本節分析一下ngx_get_options()
函數,這個函數的做用就是解析nginx
的啓動命令傳遞的參數,好比/usr/local/nginx/sbin/nginx -s reload
, /usr/local/nginx/sbin/nginx -t
等。html
http://nginx.org/en/docs/switches.html
nginx supports the following command-line parameters:
-? | -h — print help for command-line parameters.
-c file — use an alternative configuration file instead of a default file.
-g directives — set global configuration directives, for example,
nginx -g "pid /var/run/nginx.pid; worker_processes `sysctl -n hw.ncpu`;"
-p prefix — set nginx path prefix, i.e. a directory that will keep server files (default value is /usr/local/nginx).
-q — suppress non-error messages during configuration testing.不輸出error級別下的信息,配合-t參數使用
-s signal — send a signal to the master process. The argument signal can be one of:
stop — shut down quickly
quit — shut down gracefully
reload — reload configuration, start the new worker process with a new configuration, gracefully shut down old worker processes.
reopen — reopen log files
-t — test the configuration file: nginx checks the configuration for correct syntax, and then tries to open files referred in the configuration.
-T — same as -t, but additionally dump configuration files to standard output (1.9.2).
-v — print nginx version.
-V — print nginx version, compiler version, and configure parameters.
複製代碼
咱們先看一下ngx_get_options
的源碼,以下:nginx
static ngx_int_t
ngx_get_options(int argc, char *const *argv)
{
u_char *p;
ngx_int_t i;
// 第0個參數是nginx自己,因此從第一個參數進行解析
for (i = 1; i < argc; i++) {
p = (u_char *) argv[i];
// 參數必須以短橫線開頭
if (*p++ != '-') {
ngx_log_stderr(0, "invalid option: \"%s\"", argv[i]);
return NGX_ERROR;
}
while (*p) {
switch (*p++) {
case '?':
case 'h':
ngx_show_version = 1;
ngx_show_help = 1;
break;
case 'v':
ngx_show_version = 1;
break;
case 'V':
ngx_show_version = 1;
ngx_show_configure = 1;
break;
case 't':
ngx_test_config = 1;
break;
case 'T':
ngx_test_config = 1;
ngx_dump_config = 1;
break;
case 'q':
ngx_quiet_mode = 1;
break;
case 'p':
if (*p) {
ngx_prefix = p;
goto next;
}
if (argv[++i]) {
ngx_prefix = (u_char *) argv[i];
goto next;
}
ngx_log_stderr(0, "option \"-p\" requires directory name");
return NGX_ERROR;
case 'c':
if (*p) {
ngx_conf_file = p;
goto next;
}
if (argv[++i]) {
ngx_conf_file = (u_char *) argv[i];
goto next;
}
ngx_log_stderr(0, "option \"-c\" requires file name");
return NGX_ERROR;
case 'g':
if (*p) {
ngx_conf_params = p;
goto next;
}
if (argv[++i]) {
ngx_conf_params = (u_char *) argv[i];
goto next;
}
ngx_log_stderr(0, "option \"-g\" requires parameter");
return NGX_ERROR;
case 's':
if (*p) {
ngx_signal = (char *) p;
} else if (argv[++i]) {
ngx_signal = argv[i];
} else {
ngx_log_stderr(0, "option \"-s\" requires parameter");
return NGX_ERROR;
}
if (ngx_strcmp(ngx_signal, "stop") == 0
|| ngx_strcmp(ngx_signal, "quit") == 0
|| ngx_strcmp(ngx_signal, "reopen") == 0
|| ngx_strcmp(ngx_signal, "reload") == 0)
{
ngx_process = NGX_PROCESS_SIGNALLER;
goto next;
}
ngx_log_stderr(0, "invalid option: \"-s %s\"", ngx_signal);
return NGX_ERROR;
default:
ngx_log_stderr(0, "invalid option: \"%c\"", *(p - 1));
return NGX_ERROR;
}
}
next:
continue;
}
return NGX_OK;
}
複製代碼
Q1:
爲何有一個while
循環?A1:
一個減號後面能夠帶有多個參數。好比-thv
等。web
Q2:
爲何處理-p
的時候要先判斷一下if(*p)
呢?sql
// 爲何要先判斷一次 *p, 而後再判斷argv[++i]呢?
if (*p) {
ngx_prefix = p;
goto next;
}
if (argv[++i]) {
ngx_prefix = (u_char *) argv[i];
goto next;
}
ngx_log_stderr(0, "option \"-p\" requires directory name");
return NGX_ERROR;
複製代碼
A2:
由於nginx
的-p
的參數既能夠緊跟着p
,也能夠和-p
中間隔若干個空格。
好比/usr/local/nginx/sbin/nginx -p/usr/local/nginx/html/
,也能夠/usr/local/nginx/sbin/nginx -p /usr/local/nginx/html/
,因此這裏有兩種處理方式了。if(*p)
是處理第一種中間沒有空格的狀況。數組
要知道,argv[]
是一個字符串指針數組,每一個元素都是以\0
結尾的,而且數組的最後一個元素是NULL
。因此若是*p != NULL
,那麼就說明-p
的參數是緊挨着-p
的。app
從這裏咱們也能夠看出來,處理完-p
指令以後執行了goto next
,而不是break
,這裏也說明:若是-p
指令和其餘指令一塊兒使用的時候,-p
必須放到最後,好比/usr/local/nginx/sbin/nginx -tp /usr/local/nginx/html/
, 而不能是/usr/local/nginx/sbin/nginx -pt /usr/local/nginx/html/
。(注意p
和t
的順序)函數
對於每種參數的解析都是相似的,會設置一個變量。
好比,若是是-v
,那麼就會設置ngx_show_version = 1
等。源碼分析
TODO: 此處缺乏一張歸納圖ui
本文就先簡單的分析一下啓動過程當中的解析命令行參數的函數。若是喜歡本文,能夠關注公衆號Nginx源碼分析
.spa