njs cannot read from body file stored (using fs.readFileSync)

[exxocism]

Env

Version    : 0.7.0
Git Commit : d457c9545e7e71ebb5c0479eb16b9d33175855e2
OS         : Ubuntu 20.04
Configure  : nothing configured, just implemented using (--add-module=../njs/nginx) options

Poc

const test = (req) => {

  let body;
  try {
    body = JSON.parse(req.requestText);
  } catch (e) {
    body = require('fs').readFileSync(req.variables.request_body_file, 'utf8');
    body = JSON.parse(body);
  }

  req.headersOut['Content-Type'] = 'application/json; charset=utf-8';
  req.return(200, JSON.stringify(body));
};

export default { test };

Result

error.log

2021/12/28 00:00:00 [warn] 00000#00000: *6 a client request body is buffered to a temporary file /usr/local/nginx/client_body_temp/0000000006, client: 000.000.000.000, server: domain.dot.com, request: "POST /some/endpoint HTTP/2.0", host: "domain.dot.com"
2021/12/28 00:00:00 [error] 00000#00000: *6 js exception: Error: No such file or directory
    at fs.readFileSync (native)
    at anonymous (test.js:7)
, client: 000.000.000.000, server: domain.dot.com, request: "POST /some/endpoint HTTP/2.0", host: "domain.dot.com"

cannot read body file stored... idk why

[exxocism]

I think it's definitely a bug.
i turned on this settings to on and got the desired result:

client_body_in_file_only on;

[xeioex]

Hi @exxocism,

By default, nginx unlinks (removes) the open temp file from the directory, thus making it invisible.

https://github.com/nginx/nginx/blob/master/src/http/ngx_http_request_body.c#L556

        // by default persistent is 0 and client_body_in_file_only sets it to 1
        tf->persistent = r->request_body_in_persistent_file;
        tf->clean = r->request_body_in_clean_file;

        if (r->request_body_file_group_access) {
            tf->access = 0660;
        }

        rb->temp_file = tf;

        if (rb->bufs == NULL) {
            /* empty body with r->request_body_in_file_only */

            if (ngx_create_temp_file(&tf->file, tf->path, tf->pool,
                                     tf->persistent, tf->clean, tf->access)
                != NGX_OK)
            {
                return NGX_ERROR;
            }

https://github.com/nginx/nginx/blob/master/src/os/unix/ngx_files.c#L276

ngx_fd_t
ngx_open_tempfile(u_char *name, ngx_uint_t persistent, ngx_uint_t access)
{
    ngx_fd_t  fd;

    fd = open((const char *) name, O_CREAT|O_EXCL|O_RDWR,
              access ? access : 0600);

    if (fd != -1 && !persistent) {
        (void) unlink((const char *) name);
    }

    return fd;
}

[xeioex]

@exxocism

To ensure, the file is always in memory consider changing client_body_buffer_size directive.

[exxocism]

@xeioex Thank you.
I increased the buffer, and changed client_body_in_file_only to clean and got it working.

currently I'm working on njs to look like node.js Express
and it's so cool!

thank you for this amazing plugin.