The Android Open Source Project | f53ebec | 2009-03-03 19:32:14 -0800 | [diff] [blame^] | 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_PATH "/system/lib/hw" |
| 32 | |
| 33 | /** |
| 34 | * There are a set of variant filename for modules. The form of the filename |
| 35 | * is "<MODULE_ID>.variant.so" so for the led module the Dream variants |
| 36 | * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be: |
| 37 | * |
| 38 | * led.trout.so |
| 39 | * led.msm7k.so |
| 40 | * led.ARMV6.so |
| 41 | * led.default.so |
| 42 | */ |
| 43 | |
| 44 | #define HAL_DEFAULT_VARIANT "default" |
| 45 | #define HAL_VARIANT_KEYS_COUNT 4 |
| 46 | static const char *variant_keys[HAL_VARIANT_KEYS_COUNT] = { |
| 47 | "ro.product.board", |
| 48 | "ro.board.platform", |
| 49 | "ro.arch", |
| 50 | HAL_DEFAULT_VARIANT |
| 51 | }; |
| 52 | |
| 53 | /** |
| 54 | * Load the file defined by the path and if succesfull |
| 55 | * return the dlopen handle and the hmi. |
| 56 | * @return 0 = success, !0 = failure. |
| 57 | */ |
| 58 | static int load(const char *id, |
| 59 | const char *path, |
| 60 | void **pHandle, |
| 61 | const struct hw_module_t **pHmi) |
| 62 | { |
| 63 | int status; |
| 64 | void *handle; |
| 65 | const struct hw_module_t *hmi; |
| 66 | |
| 67 | LOGV("load: E id=%s path=%s", id, path); |
| 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 | LOGW("load: module=%s error=%s", path, err_str); |
| 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 = (const struct hw_module_t *)dlsym(handle, sym); |
| 85 | if (hmi == NULL) { |
| 86 | char const *err_str = dlerror(); |
| 87 | LOGE("load: couldn't find symbol %s", sym); |
| 88 | status = -EINVAL; |
| 89 | goto done; |
| 90 | } |
| 91 | |
| 92 | /* Check that the id matches */ |
| 93 | if (strcmp(id, hmi->id) != 0) { |
| 94 | LOGE("load: id=%s != hmi->id=%s", id, hmi->id); |
| 95 | status = -EINVAL; |
| 96 | goto done; |
| 97 | } |
| 98 | |
| 99 | /* success */ |
| 100 | status = 0; |
| 101 | |
| 102 | done: |
| 103 | if (status != 0) { |
| 104 | hmi = NULL; |
| 105 | if (handle != NULL) { |
| 106 | dlclose(handle); |
| 107 | handle = NULL; |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | *pHmi = hmi; |
| 112 | *pHandle = handle; |
| 113 | |
| 114 | LOGV("load: X id=%s path=%s hmi=%p pHandle=%p status=%d", |
| 115 | id, path, *pHmi, *pHandle, status); |
| 116 | return status; |
| 117 | } |
| 118 | |
| 119 | int hw_get_module(const char *id, const struct hw_module_t **module) |
| 120 | { |
| 121 | int status; |
| 122 | const struct hw_module_t *hmi = NULL; |
| 123 | char path[PATH_MAX]; |
| 124 | char variant[PATH_MAX]; |
| 125 | void *handle = NULL; |
| 126 | int i; |
| 127 | |
| 128 | /* |
| 129 | * Here we rely on the fact that calling dlopen multiple times on |
| 130 | * the same .so will simply increment a refcount (and not load |
| 131 | * a new copy of the library). |
| 132 | * We also assume that dlopen() is thread-safe. |
| 133 | */ |
| 134 | |
| 135 | LOGV("hal_module_info_get: Load module id=%s", id); |
| 136 | |
| 137 | /* Loop through the configuration variants looking for a module */ |
| 138 | status = -EINVAL; |
| 139 | for (i = 0; (status != 0) && (i < HAL_VARIANT_KEYS_COUNT); i++) { |
| 140 | |
| 141 | /* Get variant or default */ |
| 142 | if (strcmp(variant_keys[i], HAL_DEFAULT_VARIANT) == 0) { |
| 143 | strncpy(variant, HAL_DEFAULT_VARIANT, sizeof(variant)-1); |
| 144 | variant[sizeof(variant)-1] = 0; |
| 145 | } else { |
| 146 | if (property_get(variant_keys[i], variant, NULL) == 0) { |
| 147 | continue; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | /* Construct the path then try to load */ |
| 152 | snprintf(path, sizeof(path), "%s/%s.%s.so", |
| 153 | HAL_LIBRARY_PATH, id, variant); |
| 154 | status = load(id, path, &handle, &hmi); |
| 155 | } |
| 156 | if (status != 0) { |
| 157 | hmi = NULL; |
| 158 | if (handle != NULL) { |
| 159 | dlclose(handle); |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | *module = hmi; |
| 164 | LOGV("hal_module_info_get: X id=%s hmi=%p status=%d", id, hmi, status); |
| 165 | |
| 166 | return status; |
| 167 | } |