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 #define HAL_LIBRARY_PATH1 "/system/lib/hw" 32 #define HAL_LIBRARY_PATH2 "/vendor/lib/hw" 33 34 /** 35 * There are a set of variant filename for modules. The form of the filename 36 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants 37 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be: 38 * 39 * led.trout.so 40 * led.msm7k.so 41 * led.ARMV6.so 42 * led.default.so 43 */ 44 45 static const char *variant_keys[] = { 46 "ro.hardware", /* This goes first so that it can pick up a different 47 file on the emulator. */ 48 "ro.product.board", 49 "ro.board.platform", 50 "ro.arch" 51 }; 52 53 static const int HAL_VARIANT_KEYS_COUNT = 54 (sizeof(variant_keys)/sizeof(variant_keys[0])); 55 56 /** 57 * Load the file defined by the variant and if successful 58 * return the dlopen handle and the hmi. 59 * @return 0 = success, !0 = failure. 60 */ 61 static int load(const char *id, 62 const char *path, 63 const struct hw_module_t **pHmi) 64 { 65 int status; 66 void *handle; 67 struct hw_module_t *hmi; 68 69 /* 70 * load the symbols resolving undefined symbols before 71 * dlopen returns. Since RTLD_GLOBAL is not or'd in with 72 * RTLD_NOW the external symbols will not be global 73 */ 74 handle = dlopen(path, RTLD_NOW); 75 if (handle == NULL) { 76 char const *err_str = dlerror(); 77 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown"); 78 status = -EINVAL; 79 goto done; 80 } 81 82 /* Get the address of the struct hal_module_info. */ 83 const char *sym = HAL_MODULE_INFO_SYM_AS_STR; 84 hmi = (struct hw_module_t *)dlsym(handle, sym); 85 if (hmi == NULL) { 86 ALOGE("load: couldn't find symbol %s", sym); 87 status = -EINVAL; 88 goto done; 89 } 90 91 /* Check that the id matches */ 92 if (strcmp(id, hmi->id) != 0) { 93 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id); 94 status = -EINVAL; 95 goto done; 96 } 97 98 hmi->dso = handle; 99 100 /* success */ 101 status = 0; 102 103 done: 104 if (status != 0) { 105 hmi = NULL; 106 if (handle != NULL) { 107 dlclose(handle); 108 handle = NULL; 109 } 110 } else { 111 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p", 112 id, path, *pHmi, handle); 113 } 114 115 *pHmi = hmi; 116 117 return status; 118 } 119 120 int hw_get_module_by_class(const char *class_id, const char *inst, 121 const struct hw_module_t **module) 122 { 123 int status; 124 int i; 125 const struct hw_module_t *hmi = NULL; 126 char prop[PATH_MAX]; 127 char path[PATH_MAX]; 128 char name[PATH_MAX]; 129 130 if (inst) 131 snprintf(name, PATH_MAX, "%s.%s", class_id, inst); 132 else 133 strlcpy(name, class_id, PATH_MAX); 134 135 /* 136 * Here we rely on the fact that calling dlopen multiple times on 137 * the same .so will simply increment a refcount (and not load 138 * a new copy of the library). 139 * We also assume that dlopen() is thread-safe. 140 */ 141 142 /* Loop through the configuration variants looking for a module */ 143 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT+1 ; i++) { 144 if (i < HAL_VARIANT_KEYS_COUNT) { 145 if (property_get(variant_keys[i], prop, NULL) == 0) { 146 continue; 147 } 148 snprintf(path, sizeof(path), "%s/%s.%s.so", 149 HAL_LIBRARY_PATH2, name, prop); 150 if (access(path, R_OK) == 0) break; 151 152 snprintf(path, sizeof(path), "%s/%s.%s.so", 153 HAL_LIBRARY_PATH1, name, prop); 154 if (access(path, R_OK) == 0) break; 155 } else { 156 snprintf(path, sizeof(path), "%s/%s.default.so", 157 HAL_LIBRARY_PATH1, name); 158 if (access(path, R_OK) == 0) break; 159 } 160 } 161 162 status = -ENOENT; 163 if (i < HAL_VARIANT_KEYS_COUNT+1) { 164 /* load the module, if this fails, we're doomed, and we should not try 165 * to load a different variant. */ 166 status = load(class_id, path, module); 167 } 168 169 return status; 170 } 171 172 int hw_get_module(const char *id, const struct hw_module_t **module) 173 { 174 return hw_get_module_by_class(id, NULL, module); 175 } 176
