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1 /* | |
2 * Copyright (C) 2008 The Android Open Source Project | |
3 * | |
4 * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 * you may not use this file except in compliance with the License. | |
6 * You may obtain a copy of the License at | |
7 * | |
8 * http://www.apache.org/licenses/LICENSE-2.0 | |
9 * | |
10 * Unless required by applicable law or agreed to in writing, software | |
11 * distributed under the License is distributed on an "AS IS" BASIS, | |
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 * See the License for the specific language governing permissions and | |
14 * limitations under the License. | |
15 */ | |
16 | |
17 #include <hardware/hardware.h> | |
18 | |
19 #include <cutils/properties.h> | |
20 | |
21 #include <dlfcn.h> | |
22 #include <string.h> | |
23 #include <pthread.h> | |
24 #include <errno.h> | |
25 #include <limits.h> | |
26 #include <stdlib.h> | |
27 | |
28 #define LOG_TAG "HAL" | |
29 #ifdef ANDROID | |
30 #include <utils/Log.h> | |
31 #else | |
32 #include <stdio.h> | |
33 #include <unistd.h> | |
34 #include <log/log.h> | |
35 #endif | |
36 | |
37 #if defined(__LP64__) | |
38 #define _64 "64" | |
39 #else | |
40 #define _64 "" | |
41 #endif | |
42 | |
43 /** Base path of the hal modules */ | |
44 #ifndef HAL_LIBRARY_PATH1 | |
45 #define HAL_LIBRARY_PATH1 "/system/lib" _64 "/hw" | |
46 #endif | |
47 #ifndef HAL_LIBRARY_PATH2 | |
48 #define HAL_LIBRARY_PATH2 "/vendor/lib" _64 "/hw" | |
49 #endif | |
50 | |
51 /** | |
52 * There are a set of variant filename for modules. The form of the filename | |
53 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants | |
54 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be: | |
55 * | |
56 * led.trout.so | |
57 * led.msm7k.so | |
58 * led.ARMV6.so | |
59 * led.default.so | |
60 */ | |
61 | |
62 static const char *variant_keys[] = { | |
63 "ro.hardware", /* This goes first so that it can pick up a different | |
64 file on the emulator. */ | |
65 "ro.product.board", | |
66 "ro.board.platform", | |
67 "ro.arch" | |
68 }; | |
69 | |
70 static const int HAL_VARIANT_KEYS_COUNT = | |
71 (sizeof(variant_keys)/sizeof(variant_keys[0])); | |
72 | |
73 /** | |
74 * Load the file defined by the variant and if successful | |
75 * return the dlopen handle and the hmi. | |
76 * @return 0 = success, !0 = failure. | |
77 */ | |
78 static int load(const char *id, | |
79 const char *path, | |
80 const struct hw_module_t **pHmi) | |
81 { | |
82 int status; | |
83 void *handle; | |
84 struct hw_module_t *hmi; | |
85 | |
86 /* | |
87 * load the symbols resolving undefined symbols before | |
88 * dlopen returns. Since RTLD_GLOBAL is not or'd in with | |
89 * RTLD_NOW the external symbols will not be global | |
90 */ | |
91 handle = dlopen(path, RTLD_NOW); | |
92 if (handle == NULL) { | |
93 char const *err_str = dlerror(); | |
94 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown"); | |
95 status = -EINVAL; | |
96 goto done; | |
97 } | |
98 | |
99 /* Get the address of the struct hal_module_info. */ | |
100 const char *sym = HAL_MODULE_INFO_SYM_AS_STR; | |
101 hmi = (struct hw_module_t *)dlsym(handle, sym); | |
102 if (hmi == NULL) { | |
103 ALOGE("load: couldn't find symbol %s", sym); | |
104 status = -EINVAL; | |
105 goto done; | |
106 } | |
107 | |
108 /* Check that the id matches */ | |
109 if (strcmp(id, hmi->id) != 0) { | |
110 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id); | |
111 status = -EINVAL; | |
112 goto done; | |
113 } | |
114 | |
115 hmi->dso = handle; | |
116 | |
117 /* success */ | |
118 status = 0; | |
119 | |
120 done: | |
121 if (status != 0) { | |
122 hmi = NULL; | |
123 if (handle != NULL) { | |
124 dlclose(handle); | |
125 handle = NULL; | |
126 } | |
127 } else { | |
128 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p", | |
129 id, path, *pHmi, handle); | |
130 } | |
131 | |
132 *pHmi = hmi; | |
133 | |
134 return status; | |
135 } | |
136 | |
137 /* | |
138 * Check if a HAL with given name and subname exists, if so return 0, otherwise | |
139 * otherwise return negative. On success path will contain the path to the HAL. | |
140 */ | |
141 static int hw_module_exists(char *path, size_t path_len, const char *name, | |
142 const char *subname) | |
143 { | |
144 char *hal_library_path = getenv("HAL_LIBRARY_PATH"); | |
145 if (hal_library_path) { | |
146 snprintf(path, path_len, "%s/%s.%s.so", | |
147 hal_library_path, name, subname); | |
148 if (access(path, R_OK) == 0) | |
149 return 0; | |
150 } | |
151 | |
152 snprintf(path, path_len, "%s/%s.%s.so", | |
153 HAL_LIBRARY_PATH2, name, subname); | |
154 if (access(path, R_OK) == 0) | |
155 return 0; | |
156 | |
157 snprintf(path, path_len, "%s/%s.%s.so", | |
158 HAL_LIBRARY_PATH1, name, subname); | |
159 if (access(path, R_OK) == 0) | |
160 return 0; | |
161 | |
162 return -ENOENT; | |
163 } | |
164 | |
165 int hw_get_module_by_class(const char *class_id, const char *inst, | |
166 const struct hw_module_t **module) | |
167 { | |
168 int i; | |
169 char prop[PATH_MAX]; | |
170 char path[PATH_MAX]; | |
171 char name[PATH_MAX]; | |
172 char prop_name[PATH_MAX]; | |
173 | |
174 if (inst) | |
175 snprintf(name, PATH_MAX, "%s.%s", class_id, inst); | |
176 else | |
177 strlcpy(name, class_id, PATH_MAX); | |
178 | |
179 /* | |
180 * Here we rely on the fact that calling dlopen multiple times on | |
181 * the same .so will simply increment a refcount (and not load | |
182 * a new copy of the library). | |
183 * We also assume that dlopen() is thread-safe. | |
184 */ | |
185 | |
186 /* First try a property specific to the class and possibly instance */ | |
187 snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name); | |
188 if (property_get(prop_name, prop, NULL) > 0) { | |
189 if (hw_module_exists(path, sizeof(path), name, prop) == 0) { | |
190 goto found; | |
191 } | |
192 } | |
193 | |
194 /* Loop through the configuration variants looking for a module */ | |
195 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) { | |
196 if (property_get(variant_keys[i], prop, NULL) == 0) { | |
197 continue; | |
198 } | |
199 if (hw_module_exists(path, sizeof(path), name, prop) == 0) { | |
200 goto found; | |
201 } | |
202 } | |
203 | |
204 /* Nothing found, try the default */ | |
205 if (hw_module_exists(path, sizeof(path), name, "default") == 0) { | |
206 goto found; | |
207 } | |
208 | |
209 return -ENOENT; | |
210 | |
211 found: | |
212 /* load the module, if this fails, we're doomed, and we should not try | |
213 * to load a different variant. */ | |
214 return load(class_id, path, module); | |
215 } | |
216 | |
217 int hw_get_module(const char *id, const struct hw_module_t **module) | |
218 { | |
219 return hw_get_module_by_class(id, NULL, module); | |
220 } | |
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