libubox组件（2）——blob/blobmsg （转载 https://segmentfault.com/a/1190000002391970）
一：blob相关接口
1.数据结构
1: struct blob_attr {
2: uint32_t id_len; /** 高1位为extend标志，高7位存储id，
3: * 低24位存储data的内存大小+结构大小(blob_attr) */
4: char data[];
5: } __packed; 6: 实际使用中每个blob_attr的长度包含：结构长度(4)+数据长度+对齐特性= id_len+pad_len7: struct blob_attr_info {
8: unsigned int type;
9: unsigned int minlen;
10: unsigned int maxlen;
11: bool (*validate)(const struct blob_attr_info *, struct blob_attr *);
12: }; 13: 14: struct blob_buf {
15: struct blob_attr *head;
16: bool (*grow)(struct blob_buf *buf, int minlen);
17: int buflen;
18: void *buf;
19: };
2. 存储结构
3.获取BLOB属性信息
1: /**
2: * 返回指向BLOB属性数据区指针
3: */
4: static inline void * blob_data(const struct blob_attr *attr)
5: 6: /**
7: * 返回BLOB属性ID
8: */
9: static inline unsigned int blob_id(const struct blob_attr *attr)
10: 11: /**
12: * 判断BLOB属性扩展标志是否为真
13: */
14: static inline bool blob_is_extended(const struct blob_attr *attr)
15: 16: /**
17: * 返回BLOB属性有效存储空间大小
18: */
19: static inline unsigned int blob_len(const struct blob_attr *attr)
20: 21: /*
22: * 返回BLOB属性完全存储空间大小(包括头部)
23: */
24: static inline unsigned int blob_raw_len(const struct blob_attr *attr)
25: 26: /*
27: * 返回BLOB属性填补后存储空间大小(包括头部)
28: */
29: static inline unsigned int blob_pad_len(const struct blob_attr *attr)
4.获取BLOB数据信息
1: static inline uint8_t blob_get_u8(const struct blob_attr *attr)
2: 3: static inline uint16_t blob_get_u16(const struct blob_attr *attr)
4: 5: static inline uint32_t blob_get_u32(const struct blob_attr *attr)
6: 7: static inline uint64_t blob_get_u64(const struct blob_attr *attr)
8: 9: static inline int8_t blob_get_int8(const struct blob_attr *attr)
10: 11: static inline int16_t blob_get_int16(const struct blob_attr *attr)
12: 13: static inline int32_t blob_get_int32(const struct blob_attr *attr)
14: 15: static inline int64_t blob_get_int64(const struct blob_attr *attr)
16: 17: static inline const char * blob_get_string(const struct blob_attr *attr)
5.设置BLOB数据信息
1: static inline struct blob_attr *
2: blob_put_string(struct blob_buf *buf, int id, const char *str)
3: 4: static inline struct blob_attr *
5: blob_put_u8(struct blob_buf *buf, int id, uint8_t val)
6: 7: static inline struct blob_attr *
8: blob_put_u16(struct blob_buf *buf, int id, uint16_t val)
9: 10: static inline struct blob_attr *
11: blob_put_u32(struct blob_buf *buf, int id, uint32_t val)
12: 13: static inline struct blob_attr *
14: blob_put_u64(struct blob_buf *buf, int id, uint64_t val)
15: 16: #define blob_put_int8 blob_put_u8
17: #define blob_put_int16 blob_put_u16
18: #define blob_put_int32 blob_put_u32
19: #define blob_put_int64 blob_put_u64
20: 21: struct blob_attr *
22: blob_put(struct blob_buf *buf, int id, const void *ptr, unsigned int len)
23: 24: /**
25: * ptr - 指向struct blob_attr
26: */
27: struct blob_attr *
28: blob_put_raw(struct blob_buf *buf, const void *ptr, unsigned int len)
6. 遍历
#define __blob_for_each_attr(pos, attr, rem)
#define blob_for_each_attr(pos, attr, rem)7. 复制
struct blob_attr * blob_memdup(struct blob_attr *attr)8. 数据类型判断
1: enum {
2: BLOB_ATTR_UNSPEC,3: BLOB_ATTR_NESTED, /** 嵌套 */
4: BLOB_ATTR_BINARY, 5: BLOB_ATTR_STRING, 6: BLOB_ATTR_INT8, 7: BLOB_ATTR_INT16, 8: BLOB_ATTR_INT32, 9: BLOB_ATTR_INT64, 10: BLOB_ATTR_LAST 11: };12: bool blob_check_type(const void *ptr, unsigned int len, int type)
9.嵌套操作
1: void * blob_nest_start(struct blob_buf *buf, int id)
2: Void blob_nest_end(struct blob_buf *buf, void *cookie)
10.判断
bool blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)11.初始/销毁，解析
1: /**
2: * 初始化BLOB buffer
3: */
4: int blob_buf_init(struct blob_buf *buf, int id)
5: 6: /**
7: * 销毁BLOB buffer
8: */
9: void blob_buf_free(struct blob_buf *buf)
10: 11: /**
12: * 从attr串中根据info策略过滤，得到的结果存储在data属性数组中
13: *
14: * @param attr 输入BLOB属性串
15: * @param data 输出BLOB属性数组
16: * @param info 属性过滤策略
17: * @param max data数组大小
18: */
19: int blob_parse(struct blob_attr *attr, struct blob_attr **data,
20: const struct blob_attr_info *info, int max)
二：blobmsg相关接口
1.数据结构
1: struct blobmsg_hdr {
2: uint16_t namelen; 3: uint8_t name[]; 4: } __packed; 5: 6: struct blobmsg_policy {
7: const char *name;
8: enum blobmsg_type type;
9: };2.存储结构
3.消息类型
1: enum blobmsg_type {
2: BLOBMSG_TYPE_UNSPEC, 3: BLOBMSG_TYPE_ARRAY, 4: BLOBMSG_TYPE_TABLE, 5: BLOBMSG_TYPE_STRING, 6: BLOBMSG_TYPE_INT64, 7: BLOBMSG_TYPE_INT32, 8: BLOBMSG_TYPE_INT16, 9: BLOBMSG_TYPE_INT8, 10: __BLOBMSG_TYPE_LAST, 11: BLOBMSG_TYPE_LAST = __BLOBMSG_TYPE_LAST - 1, 12: BLOBMSG_TYPE_BOOL = BLOBMSG_TYPE_INT8, 13: };
4.基本操作
1: /**
2: * 根据BLOB消息名字长度计算出blobmsg头部大小
3: */
4: static inline int blobmsg_hdrlen(unsigned int namelen)
5: 6: /**
7: * 获取BLOB消息名字
8: */
9: static inline const char *blobmsg_name(const struct blob_attr *attr)
10: 11: /**
12: * 获取BLOB消息类型
13: */
14: static inline int blobmsg_type(const struct blob_attr *attr)
15: 16: /**
17: * 获取BLOB消息数据内容
18: */
19: static inline void *blobmsg_data(const struct blob_attr *attr)
20: 21: /**
22: * 获取BLOB消息数据内容大小
23: */
24: static inline int blobmsg_data_len(const struct blob_attr *attr)
25: static inline int blobmsg_len(const struct blob_attr *attr)
26: 数据类型判断 27: 28: /**
29: * 判断BLOBMSG属性类型是否合法
30: */
31: bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
32: 设置 33: 34: int blobmsg_add_field(struct blob_buf *buf, int type, const char *name,
35: const void *data, unsigned int len)
36: 37: static inline int
38: blobmsg_add_u8(struct blob_buf *buf, const char *name, uint8_t val)
39: 40: static inline int
41: blobmsg_add_u16(struct blob_buf *buf, const char *name, uint16_t val)
42: 43: static inline int
44: blobmsg_add_u32(struct blob_buf *buf, const char *name, uint32_t val)
45: 46: static inline int
47: blobmsg_add_u64(struct blob_buf *buf, const char *name, uint64_t val)
48: 49: static inline int
50: blobmsg_add_string(struct blob_buf *buf, const char *name, const char *string)
51: 52: static inline int
53: blobmsg_add_blob(struct blob_buf *buf, struct blob_attr *attr)
54: 55: /**
56: * 格式化设备BLOGMSG
57: */
58: void blobmsg_printf(struct blob_buf *buf, const char *name, const char *format, ...)
59: 获取 60: 61: static inline uint8_t blobmsg_get_u8(struct blob_attr *attr)
62: static inline bool blobmsg_get_bool(struct blob_attr *attr)
63: static inline uint16_t blobmsg_get_u16(struct blob_attr *attr)
64: static inline uint32_t blobmsg_get_u32(struct blob_attr *attr)
65: static inline uint64_t blobmsg_get_u64(struct blob_attr *attr)
66: static inline char *blobmsg_get_string(struct blob_attr *attr)
67: 创建 68: 69: /**
70: * 创建BLOBMSG，返回数据区开始地址
71: */
72: void *blobmsg_alloc_string_buffer(struct blob_buf *buf, const char *name,
73: unsigned int maxlen)
74: 75: /**
76: * 扩大BLOGMSG，返回数据区开始地址
77: */
78: void *blobmsg_realloc_string_buffer(struct blob_buf *buf, unsigned int maxlen)
79: 80: void blobmsg_add_string_buffer(struct blob_buf *buf)
81: 遍历 82: 83: #define blobmsg_for_each_attr(pos, attr, rem)
84: 嵌套 85: 86: static inline void * blobmsg_open_array(struct blob_buf *buf, const char *name)
87: static inline void blobmsg_close_array(struct blob_buf *buf, void *cookie)
88: 89: static inline void *blobmsg_open_table(struct blob_buf *buf, const char *name)
90: static inline void blobmsg_close_table(struct blob_buf *buf, void *cookie)
91: 解析BLOGMSG 92: 93: /**
94: * 从data BLOGMSG串中根据policy策略过滤，得到的结果存储在tb BLOGATTR数组中
95: *
96: * @param policy 过滤策略
97: * @param policy_len 策略个数
98: * @param tb 返回属性数据
99: * @param len data属性个数
100: */
101: int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
102: struct blob_attr **tb, void *data, unsigned int len)
三：实例操作
把UCI转化为BLOB
UCI配置文件:
/etc/config/test
config policy test
option name 'test'
option enable '1'
option dns '1.1.1.1 2.2.2.2' 1: 定义参数列表: 2: 3: enum {
4: POLICY_ATTR_NAME, /** name */
5: POLICY_ATTR_ENABLE, /** enable */
6: POLICY_ATTR_DNS, /** dns */
7: __POLICY_ATTR_MAX 8: }; 9: 10: static const struct blobmsg_policy policy_attrs[__POLICY_ATTR_MAX] = {
11: [POLICY_ATTR_NAME] = { .name = "name", .type = BLOBMSG_TYPE_STRING },
12: [POLICY_ATTR_ENABLE] = { .name = "enable", .type = BLOBMSG_TYPE_BOOL },
13: [POLICY_ATTR_DNS] = { .name = "dns", .type = BLOBMSG_TYPE_ARRAY },
14: }; 15: 16: /** 定义BLOBMSG_TYPE_ARRAY类型参数的实际数据类型 */
17: static const struct uci_blob_param_info policy_attr_info[__POLICY_ATTR_MAX] = {
18: [POLICY_ATTR_DNS] = { .type = BLOBMSG_TYPE_STRING }, 19: }; 20: 21: static const struct uci_blob_param_list policy_attr_list = {
22: .n_params = __POLICY_ATTR_MAX,23: .params = policy_attrs,
24: .info = policy_attr_info, 25: }; 26: 转化为BLOB: 27: 28: static struct uci_context *g_uci_ctx;
29: static struct blob_buf *b;
30: 31: void
32: transform(const char *config)
33: {34: struct uci_context *ctx = g_uci_ctx;
35: struct uci_package *p = NULL;
36: 37: if (!ctx) {
38: ctx = uci_alloc_context(); 39: g_uci_ctx = ctx; 40: uci_set_confdir(ctx, NULL);41: } else {
42: p = uci_lookup_package(ctx, config);43: if (p)
44: uci_unload(ctx, p); 45: } 46: 47: if (uci_load(ctx, config, &p))
48: return;
49: 50: struct uci_element *e;
51: struct blob_attr *config = NULL;
52: uci_foreach_element(&p->sectons, e) {53: struct uci_section *s = uci_to_section(e);
54: 55: blob_buf_init(&b, 0); 56: uci_to_blob(&b, s, &policy_attr_list); 57: config = blob_memdup(b.head); 58: 59: /**
60: * do something with `config`
61: * free(config), when not use it
62: */
63: } 64: } 65: 使用转化后的blob_attr 66: 67: void 68: foo(blob_attr *confg) 69: {70: struct blob_attr *tb[__POLICY_ATTR_MAX];
71: 72: blobmsg_parse(policy_attrs, __POLICY_ATTR_MAX, tb, 73: blob_data(config), blob_len(config)); 74: 75: /**
76: * do something with *tb[]
77: */
78: }