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