loader: Factor out the common driver opening logic from each loader.

I copied the code from egl_dri2.c, but the functionality was equivalent
between all the loaders other than their particular environment variables.

v2: Drop the logging function equivalent to loader_default_logger()
    (requested by Eric, Emil).  Move the SCons workaround across.  Drop
    the now-unused driGetDriverExtensions() declaration that was lost in a
    rebase.

Reviewed-by: Eric Engestrom <[email protected]> (v1)
Reviewed-by: Emil Velikov <[email protected]> (v1)

3 files changed, 12 insertions, 74 deletions

diff --git a/src/gbm/Makefile.am b/src/gbm/Makefile.am
index 5097212cda0..bb246ecebf5 100644
--- a/src/gbm/Makefile.am
+++ b/src/gbm/Makefile.am
@@ -42,7 +42,6 @@ libgbm_la_SOURCES += \
 	$(gbm_dri_FILES)
 
 AM_CFLAGS += \
-	-DDEFAULT_DRIVER_DIR='"$(DRI_DRIVER_SEARCH_DIR)"' \
 	$(LIBDRM_CFLAGS) \
 	$(PTHREADSTUBS_CFLAGS)
 
diff --git a/src/gbm/backends/dri/gbm_dri.c b/src/gbm/backends/dri/gbm_dri.c
index f32c0cd9885..aeb13962cdc 100644
--- a/src/gbm/backends/dri/gbm_dri.c
+++ b/src/gbm/backends/dri/gbm_dri.c
@@ -304,28 +304,6 @@ dri_bind_extensions(struct gbm_dri_device *dri,
 static const __DRIextension **
 dri_open_driver(struct gbm_dri_device *dri)
 {
-   const __DRIextension **extensions = NULL;
-   char path[PATH_MAX], *search_paths, *p, *next, *end;
-   char *get_extensions_name;
-
-   search_paths = NULL;
-   /* don't allow setuid apps to use LIBGL_DRIVERS_PATH or GBM_DRIVERS_PATH */
-   if (geteuid() == getuid()) {
-      /* Read GBM_DRIVERS_PATH first for compatibility, but LIBGL_DRIVERS_PATH
-       * is recommended over GBM_DRIVERS_PATH.
-       */
-      search_paths = getenv("GBM_DRIVERS_PATH");
-
-      /* Read LIBGL_DRIVERS_PATH if GBM_DRIVERS_PATH was not set.
-       * LIBGL_DRIVERS_PATH is recommended over GBM_DRIVERS_PATH.
-       */
-      if (search_paths == NULL) {
-         search_paths = getenv("LIBGL_DRIVERS_PATH");
-      }
-   }
-   if (search_paths == NULL)
-      search_paths = DEFAULT_DRIVER_DIR;
-
    /* Temporarily work around dri driver libs that need symbols in libglapi
     * but don't automatically link it in.
     */
@@ -334,56 +312,18 @@ dri_open_driver(struct gbm_dri_device *dri)
     */
    dlopen("libglapi.so.0", RTLD_LAZY | RTLD_GLOBAL);
 
-   dri->driver = NULL;
-   end = search_paths + strlen(search_paths);
-   for (p = search_paths; p < end && dri->driver == NULL; p = next + 1) {
-      int len;
-      next = strchr(p, ':');
-      if (next == NULL)
-         next = end;
-
-      len = next - p;
-#if GLX_USE_TLS
-      snprintf(path, sizeof path,
-               "%.*s/tls/%s_dri.so", len, p, dri->driver_name);
-      dri->driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
-#endif
-      if (dri->driver == NULL) {
-         snprintf(path, sizeof path,
-                  "%.*s/%s_dri.so", len, p, dri->driver_name);
-         dri->driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
-      }
-      /* not need continue to loop all paths once the driver is found */
-      if (dri->driver != NULL)
-         break;
-   }
-
-   if (dri->driver == NULL) {
-      fprintf(stderr, "gbm: failed to open any driver (search paths %s)\n",
-              search_paths);
-      fprintf(stderr, "gbm: Last dlopen error: %s\n", dlerror());
-      return NULL;
-   }
-
-   get_extensions_name = loader_get_extensions_name(dri->driver_name);
-   if (get_extensions_name) {
-      const __DRIextension **(*get_extensions)(void);
-
-      get_extensions = dlsym(dri->driver, get_extensions_name);
-      free(get_extensions_name);
-
-      if (get_extensions)
-         extensions = get_extensions();
-   }
-
-   if (!extensions)
-      extensions = dlsym(dri->driver, __DRI_DRIVER_EXTENSIONS);
-   if (extensions == NULL) {
-      fprintf(stderr, "gbm: driver exports no extensions (%s)", dlerror());
-      dlclose(dri->driver);
-   }
-
-   return extensions;
+   static const char *search_path_vars[] = {
+      /* Read GBM_DRIVERS_PATH first for compatibility, but LIBGL_DRIVERS_PATH
+       * is recommended over GBM_DRIVERS_PATH.
+       */
+      "GBM_DRIVERS_PATH"
+      /* Read LIBGL_DRIVERS_PATH if GBM_DRIVERS_PATH was not set.
+       * LIBGL_DRIVERS_PATH is recommended over GBM_DRIVERS_PATH.
+       */
+      "LIBGL_DRIVERS_PATH",
+      NULL
+   };
+   return loader_open_driver(dri->driver_name, &dri->driver, search_path_vars);
 }
 
 static int
diff --git a/src/gbm/meson.build b/src/gbm/meson.build
index 719f9c1a9b8..007f50a9ae3 100644
--- a/src/gbm/meson.build
+++ b/src/gbm/meson.build
@@ -37,7 +37,6 @@ incs_gbm = [
 if with_dri2
   files_gbm += files('backends/dri/gbm_dri.c', 'backends/dri/gbm_driint.h')
   deps_gbm += dep_libdrm # TODO: pthread-stubs
-  args_gbm += '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path)
 endif
 if with_platform_wayland
   deps_gbm += dep_wayland_server