Android BlueDroid分析: 配置文件(bt_stack.conf bt_vendor.conf )的加载与分析

说明

在Android BlueDroid启动,即stack启动的时候,回去加载好几个配置文件, 然后BlueDroid Stack根据这几个配置文件会进行调整, 例如Device ID(did), Log相关的Trace Level, COD(即Class of Device), BT snoop log相关配置等等.下面结合代码和配置文件一起来说明分析.

配置文件说明

配置文件分为运行时动态加载和编译的时候直接解析使用的.主要有下面三个, 冒号后面是简要的作用说明.

编译完成后,这些配置文件都是位于: /system/etc/bluetooth/

如果是编译之前,那么是在device相关的vendor board中, 或者是默认的stack里面自带的文件.

 bt_stack.conf: 对stack进行配置, 包括不同的stack里面的log level, bt snoop的控制

 bt_did.conf : 记录和配置BLE Controller的信息, 例如VendorID可能是QualComm也可以是Broadcom等等.

 auto_pair_devlist.conf: 将某些slave/peripheral加入到BlackList中不让其配对

config格式

绝大部分都是用等号表示的string=value对, 也有使用{}与逗号区分的一串数据, 例如COD.

代码分析

配置文件的解析位于bte_config.c中, 其含有下面这些函数:

▼ functions
device_name_cfg(char *p_conf_name, char *p_conf_value)
device_class_cfg(char *p_conf_name, char *p_conf_value)
logging_cfg_onoff(char *p_conf_name, char *p_conf_value)
logging_set_filepath(char *p_conf_name, char *p_conf_value)
trace_cfg_onoff(char *p_conf_name, char *p_conf_value)
bte_load_conf(const char *p_path)
-bte_parse_did_conf(const char *p_path, UINT32 num, tKEY_VALUE_PAIRS *conf_pairs, UINT32 conf_pairs_num)
bte_load_did_conf(const char *p_path)


其中有trace log level解析相关的函数, 对于不同的文件解析使用的函数不同, 例如did使用did相关函数, 而bt_stack.conf使用bte_load_conf来解析.
而代码的实现也比较简单, 使用最多的函数就是strtok, 即对token的解析(可以参考C++程序设计原理与实践). 

解析完成后进行赋值完事.

那么对于did都有哪些assignment item:

/*******************************************************************************
**
** Function bte_load_did_conf
**
** Description Set local Device ID records, reading from configuration files
**
** Returns None
**
*******************************************************************************/

void bte_load_did_conf (const char *p_path)
{
tBTA_DI_RECORD rec;
UINT32 rec_num, i, j;

for (i=1; i<=BTA_DI_NUM_MAX; i++) {
for (j=0; j<CONF_DID_MAX; j++) {
*did_conf_pairs[j].value = 0;
}

if (bte_parse_did_conf(p_path, i, did_conf_pairs, CONF_DID_MAX)) {
memset(&rec, 0, sizeof(rec));

if (*did_conf_pairs[CONF_DID_RECORD_NUM].value) {
rec_num = (UINT32)(strtoul(did_conf_pairs[CONF_DID_RECORD_NUM].value, NULL, 0)-1);
} else {
debug("[%d] Unknown %s", (unsigned int)i, did_conf_pairs[CONF_DID_RECORD_NUM].key);
continue;
}

if (*did_conf_pairs[CONF_DID_VENDOR_ID].value) {
rec.vendor = (UINT16)strtoul(did_conf_pairs[CONF_DID_VENDOR_ID].value, NULL, 0);
} else {
rec.vendor = LMP_COMPID_BROADCOM;
}

if (*did_conf_pairs[CONF_DID_VENDOR_ID_SOURCE].value) {
rec.vendor_id_source = (UINT16)strtoul(did_conf_pairs[CONF_DID_VENDOR_ID_SOURCE].value, NULL, 0);
} else {
rec.vendor_id_source = DI_VENDOR_ID_SOURCE_BTSIG;
}

if ((*did_conf_pairs[CONF_DID].value == 0) ||
(rec_num >= BTA_DI_NUM_MAX) ||
(!((rec.vendor_id_source >= DI_VENDOR_ID_SOURCE_BTSIG) &&
(rec.vendor_id_source <= DI_VENDOR_ID_SOURCE_USBIF))) ||
(rec.vendor == DI_VENDOR_ID_DEFAULT)) {

error("DID record #%u not set", (unsigned int)i);
for (j=0; j<CONF_DID_MAX; j++) {
error("%s:%s", did_conf_pairs[j].key, did_conf_pairs[j].value);
}
continue;
}

rec.product = (UINT16)strtoul(did_conf_pairs[CONF_DID_PRODUCT_ID].value, NULL, 0);
rec.version = (UINT16)strtoul(did_conf_pairs[CONF_DID_VERSION].value, NULL, 0);

strncpy(rec.client_executable_url,
did_conf_pairs[CONF_DID_CLIENT_EXECUTABLE_URL].value,
SDP_MAX_ATTR_LEN);
strncpy(rec.service_description,
did_conf_pairs[CONF_DID_SERVICE_DESCRIPTION].value,
SDP_MAX_ATTR_LEN);
strncpy(rec.documentation_url,
did_conf_pairs[CONF_DID_DOCUMENTATION_URL].value,
SDP_MAX_ATTR_LEN);

for (j=0; j<strlen(did_conf_pairs[CONF_DID_PRIMARY_RECORD].value); j++) {
did_conf_pairs[CONF_DID_PRIMARY_RECORD].value[j] =
tolower(did_conf_pairs[CONF_DID_PRIMARY_RECORD].value[j]);
}
if ((!strcmp(did_conf_pairs[CONF_DID_PRIMARY_RECORD].value, "true")) ||
(!strcmp(did_conf_pairs[CONF_DID_PRIMARY_RECORD].value, "1"))) {
rec.primary_record = TRUE;
} else {
rec.primary_record = FALSE;
}

info("[%u] primary_record=%d vendor_id=0x%04X vendor_id_source=0x%04X product_id=0x%04X version=0x%04X",
(unsigned int)rec_num+1, rec.primary_record, rec.vendor,
rec.vendor_id_source, rec.product, rec.version);
if (*rec.client_executable_url) {
info(" client_executable_url=%s", rec.client_executable_url);
}
if (*rec.service_description) {
info(" service_description=%s", rec.service_description);
}
if (*rec.documentation_url) {
info(" documentation_url=%s", rec.documentation_url);
}

if (BTA_DmSetLocalDiRecord(&rec, &rec_num) != BTA_SUCCESS) {
error("SetLocalDiInfo failed for #%u!", (unsigned int)i);
}
}
}
}



上面的代码看起来有一片,但是根据数组的下表宏,可以很清晰的知道只有这么几个:
▼ __anon3* : enum
[enumerators]
-CONF_DID
-CONF_DID_RECORD_NUM
-CONF_DID_PRIMARY_RECORD
-CONF_DID_VENDOR_ID
-CONF_DID_VENDOR_ID_SOURCE
-CONF_DID_PRODUCT_ID
-CONF_DID_VERSION
-CONF_DID_CLIENT_EXECUTABLE_URL
-CONF_DID_SERVICE_DESCRIPTION
-CONF_DID_DOCUMENTATION_URL


对应的意义如下:
static tKEY_VALUE_PAIRS did_conf_pairs[CONF_DID_MAX] = {
{ "[DID]", "" },
{ "recordNumber", "" },
{ "primaryRecord", "" },
{ "vendorId", "" },
{ "vendorIdSource", "" },
{ "productId", "" },
{ "version", "" },
{ "clientExecutableURL", "" },
{ "serviceDescription", "" },
{ "documentationURL", "" },
};


对于bt_stack.conf的解析分为两类, 一类是Trace Log Level, 还有就是其他的,具体见下面代码中的注释, 下面就是所有的可用被用来配置的string:
static const conf_entry_t conf_table[] = {
/*{"Name", device_name_cfg},
{"Class", device_class_cfg},*/
{"BtSnoopLogOutput", logging_cfg_onoff},
{"BtSnoopFileName", logging_set_filepath},
{"TraceConf", trace_cfg_onoff},
{(const char *) NULL, NULL}
};
解析的代码如下:
void bte_load_conf(const char *p_path)
{
FILE *p_file;
char *p_name;
char *p_value;
conf_entry_t *p_entry;
char line[CONF_MAX_LINE_LEN+1]; /* add 1 for \0 char */
BOOLEAN name_matched;

ALOGI("Attempt to load stack conf from %s", p_path);

if ((p_file = fopen(p_path, "r")) != NULL)
{
/* read line by line */
while (fgets(line, CONF_MAX_LINE_LEN+1, p_file) != NULL)
{
if (line[0] == CONF_COMMENT)
continue;

p_name = strtok(line, CONF_DELIMITERS);

if (NULL == p_name)
{
continue;
}

p_value = strtok(NULL, CONF_VALUES_DELIMITERS);

if (NULL == p_value)
{
ALOGW("bte_load_conf: missing value for name: %s", p_name);
continue;
}

name_matched = FALSE;
p_entry = (conf_entry_t *)conf_table;

while (p_entry->conf_entry != NULL)
{
if (strcmp(p_entry->conf_entry, (const char *)p_name) == 0)//判断是否是前面list中的
{
name_matched = TRUE;
if (p_entry->p_action != NULL)
p_entry->p_action(p_name, p_value);
break;
}

p_entry++;
}

if ((name_matched == FALSE) && (trace_conf_enabled == TRUE)) //判断是否是TraceLevel
{
/* Check if this is a TRC config item */
bte_trace_conf(p_name, p_value);
}
}

fclose(p_file);
}
else
{
ALOGI( "bte_load_conf file >%s< not found", p_path);
}
}

总结

实际上,除了上面三个conf文件, 我们还会看到一个额外的bt_vendor.conf, 在某些设备上面, 这个配置文件是给libbt-vendor.so中用的,用来配置串口与firmware.