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 */ 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 */ 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 } 151 152 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 } 204 205 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
