ngx_log_init 分析

ngx_log_init()

初始化ngx_log，設置日誌級別ngx_log.log_level，並獲得日誌的文件句柄ngx_log_file.fd。

結構體ngx_log_t

static ngx_log_t        ngx_log;

struct ngx_log_s {
    ngx_uint_t           log_level;
    ngx_open_file_t     *file;

    ngx_atomic_uint_t    connection;

    ngx_log_handler_pt   handler;
    void                *data;

    /*
     * we declare "action" as "char *" because the actions are usually
     * the static strings and in the "u_char *" case we have to override
     * their types all the time
     */

    char                *action;

    ngx_log_t           *next;
};
typedef struct ngx_log_s         ngx_log_t;

結構體ngx_open_file_t

static ngx_open_file_t  ngx_log_file;

struct ngx_open_file_s {
    ngx_fd_t              fd;
    ngx_str_t             name;

    void                (*flush)(ngx_open_file_t *file, ngx_log_t *log);
    void                 *data;
};
typedef struct ngx_open_file_s   ngx_open_file_t;

 

ngx_log_init()代碼

ngx_log_t *
ngx_log_init(u_char *prefix)
{
    u_char  *p, *name;
    size_t   nlen, plen;

    ngx_log.file = &ngx_log_file;
    ngx_log.log_level = NGX_LOG_NOTICE;

    name = (u_char *) NGX_ERROR_LOG_PATH;

    /*
     * we use ngx_strlen() here since BCC warns about
     * condition is always false and unreachable code
     */

    nlen = ngx_strlen(name);

    if (nlen == 0) {
        ngx_log_file.fd = ngx_stderr;
        return &ngx_log;
    }

    p = NULL;

#if (NGX_WIN32)
    if (name[1] != ':') {
#else
    if (name[0] != '/') {
#endif

        if (prefix) {
            plen = ngx_strlen(prefix);

        } else {
#ifdef NGX_PREFIX
            prefix = (u_char *) NGX_PREFIX;
            plen = ngx_strlen(prefix);
#else
            plen = 0;
#endif
        }

        if (plen) {
            name = malloc(plen + nlen + 2);
            if (name == NULL) {
                return NULL;
            }

            p = ngx_cpymem(name, prefix, plen);

            if (!ngx_path_separator(*(p - 1))) {
                *p++ = '/';
            }

            ngx_cpystrn(p, (u_char *) NGX_ERROR_LOG_PATH, nlen + 1);

            p = name;
        }
    }

    ngx_log_file.fd = ngx_open_file(name, NGX_FILE_APPEND,
                                    NGX_FILE_CREATE_OR_OPEN,
                                    NGX_FILE_DEFAULT_ACCESS);

    if (ngx_log_file.fd == NGX_INVALID_FILE) {
        ngx_log_stderr(ngx_errno,
                       "[alert] could not open error log file: "
                       ngx_open_file_n " \"%s\" failed", name);
#if (NGX_WIN32)
        ngx_event_log(ngx_errno,
                       "could not open error log file: "
                       ngx_open_file_n " \"%s\" failed", name);
#endif

        ngx_log_file.fd = ngx_stderr;
    }

    if (p) {
        ngx_free(p);
    }

    return &ngx_log;
}

 

NGX_ERROR_LOG_PATH和NGX_PREFIX

當編譯完 Nginx 之後，能夠在 objs 目錄下面看到一個ngx_auto_config.h文件

#ifndef NGX_PREFIX
#define NGX_PREFIX  "/usr/local/"
#endif


#ifndef NGX_CONF_PREFIX
#define NGX_CONF_PREFIX  "conf/"
#endif


#ifndef NGX_SBIN_PATH
#define NGX_SBIN_PATH  ""
#endif

#ifndef NGX_CONF_PATH
#define NGX_CONF_PATH  "conf/nginx.conf"
#endif


#ifndef NGX_PID_PATH
#define NGX_PID_PATH  "logs/nginx.pid"
#endif


#ifndef NGX_LOCK_PATH
#define NGX_LOCK_PATH  "logs/nginx.lock"
#endif


#ifndef NGX_ERROR_LOG_PATH
#define NGX_ERROR_LOG_PATH  "logs/error.log"
#endif


#ifndef NGX_HTTP_LOG_PATH
#define NGX_HTTP_LOG_PATH  "logs/access.log"
#endif

所以日誌文件路徑爲：

/usr/local/logs/error.log