[数据结构与算法]解码ios syscefdata 核心代码

int CSysCfgData::ParseSysCfg(const char* data, uint64_t size)
{
	KeyList.clear();
	m_bValid = false;
	struct syscfg_hdr* hdr;
	struct syscfg_key* key;

	if (!data) {
		return NULL;
	}

	if (!size)
		size = DATALEN;

	if (size < sizeof(struct syscfg_hdr)) {
		return ERROR_DATA_LEN_LESS;
	}

	hdr = (syscfg_hdr*)data;
	if (memcmp(hdr->magic, MAGICNUMBER, 4)) {
		return ERROR_DATA_INV;
	}
	if (hdr->size > size) {
		return ERROR_DATA_LEN_LESS;
	}
	if (hdr->nkeys * sizeof(struct syscfg_key) + sizeof(struct syscfg_hdr) > hdr->size) {
		return ERROR_DATA_LEN_LESS;
	}

	key = (syscfg_key*)(hdr + 1);
	char name[4];
	for (unsigned idx = 0; idx < hdr->nkeys; idx++)
		if (memcmp(key[idx].name, "BTNC", 4)) {
			flip4(name, key[idx].name);

			KeyList.insert(std::map<std::string, std::string>::value_type(
				std::string(name, 4),
				std::string(key[idx].value, sizeof(key[idx].value))));

		}
		else {
			if (key[idx].jumbo.offset > hdr->size || key[idx].jumbo.offset + key[idx].jumbo.size > hdr->size)
				return ERROR_DATA_LEN_LESS;
			flip4(name, key[idx].jumbo.name);

			KeyList.insert(std::map<std::string, std::string>::value_type(
				std::string(name, 4),
				std::string(data + key[idx].jumbo.offset, key[idx].jumbo.size)));

		}
	m_bValid = true;
	return ERROR_OK;
}

//固定头gfCS	
#define MAGICNUMBER "gfCS"
	//固定大小128K
#define DATALEN 131072
	void flip4(char* out, char* in)
	{
		for (unsigned i = 0; i < 4; i++)
			out[i] = in[3 - i];
	}

其中KeyList为一个map。这样就可保存所有解析出来的数据。