1 /*
2 * Copyright © 2013 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, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #include <stdio.h>
25 #include "dri_util.h"
26 #include <dlfcn.h>
27 #include "main/macros.h"
28
29 /* We need GNU extensions to dlfcn.h in order to provide backward
30 * compatibility for the older DRI driver loader mechanism. (dladdr,
31 * Dl_info, and RTLD_DEFAULT)
32 */
33 #if defined(RTLD_DEFAULT) && defined(HAVE_DLADDR)
34
35 #define MEGADRIVER_STUB_MAX_EXTENSIONS 10
36 #define LIB_PATH_SUFFIX "_dri.so"
37 #define LIB_PATH_SUFFIX_LENGTH (sizeof(LIB_PATH_SUFFIX)-1)
38
39 /* This is the table of extensions that the loader will dlsym() for.
40 *
41 * Initially it is empty for the megadriver stub, but the library
42 * constructor may initialize it based on the name of the library that
43 * is being loaded.
44 */
45 PUBLIC const __DRIextension *
46 __driDriverExtensions[MEGADRIVER_STUB_MAX_EXTENSIONS] = {
47 NULL
48 };
49
50 /**
51 * This is a constructor function for the megadriver dynamic library.
52 *
53 * When the driver is dlopen'ed, this function will run. It will
54 * search for the name of the foo_dri.so file that was opened using
55 * the dladdr function.
56 *
57 * After finding foo's name, it will call __driDriverGetExtensions_foo
58 * and use the return to update __driDriverExtensions to enable
59 * compatibility with older DRI driver loaders.
60 */
61 __attribute__((constructor)) static void
megadriver_stub_init(void)62 megadriver_stub_init(void)
63 {
64 Dl_info info;
65 char *driver_name;
66 size_t name_len;
67 char *get_extensions_name;
68 const __DRIextension **(*get_extensions)(void);
69 const __DRIextension **extensions;
70 int i;
71
72 /* Call dladdr on __driDriverExtensions. We are really
73 * interested in the returned info.dli_fname so we can
74 * figure out the path name of the library being loaded.
75 */
76 i = dladdr((void*) __driDriverExtensions, &info);
77 if (i == 0)
78 return;
79
80 /* Search for the last '/' character in the path. */
81 driver_name = strrchr(info.dli_fname, '/');
82 if (driver_name != NULL) {
83 /* Skip '/' character */
84 driver_name++;
85 } else {
86 /* Try using the start of the path */
87 driver_name = (char*) info.dli_fname;
88 }
89
90 /* Make sure the path ends with _dri.so */
91 name_len = strlen(driver_name);
92 i = name_len - LIB_PATH_SUFFIX_LENGTH;
93 if (i < 0 || strcmp(driver_name + i, LIB_PATH_SUFFIX) != 0)
94 return;
95
96 /* Duplicate the string so we can modify it.
97 * So far we've been using info.dli_fname.
98 */
99 driver_name = strdup(driver_name);
100 if (!driver_name)
101 return;
102
103 /* The path ends with _dri.so. Chop this part of the
104 * string off. Then we'll have the driver's final name.
105 */
106 driver_name[i] = '\0';
107
108 i = asprintf(&get_extensions_name, "%s_%s",
109 __DRI_DRIVER_GET_EXTENSIONS, driver_name);
110 free(driver_name);
111 if (i == -1)
112 return;
113
114 /* dlsym to get the driver's get extensions function. We
115 * don't have the dlopen handle, so we have to use
116 * RTLD_DEFAULT. It seems unlikely that the symbol will
117 * be found in another library, but this isn't optimal.
118 */
119 get_extensions = dlsym(RTLD_DEFAULT, get_extensions_name);
120 free(get_extensions_name);
121 if (!get_extensions)
122 return;
123
124 /* Use the newer DRI loader entrypoint to find extensions.
125 * We will then expose these extensions via the older
126 * __driDriverExtensions symbol.
127 */
128 extensions = get_extensions();
129
130 /* Copy the extensions into the __driDriverExtensions array
131 * we declared.
132 */
133 for (i = 0; i < ARRAY_SIZE(__driDriverExtensions); i++) {
134 __driDriverExtensions[i] = extensions[i];
135 if (extensions[i] == NULL)
136 break;
137 }
138
139 /* If the driver had more extensions than we reserved, then
140 * bail out.
141 */
142 if (i == ARRAY_SIZE(__driDriverExtensions)) {
143 __driDriverExtensions[0] = NULL;
144 fprintf(stderr, "Megadriver stub did not reserve enough extension "
145 "slots.\n");
146 return;
147 }
148 }
149
150 #endif /* RTLD_DEFAULT && HAVE_DLADDR */
151
152 static const
stub_error_init_screen(__DRIscreen * psp)153 __DRIconfig **stub_error_init_screen(__DRIscreen *psp)
154 {
155 fprintf(stderr, "An updated DRI driver loader (libGL.so or X Server) is "
156 "required for this Mesa driver.\n");
157 return NULL;
158 }
159
160 /**
161 * This is a stub driDriverAPI that is referenced by dri_util.c but should
162 * never be used.
163 */
164 const struct __DriverAPIRec driDriverAPI = {
165 .InitScreen = stub_error_init_screen,
166 };
167