NGINX Coding Style¶

The NGINX source code is written in the C programming language by Kernighan and Ritchie and maintains a consistent style.

Rules¶

K&R style indentation
4 space indentation, no tabs
2 line breaks between blocks at global level
C style comments only (/* ... */, not //)

Example¶

From the FastCGI module:

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef struct {
    ngx_http_upstream_conf_t       upstream;

    ngx_str_t                      index;

    ngx_array_t                   *flushes;
    ngx_array_t                   *params_len;
    ngx_array_t                   *params;
    ngx_array_t                   *params_source;
    ngx_array_t                   *catch_stderr;

    ngx_array_t                   *fastcgi_lengths;
    ngx_array_t                   *fastcgi_values;

#if (NGX_HTTP_CACHE)
    ngx_http_complex_value_t       cache_key;
#endif

#if (NGX_PCRE)
    ngx_regex_t                   *split_regex;
    ngx_str_t                      split_name;
#endif
} ngx_http_fastcgi_loc_conf_t;


typedef enum {
    ngx_http_fastcgi_st_version = 0,
    ngx_http_fastcgi_st_type,
    ngx_http_fastcgi_st_request_id_hi,
    ngx_http_fastcgi_st_request_id_lo,
    ngx_http_fastcgi_st_content_length_hi,
    ngx_http_fastcgi_st_content_length_lo,
    ngx_http_fastcgi_st_padding_length,
    ngx_http_fastcgi_st_reserved,
    ngx_http_fastcgi_st_data,
    ngx_http_fastcgi_st_padding
} ngx_http_fastcgi_state_e;


typedef struct {
    u_char                        *start;
    u_char                        *end;
} ngx_http_fastcgi_split_part_t;

Key Observations¶

Pattern	Example
Two blank lines between top-level blocks	Between `#include` and `typedef`
Pointer `*` aligned to right	`ngx_array_t *flushes;`
Single space after keywords	`if (`, `for (`, `while (`
No space for function calls	`ngx_palloc(pool, size)`
Struct member alignment	Members aligned with spaces