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_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:  };

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2. 存储结构

libubox组件（2）——blob/blobmsg （转载 https://segmentfault.com/a/1190000002391970）

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

libubox组件（2）——blob/blobmsg （转载 https://segmentfault.com/a/1190000002391970）

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:  }

秒客网

libubox组件（2）——blob/blobmsg （转载 https://segmentfault.com/a/1190000002391970）

7. 复制

把UCI转化为BLOB

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