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)

1 files changed, 90 insertions, 0 deletions

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;
+}