feature: add FFI implementation for ngx.arg getter (#386)

Author: spacewander

README.markdown

@@ -29,6 +29,7 @@ Table of Contents
     * [resty.core.phase](#restycorephase)
     * [resty.core.ndk](#restycorendk)
     * [resty.core.socket](#restycoresocket)
+    * [resty.core.param](#restycoreparam)
     * [ngx.semaphore](#ngxsemaphore)
     * [ngx.balancer](#ngxbalancer)
     * [ngx.ssl](#ngxssl)
@@ -273,6 +274,12 @@ in the current request before you reusing the `ctx` table in some other place.
 
 [Back to TOC](#table-of-contents)
 
+## resty.core.param
+
+* [ngx.arg](https://github.com/openresty/lua-nginx-module#ngxarg) (getter only)
+
+[Back to TOC](#table-of-contents)
+
 ## ngx.semaphore
 
 This Lua module implements a semaphore API for efficient "light thread" synchronization,

lib/resty/core.lua

@@ -21,6 +21,7 @@ if subsystem == 'http' then
     require "resty.core.ndk"
     require "resty.core.socket"
     require "resty.core.coroutine"
+    require "resty.core.param"
 end
 
 

lib/resty/core/param.lua

@@ -0,0 +1,103 @@
+-- Copyright (C) Yichun Zhang (agentzh)
+
+
+local ffi = require 'ffi'
+local base = require "resty.core.base"
+require "resty.core.phase"  -- for ngx.get_phase
+
+
+local C = ffi.C
+local ffi_str = ffi.string
+local FFI_AGAIN = base.FFI_AGAIN
+local FFI_OK = base.FFI_OK
+local get_request = base.get_request
+local get_string_buf = base.get_string_buf
+local getmetatable = getmetatable
+local ngx = ngx
+local ngx_phase = ngx.get_phase
+
+
+local _M = {
+    version = base.version
+}
+
+
+ffi.cdef[[
+    typedef unsigned char u_char;
+
+    void ngx_http_lua_ffi_get_setby_param(ngx_http_request_t *r, int idx,
+        u_char **data, size_t *len);
+    int ngx_http_lua_ffi_get_body_filter_param_eof(ngx_http_request_t *r);
+    int ngx_http_lua_ffi_get_body_filter_param_body(ngx_http_request_t *r,
+        u_char **data_p, size_t *len_p);
+    int ngx_http_lua_ffi_copy_body_filter_param_body(ngx_http_request_t *r,
+        u_char *data);
+]]
+local data_p = ffi.new("unsigned char*[1]")
+local len_p = ffi.new("size_t[1]")
+
+
+local function get_setby_param(r, idx)
+    C.ngx_http_lua_ffi_get_setby_param(r, idx, data_p, len_p)
+    if len_p[0] == 0 then
+        return nil
+    end
+
+    return ffi_str(data_p[0], len_p[0])
+end
+
+
+local function get_body_filter_param(r, idx)
+    if idx == 1 then
+        data_p[0] = nil
+        local rc = C.ngx_http_lua_ffi_get_body_filter_param_body(r, data_p,
+                                                                 len_p)
+        if rc == FFI_AGAIN then
+            local buf = get_string_buf(len_p[0])
+            assert(C.ngx_http_lua_ffi_copy_body_filter_param_body(r, buf)
+                   == FFI_OK)
+            return ffi_str(buf, len_p[0])
+        end
+
+        if len_p[0] == 0 then
+            return ""
+        end
+
+        return ffi_str(data_p[0], len_p[0])
+
+    elseif idx == 2 then
+        local rc = C.ngx_http_lua_ffi_get_body_filter_param_eof(r)
+        return rc == 1
+
+    else
+        return nil
+    end
+end
+
+
+local function get_param(tb, idx)
+    local r = get_request()
+    if not r then
+        error("no request found")
+    end
+
+    local phase = ngx_phase()
+    if phase == "set" then
+        return get_setby_param(r, idx)
+    end
+
+    if phase == "body_filter" then
+        return get_body_filter_param(r, idx)
+    end
+
+    error("API disabled in the current context")
+end
+
+
+do
+    local mt = getmetatable(ngx.arg)
+    mt.__index = get_param
+end
+
+
+return _M

t/param.t

@@ -0,0 +1,66 @@
+# vim:set ft= ts=4 sw=4 et fdm=marker:
+use lib '.';
+use t::TestCore;
+
+#worker_connections(1014);
+#master_process_enabled(1);
+#log_level('warn');
+
+repeat_each(2);
+
+plan tests => repeat_each() * (blocks() * 4 + 1);
+
+#no_diff();
+#no_long_string();
+check_accum_error_log();
+run_tests();
+
+__DATA__
+
+=== TEST 1: ngx.arg getter in set_by_lua
+--- config
+    location = /t {
+        # set_by_lua_block doesn't support arguments
+        set_by_lua $res '
+            local arg = ngx.arg
+            local val
+            for i = 1, 30 do
+                val = arg[1] + arg[2]
+            end
+            return val
+        ' $arg_a $arg_b;
+        echo $res;
+    }
+--- request
+GET /t?a=1&b=2
+--- response_body
+3
+--- error_log eval
+qr/\[TRACE\s+\d+ set_by_lua\(nginx\.conf:\d+\):4 loop\]/
+--- no_error_log
+[error]
+ -- NYI: (?!return to lower frame)
+
+
+
+=== TEST 2: ngx.arg getter in body_filter_by_lua
+--- config
+    location = /t {
+        echo hello;
+        body_filter_by_lua_block {
+            local arg = ngx.arg
+            local eof
+            local body = ""
+            for i = 1, 30 do
+                body = body .. arg[1]
+                eof = arg[2]
+            end
+        }
+    }
+--- request
+GET /t
+--- error_log eval
+qr/\[TRACE\s+\d+ body_filter_by_lua\(nginx\.conf:\d+\):5 loop\]/
+--- no_error_log
+[error]
+ -- NYI: (?!return to lower frame)