Basic Data Structures

First, it is an integer type:
Src/core/ngx_config.h

typedef intptr_t        ngx_int_t;typedef uintptr_t       ngx_uint_t;typedef intptr_t        ngx_flag_t;

That is, integers, unsigned integers, and bool. Three types of intptr_t are defined as follows:
/usr/local/include/stdint.h

/* Types for `void *' pointers.  */#if __WORDSIZE == 64# ifndef __intptr_t_definedlongint        intptr_t;#  define __intptr_t_defined# endiflongint   uintptr_t;#else# ifndef __intptr_t_definedint         intptr_t;#  define __intptr_t_defined# endifint        uintptr_t;#endif

That is: The 64 system uses a long shape (8 bytes), otherwise it uses shaping (4 bytes).

Then the string type:
/src/core/ngx_string.h

typedef struct {    size_t      len;    u_char     *data;} ngx_str_t;

Next, a bunch of string-related functions are defined, similar to the member functions that correspond to ngx_str_t.

function	Description
Ngx_string (str)	constructor, Str points to the end of the string
Ngx_null_string	Empty constructors
Ngx_str_set (str, text)	Text pointing to the end of the string, set it to the ngx_str_t object str
ngx_strncmp	Package strncmp
ngx_strcmp	Package strcmp
...	...

In addition, several other types are defined by the way:

typedefstruct {    ngx_str_t   key;    ngx_str_t   value;} ngx_keyval_t;typedefstruct {  // 位域用来标示类型等元信息unsigned    len:28;    unsigned    valid:1;    unsigned    no_cacheable:1;    unsigned    not_found:1;    unsigned    escape:1;    u_char     *data;} ngx_variable_value_t;typedefstruct {    ngx_rbtree_node_t         node;    ngx_str_t                 str;} ngx_str_node_t;

Defines your own error type: (Because the system's strerror and STRERROR_R functions are not signal-safe, so the author copies the error msg corresponding to the error code, maintains it itself, writes the function very simply, is the signal safe)
Src/os/unix/ngx_errno.h

typedefint               ngx_err_t;// 根据错误号err,将对应的描述信息拷贝到errstr，最多拷贝size字节u_char *ngx_strerror(ngx_err_t err, u_char *errstr, size_t size); ngx_int_t ngx_strerror_init(void);

The error number is defined in the system's errno.h, and the final error number after the multilayer include is defined in/usr/include/asm-generic/errno.h.
The strerror and STRERROR_R functions are declared in String.h

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