nginx0.1.0之http模块初始化源码分析（1）

static char *ngx_http_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char                        *rv;
    ngx_uint_t                   mi, m, s, l, p, a, n;
    ngx_uint_t                   port_found, addr_found, virtual_names;
    ngx_conf_t                   pcf;
    ngx_array_t                  in_ports;
    ngx_listening_t             *ls;
    ngx_http_listen_t           *lscf;
    ngx_http_module_t           *module;
    ngx_http_handler_pt         *h;
    ngx_http_conf_ctx_t         *ctx;
    ngx_http_in_port_t          *in_port, *inport;
    ngx_http_in_addr_t          *in_addr, *inaddr;
    ngx_http_server_name_t      *s_name, *name;
    ngx_http_core_srv_conf_t   **cscfp, *cscf;
    ngx_http_core_loc_conf_t    *clcf;
    ngx_http_core_main_conf_t   *cmcf;
#if (WIN32)
    ngx_iocp_conf_t             *iocpcf;
#endif

    /* the main http context */
    ngx_test_null(ctx,
                  ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t)),
                  NGX_CONF_ERROR);
    // 创建一个ngx_http_conf_ctx_t结构体挂载到cycle的ctx中
    *(ngx_http_conf_ctx_t **) conf = ctx;

    /* count the number of the http modules and set up their indices */

    ngx_http_max_module = 0;
    // 遍历所有的nginx模块，筛选出http模块
    for (m = 0; ngx_modules[m]; m++) {
        if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }
        // 标记该模块在http中的索引，位置
        ngx_modules[m]->ctx_index = ngx_http_max_module++;
    }
    // 根据http的模块数，分配一个数组，分别由下面三个字段指向
    /* the main http main_conf, it's the same in the all http contexts */
    ngx_test_null(ctx->main_conf,
                  ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module),
                  NGX_CONF_ERROR);

    /* the http null srv_conf, it's used to merge the server{}s' srv_conf's */
    ngx_test_null(ctx->srv_conf,
                  ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module),
                  NGX_CONF_ERROR);

    /* the http null loc_conf, it's used to merge the server{}s' loc_conf's */
    ngx_test_null(ctx->loc_conf,
                  ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module),
                  NGX_CONF_ERROR);


    /* create the main_conf, srv_conf and loc_conf in all http modules */

    for (m = 0; ngx_modules[m]; m++) {
        if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }
        // http模块的上下文，是ngx_http_module_t结构体
        module = ngx_modules[m]->ctx;
        mi = ngx_modules[m]->ctx_index;
        // 解析http配置前执行的钩子
        if (module->pre_conf) {
            if (module->pre_conf(cf) != NGX_OK) {
                return NGX_CONF_ERROR;
            }
        }
        // 创建一个ngx_http_core_main_conf_t结构体，挂到main_conf数组相应的位置
        if (module->create_main_conf) {
            ngx_test_null(ctx->main_conf[mi], module->create_main_conf(cf),
                          NGX_CONF_ERROR);
        }
        // 创建一个ngx_http_core_srv_conf_t结构体，挂到srv_conf数组相应的位置
        if (module->create_srv_conf) {
            ngx_test_null(ctx->srv_conf[mi], module->create_srv_conf(cf), 
                          NGX_CONF_ERROR);
        }
        // 创建一个ngx_http_core_loc_conf_s 结构体，挂到loc_conf数组相应的位置
        if (module->create_loc_conf) {
            ngx_test_null(ctx->loc_conf[mi], module->create_loc_conf(cf),
                          NGX_CONF_ERROR);
        }
    }
    ...
}

ngx_http_log_op_name_t ngx_http_log_fmt_ops[] = {
    { ngx_string("addr"), INET_ADDRSTRLEN - 1, ngx_http_log_addr },
    { ngx_string("conn"), NGX_INT32_LEN, ngx_http_log_connection },
    { ngx_string("pipe"), 1, ngx_http_log_pipe },
    { ngx_string("time"), sizeof("28/Sep/1970:12:00:00") - 1,
                          ngx_http_log_time },
    { ngx_string("msec"), TIME_T_LEN + 4, ngx_http_log_msec },
    { ngx_string("request"), 0, ngx_http_log_request },
    { ngx_string("status"), 3, ngx_http_log_status },
    { ngx_string("length"), NGX_OFF_T_LEN, ngx_http_log_length },
    { ngx_string("apache_length"), NGX_OFF_T_LEN, ngx_http_log_apache_length },
    { ngx_string("i"), NGX_HTTP_LOG_ARG, ngx_http_log_header_in },
    { ngx_string("o"), NGX_HTTP_LOG_ARG, ngx_http_log_header_out },
    { ngx_null_string, 0, NULL }
};

static ngx_int_t ngx_http_log_pre_conf(ngx_conf_t *cf)
{
    ngx_http_log_op_name_t  *op;

    for (op = ngx_http_log_fmt_ops; op->name.len; op++) { /* void */ }
    op->op = NULL;

    return NGX_OK;
}

static ngx_http_log_op_name_t ngx_http_gzip_log_fmt_ops[] = {
    { ngx_string("gzip_ratio"), NGX_INT32_LEN + 3, ngx_http_gzip_log_ratio },
    { ngx_null_string, 0, NULL }
};

static ngx_int_t ngx_http_gzip_pre_conf(ngx_conf_t *cf)
{
    ngx_http_log_op_name_t  *op;
    /*
        找到第一个没有名字的项，即最后一项，然后把op置空，
        为了防止下面一个for循环的时候op->op为空，不会导致死循环,
        因为执行完该函数后，op->op是下一个pre_conf函数执行时，
        ngx_http_log_fmt_ops数组的最后一个被判断的op->op
    */
    for (op = ngx_http_gzip_log_fmt_ops; op->name.len; op++) { /* void */ }
    op->op = NULL;

    op = ngx_http_log_fmt_ops;
    /*
        找到最后一个op有值但是没有名字的项，这里其实是一个巧妙的设计，
        因为op有值但是没有名字的项，op->op指向的是一个ngx_http_log_op_name_t数组，
        然后op继续指向该数组第一个元素，继续迭代
    */
    for (op = ngx_http_log_fmt_ops; op->op; op++) {
        if (op->name.len == 0) {
            op = (ngx_http_log_op_name_t *) op->op;
        }
    }
    /*
        每个模块中的ngx_http_log_op_name_t数组最后一个元素都是空的，
        然后在这给op->op赋值，op->op指向的数组的最后一个元素也是空项，以此类推
    */
    op->op = (ngx_http_log_op_pt) ngx_http_gzip_log_fmt_ops;

    return NGX_OK;
}

static ngx_http_log_op_name_t ngx_http_userid_log_fmt_ops[] = {
    { ngx_string("uid_got"), 0, ngx_http_userid_log_uid_got },
    { ngx_string("uid_set"), 0, ngx_http_userid_log_uid_set },
    { ngx_null_string, 0, NULL }
};
static ngx_int_t ngx_http_userid_pre_conf(ngx_conf_t *cf)
{
    ngx_http_log_op_name_t  *op;

    for (op = ngx_http_userid_log_fmt_ops; op->name.len; op++) { /* void */ }
    op->op = NULL;

    op = ngx_http_log_fmt_ops;

    for (op = ngx_http_log_fmt_ops; op->op; op++) {
        if (op->name.len == 0) {
            op = (ngx_http_log_op_name_t *) op->op;
        }
    }

    op->op = (ngx_http_log_op_pt) ngx_http_userid_log_fmt_ops;

    return NGX_OK;
}

static void *ngx_http_core_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_core_main_conf_t *cmcf;

    ngx_test_null(cmcf,
                  ngx_pcalloc(cf->pool, sizeof(ngx_http_core_main_conf_t)),
                  NGX_CONF_ERROR);

    ngx_init_array(cmcf->servers, cf->pool,
                   5, sizeof(ngx_http_core_srv_conf_t *),
                   NGX_CONF_ERROR);

    return cmcf;
}

static void *ngx_http_charset_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_charset_main_conf_t  *mcf;

    if (!(mcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_charset_main_conf_t)))) {
        return NGX_CONF_ERROR;
    }

    ngx_init_array(mcf->charsets, cf->pool, 5, sizeof(ngx_http_charset_t),
                   NGX_CONF_ERROR);

    ngx_init_array(mcf->tables, cf->pool, 10, sizeof(ngx_http_charset_tables_t),
                   NGX_CONF_ERROR);

    return mcf;
}

static void *ngx_http_log_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_log_main_conf_t  *conf;

    char       *rc;
    ngx_str_t  *value;

    if (!(conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_log_main_conf_t)))) {
        return NGX_CONF_ERROR;
    }

    ngx_init_array(conf->formats, cf->pool, 5, sizeof(ngx_http_log_fmt_t),
                  NGX_CONF_ERROR);

    cf->args->nelts = 0;
    // 设置参数，在ngx_http_log_set_format里使用
    if (!(value = ngx_push_array(cf->args))) {
        return NGX_CONF_ERROR;
    }

    if (!(value = ngx_push_array(cf->args))) {
        return NGX_CONF_ERROR;
    }

    value->len = sizeof("combined") - 1;
    value->data = (u_char *) "combined";

    if (!(value = ngx_push_array(cf->args))) {
        return NGX_CONF_ERROR;
    }

    *value = ngx_http_combined_fmt;

    rc = ngx_http_log_set_format(cf, NULL, conf);
    if (rc != NGX_CONF_OK) {
        return NULL;
    }

    return conf;
}