nginx原始碼分析——初始化log

nginx在main函式中首先對log進行初始化，將配置檔案中的log檔名開啟，將開啟log檔案控制程式碼等相應的屬性存在log變數中，本人覺得該程式碼寫的挺好，有借鑑之處，因而在次貼出。

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;

};(src/core/ngx_log.h)

typedef struct ngx_log_s         ngx_log_t;  (src/core/ngx_core.h)

ngx_log_t        *log;    (src/core/nginx.c)

log = ngx_log_init(ngx_prefix);  (src/core/nginx.c)

ngx_log_init  定義在src/core/ngx_log.c中

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;
}