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

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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:

▼ functionsdevice_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. 

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