.Load();
+        gl.Load(handle);
     }
 
     void *func = nullptr;
@@ -332,8 +332,6 @@ static void *find_ptr(const char *name)
 }
 
 EXPORT_C_(void *) glXGetProcAddress(const unsigned char* procName) {
-    gl.Load();
-
     //std::cerr << __func__ << ":" << procName << std::endl;
 
     void* func = find_ptr( (const char*)procName );
@@ -344,8 +342,6 @@ EXPORT_C_(void *) glXGetProcAddress(const unsigned char* procName) {
 }
 
 EXPORT_C_(void *) glXGetProcAddressARB(const unsigned char* procName) {
-    gl.Load();
-
     //std::cerr << __func__ << ":" << procName << std::endl;
 
     void* func = find_ptr( (const char*)procName );

src/gl/real_dlsym.cpp

@@ -1,18 +1,83 @@
-#include "real_dlsym.h"
+/**
+ * \author Pyry Haulos <pyry.haulos@gmail.com>
+ * \date 2007-2008
+ * For conditions of distribution and use, see copyright notice in elfhacks.h
+ */
 
+#include <stdio.h>
 #include <stdlib.h>
-#include <dlfcn.h>
+#include "real_dlsym.h"
+#include "elfhacks.h"
 
-extern "C" void* __libc_dlsym( void* handle, const char* name );
+void *(*__dlopen)(const char *, int) = nullptr;
+void *(*__dlsym)(void *, const char *) = nullptr;
+static bool print_dlopen = getenv("MANGOHUD_DEBUG_DLOPEN") != nullptr;
+static bool print_dlsym = getenv("MANGOHUD_DEBUG_DLSYM") != nullptr;
 
-void* real_dlsym( void* handle, const char* name )
+void get_real_functions()
 {
-    static void *(*the_real_dlsym)( void*, const char* );
+    eh_obj_t libdl;
 
-    if (!the_real_dlsym) {
-        void* libdl = dlopen( "libdl.so", RTLD_NOW | RTLD_LOCAL );
-        the_real_dlsym = reinterpret_cast<decltype(the_real_dlsym)> (__libc_dlsym( libdl, "dlsym" ));
+    if (eh_find_obj(&libdl, "*libdl.so*")) {
+        fprintf(stderr, "can't get libdl.so\n");
+        exit(1);
     }
 
-    return the_real_dlsym( handle, name );
+    if (eh_find_sym(&libdl, "dlopen", (void **) &__dlopen)) {
+        fprintf(stderr, "can't get dlopen()\n");
+        exit(1);
+    }
+
+    if (eh_find_sym(&libdl, "dlsym", (void **) &__dlsym)) {
+        fprintf(stderr, "can't get dlsym()\n");
+        exit(1);
+    }
+
+    eh_destroy_obj(&libdl);
+}
+
+/**
+ * \brief dlopen() wrapper, just passes calls to real dlopen()
+ *        and writes information to standard output
+ */
+void *real_dlopen(const char *filename, int flag)
+{
+    if (__dlopen == nullptr)
+        get_real_functions();
+
+    void *result = __dlopen(filename, flag);
+
+    if (print_dlopen) {
+        printf("dlopen(%s, ", filename);
+        const char *fmt = "%s";
+        #define FLAG(test) if (flag & test) { printf(fmt, #test); fmt = "|%s"; }
+        FLAG(RTLD_LAZY)
+        FLAG(RTLD_NOW)
+        FLAG(RTLD_GLOBAL)
+        FLAG(RTLD_LOCAL)
+        FLAG(RTLD_NODELETE)
+        FLAG(RTLD_NOLOAD)
+        FLAG(RTLD_DEEPBIND)
+        #undef FLAG
+        printf(") = %p\n", result);
+    }
+
+    return result;
+}
+
+/**
+ * \brief dlsym() wrapper, passes calls to real dlsym() and
+ *        writes information to standard output
+ */
+void *real_dlsym(void *handle, const char *symbol)
+{
+    if (__dlsym == nullptr)
+        get_real_functions();
+
+    void *result = __dlsym(handle, symbol);
+
+    if (print_dlsym)
+        printf("dlsym(%p, %s) = %p\n", handle, symbol, result);
+
+    return result;
 }

src/gl/real_dlsym.h

@@ -1,22 +1,4 @@
-/*
-Copyright (C) 2016-2017 Björn Spindel
-
-This file is part of libstrangle.
-
-libstrangle is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
-
-libstrangle is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with libstrangle.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
 #pragma once
 
+void *real_dlopen(const char *filename, int flag);
 void* real_dlsym( void*, const char* );

src/loaders/loader_gl.cpp

@@ -8,14 +8,17 @@ gl_loader::~gl_loader() {
   CleanUp(loaded_);
 }
 
-bool gl_loader::Load(bool egl_only) {
+bool gl_loader::Load(void *handle, bool egl_only) {
   if (loaded_) {
     return true;
   }
 
+  if (!handle)
+    handle = RTLD_NEXT;
+
   eglSwapBuffers =
       reinterpret_cast<decltype(this->eglSwapBuffers)>(
-          real_dlsym(RTLD_NEXT, "eglSwapBuffers"));
+          real_dlsym(handle, "eglSwapBuffers"));
 
   if (egl_only) {
     loaded_ = true;
@@ -24,11 +27,11 @@ bool gl_loader::Load(bool egl_only) {
 
   glXGetProcAddress =
       reinterpret_cast<decltype(this->glXGetProcAddress)>(
-          real_dlsym(RTLD_NEXT, "glXGetProcAddress"));
+          real_dlsym(handle, "glXGetProcAddress"));
 
   glXGetProcAddressARB =
       reinterpret_cast<decltype(this->glXGetProcAddressARB)>(
-          real_dlsym(RTLD_NEXT, "glXGetProcAddressARB"));
+          real_dlsym(handle, "glXGetProcAddressARB"));
 
   if (!glXGetProcAddress) {
     CleanUp(true);

src/loaders/loader_gl.h

@@ -9,7 +9,7 @@ class gl_loader {
   gl_loader();
   ~gl_loader();
 
-  bool Load(bool egl_only = false);
+  bool Load(void *handle = nullptr, bool egl_only = false);
   bool IsLoaded() { return loaded_; }
 
   decltype(&::glXGetProcAddress) glXGetProcAddress;

src/meson.build

@@ -51,6 +51,7 @@ vklayer_files = files(
   'iostats.cpp',
   'gpu.cpp',
   'notify.cpp',
+  'elfhacks.cpp',
 )
 
 opengl_files = files(