1 /*
2 * Copyright © 2011 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
19 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
20 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
23 *
24 * Authors:
25 * Benjamin Franzke <benjaminfranzke@googlemail.com>
26 */
27
28 #include <stdio.h>
29 #include <stddef.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <limits.h>
33 #include <dlfcn.h>
34
35 #include "backend.h"
36
37 #define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
38
39 extern const struct gbm_backend gbm_dri_backend;
40
41 struct backend_desc {
42 const char *name;
43 const struct gbm_backend *builtin;
44 };
45
46 static const struct backend_desc backends[] = {
47 { "gbm_dri.so", &gbm_dri_backend },
48 { "gbm_gallium_drm.so", NULL },
49 };
50
51 static const void *
load_backend(const struct backend_desc * backend)52 load_backend(const struct backend_desc *backend)
53 {
54 char path[PATH_MAX];
55 const void *init = NULL;
56 void *module;
57 const char *name;
58 const char *entrypoint = "gbm_backend";
59
60 if (backend == NULL)
61 return NULL;
62
63 name = backend->name;
64
65 if (backend->builtin) {
66 init = backend->builtin;
67 } else {
68 if (name[0] != '/')
69 snprintf(path, sizeof path, MODULEDIR "/%s", name);
70 else
71 snprintf(path, sizeof path, "%s", name);
72
73 module = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
74 if (!module) {
75 fprintf(stderr,
76 "failed to load module: %s\n", dlerror());
77 return NULL;
78 }
79
80 init = dlsym(module, entrypoint);
81 if (!init)
82 return NULL;
83 }
84
85 return init;
86 }
87
88 static const struct backend_desc *
find_backend(const char * name)89 find_backend(const char *name)
90 {
91 const struct backend_desc *backend = NULL;
92 int i;
93
94 for (i = 0; i < ARRAY_SIZE(backends); ++i) {
95 if (strcmp(backends[i].name, name) == 0) {
96 backend = &backends[i];
97 break;
98 }
99 }
100
101 return backend;
102 }
103
104 struct gbm_device *
_gbm_create_device(int fd)105 _gbm_create_device(int fd)
106 {
107 const struct gbm_backend *backend = NULL;
108 struct gbm_device *dev = NULL;
109 int i;
110 const char *b;
111
112 b = getenv("GBM_BACKEND");
113 if (b)
114 backend = load_backend(find_backend(b));
115
116 if (backend)
117 dev = backend->create_device(fd);
118
119 for (i = 0; i < ARRAY_SIZE(backends) && dev == NULL; ++i) {
120 backend = load_backend(&backends[i]);
121 if (backend == NULL)
122 continue;
123
124 dev = backend->create_device(fd);
125 }
126
127 return dev;
128 }
129