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 */ 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 */ 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 } 164 165 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 } 216 217 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
