third_party/hwcplus/src/hardware.c

   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 }