libubox組件（2）——blob/blobmsg （轉載 https://segmentfault.com/a/1190000002391970）

一：blob相關接口

1.數據結構

 1: struct blob_attr {

 2:     uint32_t id_len;    /** 高1位爲extend標誌，高7位存儲id，

 3:  * 低24位存儲data的內存大小+結構大小(blob_attr) */

 4:     char data[];

 5: } __packed;

 6:  實際使用中每一個blob_attr的長度包含：結構長度(4)+數據長度+對齊特性= id_len+pad_len

 7: 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. 存儲結構

3.獲取BLOB屬性信息

 1: /**

 2:  * 返回指向BLOB屬性數據區指針

 3:  */

 4: static inline void * blob_data(const struct blob_attr *attr)

 5:  

 6: /**

 7:  * 返回BLOB屬性ID

 8:  */

 9: static inline unsigned int blob_id(const struct blob_attr *attr)

 10:  

 11: /**

 12:  * 判斷BLOB屬性擴展標誌是否爲真

 13:  */

 14: static inline bool blob_is_extended(const struct blob_attr *attr)

 15:  

 16: /**

 17:  * 返回BLOB屬性有效存儲空間大小

 18:  */

 19: static inline unsigned int blob_len(const struct blob_attr *attr)

 20:  

 21: /*

 22:  * 返回BLOB屬性徹底存儲空間大小(包括頭部)

 23:  */

 24: static inline unsigned int blob_raw_len(const struct blob_attr *attr)

 25:  

 26: /*

 27:  * 返回BLOB屬性填補後存儲空間大小(包括頭部)

 28:  */

 29: static inline unsigned int blob_pad_len(const struct blob_attr *attr)

4.獲取BLOB數據信息

 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.設置BLOB數據信息

 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. 遍歷

#define __blob_for_each_attr(pos, attr, rem) #define blob_for_each_attr(pos, attr, rem)

7. 複製

struct blob_attr * blob_memdup(struct blob_attr *attr)

8. 數據類型判斷

 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.嵌套操做

 1: void * blob_nest_start(struct blob_buf *buf, int id)

 2: Void blob_nest_end(struct blob_buf *buf, void *cookie)

10.判斷

bool blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)

11.初始/銷燬，解析

 1: /**

 2:  * 初始化BLOB buffer

 3:  */

 4: int blob_buf_init(struct blob_buf *buf, int id)

 5:  

 6: /**

 7:  * 銷燬BLOB buffer

 8:  */

 9: void blob_buf_free(struct blob_buf *buf)

 10:  

 11: /**

 12:  * 從attr串中根據info策略過濾，獲得的結果存儲在data屬性數組中

 13:  *

 14:  * @param attr 輸入BLOB屬性串

 15:  * @param data 輸出BLOB屬性數組

 16:  * @param info 屬性過濾策略

 17:  * @param max data數組大小

 18:  */

 19: int blob_parse(struct blob_attr *attr, struct blob_attr **data, 

 20:                const struct blob_attr_info *info, int max)

二：blobmsg相關接口

1.數據結構

 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.存儲結構

3.消息類型

 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.基本操做

 1: /**

 2:  * 根據BLOB消息名字長度計算出blobmsg頭部大小

 3:  */

 4: static inline int blobmsg_hdrlen(unsigned int namelen)

 5:  

 6: /**

 7:  * 獲取BLOB消息名字

 8:  */

 9: static inline const char *blobmsg_name(const struct blob_attr *attr)

 10:  

 11: /**

 12:  * 獲取BLOB消息類型

 13:  */

 14: static inline int blobmsg_type(const struct blob_attr *attr)

 15:  

 16: /**

 17:  * 獲取BLOB消息數據內容

 18:  */

 19: static inline void *blobmsg_data(const struct blob_attr *attr)

 20:  

 21: /**

 22:  * 獲取BLOB消息數據內容大小

 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: 數據類型判斷

 27:  

 28: /**

 29:  * 判斷BLOBMSG屬性類型是否合法

 30:  */

 31: bool blobmsg_check_attr(const struct blob_attr *attr, bool name)

 32: 設置

 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:  * 格式化設備BLOGMSG

 57:  */

 58: void blobmsg_printf(struct blob_buf *buf, const char *name, const char *format, ...)

 59: 獲取

 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: 建立

 68:  

 69: /**

 70:  * 建立BLOBMSG，返回數據區開始地址

 71:  */

 72: void *blobmsg_alloc_string_buffer(struct blob_buf *buf, const char *name, 

 73: unsigned int maxlen)

 74:  

 75: /**

 76:  * 擴大BLOGMSG，返回數據區開始地址

 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: 遍歷

 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:  * 從data BLOGMSG串中根據policy策略過濾，獲得的結果存儲在tb BLOGATTR數組中

 95:  *

 96:  * @param policy 過濾策略

 97:  * @param policy_len 策略個數

 98:  * @param tb 返回屬性數據

 99:  * @param len data屬性個數

 100:  */

 101: int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,

 102:                   struct blob_attr **tb, void *data, unsigned int len)

三：實例操做

把UCI轉化爲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: 定義參數列表:

 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: /** 定義BLOBMSG_TYPE_ARRAY類型參數的實際數據類型 */

 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: 轉化爲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: 使用轉化後的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: }