Try to do the right thing with EGL symbols.

2 files changed, 48 insertions, 27 deletions

diff --git a/glproc_egl.cpp b/glproc_egl.cpp
index 08556ec..4ceb2ff 100644
--- a/glproc_egl.cpp
+++ b/glproc_egl.cpp
@@ -41,7 +41,7 @@
 #if defined(_WIN32)
 HINSTANCE __libGlHandle = NULL;
 #else
-void *__libGlHandle = RTLD_NEXT;
+void *__libGlHandle = NULL;
 #endif
 
 
@@ -57,34 +57,44 @@ void *__libGlHandle = RTLD_NEXT;
 #else
 
 /*
- * Lookup a EGL or GLES symbol
+ * Lookup a public EGL/GL/GLES symbol
+ *
+ * The spec states that eglGetProcAddress should only be used for non-core
+ * (extensions) entry-points.  Core entry-points should be taken directly from
+ * the API specific libraries.
+ *
+ * We cannot tell here which API a symbol is meant for here (as some are
+ * exported by many).  So this code assumes that the appropriate shared
+ * libraries have been loaded previously (either dlopened with RTLD_GLOBAL, or
+ * as part of the executable dependencies), and that their symbols available
+ * for quering via dlsym(RTLD_NEXT, ...).
  */
-static inline void *
-__libegl_sym(const char *symbol)
-{
-    void *proc;
-
-    /* Always try dlsym before eglGetProcAddress as spec 3.10 says
-     * implementation may choose to also export extension functions
-     * publicly.
-     */
-    proc = dlsym(__libGlHandle, symbol);
-    if (!proc && symbol[0] == 'g' && symbol[1] == 'l')
-        proc = (void *) __eglGetProcAddress(symbol);
-
-    return proc;
-}
-
 void *
 __getPublicProcAddress(const char *procName)
 {
-    return __libegl_sym(procName);
+    return dlsym(RTLD_NEXT, procName);
 }
 
+/*
+ * Lookup a private EGL/GL/GLES symbol
+ *
+ * Private symbols should always be available through eglGetProcAddress, and
+ * they are guaranteed to work with any context bound (regardless of the API).
+ *
+ * However, per issue#57, eglGetProcAddress returns garbage on some
+ * implementations, and the spec states that implementations may choose to also
+ * export extension functions publicly, so we always attempt dlsym before
+ * eglGetProcAddress to mitigate that.
+ */
 void *
 __getPrivateProcAddress(const char *procName)
 {
-    return __libegl_sym(procName);
+    void *proc;
+    proc = dlsym(RTLD_NEXT, procName);
+    if (!proc && procName[0] == 'g' && procName[1] == 'l')
+        proc = (void *) __eglGetProcAddress(procName);
+
+    return proc;
 }
 
 #endif
diff --git a/glws_egl_xlib.cpp b/glws_egl_xlib.cpp
index eb284ab..211cb62 100644
--- a/glws_egl_xlib.cpp
+++ b/glws_egl_xlib.cpp
@@ -220,8 +220,23 @@ public:
     }
 };
 
+/**
+ * Load the symbols from the specified shared object into global namespace, so
+ * that they can be later found by dlsym(RTLD_NEXT, ...);
+ */
+static void
+load(const char *filename)
+{
+    if (!dlopen(filename, RTLD_GLOBAL | RTLD_LAZY)) {
+        std::cerr << "error: unable to open " << filename << "\n";
+        exit(1);
+    }
+}
+
 void
 init(void) {
+    load("libEGL.so.1");
+
     display = XOpenDisplay(NULL);
     if (!display) {
         std::cerr << "error: unable to open display " << XDisplayName(NULL) << "\n";
@@ -230,13 +245,6 @@ init(void) {
 
     screen = DefaultScreen(display);
 
-    __libGlHandle = dlopen("libEGL.so", RTLD_GLOBAL | RTLD_LAZY);
-    if (!__libGlHandle) {
-        std::cerr << "error: unable to open libEGL.so\n";
-        XCloseDisplay(display);
-        exit(1);
-    }
-
     eglDisplay = eglGetDisplay(display);
     if (eglDisplay == EGL_NO_DISPLAY) {
         std::cerr << "error: unable to get EGL display\n";
@@ -328,12 +336,15 @@ createContext(const Visual *_visual, Context *shareContext, Profile profile)
 
     switch (profile) {
     case PROFILE_COMPAT:
+        load("libGL.so.1");
         eglBindAPI(EGL_OPENGL_API);
         break;
     case PROFILE_ES1:
+        load("libGLESv1_CM.so.1");
         eglBindAPI(EGL_OPENGL_ES_API);
         break;
     case PROFILE_ES2:
+        load("libGLESv2.so.1");
         eglBindAPI(EGL_OPENGL_ES_API);
         attribs.add(EGL_CONTEXT_CLIENT_VERSION, 2);
         break;