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
27 #define LOG_TAG "HAL"
28 #include <utils/Log.h>
29
30 /** Base path of the hal modules */
31 #if defined(__LP64__)
32 #define HAL_LIBRARY_PATH1 "/system/lib64/hw"
33 #define HAL_LIBRARY_PATH2 "/vendor/lib64/hw"
34 #define HAL_LIBRARY_PATH3 "/odm/lib64/hw"
35 #else
36 #define HAL_LIBRARY_PATH1 "/system/lib/hw"
37 #define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
38 #define HAL_LIBRARY_PATH3 "/odm/lib/hw"
39 #endif
40
41 /**
42 * There are a set of variant filename for modules. The form of the filename
43 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
44 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
45 *
46 * led.trout.so
47 * led.msm7k.so
48 * led.ARMV6.so
49 * led.default.so
50 */
51
52 static const char *variant_keys[] = {
53 "ro.hardware", /* This goes first so that it can pick up a different
54 file on the emulator. */
55 "ro.product.board",
56 "ro.board.platform",
57 "ro.arch"
58 };
59
60 static const int HAL_VARIANT_KEYS_COUNT =
61 (sizeof(variant_keys)/sizeof(variant_keys[0]));
62
63 /**
64 * Load the file defined by the variant and if successful
65 * return the dlopen handle and the hmi.
66 * @return 0 = success, !0 = failure.
67 */
load(const char * id,const char * path,const struct hw_module_t ** pHmi)68 static int load(const char *id,
69 const char *path,
70 const struct hw_module_t **pHmi)
71 {
72 int status = -EINVAL;
73 void *handle = NULL;
74 struct hw_module_t *hmi = NULL;
75
76 /*
77 * load the symbols resolving undefined symbols before
78 * dlopen returns. Since RTLD_GLOBAL is not or'd in with
79 * RTLD_NOW the external symbols will not be global
80 */
81 handle = dlopen(path, RTLD_NOW);
82 if (handle == NULL) {
83 char const *err_str = dlerror();
84 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
85 status = -EINVAL;
86 goto done;
87 }
88
89 /* Get the address of the struct hal_module_info. */
90 const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
91 hmi = (struct hw_module_t *)dlsym(handle, sym);
92 if (hmi == NULL) {
93 ALOGE("load: couldn't find symbol %s", sym);
94 status = -EINVAL;
95 goto done;
96 }
97
98 /* Check that the id matches */
99 if (strcmp(id, hmi->id) != 0) {
100 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
101 status = -EINVAL;
102 goto done;
103 }
104
105 hmi->dso = handle;
106
107 /* success */
108 status = 0;
109
110 done:
111 if (status != 0) {
112 hmi = NULL;
113 if (handle != NULL) {
114 dlclose(handle);
115 handle = NULL;
116 }
117 } else {
118 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
119 id, path, *pHmi, handle);
120 }
121
122 *pHmi = hmi;
123
124 return status;
125 }
126
127 /*
128 * Check if a HAL with given name and subname exists, if so return 0, otherwise
129 * otherwise return negative. On success path will contain the path to the HAL.
130 */
hw_module_exists(char * path,size_t path_len,const char * name,const char * subname)131 static int hw_module_exists(char *path, size_t path_len, const char *name,
132 const char *subname)
133 {
134 snprintf(path, path_len, "%s/%s.%s.so",
135 HAL_LIBRARY_PATH3, name, subname);
136 if (access(path, R_OK) == 0)
137 return 0;
138
139 snprintf(path, path_len, "%s/%s.%s.so",
140 HAL_LIBRARY_PATH2, name, subname);
141 if (access(path, R_OK) == 0)
142 return 0;
143
144 snprintf(path, path_len, "%s/%s.%s.so",
145 HAL_LIBRARY_PATH1, name, subname);
146 if (access(path, R_OK) == 0)
147 return 0;
148
149 return -ENOENT;
150 }
151
hw_get_module_by_class(const char * class_id,const char * inst,const struct hw_module_t ** module)152 int hw_get_module_by_class(const char *class_id, const char *inst,
153 const struct hw_module_t **module)
154 {
155 int i = 0;
156 char prop[PATH_MAX] = {0};
157 char path[PATH_MAX] = {0};
158 char name[PATH_MAX] = {0};
159 char prop_name[PATH_MAX] = {0};
160
161
162 if (inst)
163 snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
164 else
165 strlcpy(name, class_id, PATH_MAX);
166
167 /*
168 * Here we rely on the fact that calling dlopen multiple times on
169 * the same .so will simply increment a refcount (and not load
170 * a new copy of the library).
171 * We also assume that dlopen() is thread-safe.
172 */
173
174 /* First try a property specific to the class and possibly instance */
175 snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
176 if (property_get(prop_name, prop, NULL) > 0) {
177 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
178 goto found;
179 }
180 }
181
182 /* Loop through the configuration variants looking for a module */
183 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
184 if (property_get(variant_keys[i], prop, NULL) == 0) {
185 continue;
186 }
187 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
188 goto found;
189 }
190 }
191
192 /* Nothing found, try the default */
193 if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
194 goto found;
195 }
196
197 return -ENOENT;
198
199 found:
200 /* load the module, if this fails, we're doomed, and we should not try
201 * to load a different variant. */
202 return load(class_id, path, module);
203 }
204
hw_get_module(const char * id,const struct hw_module_t ** module)205 int hw_get_module(const char *id, const struct hw_module_t **module)
206 {
207 return hw_get_module_by_class(id, NULL, module);
208 }
209