上一篇nginx的文章中，我们理解了整个http正向代理的运行流程原理，主要就是事件机制接入，header解析，body解析，然后遍历各种checker，直到处理成功为止。
我们以访问一个普通文件为例，nginx到底是如何找到这个文件并返回信息的呢？它会不会有些什么限制呢？
按我们自己的理解，它应该是uri栏里截取出相应的路径，然后对应到root下，查找到相应文件，返回即可。那么，它又是如何处理html和其他的各种不同格式的文件呢？
就让我们一起来探秘nginx文件的查找实现吧！
1. checker的遍历回顾
我们先来回顾下，nginx是如何遍历各个checker的吧！
// http/ngx_http_core_module.c
// 响应客户端操作, 多阶段式操作
void
ngx_http_core_run_phases(ngx_http_request_t *r)
{
ngx_int_t rc;
ngx_http_phase_handler_t *ph;
ngx_http_core_main_conf_t *cmcf;
cmcf = ngx_http_get_module_main_conf(r, ngx_http_core_module);
ph = cmcf->phase_engine.handlers;
// 依次调用各 checker, 直到有响应 OK 的checker为止
while (ph[r->phase_handler].checker) {
// 每次调用 checker 之后, 内部都会将 r->phase_handler++, 即迭代下一个
// 此处的 checker 非常之多, 是在各模块启动时, 自动向 ngx_http_core_module.main_conf 中进行注册的
/**
* 定义如下:
typedef enum {
NGX_HTTP_POST_READ_PHASE = 0,
NGX_HTTP_SERVER_REWRITE_PHASE,
NGX_HTTP_FIND_CONFIG_PHASE,
NGX_HTTP_REWRITE_PHASE,
NGX_HTTP_POST_REWRITE_PHASE,
NGX_HTTP_PREACCESS_PHASE,
NGX_HTTP_ACCESS_PHASE,
NGX_HTTP_POST_ACCESS_PHASE,
NGX_HTTP_PRECONTENT_PHASE,
NGX_HTTP_CONTENT_PHASE,
NGX_HTTP_LOG_PHASE
} ngx_http_phases;
// 注册方式
cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
h = ngx_array_push(&cmcf->phases[NGX_HTTP_ACCESS_PHASE].handlers);
*h = ngx_http_access_handler;
*/
// 将请求信息和 handler 本身传入调用(不是面向, 只能这么做了)
rc = ph[r->phase_handler].checker(r, &ph[r->phase_handler]);
// 只要有一个处理成功, 则后续不再调用
if (rc == NGX_OK) {
return;
}
}
}
可以说，它的各checker是非常复杂的，各模块都可以向其中注册处理器。这也是nginx灵活性的体现。不过我们不想关注太多。
文件的查找是在 static_module 中完成的，我们只需关注这个即可。
2. 静态文件模块的注册
静态文件模块主要就是负责静态文件的查找处理。几乎所有的http处理模块，都是先进行注册，然后再被调用的过程。static_module 自然不例外。
// http/modules/ngx_http_static_handler.c
static ngx_int_t
ngx_http_static_init(ngx_conf_t *cf)
{
ngx_http_handler_pt *h;
ngx_http_core_main_conf_t *cmcf;
cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
// 获取http_core_module的配置
// 将ngx_http_static_handler 添加到 NGX_HTTP_CONTENT_PHASE 的handlers中
h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers);
if (h == NULL) {
return NGX_ERROR;
}
*h = ngx_http_static_handler;
return NGX_OK;
}
// 下面是一些nginx的模块暴露规范，只有这样，这个模块才会被接入到整个系统中
static ngx_http_module_t ngx_http_static_module_ctx = {
NULL, /* preconfiguration */
ngx_http_static_init, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
NULL, /* create location configuration */
NULL /* merge location configuration */
};
ngx_module_t ngx_http_static_module = {
NGX_MODULE_V1,
&ngx_http_static_module_ctx, /* module context */
NULL, /* module directives */
NGX_HTTP_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
};
3. 文件查找实现
经过前面的模块注册到 NGX_HTTP_CONTENT_PHASE 中，就会被nginx调用。前提是没有其他更合适的处理器的时候。而因为 static_module 是在 NGX_HTTP_CONTENT_PHASE 中，所以都会走content的处理器：
// http/ngx_http_core_module.c
ngx_int_t
ngx_http_core_content_phase(ngx_http_request_t *r,
ngx_http_phase_handler_t *ph)
{
size_t root;
ngx_int_t rc;
ngx_str_t path;
if (r->content_handler) {
r->write_event_handler = ngx_http_request_empty_handler;
ngx_http_finalize_request(r, r->content_handler(r));
return NGX_OK;
}
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"content phase: %ui", r->phase_handler);
rc = ph->handler(r);
// 处理成功，则返回ok
if (rc != NGX_DECLINED) {
ngx_http_finalize_request(r, rc);
return NGX_OK;
}
/* rc == NGX_DECLINED */
ph++;
if (ph->checker) {
r->phase_handler++;
return NGX_AGAIN;
}
/* no content handler was found */
if (r->uri.data[r->uri.len - 1] == '/') {
if (ngx_http_map_uri_to_path(r, &path, &root, 0) != NULL) {
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
"directory index of \"%s\" is forbidden", path.data);
}
ngx_http_finalize_request(r, NGX_HTTP_FORBIDDEN);
return NGX_OK;
}
ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "no handler found");
ngx_http_finalize_request(r, NGX_HTTP_NOT_FOUND);
return NGX_OK;
}
// http/modules/ngx_http_static_handler.c
static ngx_int_t
ngx_http_static_handler(ngx_http_request_t *r)
{
u_char *last, *location;
size_t root, len;
ngx_str_t path;
ngx_int_t rc;
ngx_uint_t level;
ngx_log_t *log;
ngx_buf_t *b;
ngx_chain_t out;
ngx_open_file_info_t of;
ngx_http_core_loc_conf_t *clcf;
// 仅支持 get/head/post 方法进行静态文件处理
if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD|NGX_HTTP_POST))) {
return NGX_HTTP_NOT_ALLOWED;
}
// 要求uri不能以'/'结尾，否则走其他协议
if (r->uri.data[r->uri.len - 1] == '/') {
return NGX_DECLINED;
}
log = r->connection->log;
/*
* ngx_http_map_uri_to_path() allocates memory for terminating '\0'
* so we do not need to reserve memory for '/' for possible redirect
*/
// 解析文件路径到path中
last = ngx_http_map_uri_to_path(r, &path, &root, 0);
if (last == NULL) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
path.len = last - path.data;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0,
"http filename: \"%s\"", path.data);
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
// 初始化文件实例
ngx_memzero(&of, sizeof(ngx_open_file_info_t));
of.read_ahead = clcf->read_ahead;
of.directio = clcf->directio;
of.valid = clcf->open_file_cache_valid;
of.min_uses = clcf->open_file_cache_min_uses;
of.errors = clcf->open_file_cache_errors;
of.events = clcf->open_file_cache_events;
if (ngx_http_set_disable_symlinks(r, clcf, &path, &of) != NGX_OK) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool)
!= NGX_OK)
{
switch (of.err) {
case 0:
return NGX_HTTP_INTERNAL_SERVER_ERROR;
case NGX_ENOENT:
case NGX_ENOTDIR:
case NGX_ENAMETOOLONG:
level = NGX_LOG_ERR;
rc = NGX_HTTP_NOT_FOUND;
break;
case NGX_EACCES:
#if (NGX_HAVE_OPENAT)
case NGX_EMLINK:
case NGX_ELOOP:
#endif
level = NGX_LOG_ERR;
rc = NGX_HTTP_FORBIDDEN;
break;
default:
level = NGX_LOG_CRIT;
rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
break;
}
if (rc != NGX_HTTP_NOT_FOUND || clcf->log_not_found) {
ngx_log_error(level, log, of.err,
"%s \"%s\" failed", of.failed, path.data);
}
return rc;
}
r->root_tested = !r->error_page;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http static fd: %d", of.fd);
if (of.is_dir) {
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, log, 0, "http dir");
ngx_http_clear_location(r);
r->headers_out.location = ngx_list_push(&r->headers_out.headers);
if (r->headers_out.location == NULL) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
len = r->uri.len + 1;
if (!clcf->alias && r->args.len == 0) {
location = path.data + root;
*last = '/';
} else {
if (r->args.len) {
len += r->args.len + 1;
}
location = ngx_pnalloc(r->pool, len);
if (location == NULL) {
ngx_http_clear_location(r);
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
last = ngx_copy(location, r->uri.data, r->uri.len);
*last = '/';
if (r->args.len) {
*++last = '?';
ngx_memcpy(++last, r->args.data, r->args.len);
}
}
r->headers_out.location->hash = 1;
ngx_str_set(&r->headers_out.location->key, "Location");
r->headers_out.location->value.len = len;
r->headers_out.location->value.data = location;
return NGX_HTTP_MOVED_PERMANENTLY;
}
#if !(NGX_WIN32) /* the not regular files are probably Unix specific */
if (!of.is_file) {
ngx_log_error(NGX_LOG_CRIT, log, 0,
"\"%s\" is not a regular file", path.data);
return NGX_HTTP_NOT_FOUND;
}
#endif
// 真正到内容输出的时候，post又是不被允许的方法
if (r->method == NGX_HTTP_POST) {
return NGX_HTTP_NOT_ALLOWED;
}
// 静态文件处理，将会忽略所有请求body参数
rc = ngx_http_discard_request_body(r);
if (rc != NGX_OK) {
return rc;
}
// 输出文件内容到客户端
log->action = "sending response to client";
r->headers_out.status = NGX_HTTP_OK;
r->headers_out.content_length_n = of.size;
r->headers_out.last_modified_time = of.mtime;
// 设置 ETag header
if (ngx_http_set_etag(r) != NGX_OK) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
// content-type 设置，大概就是根据文件后缀找到相应的content-type 输出即可
if (ngx_http_set_content_type(r) != NGX_OK) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
if (r != r->main && of.size == 0) {
return ngx_http_send_header(r);
}
r->allow_ranges = 1;
/* we need to allocate all before the header would be sent */
b = ngx_calloc_buf(r->pool);
if (b == NULL) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
b->file = ngx_pcalloc(r->pool, sizeof(ngx_file_t));
if (b->file == NULL) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
// 发送头信息，如果是 head 请求，则到此为止
// 该header响应会添加一些公共的请求头一并返回
// 使用一系列的filter过滤器链进行处理
// 当文件未发生变化时，会返回304, 即不再返回更多信息
/**
Accept-Ranges: bytes
Connection: keep-alive
Content-Length: 18
Content-Type: text/plain
Date: Wed, 07 Oct 2020 09:01:12 GMT
ETag: "5f66fc46-12"
Last-Modified: Sun, 20 Sep 2020 06:52:54 GMT
Server: nginx/1.19.2
*/
rc = ngx_http_send_header(r);
if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
return rc;
}
// 封装要响应的文件描述符，输出响应
b->file_pos = 0;
b->file_last = of.size;
b->in_file = b->file_last ? 1: 0;
b->last_buf = (r == r->main) ? 1: 0;
b->last_in_chain = 1;
b->file->fd = of.fd;
b->file->name = path;
b->file->log = log;
b->file->directio = of.is_directio;
out.buf = b;
out.next = NULL;
// 一系列的响应过滤器处理，响应body
/**
* range_filter
* copy_filter
* output_chain -> output_chain_copy_buf
*/
return ngx_http_output_filter(r, &out);
}
整体可以简单用一句话说明，根据uri路径，结合root路径配置，得到文件信息，响应客户端。只处理 get/head请求，对文件内容无变化情况将会返回304。上面更多的是，只限于c语言的表达能力问题，做的许多变化，无须多看。
另外，再次需要说明的一点是，nginx的性能优势是在于其巧妙地利用系统的非阻塞io，从而提升了处理能力，而且其扩展能力非常强，配置也非常友好。但其整体流程，与其他http服务器并无二致。
对于想要了解更多细节的同学，可以点开下面的代码，查看C语言的实现细节。
// http/ngx_http_core_module.c
// 解析文件路径到path中
u_char *
ngx_http_map_uri_to_path(ngx_http_request_t *r, ngx_str_t *path,
size_t *root_length, size_t reserved)
{
u_char *last;
size_t alias;
ngx_http_core_loc_conf_t *clcf;
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
alias = clcf->alias;
if (alias && !r->valid_location) {
ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
"\"alias\" cannot be used in location \"%V\" "
"where URI was rewritten", &clcf->name);
return NULL;
}
if (clcf->root_lengths == NULL) {
*root_length = clcf->root.len;
path->len = clcf->root.len + reserved + r->uri.len - alias + 1;
path->data = ngx_pnalloc(r->pool, path->len);
if (path->data == NULL) {
return NULL;
}
// 将root根目录赋值给 path
last = ngx_copy(path->data, clcf->root.data, clcf->root.len);
} else {
if (alias == NGX_MAX_SIZE_T_VALUE) {
reserved += r->add_uri_to_alias ? r->uri.len + 1 : 1;
} else {
reserved += r->uri.len - alias + 1;
}
if (ngx_http_script_run(r, path, clcf->root_lengths->elts, reserved,
clcf->root_values->elts)
== NULL)
{
return NULL;
}
if (ngx_get_full_name(r->pool, (ngx_str_t *) &ngx_cycle->prefix, path)
!= NGX_OK)
{
return NULL;
}
*root_length = path->len - reserved;
last = path->data + *root_length;
if (alias == NGX_MAX_SIZE_T_VALUE) {
if (!r->add_uri_to_alias) {
*last = '\0';
return last;
}
alias = 0;
}
}
// 将uri的相对路径拼接到 path 中
last = ngx_copy(last, r->uri.data + alias, r->uri.len - alias);
*last = '\0';
return last;
}
// http/ngx_http_core_module.c
ngx_int_t
ngx_http_set_disable_symlinks(ngx_http_request_t *r,
ngx_http_core_loc_conf_t *clcf, ngx_str_t *path, ngx_open_file_info_t *of)
{
#if (NGX_HAVE_OPENAT)
u_char *p;
ngx_str_t from;
of->disable_symlinks = clcf->disable_symlinks;
if (clcf->disable_symlinks_from == NULL) {
return NGX_OK;
}
if (ngx_http_complex_value(r, clcf->disable_symlinks_from, &from)
!= NGX_OK)
{
return NGX_ERROR;
}
if (from.len == 0
|| from.len > path->len
|| ngx_memcmp(path->data, from.data, from.len) != 0)
{
return NGX_OK;
}
if (from.len == path->len) {
of->disable_symlinks = NGX_DISABLE_SYMLINKS_OFF;
return NGX_OK;
}
p = path->data + from.len;
if (*p == '/') {
of->disable_symlinks_from = from.len;
return NGX_OK;
}
p--;
if (*p == '/') {
of->disable_symlinks_from = from.len - 1;
}
#endif
return NGX_OK;
}
// core/ngx_open_file_cache.c
// 尝试使用缓存文件
ngx_int_t
ngx_open_cached_file(ngx_open_file_cache_t *cache, ngx_str_t *name,
ngx_open_file_info_t *of, ngx_pool_t *pool)
{
time_t now;
uint32_t hash;
ngx_int_t rc;
ngx_file_info_t fi;
ngx_pool_cleanup_t *cln;
ngx_cached_open_file_t *file;
ngx_pool_cleanup_file_t *clnf;
ngx_open_file_cache_cleanup_t *ofcln;
of->fd = NGX_INVALID_FILE;
of->err = 0;
// 没有缓存，则重新打开文件
if (cache == NULL) {
if (of->test_only) {
if (ngx_file_info_wrapper(name, of, &fi, pool->log)
== NGX_FILE_ERROR)
{
return NGX_ERROR;
}
of->uniq = ngx_file_uniq(&fi);
of->mtime = ngx_file_mtime(&fi);
of->size = ngx_file_size(&fi);
of->fs_size = ngx_file_fs_size(&fi);
of->is_dir = ngx_is_dir(&fi);
of->is_file = ngx_is_file(&fi);
of->is_link = ngx_is_link(&fi);
of->is_exec = ngx_is_exec(&fi);
return NGX_OK;
}
cln = ngx_pool_cleanup_add(pool, sizeof(ngx_pool_cleanup_file_t));
if (cln == NULL) {
return NGX_ERROR;
}
// 打开文件
rc = ngx_open_and_stat_file(name, of, pool->log);
// 找到对应文件，设置 handler 为 ngx_pool_cleanup_file
if (rc == NGX_OK && !of->is_dir) {
cln->handler = ngx_pool_cleanup_file;
clnf = cln->data;
clnf->fd = of->fd;
clnf->name = name->data;
clnf->log = pool->log;
}
return rc;
}
cln = ngx_pool_cleanup_add(pool, sizeof(ngx_open_file_cache_cleanup_t));
if (cln == NULL) {
return NGX_ERROR;
}
now = ngx_time();
hash = ngx_crc32_long(name->data, name->len);
file = ngx_open_file_lookup(cache, name, hash);
if (file) {
file->uses++;
ngx_queue_remove(&file->queue);
if (file->fd == NGX_INVALID_FILE && file->err == 0 && !file->is_dir) {
/* file was not used often enough to keep open */
rc = ngx_open_and_stat_file(name, of, pool->log);
if (rc != NGX_OK && (of->err == 0 || !of->errors)) {
goto failed;
}
goto add_event;
}
if (file->use_event
|| (file->event == NULL
&& (of->uniq == 0 || of->uniq == file->uniq)
&& now - file->created < of->valid
#if (NGX_HAVE_OPENAT)
&& of->disable_symlinks == file->disable_symlinks
&& of->disable_symlinks_from == file->disable_symlinks_from
#endif
))
{
if (file->err == 0) {
of->fd = file->fd;
of->uniq = file->uniq;
of->mtime = file->mtime;
of->size = file->size;
of->is_dir = file->is_dir;
of->is_file = file->is_file;
of->is_link = file->is_link;
of->is_exec = file->is_exec;
of->is_directio = file->is_directio;
if (!file->is_dir) {
file->count++;
ngx_open_file_add_event(cache, file, of, pool->log);
}
} else {
of->err = file->err;
#if (NGX_HAVE_OPENAT)
of->failed = file->disable_symlinks ? ngx_openat_file_n
: ngx_open_file_n;
#else
of->failed = ngx_open_file_n;
#endif
}
goto found;
}
ngx_log_debug4(NGX_LOG_DEBUG_CORE, pool->log, 0,
"retest open file: %s, fd:%d, c:%d, e:%d",
file->name, file->fd, file->count, file->err);
if (file->is_dir) {
/*
* chances that directory became file are very small
* so test_dir flag allows to use a single syscall
* in ngx_file_info() instead of three syscalls
*/
of->test_dir = 1;
}
of->fd = file->fd;
of->uniq = file->uniq;
rc = ngx_open_and_stat_file(name, of, pool->log);
if (rc != NGX_OK && (of->err == 0 || !of->errors)) {
goto failed;
}
if (of->is_dir) {
if (file->is_dir || file->err) {
goto update;
}
/* file became directory */
} else if (of->err == 0) { /* file */
if (file->is_dir || file->err) {
goto add_event;
}
if (of->uniq == file->uniq) {
if (file->event) {
file->use_event = 1;
}
of->is_directio = file->is_directio;
goto update;
}
/* file was changed */
} else { /* error to cache */
if (file->err || file->is_dir) {
goto update;
}
/* file was removed, etc. */
}
if (file->count == 0) {
ngx_open_file_del_event(file);
if (ngx_close_file(file->fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, pool->log, ngx_errno,
ngx_close_file_n " \"%V\" failed", name);
}
goto add_event;
}
ngx_rbtree_delete(&cache->rbtree, &file->node);
cache->current--;
file->close = 1;
goto create;
}
/* not found */
rc = ngx_open_and_stat_file(name, of, pool->log);
if (rc != NGX_OK && (of->err == 0 || !of->errors)) {
goto failed;
}
create:
if (cache->current >= cache->max) {
ngx_expire_old_cached_files(cache, 0, pool->log);
}
file = ngx_alloc(sizeof(ngx_cached_open_file_t), pool->log);
if (file == NULL) {
goto failed;
}
file->name = ngx_alloc(name->len + 1, pool->log);
if (file->name == NULL) {
ngx_free(file);
file = NULL;
goto failed;
}
ngx_cpystrn(file->name, name->data, name->len + 1);
file->node.key = hash;
ngx_rbtree_insert(&cache->rbtree, &file->node);
cache->current++;
file->uses = 1;
file->count = 0;
file->use_event = 0;
file->event = NULL;
add_event:
ngx_open_file_add_event(cache, file, of, pool->log);
update:
file->fd = of->fd;
file->err = of->err;
#if (NGX_HAVE_OPENAT)
file->disable_symlinks = of->disable_symlinks;
file->disable_symlinks_from = of->disable_symlinks_from;
#endif
if (of->err == 0) {
file->uniq = of->uniq;
file->mtime = of->mtime;
file->size = of->size;
file->close = 0;
file->is_dir = of->is_dir;
file->is_file = of->is_file;
file->is_link = of->is_link;
file->is_exec = of->is_exec;
file->is_directio = of->is_directio;
if (!of->is_dir) {
file->count++;
}
}
file->created = now;
found:
file->accessed = now;
ngx_queue_insert_head(&cache->expire_queue, &file->queue);
ngx_log_debug5(NGX_LOG_DEBUG_CORE, pool->log, 0,
"cached open file: %s, fd:%d, c:%d, e:%d, u:%d",
file->name, file->fd, file->count, file->err, file->uses);
if (of->err == 0) {
if (!of->is_dir) {
cln->handler = ngx_open_file_cleanup;
ofcln = cln->data;
ofcln->cache = cache;
ofcln->file = file;
ofcln->min_uses = of->min_uses;
ofcln->log = pool->log;
}
return NGX_OK;
}
return NGX_ERROR;
failed:
if (file) {
ngx_rbtree_delete(&cache->rbtree, &file->node);
cache->current--;
if (file->count == 0) {
if (file->fd != NGX_INVALID_FILE) {
if (ngx_close_file(file->fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, pool->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file->name);
}
}
ngx_free(file->name);
ngx_free(file);
} else {
file->close = 1;
}
}
if (of->fd != NGX_INVALID_FILE) {
if (ngx_close_file(of->fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, pool->log, ngx_errno,
ngx_close_file_n " \"%V\" failed", name);
}
}
return NGX_ERROR;
}
// core/ngx_open_file_cache.c
// 打开文件
static ngx_int_t
ngx_open_and_stat_file(ngx_str_t *name, ngx_open_file_info_t *of,
ngx_log_t *log)
{
ngx_fd_t fd;
ngx_file_info_t fi;
if (of->fd != NGX_INVALID_FILE) {
if (ngx_file_info_wrapper(name, of, &fi, log) == NGX_FILE_ERROR) {
of->fd = NGX_INVALID_FILE;
return NGX_ERROR;
}
if (of->uniq == ngx_file_uniq(&fi)) {
goto done;
}
} else if (of->test_dir) {
if (ngx_file_info_wrapper(name, of, &fi, log) == NGX_FILE_ERROR) {
of->fd = NGX_INVALID_FILE;
return NGX_ERROR;
}
if (ngx_is_dir(&fi)) {
goto done;
}
}
if (!of->log) {
/*
* Use non-blocking open() not to hang on FIFO files, etc.
* This flag has no effect on a regular files.
*/
// 使用非阻塞io打开文件
fd = ngx_open_file_wrapper(name, of, NGX_FILE_RDONLY|NGX_FILE_NONBLOCK,
NGX_FILE_OPEN, 0, log);
} else {
fd = ngx_open_file_wrapper(name, of, NGX_FILE_APPEND,
NGX_FILE_CREATE_OR_OPEN,
NGX_FILE_DEFAULT_ACCESS, log);
}
if (fd == NGX_INVALID_FILE) {
of->fd = NGX_INVALID_FILE;
return NGX_ERROR;
}
// 检测文件有效性
if (ngx_fd_info(fd, &fi) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_CRIT, log, ngx_errno,
ngx_fd_info_n " \"%V\" failed", name);
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_close_file_n " \"%V\" failed", name);
}
of->fd = NGX_INVALID_FILE;
return NGX_ERROR;
}
if (ngx_is_dir(&fi)) {
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_close_file_n " \"%V\" failed", name);
}
of->fd = NGX_INVALID_FILE;
} else {
of->fd = fd;
// 如果文件过大，则先预读取部分数据
if (of->read_ahead && ngx_file_size(&fi) > NGX_MIN_READ_AHEAD) {
if (ngx_read_ahead(fd, of->read_ahead) == NGX_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_read_ahead_n " \"%V\" failed", name);
}
}
if (of->directio <= ngx_file_size(&fi)) {
if (ngx_directio_on(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_directio_on_n " \"%V\" failed", name);
} else {
of->is_directio = 1;
}
}
}
done:
// 复制文件信息返回
of->uniq = ngx_file_uniq(&fi);
of->mtime = ngx_file_mtime(&fi);
of->size = ngx_file_size(&fi);
of->fs_size = ngx_file_fs_size(&fi);
of->is_dir = ngx_is_dir(&fi);
of->is_file = ngx_is_file(&fi);
of->is_link = ngx_is_link(&fi);
of->is_exec = ngx_is_exec(&fi);
return NGX_OK;
}
View Code