1. module_init
1.1 get_module
system/bt/btcore/src/module.cc
const module_t* get_module(const char* name) {
module_t* module = (module_t*)dlsym(RTLD_DEFAULT, name);
CHECK(module);
return module;
}
1.1.1 MODULE 类型的定义 - module_t
system/bt/btcore/include/module.h
typedef struct {
const char* name;
module_lifecycle_fn init;
module_lifecycle_fn start_up;
module_lifecycle_fn shut_down;
module_lifecycle_fn clean_up;
const char* dependencies[BTCORE_MAX_MODULE_DEPENDENCIES];
} module_t;
typedef future_t* (*module_lifecycle_fn)(void);
struct future_t {
bool ready_can_be_called;
semaphore_t* semaphore; // NULL semaphore means immediate future
void* result;
};
1.1.2 dlsym()
根据 动态链接库 操作句柄(handle)与符号(symbol)，返回符号对应的地址。
使用这个函数不但可以获取函数地址，也可以获取变量地址。
1.2 module_init
system/bt/btcore/src/module.cc
bool module_init(const module_t* module) {
......
if (!call_lifecycle_function(module->init)) {
return false;
}
set_module_state(module, MODULE_STATE_INITIALIZED);
return true;
}
module_init 中执行了 module 的 init 方法
static bool call_lifecycle_function(module_lifecycle_fn function) {
// A NULL lifecycle function means it isn't needed, so assume success
if (!function) return true;
future_t* future = function();
// A NULL future means synchronous success
if (!future) return true;
// Otherwise fall back to the future
return future_await(future);
}
2. module_init(get_module(OSI_MODULE));
2.1 OSI_MODULE 的定义
system/bt/btcore/src/osi_module.cc
EXPORT_SYMBOL extern const module_t osi_module = {.name = OSI_MODULE,
.init = osi_init,
.start_up = NULL,
.shut_down = NULL,
.clean_up = osi_clean_up,
.dependencies = {NULL}};
future_t* osi_init(void) {
return future_new_immediate(FUTURE_SUCCESS);
}
future_t* future_new_immediate(void* value) {
future_t* ret = static_cast<future_t*>(osi_calloc(sizeof(future_t)));
ret->result = value;
ret->ready_can_be_called = false;
return ret;
}
3. module_init(get_module(BT_UTILS_MODULE));
system/bt/utils/src/bt_utils.cc
EXPORT_SYMBOL extern const module_t bt_utils_module = {.name = BT_UTILS_MODULE,
.init = init,
.start_up = NULL,
.shut_down = NULL,
.clean_up = clean_up,
.dependencies = {NULL}};
static pthread_once_t g_DoSchedulingGroupOnce[TASK_HIGH_MAX];
static bool g_DoSchedulingGroup[TASK_HIGH_MAX];
static int g_TaskIDs[TASK_HIGH_MAX];
static future_t* init(void) {
int i;
for (i = 0; i < TASK_HIGH_MAX; i++) {
g_DoSchedulingGroupOnce[i] = PTHREAD_ONCE_INIT;
g_DoSchedulingGroup[i] = true;
g_TaskIDs[i] = INVALID_TASK_ID;
}
return NULL;
}
4. module_init(get_module(BTIF_CONFIG_MODULE));
system/bt/btif/src/btif_config.cc
EXPORT_SYMBOL module_t btif_config_module = {.name = BTIF_CONFIG_MODULE,
.init = init,
.start_up = NULL,
.shut_down = shut_down,
.clean_up = clean_up};
static future_t* init(void) {
std::unique_lock<std::recursive_mutex> lock(config_lock);
std::unique_ptr<config_t> config;
if (is_factory_reset()) delete_config_files();
std::string file_source;
if (config_checksum_pass(CONFIG_FILE_COMPARE_PASS)) {
config = btif_config_open(CONFIG_FILE_PATH);
btif_config_source = ORIGINAL;
}
if (!config) {
if (config_checksum_pass(CONFIG_BACKUP_COMPARE_PASS)) {
config = btif_config_open(CONFIG_BACKUP_PATH);
btif_config_source = BACKUP;
file_source = "Backup";
}
}
if (!config) {
config = btif_config_transcode(CONFIG_LEGACY_FILE_PATH);
btif_config_source = LEGACY;
file_source = "Legacy";
}
if (!config) {
config = storage_config_get_interface()->config_new_empty();
btif_config_source = NEW_FILE;
file_source = "Empty";
}
// move persistent config data from btif_config file to btif config cache
btif_config_cache.Init(std::move(config));
if (!file_source.empty()) {
btif_config_cache.SetString(INFO_SECTION, FILE_SOURCE, file_source);
}
// Cleanup temporary pairings if we have left guest mode
if (!is_restricted_mode()) {
btif_config_cache.RemovePersistentSectionsWithKey("Restricted");
}
// Read or set config file creation timestamp
auto time_str = btif_config_cache.GetString(INFO_SECTION, FILE_TIMESTAMP);
if (!time_str) {
time_t current_time = time(NULL);
struct tm* time_created = localtime(¤t_time);
strftime(btif_config_time_created, TIME_STRING_LENGTH, TIME_STRING_FORMAT,
time_created);
btif_config_cache.SetString(INFO_SECTION, FILE_TIMESTAMP,
btif_config_time_created);
} else {
strlcpy(btif_config_time_created, time_str->c_str(), TIME_STRING_LENGTH);
}
// Read or set metrics 256 bit hashing salt
read_or_set_metrics_salt();
// Initialize MetricIdAllocator
init_metric_id_allocator();
// TODO(sharvil): use a non-wake alarm for this once we have
// API support for it. There's no need to wake the system to
// write back to disk.
config_timer = alarm_new("btif.config");
if (!config_timer) {
LOG_ERROR(LOG_TAG, "%s unable to create alarm.", __func__);
goto error;
}
LOG_EVENT_INT(BT_CONFIG_SOURCE_TAG_NUM, btif_config_source);
return future_new_immediate(FUTURE_SUCCESS);
......
}
5. module_init(get_module(INTEROP_MODULE));
system/bt/device/src/interop.cc
EXPORT_SYMBOL module_t interop_module = {
.name = INTEROP_MODULE,
.init = NULL,
.start_up = NULL,
.shut_down = NULL,
.clean_up = interop_clean_up,
.dependencies = {NULL},
};
6. module_init(get_module(STACK_CONFIG_MODULE));
读取配置文件 /etc/bluetooth/bt_stack.conf
system/bt/main/stack_config.cc
EXPORT_SYMBOL extern const module_t stack_config_module = {
.name = STACK_CONFIG_MODULE,
.init = init,
.start_up = NULL,
.shut_down = NULL,
.clean_up = clean_up,
.dependencies = {NULL}};
static future_t* init() {
#if defined(OS_GENERIC)
const char* path = "bt_stack.conf";
#else // !defined(OS_GENERIC)
const char* path = "/etc/bluetooth/bt_stack.conf";
#endif // defined(OS_GENERIC)
config = config_new(path);
......
return future_new_immediate(FUTURE_SUCCESS);
}
std::unique_ptr<config_t> config_new(const char* filename) {
CHECK(filename != nullptr);
std::unique_ptr<config_t> config = config_new_empty();
FILE* fp = fopen(filename, "rt");
......
if (!config_parse(fp, config.get())) {
config.reset();
}
fclose(fp);
return config;
}
static bool config_parse(FILE* fp, config_t* config) {
......
int line_num = 0;
char line[1024];
char section[1024];
strcpy(section, CONFIG_DEFAULT_SECTION);
while (fgets(line, sizeof(line), fp)) {
char* line_ptr = trim(line);
++line_num;
// Skip blank and comment lines.
if (*line_ptr == '\0' || *line_ptr == '#') continue;
if (*line_ptr == '[') {
size_t len = strlen(line_ptr);
if (line_ptr[len - 1] != ']') {
return false;
}
strncpy(section, line_ptr + 1, len - 2); // NOLINT (len < 1024)
section[len - 2] = '\0';
} else {
char* split = strchr(line_ptr, '=');
if (!split) {
return false;
}
*split = '\0';
config_set_string(config, section, trim(line_ptr), trim(split + 1));
}
}
return true;
}
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