Functional gl injection on linux games

git-svn-id: https://mumble.svn.sourceforge.net/svnroot/mumble/trunk@537 05730e5d-ab1b-0410-a4ac-84af385074fa

2 files changed, 104 insertions, 0 deletions

diff --git a/overlay_gl/overlay.cpp b/overlay_gl/overlay.cpp
new file mode 100644
index 000000000..3a5ea51b5
--- /dev/null
+++ b/overlay_gl/overlay.cpp
@@ -0,0 +1,96 @@
+/* Copyright (C) 2005-2007, Thorvald Natvig <thorvald@natvig.com>
+
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+   - Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+   - Neither the name of the Mumble Developers nor the names of its
+     contributors may be used to endorse or promote products derived from this
+     software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <GL/glx.h>
+#include <GL/gl.h>
+#include <dlfcn.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+// Typdefs for functions we're overriding
+typedef void *(*fdlsym)(void *, const char *);
+typedef void(*fglXSwapBuffers)(Display *,GLXDrawable);
+
+// Original and replacement swapbuffers
+static fglXSwapBuffers oglXSwapBuffers;
+void glXSwapBuffers(Display *, GLXDrawable);
+
+// Define for the dlsym we're chaining to. Ugly hack.
+extern "C" void * __libc_dlsym(void *, const char *);
+
+// if true, we'll always return the "true" symbol.
+static bool bTrueSymbol = false;
+
+/*
+ * This is a truly ugly hack, but as many games dlopen the GL
+ * libraries and then dlsym the functions directly, we have
+ * to override dlsym. And we also have to call the original dlsym,
+ * which leaves us a problem, as we can't very well dlsym("dlsym").
+ *
+ * This works, but requires glibc2.
+ */
+
+void *dlsym(void *ctx, const char *fname) {
+  static fdlsym gdlsym;
+  if (gdlsym == NULL) {
+    void *dl = dlopen("libdl.so.2", RTLD_LAZY);
+    if (! dl) {
+      fprintf(stderr, "Failed to open libdl.so.2\n");
+    } else {
+      gdlsym=(fdlsym) __libc_dlsym(dl, "dlsym");
+    }
+  }
+  if (! bTrueSymbol) {
+    if (strcmp(fname, "glXSwapBuffers")==0) {
+      oglXSwapBuffers = (fglXSwapBuffers) gdlsym(ctx, fname);
+      if (oglXSwapBuffers)
+        return (void *) glXSwapBuffers;
+      else
+        return (void *) oglXSwapBuffers;
+    }
+  }
+  return gdlsym(ctx, fname);
+}
+
+static void *glsym(const char *fname) {
+  bTrueSymbol = true;
+  void *r=dlsym(RTLD_NEXT, fname);
+  bTrueSymbol = false;
+  return r;
+}
+
+void glXSwapBuffers(Display *dpy, GLXDrawable draw) {
+  if (! oglXSwapBuffers)
+    oglXSwapBuffers = (fglXSwapBuffers) glsym("glXSwapBuffers");
+  fprintf(stderr, "Swapping\n");
+  oglXSwapBuffers(dpy, draw);
+}
diff --git a/overlay_gl/overlay_gl.pro b/overlay_gl/overlay_gl.pro
new file mode 100644
index 000000000..a899d9802
--- /dev/null
+++ b/overlay_gl/overlay_gl.pro
@@ -0,0 +1,8 @@
+# Simple project file to build Speex with same compilers
+# as Qt used.
+
+TEMPLATE = lib
+CONFIG -= qt
+CONFIG += release
+TARGET = mumble_ol
+SOURCES = overlay.cpp