Add utility lib with dlsym hooking

bin/mangohud.in

@@ -1,8 +1,8 @@
 #!/bin/sh
 
 MANGOHUD_LIB_NAME="libMangoHud.so"
-if [ "$MANGOHUD_NODLSYM" = "1" ]; then
-	MANGOHUD_LIB_NAME="libMangoHud_nodlsym.so"
+if [ "$MANGOHUD_DLSYM" = "1" ]; then
+	MANGOHUD_LIB_NAME="libMangoHud_dlsym.so:${MANGOHUD_LIB_NAME}"
 fi
 
 if [ "$#" -eq 0 ]; then

build.sh

@@ -185,6 +185,8 @@ install() {
 
     /usr/bin/install -vm644 -D ./build/release/usr/lib/mangohud/lib32/libMangoHud.so /usr/lib/mangohud/lib32/libMangoHud.so
     /usr/bin/install -vm644 -D ./build/release/usr/lib/mangohud/lib64/libMangoHud.so /usr/lib/mangohud/lib64/libMangoHud.so
+    /usr/bin/install -vm644 -D ./build/release/usr/lib/mangohud/lib32/libMangoHud_dlsym.so /usr/lib/mangohud/lib32/libMangoHud_dlsym.so
+    /usr/bin/install -vm644 -D ./build/release/usr/lib/mangohud/lib64/libMangoHud_dlsym.so /usr/lib/mangohud/lib64/libMangoHud_dlsym.so
     /usr/bin/install -vm644 -D ./build/release/usr/share/vulkan/implicit_layer.d/MangoHud.x86.json /usr/share/vulkan/implicit_layer.d/MangoHud.x86.json
     /usr/bin/install -vm644 -D ./build/release/usr/share/vulkan/implicit_layer.d/MangoHud.x86_64.json /usr/share/vulkan/implicit_layer.d/MangoHud.x86_64.json
     /usr/bin/install -vm644 -D ./build/release/usr/share/doc/mangohud/MangoHud.conf.example /usr/share/doc/mangohud/MangoHud.conf.example

src/gl/inject_egl.cpp

@@ -84,7 +84,7 @@ static std::array<const func_ptr, 1> name_to_funcptr_map = {{
 #undef ADD_HOOK
 }};
 
-void *find_egl_ptr(const char *name)
+EXPORT_C_(void *) mangohud_find_egl_ptr(const char *name)
 {
   if (is_blacklisted())
       return nullptr;
@@ -100,7 +100,7 @@ void *find_egl_ptr(const char *name)
 EXPORT_C_(void *) eglGetProcAddress(const char* procName) {
     //std::cerr << __func__ << ": " << procName << std::endl;
 
-    void* func = find_egl_ptr(procName);
+    void* func = mangohud_find_egl_ptr(procName);
     if (func)
         return func;
 

src/gl/inject_glx.cpp

@@ -200,7 +200,7 @@ static std::array<const func_ptr, 9> name_to_funcptr_map = {{
 #undef ADD_HOOK
 }};
 
-void *find_glx_ptr(const char *name)
+EXPORT_C_(void *) mangohud_find_glx_ptr(const char *name)
 {
   if (is_blacklisted())
       return nullptr;
@@ -216,7 +216,7 @@ void *find_glx_ptr(const char *name)
 EXPORT_C_(void *) glXGetProcAddress(const unsigned char* procName) {
     //std::cerr << __func__ << ":" << procName << std::endl;
 
-    void* func = find_glx_ptr( (const char*)procName );
+    void* func = mangohud_find_glx_ptr( (const char*)procName );
     if (func)
         return func;
 
@@ -226,7 +226,7 @@ EXPORT_C_(void *) glXGetProcAddress(const unsigned char* procName) {
 EXPORT_C_(void *) glXGetProcAddressARB(const unsigned char* procName) {
     //std::cerr << __func__ << ":" << procName << std::endl;
 
-    void* func = find_glx_ptr( (const char*)procName );
+    void* func = mangohud_find_glx_ptr( (const char*)procName );
     if (func)
         return func;
 

src/hook_dlsym.cpp

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+#include "real_dlsym.h"
+
+EXPORT_C_(void*) dlsym(void * handle, const char * name)
+{
+    void *(*find_glx_ptr)(const char *name) = nullptr;
+    void *(*find_egl_ptr)(const char *name) = nullptr;
+
+    if (!find_glx_ptr)
+        find_glx_ptr = reinterpret_cast<decltype(find_glx_ptr)> (real_dlsym(RTLD_NEXT, "mangohud_find_glx_ptr"));
+
+    if (!find_egl_ptr)
+        find_egl_ptr = reinterpret_cast<decltype(find_egl_ptr)> (real_dlsym(RTLD_NEXT, "mangohud_find_egl_ptr"));
+
+    void* func = nullptr;
+
+    if (find_glx_ptr) {
+        func = find_glx_ptr(name);
+        if (func) {
+            //fprintf(stderr,"%s: local: %s\n",  __func__ , name);
+            return func;
+        }
+    }
+
+    if (find_egl_ptr) {
+        func = find_egl_ptr(name);
+        if (func) {
+            //fprintf(stderr,"%s: local: %s\n",  __func__ , name);
+            return func;
+        }
+    }
+
+    //fprintf(stderr,"%s: foreign: %s\n",  __func__ , name);
+    return real_dlsym(handle, name);
+}

src/meson.build

@@ -140,6 +140,29 @@ vklayer_mesa_overlay = shared_library(
   install : true
 )
 
+mangohud_dlsym = shared_library(
+  'MangoHud_dlsym',
+  files(
+    'elfhacks.cpp',
+    'real_dlsym.cpp',
+    'hook_dlsym.cpp',
+  ),
+  c_args : [
+    pre_args,
+    c_vis_args,
+    no_override_init_args,
+    ],
+  cpp_args : [
+    pre_args,
+    cpp_vis_args,
+    ],
+  dependencies : [dep_dl],
+  include_directories : [inc_common],
+  link_args : cc.get_supported_link_arguments(['-Wl,-Bsymbolic-functions', '-Wl,-z,relro', '-Wl,--exclude-libs,ALL']),
+  install_dir : libdir_mangohud,
+  install : true
+)
+
 configure_file(input : 'mangohud.json.in',
   output : '@0@.@1@.json'.format(meson.project_name(), target_machine.cpu_family()),
   configuration : {'libdir_mangohud' : libdir_mangohud + '/',

src/real_dlsym.cpp

@@ -91,21 +91,21 @@ void* get_proc_address(const char* name) {
 }
 
 #ifdef HOOK_DLSYM
-extern void *find_glx_ptr(const char *name);
-extern void *find_egl_ptr(const char *name);
+EXPORT_C_(void *) mangohud_find_glx_ptr(const char *name);
+EXPORT_C_(void *) mangohud_find_egl_ptr(const char *name);
 
 EXPORT_C_(void*) dlsym(void * handle, const char * name)
 {
     void* func = nullptr;
 #ifdef HAVE_X11
-    func = find_glx_ptr(name);
+    func = mangohud_find_glx_ptr(name);
     if (func) {
         //fprintf(stderr,"%s: local: %s\n",  __func__ , name);
         return func;
     }
 #endif
 
-    func = find_egl_ptr(name);
+    func = mangohud_find_egl_ptr(name);
     if (func) {
         //fprintf(stderr,"%s: local: %s\n",  __func__ , name);
         return func;