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 */
load(const char * id,const char * path,const struct hw_module_t ** pHmi)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 */
hw_module_exists(char * path,size_t path_len,const char * name,const char * subname)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
hw_get_module_by_class(const char * class_id,const char * inst,const struct hw_module_t ** module)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
hw_get_module(const char * id,const struct hw_module_t ** module)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 }
221