aboutsummaryrefslogtreecommitdiffstats
path: root/src/mesa/drivers/dri/common/megadriver_stub.c
blob: d085080a19738ff44aa376c93b338c60e7f11b03 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
/*
 * Copyright © 2013 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.
 */

#include <stdio.h>
#include "dri_util.h"
#include <dlfcn.h>
#include "main/macros.h"

/* We need GNU extensions to dlfcn.h in order to provide backward
 * compatibility for the older DRI driver loader mechanism. (dladdr,
 * Dl_info, and RTLD_DEFAULT)
 */
#if defined(RTLD_DEFAULT) && defined(HAVE_DLADDR)

#define MEGADRIVER_STUB_MAX_EXTENSIONS 10
#define LIB_PATH_SUFFIX "_dri.so"
#define LIB_PATH_SUFFIX_LENGTH (sizeof(LIB_PATH_SUFFIX)-1)

/* This is the table of extensions that the loader will dlsym() for.
 *
 * Initially it is empty for the megadriver stub, but the library
 * constructor may initialize it based on the name of the library that
 * is being loaded.
 */
PUBLIC const __DRIextension *
__driDriverExtensions[MEGADRIVER_STUB_MAX_EXTENSIONS] = {
   NULL
};

/**
 * This is a constructor function for the megadriver dynamic library.
 *
 * When the driver is dlopen'ed, this function will run. It will
 * search for the name of the foo_dri.so file that was opened using
 * the dladdr function.
 *
 * After finding foo's name, it will call __driDriverGetExtensions_foo
 * and use the return to update __driDriverExtensions to enable
 * compatibility with older DRI driver loaders.
 */
__attribute__((constructor)) static void
megadriver_stub_init(void)
{
   Dl_info info;
   char *driver_name;
   size_t name_len;
   char *get_extensions_name;
   const __DRIextension **(*get_extensions)(void);
   const __DRIextension **extensions;
   int i;

   /* Call dladdr on __driDriverExtensions. We are really
    * interested in the returned info.dli_fname so we can
    * figure out the path name of the library being loaded.
    */
   i = dladdr((void*) __driDriverExtensions, &info);
   if (i == 0)
      return;

   /* Search for the last '/' character in the path. */
   driver_name = strrchr(info.dli_fname, '/');
   if (driver_name != NULL) {
      /* Skip '/' character */
      driver_name++;
   } else {
      /* Try using the start of the path */
      driver_name = (char*) info.dli_fname;
   }

   /* Make sure the path ends with _dri.so */
   name_len = strlen(driver_name);
   i = name_len - LIB_PATH_SUFFIX_LENGTH;
   if (i < 0 || strcmp(driver_name + i, LIB_PATH_SUFFIX) != 0)
      return;

   /* Duplicate the string so we can modify it.
    * So far we've been using info.dli_fname.
    */
   driver_name = strdup(driver_name);
   if (!driver_name)
      return;

   /* The path ends with _dri.so. Chop this part of the
    * string off. Then we'll have the driver's final name.
    */
   driver_name[i] = '\0';

   i = asprintf(&get_extensions_name, "%s_%s",
                __DRI_DRIVER_GET_EXTENSIONS, driver_name);
   free(driver_name);
   if (i == -1)
      return;

   /* dlsym to get the driver's get extensions function. We
    * don't have the dlopen handle, so we have to use
    * RTLD_DEFAULT. It seems unlikely that the symbol will
    * be found in another library, but this isn't optimal.
    */
   get_extensions = dlsym(RTLD_DEFAULT, get_extensions_name);
   free(get_extensions_name);
   if (!get_extensions)
      return;

   /* Use the newer DRI loader entrypoint to find extensions.
    * We will then expose these extensions via the older
    * __driDriverExtensions symbol.
    */
   extensions = get_extensions();

   /* Copy the extensions into the __driDriverExtensions array
    * we declared.
    */
   for (i = 0; i < ARRAY_SIZE(__driDriverExtensions); i++) {
      __driDriverExtensions[i] = extensions[i];
      if (extensions[i] == NULL)
         break;
   }

   /* If the driver had more extensions than we reserved, then
    * bail out.
    */
   if (i == ARRAY_SIZE(__driDriverExtensions)) {
      __driDriverExtensions[0] = NULL;
      fprintf(stderr, "Megadriver stub did not reserve enough extension "
              "slots.\n");
      return;
   }
}

#endif /* RTLD_DEFAULT && HAVE_DLADDR */

static const
__DRIconfig **stub_error_init_screen(__DRIscreen *psp)
{
   fprintf(stderr, "An updated DRI driver loader (libGL.so or X Server) is "
           "required for this Mesa driver.\n");
   return NULL;
}

/**
 * This is a stub driDriverAPI that is referenced by dri_util.c but should
 * never be used.
 */
const struct __DriverAPIRec driDriverAPI = {
   .InitScreen = stub_error_init_screen,
};