Add gbm (generic/graphics buffer manager)

1 files changed, 124 insertions, 0 deletions

diff --git a/src/gbm/main/backend.c b/src/gbm/main/backend.c
new file mode 100644
index 00000000000..2079bbb710d
--- /dev/null
+++ b/src/gbm/main/backend.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright © 2011 Intel Corporation
+ *
+ * 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 (including the next
+ * paragraph) 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:
+ *    Benjamin Franzke <[email protected]>
+ */
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <dlfcn.h>
+
+#include "backend.h"
+
+#define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
+
+struct backend_desc {
+   const char *name;
+   const struct gbm_backend *builtin;
+};
+
+static const struct backend_desc backends[] = {
+};
+
+static const void *
+load_backend(const struct backend_desc *backend)
+{
+   char path[PATH_MAX];
+   const void *init = NULL;
+   void *module;
+   const char *name;
+   const char *entrypoint = "gbm_backend";
+
+   if (backend == NULL)
+      return NULL;
+
+   name = backend->name;
+
+   if (backend->builtin) {
+      init = backend->builtin;
+   } else { 
+      if (name[0] != '/')
+         snprintf(path, sizeof path, MODULEDIR "/%s", name);
+      else
+         snprintf(path, sizeof path, "%s", name);
+
+      module = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
+      if (!module) {
+         fprintf(stderr,
+                 "failed to load module: %s\n", dlerror());
+         return NULL;
+      }
+
+      init = dlsym(module, entrypoint);
+      if (!init)
+         return NULL;
+   }
+
+   return init;
+}
+
+static const struct backend_desc *
+find_backend(const char *name)
+{
+   const struct backend_desc *backend = NULL;
+   int i;
+
+   for (i = 0; i < ARRAY_SIZE(backends); ++i) {
+      if (strcmp(backends[i].name, name) == 0) {
+         backend = &backends[i];
+         break;
+      }
+   }
+
+   return backend;
+}
+
+struct gbm_device *
+_gbm_create_device(int fd)
+{
+   const struct gbm_backend *backend = NULL;
+   struct gbm_device *dev = NULL;
+   int i;
+   const char *b;
+
+   b = getenv("GBM_BACKEND");
+   if (b)
+      backend = load_backend(find_backend(b));
+
+   if (backend)
+      dev = backend->create_device(fd);
+
+   for (i = 0; i < ARRAY_SIZE(backends) && dev == NULL; ++i) {
+      backend = load_backend(&backends[i]);
+      if (backend == NULL)
+         continue;
+
+      dev = backend->create_device(fd);
+   }
+   
+   return dev;
+}