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)

5 files changed, 103 insertions, 1 deletions

diff --git a/src/loader/Makefile.am b/src/loader/Makefile.am
index 76252564281..3c22e0ae7e6 100644
--- a/src/loader/Makefile.am
+++ b/src/loader/Makefile.am
@@ -28,6 +28,7 @@ noinst_LTLIBRARIES = libloader.la
 AM_CPPFLAGS = \
 	-I$(top_builddir)/src/util/ \
 	-DUSE_DRICONF \
+	-DDEFAULT_DRIVER_DIR=\"$(DRI_DRIVER_SEARCH_DIR)\" \
 	$(DEFINES) \
 	-I$(top_srcdir)/include \
 	-I$(top_srcdir)/include/drm-uapi \
diff --git a/src/loader/SConscript b/src/loader/SConscript
index f70654f43ae..6a315642c2c 100644
--- a/src/loader/SConscript
+++ b/src/loader/SConscript
@@ -12,6 +12,8 @@ if env['drm']:
     env.PkgUseModules('DRM')
     env.Append(CPPDEFINES = ['HAVE_LIBDRM'])
 
+env.Append(CPPDEFINES = ['DEFAULT_DRIVER_DIR=\\"/usr/local/lib/dri\\"'])
+
 # parse Makefile.sources
 sources = env.ParseSourceList('Makefile.sources', 'LOADER_C_FILES')
 
diff --git a/src/loader/loader.c b/src/loader/loader.c
index 041a59212be..05140b6d18f 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -26,6 +26,7 @@
  *    Rob Clark <[email protected]>
  */
 
+#include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -35,6 +36,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <sys/param.h>
 #ifdef MAJOR_IN_MKDEV
 #include <sys/mkdev.h>
 #endif
@@ -510,3 +512,91 @@ loader_get_extensions_name(const char *driver_name)
 
    return name;
 }
+
+/**
+ * Opens a DRI driver using its driver name, returning the __DRIextension
+ * entrypoints.
+ *
+ * \param driverName - a name like "i965", "radeon", "nouveau", etc.
+ * \param out_driver - Address where the dlopen() return value will be stored.
+ * \param search_path_vars - NULL-terminated list of env vars that can be used
+ * to override the DEFAULT_DRIVER_DIR search path.
+ */
+const struct __DRIextensionRec **
+loader_open_driver(const char *driver_name,
+                   void **out_driver_handle,
+                   const char **search_path_vars)
+{
+   char path[PATH_MAX], *search_paths, *next, *end;
+   char *get_extensions_name;
+   const struct __DRIextensionRec **extensions = NULL;
+   const struct __DRIextensionRec **(*get_extensions)(void);
+
+   search_paths = NULL;
+   if (geteuid() == getuid() && search_path_vars) {
+      for (int i = 0; search_path_vars[i] != NULL; i++) {
+         search_paths = getenv(search_path_vars[i]);
+         if (search_paths)
+            break;
+      }
+   }
+   if (search_paths == NULL)
+      search_paths = DEFAULT_DRIVER_DIR;
+
+   void *driver = NULL;
+   end = search_paths + strlen(search_paths);
+   for (char *p = search_paths; p < end; 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, driver_name);
+      driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
+#endif
+      if (driver == NULL) {
+         snprintf(path, sizeof(path), "%.*s/%s_dri.so", len, p, driver_name);
+         driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
+         if (driver == NULL)
+            log_(_LOADER_DEBUG, "MESA-LOADER: failed to open %s: %s\n",
+                 path, dlerror());
+      }
+      /* not need continue to loop all paths once the driver is found */
+      if (driver != NULL)
+         break;
+   }
+
+   if (driver == NULL) {
+      log_(_LOADER_WARNING, "MESA-LOADER: failed to open %s (search paths %s)\n",
+           driver_name, search_paths);
+      *out_driver_handle = NULL;
+      return NULL;
+   }
+
+   log_(_LOADER_DEBUG, "MESA-LOADER: dlopen(%s)\n", path);
+
+   get_extensions_name = loader_get_extensions_name(driver_name);
+   if (get_extensions_name) {
+      get_extensions = dlsym(driver, get_extensions_name);
+      if (get_extensions) {
+         extensions = get_extensions();
+      } else {
+         log_(_LOADER_DEBUG, "MESA-LOADER: driver does not expose %s(): %s\n",
+              get_extensions_name, dlerror());
+      }
+      free(get_extensions_name);
+   }
+
+   if (!extensions)
+      extensions = dlsym(driver, __DRI_DRIVER_EXTENSIONS);
+   if (extensions == NULL) {
+      log_(_LOADER_WARNING,
+           "MESA-LOADER: driver exports no extensions (%s)\n", dlerror());
+      dlclose(driver);
+   }
+
+   *out_driver_handle = driver;
+   return extensions;
+}
diff --git a/src/loader/loader.h b/src/loader/loader.h
index 7b4dd01144f..779ec44b75d 100644
--- a/src/loader/loader.h
+++ b/src/loader/loader.h
@@ -33,6 +33,8 @@
 extern "C" {
 #endif
 
+struct __DRIextensionRec;
+
 /* Helpers to figure out driver and device name, eg. from pci-id, etc. */
 
 int
@@ -47,6 +49,11 @@ loader_get_pci_id_for_fd(int fd, int *vendor_id, int *chip_id);
 char *
 loader_get_driver_for_fd(int fd);
 
+const struct __DRIextensionRec **
+loader_open_driver(const char *driver_name,
+                   void **out_driver_handle,
+                   const char **search_path_vars);
+
 char *
 loader_get_device_name_for_fd(int fd);
 
diff --git a/src/loader/meson.build b/src/loader/meson.build
index 76fcae2cb44..e280ba41cc2 100644
--- a/src/loader/meson.build
+++ b/src/loader/meson.build
@@ -39,7 +39,9 @@ libloader = static_library(
   'loader',
   ['loader.c', 'loader.h', 'pci_id_driver_map.c', 'pci_id_driver_map.h',
    xmlpool_options_h],
-  c_args : [c_vis_args, '-DUSE_DRICONF'],
+  c_args : [c_vis_args, '-DUSE_DRICONF',
+            '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path),
+],
   include_directories : [inc_include, inc_src, inc_util],
   dependencies : [dep_libdrm, dep_thread],
   build_by_default : false,