targets/egl-static: allow st/mesa to be dynamically loaded

When shared glapi is not enabled, there are two glapi providers and we
cannot decide which one to link to at build time.  It results in
unresolved symbols in st/mesa.  This commit makes st/mesa a loadable
module when shared glapi is not enabled, and hopes that the apps will
link to one of the glapi providers (GL or GLES).

src/gallium/targets/egl-static/egl.c

@@ -170,7 +170,7 @@ loader_fini(void)
       struct st_module *stmod = &st_modules[i];
 
       if (stmod->stapi) {
-         stmod->stapi->destroy(stmod->stapi);
+         egl_st_destroy_api(stmod->stapi);
          stmod->stapi = NULL;
       }
       stmod->initialized = FALSE;

src/gallium/targets/egl-static/egl_st.c

@@ -29,52 +29,143 @@
 #include "state_tracker/st_api.h"
 #include "egl_st.h"
 
-/* for st/mesa */
-#include "state_tracker/st_gl_api.h"
-/* for st/vega */
-#include "vg_api.h"
-
-static struct st_api *
-st_GL_create_api(void)
-{
 #if FEATURE_GL || FEATURE_ES1 || FEATURE_ES2
-   return st_gl_api_create();
-#else
-   return NULL;
+#include "state_tracker/st_gl_api.h"
 #endif
+
+#if FEATURE_VG
+#include "vg_api.h"
+#endif
+
+#if _EGL_EXTERNAL_GL
+
+#include "util/u_string.h"
+#include "util/u_dl.h"
+#include "egldriver.h"
+#include "egllog.h"
+
+static struct util_dl_library *egl_st_gl_lib;
+
+static EGLBoolean
+dlopen_gl_lib_cb(const char *dir, size_t len, void *callback_data)
+{
+   const char *name = (const char *) callback_data;
+   char path[1024];
+   int ret;
+
+   if (len) {
+      ret = util_snprintf(path, sizeof(path), "%.*s/%s" UTIL_DL_EXT,
+            len, dir, name);
+   }
+   else {
+      ret = util_snprintf(path, sizeof(path), "%s" UTIL_DL_EXT, name);
+   }
+
+   if (ret > 0 && ret < sizeof(path)) {
+      egl_st_gl_lib = util_dl_open(path);
+      if (egl_st_gl_lib)
+         _eglLog(_EGL_DEBUG, "loaded %s", path);
+   }
+
+   return !egl_st_gl_lib;
 }
 
 static struct st_api *
-st_OpenVG_create_api(void)
+load_gl(const char *name, const char *procname)
 {
-#if FEATURE_VG
-   return (struct st_api *) vg_api_get();
-#else
-   return NULL;
-#endif
+   struct st_api *(*create_api)(void);
+   struct st_api *stapi = NULL;
+
+   _eglSearchPathForEach(dlopen_gl_lib_cb, (void *) name);
+   if (!egl_st_gl_lib)
+      return NULL;
+
+   create_api = (struct st_api *(*)(void))
+      util_dl_get_proc_address(egl_st_gl_lib, procname);
+   if (create_api)
+      stapi = create_api();
+
+   if (!stapi) {
+      util_dl_close(egl_st_gl_lib);
+      egl_st_gl_lib = NULL;
+   }
+
+   return stapi;
 }
 
+static struct st_api *
+egl_st_load_gl(void)
+{
+   const char module[] = "st_GL";
+   const char symbol[] = "st_api_create_OpenGL";
+   struct st_api *stapi;
+
+   stapi = load_gl(module, symbol);
+
+   /* try again with libglapi.so loaded */
+   if (!stapi) {
+      struct util_dl_library *glapi = util_dl_open("libglapi" UTIL_DL_EXT);
+
+      if (glapi) {
+         _eglLog(_EGL_DEBUG, "retry with libglapi" UTIL_DL_EXT " loaded");
+
+         stapi = load_gl(module, symbol);
+         util_dl_close(glapi);
+      }
+   }
+   if (!stapi)
+      _eglLog(_EGL_WARNING, "unable to load %s" UTIL_DL_EXT, module);
+
+   return stapi;
+}
+
+#endif /* _EGL_EXTERNAL_GL */
+
 struct st_api *
 egl_st_create_api(enum st_api_type api)
 {
-   struct st_api *stapi;
+   struct st_api *stapi = NULL;
 
    switch (api) {
    case ST_API_OPENGL:
-      stapi = st_GL_create_api();
+#if FEATURE_GL || FEATURE_ES1 || FEATURE_ES2
+#if _EGL_EXTERNAL_GL
+      stapi = egl_st_load_gl();
+#else
+      stapi = st_gl_api_create();
+#endif
+#endif
       break;
    case ST_API_OPENVG:
-      stapi = st_OpenVG_create_api();
+#if FEATURE_VG
+      stapi = (struct st_api *) vg_api_get();
+#endif
       break;
    default:
       assert(!"Unknown API Type\n");
-      stapi = NULL;
       break;
    }
 
    return stapi;
 }
 
+void
+egl_st_destroy_api(struct st_api *stapi)
+{
+#if _EGL_EXTERNAL_GL
+   boolean is_gl = (stapi->api == ST_API_OPENGL);
+
+   stapi->destroy(stapi);
+
+   if (is_gl) {
+      util_dl_close(egl_st_gl_lib);
+      egl_st_gl_lib = NULL;
+   }
+#else
+   stapi->destroy(stapi);
+#endif
+}
+
 uint
 egl_st_get_profile_mask(enum st_api_type api)
 {

src/gallium/targets/egl-static/egl_st.h

@@ -34,6 +34,9 @@
 struct st_api *
 egl_st_create_api(enum st_api_type api);
 
+void
+egl_st_destroy_api(struct st_api *stapi);
+
 uint
 egl_st_get_profile_mask(enum st_api_type api);
 

src/gallium/targets/egl-static/st_GL.c

@@ -0,0 +1,35 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.10
+ *
+ * Copyright (C) 2011 LunarG Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Chia-I Wu <olv@lunarg.com>
+ */
+#include "state_tracker/st_gl_api.h"
+#include "pipe/p_compiler.h"
+
+PUBLIC struct st_api *
+st_api_create_OpenGL(void)
+{
+   return st_gl_api_create();
+}