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      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 (at) 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 
     34 #include "backend.h"
     35 
     36 #define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
     37 
     38 extern const struct gbm_backend gbm_dri_backend;
     39 
     40 struct backend_desc {
     41    const char *name;
     42    const struct gbm_backend *builtin;
     43 };
     44 
     45 static const struct backend_desc backends[] = {
     46    { "gbm_dri.so", &gbm_dri_backend },
     47 };
     48 
     49 static const void *
     50 load_backend(const struct backend_desc *backend)
     51 {
     52    const void *init = NULL;
     53 
     54    if (backend == NULL)
     55       return NULL;
     56 
     57    if (backend->builtin) {
     58       init = backend->builtin;
     59    }
     60 
     61    return init;
     62 }
     63 
     64 static const struct backend_desc *
     65 find_backend(const char *name)
     66 {
     67    const struct backend_desc *backend = NULL;
     68    unsigned i;
     69 
     70    for (i = 0; i < ARRAY_SIZE(backends); ++i) {
     71       if (strcmp(backends[i].name, name) == 0) {
     72          backend = &backends[i];
     73          break;
     74       }
     75    }
     76 
     77    return backend;
     78 }
     79 
     80 struct gbm_device *
     81 _gbm_create_device(int fd)
     82 {
     83    const struct gbm_backend *backend = NULL;
     84    struct gbm_device *dev = NULL;
     85    unsigned i;
     86    const char *b;
     87 
     88    b = getenv("GBM_BACKEND");
     89    if (b)
     90       backend = load_backend(find_backend(b));
     91 
     92    if (backend)
     93       dev = backend->create_device(fd);
     94 
     95    for (i = 0; i < ARRAY_SIZE(backends) && dev == NULL; ++i) {
     96       backend = load_backend(&backends[i]);
     97       if (backend == NULL)
     98          continue;
     99 
    100       dev = backend->create_device(fd);
    101    }
    102 
    103    return dev;
    104 }
    105