Nginx学习笔记（六） 源码分析&启动过程

Nginx的启动过程

　　主要介绍Nginx的启动过程，可以在/core/nginx.c中找到Nginx的主函数main()，那么就从这里开始分析Nginx的启动过程。

涉及到的基本函数

源码：

 /*
  * Copyright (C) Igor Sysoev
  * Copyright (C) Nginx, Inc.
  */

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

 static ngx_int_t ngx_add_inherited_sockets(ngx_cycle_t *cycle);
 static ngx_int_t ngx_get_options(int argc, char *const *argv);
 static ngx_int_t ngx_process_options(ngx_cycle_t *cycle);
 static ngx_int_t ngx_save_argv(ngx_cycle_t *cycle, int argc, char *const *argv);
 static void *ngx_core_module_create_conf(ngx_cycle_t *cycle);
 static char *ngx_core_module_init_conf(ngx_cycle_t *cycle, void *conf);
 static char *ngx_set_user(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static char *ngx_set_env(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static char *ngx_set_priority(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static char *ngx_set_cpu_affinity(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
 static char *ngx_set_worker_processes(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);

 static ngx_conf_enum_t  ngx_debug_points[] = {
     { ngx_string("stop"), NGX_DEBUG_POINTS_STOP },
     { ngx_string("abort"), NGX_DEBUG_POINTS_ABORT },
     { ngx_null_string,  }
 };

 static ngx_command_t  ngx_core_commands[] = {

     { ngx_string("daemon"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
       ,
       offsetof(ngx_core_conf_t, daemon),
       NULL },

     { ngx_string("master_process"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
       ,
       offsetof(ngx_core_conf_t, master),
       NULL },

     { ngx_string("timer_resolution"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_msec_slot,
       ,
       offsetof(ngx_core_conf_t, timer_resolution),
       NULL },

     { ngx_string("pid"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_str_slot,
       ,
       offsetof(ngx_core_conf_t, pid),
       NULL },

     { ngx_string("lock_file"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_str_slot,
       ,
       offsetof(ngx_core_conf_t, lock_file),
       NULL },

     { ngx_string("worker_processes"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_set_worker_processes,
       ,
       ,
       NULL },

     { ngx_string("debug_points"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_enum_slot,
       ,
       offsetof(ngx_core_conf_t, debug_points),
       &ngx_debug_points },

     { ngx_string("user"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE12,
       ngx_set_user,
       ,
       ,
       NULL },

     { ngx_string("worker_priority"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_set_priority,
       ,
       ,
       NULL },

     { ngx_string("worker_cpu_affinity"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_1MORE,
       ngx_set_cpu_affinity,
       ,
       ,
       NULL },

     { ngx_string("worker_rlimit_nofile"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_num_slot,
       ,
       offsetof(ngx_core_conf_t, rlimit_nofile),
       NULL },

     { ngx_string("worker_rlimit_core"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_off_slot,
       ,
       offsetof(ngx_core_conf_t, rlimit_core),
       NULL },

     { ngx_string("worker_rlimit_sigpending"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_num_slot,
       ,
       offsetof(ngx_core_conf_t, rlimit_sigpending),
       NULL },

     { ngx_string("working_directory"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_str_slot,
       ,
       offsetof(ngx_core_conf_t, working_directory),
       NULL },

     { ngx_string("env"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_set_env,
       ,
       ,
       NULL },

 #if (NGX_THREADS)

     { ngx_string("worker_threads"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_num_slot,
       ,
       offsetof(ngx_core_conf_t, worker_threads),
       NULL },

     { ngx_string("thread_stack_size"),
       NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_size_slot,
       ,
       offsetof(ngx_core_conf_t, thread_stack_size),
       NULL },

 #endif

       ngx_null_command
 };

 static ngx_core_module_t  ngx_core_module_ctx = {
     ngx_string("core"),
     ngx_core_module_create_conf,
     ngx_core_module_init_conf
 };

 ngx_module_t  ngx_core_module = {
     NGX_MODULE_V1,
     &ngx_core_module_ctx,                  /* module context */
     ngx_core_commands,                     /* module directives */
     NGX_CORE_MODULE,                       /* module type */
     NULL,                                  /* init master */
     NULL,                                  /* init module */
     NULL,                                  /* init process */
     NULL,                                  /* init thread */
     NULL,                                  /* exit thread */
     NULL,                                  /* exit process */
     NULL,                                  /* exit master */
     NGX_MODULE_V1_PADDING
 };

 ngx_uint_t          ngx_max_module;

 static ngx_uint_t   ngx_show_help;
 static ngx_uint_t   ngx_show_version;
 static ngx_uint_t   ngx_show_configure;
 static u_char      *ngx_prefix;
 static u_char      *ngx_conf_file;
 static u_char      *ngx_conf_params;
 static char        *ngx_signal;

 static char **ngx_os_environ;

 int ngx_cdecl
 main(int argc, char *const *argv)
 {
     ngx_int_t         i;
     ngx_log_t        *log;
     ngx_cycle_t      *cycle, init_cycle;
     ngx_core_conf_t  *ccf;

     ngx_debug_init();

     if (ngx_strerror_init() != NGX_OK) {
         return ;
     }

     if (ngx_get_options(argc, argv) != NGX_OK) {
         return ;
     }

     if (ngx_show_version) {
         ngx_write_stderr("nginx version: " NGINX_VER NGX_LINEFEED);

         if (ngx_show_help) {
             ngx_write_stderr(
                 "Usage: nginx [-?hvVtq] [-s signal] [-c filename] "
                              "[-p prefix] [-g directives]" NGX_LINEFEED
                              NGX_LINEFEED
                 "Options:" NGX_LINEFEED
                 "  -?,-h         : this help" NGX_LINEFEED
                 "  -v            : show version and exit" NGX_LINEFEED
                 "  -V            : show version and configure options then exit"
                                    NGX_LINEFEED
                 "  -t            : test configuration and exit" NGX_LINEFEED
                 "  -q            : suppress non-error messages "
                                    "during configuration testing" NGX_LINEFEED
                 "  -s signal     : send signal to a master process: "
                                    "stop, quit, reopen, reload" NGX_LINEFEED
 #ifdef NGX_PREFIX
                 "  -p prefix     : set prefix path (default: "
                                    NGX_PREFIX ")" NGX_LINEFEED
 #else
                 "  -p prefix     : set prefix path (default: NONE)" NGX_LINEFEED
 #endif
                 "  -c filename   : set configuration file (default: "
                                    NGX_CONF_PATH ")" NGX_LINEFEED
                 "  -g directives : set global directives out of configuration "
                                    "file" NGX_LINEFEED NGX_LINEFEED
                 );
         }

         if (ngx_show_configure) {
             ngx_write_stderr(
 #ifdef NGX_COMPILER
                 "built by " NGX_COMPILER NGX_LINEFEED
 #endif
 #if (NGX_SSL)
 #ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
                 "TLS SNI support enabled" NGX_LINEFEED
 #else
                 "TLS SNI support disabled" NGX_LINEFEED
 #endif
 #endif
                 "configure arguments:" NGX_CONFIGURE NGX_LINEFEED);
         }

         if (!ngx_test_config) {
             return ;
         }
     }

     /* TODO */ ngx_max_sockets = -;

     ngx_time_init();

 #if (NGX_PCRE)
     ngx_regex_init();
 #endif

     ngx_pid = ngx_getpid();

     log = ngx_log_init(ngx_prefix);
     if (log == NULL) {
         return ;
     }

     /* STUB */
 #if (NGX_OPENSSL)
     ngx_ssl_init(log);
 #endif

     /*
      * init_cycle->log is required for signal handlers and
      * ngx_process_options()
      */

     ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));
     init_cycle.log = log;
     ngx_cycle = &init_cycle;

     init_cycle.pool = ngx_create_pool(, log);
     if (init_cycle.pool == NULL) {
         return ;
     }

     if (ngx_save_argv(&init_cycle, argc, argv) != NGX_OK) {
         return ;
     }

     if (ngx_process_options(&init_cycle) != NGX_OK) {
         return ;
     }

     if (ngx_os_init(log) != NGX_OK) {
         return ;
     }

     /*
      * ngx_crc32_table_init() requires ngx_cacheline_size set in ngx_os_init()
      */

     if (ngx_crc32_table_init() != NGX_OK) {
         return ;
     }

     if (ngx_add_inherited_sockets(&init_cycle) != NGX_OK) {
         return ;
     }

     ngx_max_module = ;
     for (i = ; ngx_modules[i]; i++) {
         ngx_modules[i]->index = ngx_max_module++;
     }

     cycle = ngx_init_cycle(&init_cycle);
     if (cycle == NULL) {
         if (ngx_test_config) {
             ngx_log_stderr(, "configuration file %s test failed",
                            init_cycle.conf_file.data);
         }

         return ;
     }

     if (ngx_test_config) {
         if (!ngx_quiet_mode) {
             ngx_log_stderr(, "configuration file %s test is successful",
                            cycle->conf_file.data);
         }

         return ;
     }

     if (ngx_signal) {
         return ngx_signal_process(cycle, ngx_signal);
     }

     ngx_os_status(cycle->log);

     ngx_cycle = cycle;

     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

     if (ccf->master && ngx_process == NGX_PROCESS_SINGLE) {
         ngx_process = NGX_PROCESS_MASTER;
     }

 #if !(NGX_WIN32)

     if (ngx_init_signals(cycle->log) != NGX_OK) {
         return ;
     }

     if (!ngx_inherited && ccf->daemon) {
         if (ngx_daemon(cycle->log) != NGX_OK) {
             return ;
         }

         ngx_daemonized = ;
     }

     if (ngx_inherited) {
         ngx_daemonized = ;
     }

 #endif

     if (ngx_create_pidfile(&ccf->pid, cycle->log) != NGX_OK) {
         return ;
     }

     if (cycle->log->file->fd != ngx_stderr) {

         if (ngx_set_stderr(cycle->log->file->fd) == NGX_FILE_ERROR) {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                           ngx_set_stderr_n " failed");
             return ;
         }
     }

     if (log->file->fd != ngx_stderr) {
         if (ngx_close_file(log->file->fd) == NGX_FILE_ERROR) {
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                           ngx_close_file_n " built-in log failed");
         }
     }

     ngx_use_stderr = ;

     if (ngx_process == NGX_PROCESS_SINGLE) {
         ngx_single_process_cycle(cycle);

     } else {
         ngx_master_process_cycle(cycle);
     }

     return ;
 }

 static ngx_int_t
 ngx_add_inherited_sockets(ngx_cycle_t *cycle)
 {
     u_char           *p, *v, *inherited;
     ngx_int_t         s;
     ngx_listening_t  *ls;

     inherited = (u_char *) getenv(NGINX_VAR);

     if (inherited == NULL) {
         return NGX_OK;
     }

     ngx_log_error(NGX_LOG_NOTICE, cycle->log, ,
                   "using inherited sockets from \"%s\"", inherited);

     if (ngx_array_init(&cycle->listening, cycle->pool, ,
                        sizeof(ngx_listening_t))
         != NGX_OK)
     {
         return NGX_ERROR;
     }

     for (p = inherited, v = p; *p; p++) {
         if (*p == ':' || *p == ';') {
             s = ngx_atoi(v, p - v);
             if (s == NGX_ERROR) {
                 ngx_log_error(NGX_LOG_EMERG, cycle->log, ,
                               "invalid socket number \"%s\" in " NGINX_VAR
                               " environment variable, ignoring the rest"
                               " of the variable", v);
                 break;
             }

             v = p + ;

             ls = ngx_array_push(&cycle->listening);
             if (ls == NULL) {
                 return NGX_ERROR;
             }

             ngx_memzero(ls, sizeof(ngx_listening_t));

             ls->fd = (ngx_socket_t) s;
         }
     }

     ngx_inherited = ;

     return ngx_set_inherited_sockets(cycle);
 }

 char **
 ngx_set_environment(ngx_cycle_t *cycle, ngx_uint_t *last)
 {
     char             **p, **env;
     ngx_str_t         *var;
     ngx_uint_t         i, n;
     ngx_core_conf_t   *ccf;

     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

     if (last == NULL && ccf->environment) {
         return ccf->environment;
     }

     var = ccf->env.elts;

     for (i = ; i < ccf->env.nelts; i++) {
         if (ngx_strcmp(var[i].data, "TZ") ==
             || ngx_strncmp(var[i].data, "TZ=", ) == )
         {
             goto tz_found;
         }
     }

     var = ngx_array_push(&ccf->env);
     if (var == NULL) {
         return NULL;
     }

     var->len = ;
     var->data = (u_char *) "TZ";

     var = ccf->env.elts;

 tz_found:

     n = ;

     for (i = ; i < ccf->env.nelts; i++) {

         if (var[i].data[var[i].len] == '=') {
             n++;
             continue;
         }

         for (p = ngx_os_environ; *p; p++) {

             if (ngx_strncmp(*p, var[i].data, var[i].len) ==
                 && (*p)[var[i].len] == '=')
             {
                 n++;
                 break;
             }
         }
     }

     if (last) {
         env = ngx_alloc((*last + n + ) * sizeof(char *), cycle->log);
         *last = n;

     } else {
         env = ngx_palloc(cycle->pool, (n + ) * sizeof(char *));
     }

     if (env == NULL) {
         return NULL;
     }

     n = ;

     for (i = ; i < ccf->env.nelts; i++) {

         if (var[i].data[var[i].len] == '=') {
             env[n++] = (char *) var[i].data;
             continue;
         }

         for (p = ngx_os_environ; *p; p++) {

             if (ngx_strncmp(*p, var[i].data, var[i].len) ==
                 && (*p)[var[i].len] == '=')
             {
                 env[n++] = *p;
                 break;
             }
         }
     }

     env[n] = NULL;

     if (last == NULL) {
         ccf->environment = env;
         environ = env;
     }

     return env;
 }

 ngx_pid_t
 ngx_exec_new_binary(ngx_cycle_t *cycle, char *const *argv)
 {
     char             **env, *var;
     u_char            *p;
     ngx_uint_t         i, n;
     ngx_pid_t          pid;
     ngx_exec_ctx_t     ctx;
     ngx_core_conf_t   *ccf;
     ngx_listening_t   *ls;

     ngx_memzero(&ctx, sizeof(ngx_exec_ctx_t));

     ctx.path = argv[];
     ctx.name = "new binary process";
     ctx.argv = argv;

     n = ;
     env = ngx_set_environment(cycle, &n);
     if (env == NULL) {
         return NGX_INVALID_PID;
     }

     var = ngx_alloc(sizeof(NGINX_VAR)
                     + cycle->listening.nelts * (NGX_INT32_LEN + ) + ,
                     cycle->log);
     if (var == NULL) {
         ngx_free(env);
         return NGX_INVALID_PID;
     }

     p = ngx_cpymem(var, NGINX_VAR "=", sizeof(NGINX_VAR));

     ls = cycle->listening.elts;
     for (i = ; i < cycle->listening.nelts; i++) {
         p = ngx_sprintf(p, "%ud;", ls[i].fd);
     }

     *p = '\0';

     env[n++] = var;

 #if (NGX_SETPROCTITLE_USES_ENV)

     /* allocate the spare 300 bytes for the new binary process title */

     env[n++] = "SPARE=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
                "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
                "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
                "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
                "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";

 #endif

     env[n] = NULL;

 #if (NGX_DEBUG)
     {
     char  **e;
     for (e = env; *e; e++) {
         ngx_log_debug1(NGX_LOG_DEBUG_CORE, cycle->log, , "env: %s", *e);
     }
     }
 #endif

     ctx.envp = (char *const *) env;

     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

     if (ngx_rename_file(ccf->pid.data, ccf->oldpid.data) == NGX_FILE_ERROR) {
         ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                       ngx_rename_file_n " %s to %s failed "
                       "before executing new binary process \"%s\"",
                       ccf->pid.data, ccf->oldpid.data, argv[]);

         ngx_free(env);
         ngx_free(var);

         return NGX_INVALID_PID;
     }

     pid = ngx_execute(cycle, &ctx);

     if (pid == NGX_INVALID_PID) {
         if (ngx_rename_file(ccf->oldpid.data, ccf->pid.data)
             == NGX_FILE_ERROR)
         {
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                           ngx_rename_file_n " %s back to %s failed after "
                           "an attempt to execute new binary process \"%s\"",
                           ccf->oldpid.data, ccf->pid.data, argv[]);
         }
     }

     ngx_free(env);
     ngx_free(var);

     return pid;
 }

 static ngx_int_t
 ngx_get_options(int argc, char *const *argv)
 {
     u_char     *p;
     ngx_int_t   i;

     for (i = ; i < argc; i++) {

         p = (u_char *) argv[i];

         if (*p++ != '-') {
             ngx_log_stderr(, "invalid option: \"%s\"", argv[i]);
             return NGX_ERROR;
         }

         while (*p) {

             switch (*p++) {

             case '?':
             case 'h':
                 ngx_show_version = ;
                 ngx_show_help = ;
                 break;

             case 'v':
                 ngx_show_version = ;
                 break;

             case 'V':
                 ngx_show_version = ;
                 ngx_show_configure = ;
                 break;

             case 't':
                 ngx_test_config = ;
                 break;

             case 'q':
                 ngx_quiet_mode = ;
                 break;

             case 'p':
                 if (*p) {
                     ngx_prefix = p;
                     goto next;
                 }

                 if (argv[++i]) {
                     ngx_prefix = (u_char *) argv[i];
                     goto next;
                 }

                 ngx_log_stderr(, "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(, "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(, "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(, "option \"-s\" requires parameter");
                     return NGX_ERROR;
                 }

                 if (ngx_strcmp(ngx_signal, "stop") ==
                     || ngx_strcmp(ngx_signal, "quit") ==
                     || ngx_strcmp(ngx_signal, "reopen") ==
                     || ngx_strcmp(ngx_signal, "reload") == )
                 {
                     ngx_process = NGX_PROCESS_SIGNALLER;
                     goto next;
                 }

                 ngx_log_stderr(, "invalid option: \"-s %s\"", ngx_signal);
                 return NGX_ERROR;

             default:
                 ngx_log_stderr(, "invalid option: \"%c\"", *(p - ));
                 return NGX_ERROR;
             }
         }

     next:

         continue;
     }

     return NGX_OK;
 }

 static ngx_int_t
 ngx_save_argv(ngx_cycle_t *cycle, int argc, char *const *argv)
 {
 #if (NGX_FREEBSD)

     ngx_os_argv = (char **) argv;
     ngx_argc = argc;
     ngx_argv = (char **) argv;

 #else
     size_t     len;
     ngx_int_t  i;

     ngx_os_argv = (char **) argv;
     ngx_argc = argc;

     ngx_argv = ngx_alloc((argc + ) * sizeof(char *), cycle->log);
     if (ngx_argv == NULL) {
         return NGX_ERROR;
     }

     for (i = ; i < argc; i++) {
         len = ngx_strlen(argv[i]) + ;

         ngx_argv[i] = ngx_alloc(len, cycle->log);
         if (ngx_argv[i] == NULL) {
             return NGX_ERROR;
         }

         (void) ngx_cpystrn((u_char *) ngx_argv[i], (u_char *) argv[i], len);
     }

     ngx_argv[i] = NULL;

 #endif

     ngx_os_environ = environ;

     return NGX_OK;
 }

 static ngx_int_t
 ngx_process_options(ngx_cycle_t *cycle)
 {
     u_char  *p;
     size_t   len;

     if (ngx_prefix) {
         len = ngx_strlen(ngx_prefix);
         p = ngx_prefix;

         if (len && !ngx_path_separator(p[len - ])) {
             p = ngx_pnalloc(cycle->pool, len + );
             if (p == NULL) {
                 return NGX_ERROR;
             }

             ngx_memcpy(p, ngx_prefix, len);
             p[len++] = '/';
         }

         cycle->conf_prefix.len = len;
         cycle->conf_prefix.data = p;
         cycle->prefix.len = len;
         cycle->prefix.data = p;

     } else {

 #ifndef NGX_PREFIX

         p = ngx_pnalloc(cycle->pool, NGX_MAX_PATH);
         if (p == NULL) {
             return NGX_ERROR;
         }

         if (ngx_getcwd(p, NGX_MAX_PATH) == ) {
             ngx_log_stderr(ngx_errno, "[emerg]: " ngx_getcwd_n " failed");
             return NGX_ERROR;
         }

         len = ngx_strlen(p);

         p[len++] = '/';

         cycle->conf_prefix.len = len;
         cycle->conf_prefix.data = p;
         cycle->prefix.len = len;
         cycle->prefix.data = p;

 #else

 #ifdef NGX_CONF_PREFIX
         ngx_str_set(&cycle->conf_prefix, NGX_CONF_PREFIX);
 #else
         ngx_str_set(&cycle->conf_prefix, NGX_PREFIX);
 #endif
         ngx_str_set(&cycle->prefix, NGX_PREFIX);

 #endif
     }

     if (ngx_conf_file) {
         cycle->conf_file.len = ngx_strlen(ngx_conf_file);
         cycle->conf_file.data = ngx_conf_file;

     } else {
         ngx_str_set(&cycle->conf_file, NGX_CONF_PATH);
     }

     if (ngx_conf_full_name(cycle, &cycle->conf_file, ) != NGX_OK) {
         return NGX_ERROR;
     }

     for (p = cycle->conf_file.data + cycle->conf_file.len - ;
          p > cycle->conf_file.data;
          p--)
     {
         if (ngx_path_separator(*p)) {
             cycle->conf_prefix.len = p - ngx_cycle->conf_file.data + ;
             cycle->conf_prefix.data = ngx_cycle->conf_file.data;
             break;
         }
     }

     if (ngx_conf_params) {
         cycle->conf_param.len = ngx_strlen(ngx_conf_params);
         cycle->conf_param.data = ngx_conf_params;
     }

     if (ngx_test_config) {
         cycle->log->log_level = NGX_LOG_INFO;
     }

     return NGX_OK;
 }

 static void *
 ngx_core_module_create_conf(ngx_cycle_t *cycle)
 {
     ngx_core_conf_t  *ccf;

     ccf = ngx_pcalloc(cycle->pool, sizeof(ngx_core_conf_t));
     if (ccf == NULL) {
         return NULL;
     }

     /*
      * set by ngx_pcalloc()
      *
      *     ccf->pid = NULL;
      *     ccf->oldpid = NULL;
      *     ccf->priority = 0;
      *     ccf->cpu_affinity_n = 0;
      *     ccf->cpu_affinity = NULL;
      */

     ccf->daemon = NGX_CONF_UNSET;
     ccf->master = NGX_CONF_UNSET;
     ccf->timer_resolution = NGX_CONF_UNSET_MSEC;

     ccf->worker_processes = NGX_CONF_UNSET;
     ccf->debug_points = NGX_CONF_UNSET;

     ccf->rlimit_nofile = NGX_CONF_UNSET;
     ccf->rlimit_core = NGX_CONF_UNSET;
     ccf->rlimit_sigpending = NGX_CONF_UNSET;

     ccf->user = (ngx_uid_t) NGX_CONF_UNSET_UINT;
     ccf->group = (ngx_gid_t) NGX_CONF_UNSET_UINT;

 #if (NGX_THREADS)
     ccf->worker_threads = NGX_CONF_UNSET;
     ccf->thread_stack_size = NGX_CONF_UNSET_SIZE;
 #endif

     if (ngx_array_init(&ccf->env, cycle->pool, , sizeof(ngx_str_t))
         != NGX_OK)
     {
         return NULL;
     }

     return ccf;
 }

 static char *
 ngx_core_module_init_conf(ngx_cycle_t *cycle, void *conf)
 {
     ngx_core_conf_t  *ccf = conf;

     ngx_conf_init_value(ccf->daemon, );
     ngx_conf_init_value(ccf->master, );
     ngx_conf_init_msec_value(ccf->timer_resolution, );

     ngx_conf_init_value(ccf->worker_processes, );
     ngx_conf_init_value(ccf->debug_points, );

 #if (NGX_HAVE_CPU_AFFINITY)

     if (ccf->cpu_affinity_n
         && ccf->cpu_affinity_n !=
         && ccf->cpu_affinity_n != (ngx_uint_t) ccf->worker_processes)
     {
         ngx_log_error(NGX_LOG_WARN, cycle->log, ,
                       "the number of \"worker_processes\" is not equal to "
                       "the number of \"worker_cpu_affinity\" masks, "
                       "using last mask for remaining worker processes");
     }

 #endif

 #if (NGX_THREADS)

     ngx_conf_init_value(ccf->worker_threads, );
     ngx_threads_n = ccf->worker_threads;
     ngx_conf_init_size_value(ccf->thread_stack_size,  *  * );

 #endif

     if (ccf->pid.len == ) {
         ngx_str_set(&ccf->pid, NGX_PID_PATH);
     }

     if (ngx_conf_full_name(cycle, &ccf->pid, ) != NGX_OK) {
         return NGX_CONF_ERROR;
     }

     ccf->oldpid.len = ccf->pid.len + sizeof(NGX_OLDPID_EXT);

     ccf->oldpid.data = ngx_pnalloc(cycle->pool, ccf->oldpid.len);
     if (ccf->oldpid.data == NULL) {
         return NGX_CONF_ERROR;
     }

     ngx_memcpy(ngx_cpymem(ccf->oldpid.data, ccf->pid.data, ccf->pid.len),
                NGX_OLDPID_EXT, sizeof(NGX_OLDPID_EXT));

 #if !(NGX_WIN32)

     if (ccf->user == (uid_t) NGX_CONF_UNSET_UINT && geteuid() == ) {
         struct group   *grp;
         struct passwd  *pwd;

         ngx_set_errno();
         pwd = getpwnam(NGX_USER);
         if (pwd == NULL) {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                           "getpwnam(\"" NGX_USER "\") failed");
             return NGX_CONF_ERROR;
         }

         ccf->username = NGX_USER;
         ccf->user = pwd->pw_uid;

         ngx_set_errno();
         grp = getgrnam(NGX_GROUP);
         if (grp == NULL) {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                           "getgrnam(\"" NGX_GROUP "\") failed");
             return NGX_CONF_ERROR;
         }

         ccf->group = grp->gr_gid;
     }

     if (ccf->lock_file.len == ) {
         ngx_str_set(&ccf->lock_file, NGX_LOCK_PATH);
     }

     if (ngx_conf_full_name(cycle, &ccf->lock_file, ) != NGX_OK) {
         return NGX_CONF_ERROR;
     }

     {
     ngx_str_t  lock_file;

     lock_file = cycle->old_cycle->lock_file;

     if (lock_file.len) {
         lock_file.len--;

         if (ccf->lock_file.len != lock_file.len
             || ngx_strncmp(ccf->lock_file.data, lock_file.data, lock_file.len)
                != )
         {
             ngx_log_error(NGX_LOG_EMERG, cycle->log, ,
                           "\"lock_file\" could not be changed, ignored");
         }

         cycle->lock_file.len = lock_file.len + ;
         lock_file.len += sizeof(".accept");

         cycle->lock_file.data = ngx_pstrdup(cycle->pool, &lock_file);
         if (cycle->lock_file.data == NULL) {
             return NGX_CONF_ERROR;
         }

     } else {
         cycle->lock_file.len = ccf->lock_file.len + ;
         cycle->lock_file.data = ngx_pnalloc(cycle->pool,
                                       ccf->lock_file.len + sizeof(".accept"));
         if (cycle->lock_file.data == NULL) {
             return NGX_CONF_ERROR;
         }

         ngx_memcpy(ngx_cpymem(cycle->lock_file.data, ccf->lock_file.data,
                               ccf->lock_file.len),
                    ".accept", sizeof(".accept"));
     }
     }

 #endif

     return NGX_CONF_OK;
 }

 static char *
 ngx_set_user(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
 #if (NGX_WIN32)

     ngx_conf_log_error(NGX_LOG_WARN, cf, ,
                        "\"user\" is not supported, ignored");

     return NGX_CONF_OK;

 #else

     ngx_core_conf_t  *ccf = conf;

     char             *group;
     struct passwd    *pwd;
     struct group     *grp;
     ngx_str_t        *value;

     if (ccf->user != (uid_t) NGX_CONF_UNSET_UINT) {
         return "is duplicate";
     }

     if (geteuid() != ) {
         ngx_conf_log_error(NGX_LOG_WARN, cf, ,
                            "the \"user\" directive makes sense only "
                            "if the master process runs "
                            "with super-user privileges, ignored");
         return NGX_CONF_OK;
     }

     value = (ngx_str_t *) cf->args->elts;

     ccf->username = (char *) value[].data;

     ngx_set_errno();
     pwd = getpwnam((const char *) value[].data);
     if (pwd == NULL) {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, ngx_errno,
                            "getpwnam(\"%s\") failed", value[].data);
         return NGX_CONF_ERROR;
     }

     ccf->user = pwd->pw_uid;

     group = (char *) ((cf->args->nelts == ) ? value[].data : value[].data);

     ngx_set_errno();
     grp = getgrnam(group);
     if (grp == NULL) {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, ngx_errno,
                            "getgrnam(\"%s\") failed", group);
         return NGX_CONF_ERROR;
     }

     ccf->group = grp->gr_gid;

     return NGX_CONF_OK;

 #endif
 }

 static char *
 ngx_set_env(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
     ngx_core_conf_t  *ccf = conf;

     ngx_str_t   *value, *var;
     ngx_uint_t   i;

     var = ngx_array_push(&ccf->env);
     if (var == NULL) {
         return NGX_CONF_ERROR;
     }

     value = cf->args->elts;
     *var = value[];

     for (i = ; i < value[].len; i++) {

         if (value[].data[i] == '=') {

             var->len = i;

             return NGX_CONF_OK;
         }
     }

     return NGX_CONF_OK;
 }

 static char *
 ngx_set_priority(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
     ngx_core_conf_t  *ccf = conf;

     ngx_str_t        *value;
     ngx_uint_t        n, minus;

     if (ccf->priority != ) {
         return "is duplicate";
     }

     value = cf->args->elts;

     if (value[].data[] == '-') {
         n = ;
         minus = ;

     } else if (value[].data[] == '+') {
         n = ;
         minus = ;

     } else {
         n = ;
         minus = ;
     }

     ccf->priority = ngx_atoi(&value[].data[n], value[].len - n);
     if (ccf->priority == NGX_ERROR) {
         return "invalid number";
     }

     if (minus) {
         ccf->priority = -ccf->priority;
     }

     return NGX_CONF_OK;
 }

 static char *
 ngx_set_cpu_affinity(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
 #if (NGX_HAVE_CPU_AFFINITY)
     ngx_core_conf_t  *ccf = conf;

     u_char            ch;
     uint64_t         *mask;
     ngx_str_t        *value;
     ngx_uint_t        i, n;

     if (ccf->cpu_affinity) {
         return "is duplicate";
     }

     mask = ngx_palloc(cf->pool, (cf->args->nelts - ) * sizeof(uint64_t));
     if (mask == NULL) {
         return NGX_CONF_ERROR;
     }

     ccf->cpu_affinity_n = cf->args->nelts - ;
     ccf->cpu_affinity = mask;

     value = cf->args->elts;

     for (n = ; n < cf->args->nelts; n++) {

         if (value[n].len > ) {
             ngx_conf_log_error(NGX_LOG_EMERG, cf, ,
                          "\"worker_cpu_affinity\" supports up to 64 CPUs only");
             return NGX_CONF_ERROR;
         }

         mask[n - ] = ;

         for (i = ; i < value[n].len; i++) {

             ch = value[n].data[i];

             if (ch == ' ') {
                 continue;
             }

             mask[n - ] <<= ;

             if (ch == '') {
                 continue;
             }

             if (ch == '') {
                 mask[n - ] |= ;
                 continue;
             }

             ngx_conf_log_error(NGX_LOG_EMERG, cf, ,
                           "invalid character \"%c\" in \"worker_cpu_affinity\"",
                           ch);
             return NGX_CONF_ERROR;
         }
     }

 #else

     ngx_conf_log_error(NGX_LOG_WARN, cf, ,
                        "\"worker_cpu_affinity\" is not supported "
                        "on this platform, ignored");
 #endif

     return NGX_CONF_OK;
 }

 uint64_t
 ngx_get_cpu_affinity(ngx_uint_t n)
 {
     ngx_core_conf_t  *ccf;

     ccf = (ngx_core_conf_t *) ngx_get_conf(ngx_cycle->conf_ctx,
                                            ngx_core_module);

     if (ccf->cpu_affinity == NULL) {
         return ;
     }

     if (ccf->cpu_affinity_n > n) {
         return ccf->cpu_affinity[n];
     }

     return ccf->cpu_affinity[ccf->cpu_affinity_n - ];
 }

 static char *
 ngx_set_worker_processes(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
     ngx_str_t        *value;
     ngx_core_conf_t  *ccf;

     ccf = (ngx_core_conf_t *) conf;

     if (ccf->worker_processes != NGX_CONF_UNSET) {
         return "is duplicate";
     }

     value = (ngx_str_t *) cf->args->elts;

     if (ngx_strcmp(value[].data, "auto") == ) {
         ccf->worker_processes = ngx_ncpu;
         return NGX_CONF_OK;
     }

     ccf->worker_processes = ngx_atoi(value[].data, value[].len);

     if (ccf->worker_processes == NGX_ERROR) {
         return "invalid value";
     }

     return NGX_CONF_OK;
 }

　　Nginx的启动包括了很多的初始化和处理函数。这些函数相对来说，有一部分非常复杂，暂且从简单开始，从整体上对Ngixnd的启动有一个了解，方便日后的分析与学习。

　　主要函数：

//完成socket的继承
static ngx_int_t ngx_add_inherited_sockets(ngx_cycle_t *cycle);
//对参数选项进行处理
static ngx_int_t ngx_get_options(int argc, char *const *argv);
//初始化ngx_cycle内的部分内容
static ngx_int_t ngx_process_options(ngx_cycle_t *cycle);
//命令行参数保存到ngx_os_argv、ngx_argc以及ngx_argv全局的变量中
static ngx_int_t ngx_save_argv(ngx_cycle_t *cycle, int argc, char *const *argv);
//创建模块的配置信息
static void *ngx_core_module_create_conf(ngx_cycle_t *cycle);
//初始化配置信息
static char *ngx_core_module_init_conf(ngx_cycle_t *cycle, void *conf);
static char *ngx_set_user(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static char *ngx_set_env(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
//设置优先级
static char *ngx_set_priority(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
//设置CPU亲和性
static char *ngx_set_cpu_affinity(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
//设置worker进程
static char *ngx_set_worker_processes(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);

Nginx启动的主要流程

　　下图为Nginx的启动时函数的调用过程，其中大部分都是为了Nginx启动的初始化部分。从错误处理、参数设置、时间设置等方面进行初始化，并注册了我们需要的模块，最后根据信号选择单任务模式还是master-worker模式。

　　流程图：

初始化

　　主函数在开始对系统错误、参数、时间、系统变量、日志等进行了初始化。

//初始化系统中错误编号对应的含义
ngx_strerror_init();
//对参数选项进行处理
ngx_get_options(argc, argv);
//时间初始化
ngx_time_init();
//重置pcre内存管理的接口
ngx_regex_init();
//日志初始化
ngx_log_init(ngx_prefix);
//创建内存池
ngx_create_pool(1024, log);
//保存变量
ngx_save_argv();
//初始化ngx_cycle的prefix, conf_prefix, conf_file, conf_param
ngx_process_options();
//初始化系统相关变量，如内存页面大小ngx_pagesize,ngx_cacheline_size,最大连接数ngx_max_sockets等
ngx_os_init();
//初始化CRC表(后续的CRC校验通过查表进行，效率高)
ngx_crc32_table_init();

主要工作

　　初始化完成后，需要先调用ngx_add_inherited_sockets函数继承socket，并储存在Listening数组中，在运行时候进行监听。之后就可以调用ngx_init_cycle来初始化ngx_cycle结构体，这个结构体用来存储所有的连接，具体如下：

struct ngx_cycle_s {
    void                  ****conf_ctx;//配置上下文数组(含所有模块)
    ngx_pool_t               *pool;//内存池

    ngx_log_t                *log;//日志
    ngx_log_t                 new_log;

    ngx_connection_t        **files;//连接文件
    ngx_connection_t         *free_connections;//空闲连接
    ngx_uint_t                free_connection_n;//空闲连接数

    ngx_queue_t               reusable_connections_queue;////再利用连接队列  

    ngx_array_t               listening;//监听数组
    ngx_array_t               paths;//路径数组
    ngx_list_t                open_files;//打开文件链表
    ngx_list_t                shared_memory;//共享内存链表

    ngx_uint_t                connection_n;//连接个数  
    ngx_uint_t                files_n;//打开文件个数 

    ngx_connection_t         *connections;
    ngx_event_t              *read_events;//读事件
    ngx_event_t              *write_events;//写事件

    ngx_cycle_t              *old_cycle;

    ngx_str_t                 conf_file;//配置文件  
    ngx_str_t                 conf_param;//配置参数
    ngx_str_t                 conf_prefix;//配置前缀
    ngx_str_t                 prefix;//前缀
    ngx_str_t                 lock_file;//锁文件
    ngx_str_t                 hostname;

　　调用ngx_init_signals来注册信号。

//信号种类
#define NGX_PROCESS_SINGLE 0
#define NGX_PROCESS_MASTER 1
#define NGX_PROCESS_SIGNALLER 2
#define NGX_PROCESS_WORKER 3
#define NGX_PROCESS_HELPER 4

　　在进入处理之前，还要调用ngx_create_pidfile来记录进程id。最后，根据接收到的信号，来判断调用ngx_single_process_cycle还是ngx_master_process_cycle（master-worker模式）。

if (ngx_process == NGX_PROCESS_SINGLE) {
        ngx_single_process_cycle(cycle);
} else {
        ngx_master_process_cycle(cycle);
}

　　其中，守护进程函数为ngx_daemon，位于src/os/unix/Ngx_daemon.c

//daemon
ngx_int_t
ngx_daemon(ngx_log_t *log)
{
    int  fd;
    switch (fork()) {
    case -:
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "fork() failed");
        return NGX_ERROR;
    case :
        breakdefault:
        exit();
    }

    ngx_pid = ngx_getpid();//取得进程识别码

    if (setsid() == -) {  //子进程将重新获得一个新的会话(session)id
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "setsid() failed");
        return NGX_ERROR;
    }

    umask();

    fd = open("/dev/null", O_RDWR);
    if (fd == -) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                      "open(\"/dev/null\") failed");
        return NGX_ERROR;
    }

    if (dup2(fd, STDIN_FILENO) == -) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "dup2(STDIN) failed");
        return NGX_ERROR;
    }

    if (dup2(fd, STDOUT_FILENO) == -) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "dup2(STDOUT) failed");
        return NGX_ERROR;
    }

#if 0
    if (dup2(fd, STDERR_FILENO) == -) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "dup2(STDERR) failed");
        return NGX_ERROR;
    }
#endif

    if (fd > STDERR_FILENO) {
        if (close(fd) == -) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "close() failed");
            return NGX_ERROR;
        }
    }
    return NGX_OK;
}

参考

http://blog.xiuwz.com/2011/11/29/nginx-pcre-conflict/

http://blog.csdn.net/liuhongxiangm/article/details/8107613

http://www.4os.org/index.php/2010/11/25/nginx%E5%90%AF%E5%8A%A8%E5%88%9D%E5%A7%8B%E5%8C%96%E8%BF%87%E7%A8%8B%E8%BD%AC%E8%BD%BD/

http://blog.csdn.net/livelylittlefish/article/details/7243718