How to use ngx_write_chain_to_temp_file correctly? - file-io

Question

I am writing nginx module which construct nginx chain then write this chain buffer to nginx temporary file to use it later (just after write happen). I've been searching every page and the only solution come up is the one bellow:
// Create temp file to test
ngx_temp_file_t *tf;
tf = ngx_pcalloc(r->pool, sizeof (ngx_temp_file_t));
if (tf == NULL) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
tf->file.fd = NGX_INVALID_FILE;
tf->file.log = nlog;
tf->path = clcf->client_body_temp_path;
tf->pool = r->pool;
tf->log_level = r->request_body_file_log_level;
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;
// }
if (ngx_create_temp_file(&tf->file, tf->path, tf->pool, tf->persistent, tf->clean, tf->access) != NGX_OK) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
if (ngx_write_chain_to_temp_file(tf, bucket->first) == NGX_ERROR) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
This code does not return NGX_ERROR, is this meant nginx successful write temporary file into client_body_temporay_path? It the answer is yes, after that, I use fopen to open file, the file is not exist?
Can anyone please give me the right solution to handle ngx_write_chain_to_temp_file?

Answer 1

I find myself the solution
ngx_temp_file_t *tf;
tf = ngx_pcalloc(r->pool, sizeof (ngx_temp_file_t));
tf->file.fd = NGX_INVALID_FILE;
tf->file.log = nlog;
tf->path = clcf->client_body_temp_path;
tf->pool = r->pool;
tf->persistent = 1;
rc = ngx_create_temp_file(&tf->file, tf->path, tf->pool, tf->persistent, tf->clean, tf->access);
//ngx_write_chain_to_file(&tf->file, bucket->first, bucket->content_length, r->pool);
ngx_write_chain_to_temp_file(tf, bucket->first);
The only thing I cannot understand is if I set tf->persistentto false (0), after the file created, I cannot read from it even if I've not passed response to output_filter yet.