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 */ 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 */ 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 } 144 145 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 } 196 197 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
