From 3caa0399c878a6d19d86c77d4eaadae25dea0eef Mon Sep 17 00:00:00 2001
From: Thierry FOURNIER <tfournier@haproxy.com>
Date: Fri, 13 Mar 2015 13:38:17 +0100
Subject: [PATCH] BUG/MINOR: lua: set current proxy as default value if it is
 possible

Some fetches uses a proxy name as first parameter. This is used to identify
frontend, backend or table. This first argument is declared as mandatory,
but the documentation says that is optional.

The behavior of the function smp_resolve_args() is to use the current proxy
if it match the required argument.

This patch implements the same behavior in the Lua argument checker for
sample-fetches and sample-converters.
---
 src/hlua.c | 43 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/hlua.c b/src/hlua.c
index 1c239e521..1868ab0fc 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -508,6 +508,9 @@ static int hlua_lua2smp(lua_State *L, int ud, struct sample *smp)
 /* This function check the "argp" builded by another conversion function
  * is in accord with the expected argp defined by the "mask". The fucntion
  * returns true or false. It can be adjust the types if there compatibles.
+ *
+ * This function assumes thant the argp argument contains ARGM_NBARGS + 1
+ * entries.
  */
 __LJMP int hlua_lua2arg_check(lua_State *L, int first, struct arg *argp,
                               unsigned int mask, struct proxy *p)
@@ -530,8 +533,44 @@ __LJMP int hlua_lua2arg_check(lua_State *L, int first, struct arg *argp,
 
 		/* Check for mandatory arguments. */
 		if (argp[idx].type == ARGT_STOP) {
-			if (idx < min_arg)
-				WILL_LJMP(luaL_argerror(L, first + idx, "Mandatory argument expected"));
+			if (idx < min_arg) {
+
+				/* If miss other argument than the first one, we return an error. */
+				if (idx > 0)
+					WILL_LJMP(luaL_argerror(L, first + idx, "Mandatory argument expected"));
+
+				/* If first argument have a certain type, some default values
+				 * may be used. See the function smp_resolve_args().
+				 */
+				switch (mask & ARGT_MASK) {
+
+				case ARGT_FE:
+					if (!(p->cap & PR_CAP_FE))
+						WILL_LJMP(luaL_argerror(L, first + idx, "Mandatory argument expected"));
+					argp[idx].data.prx = p;
+					argp[idx].type = ARGT_FE;
+					argp[idx+1].type = ARGT_STOP;
+					break;
+
+				case ARGT_BE:
+					if (!(p->cap & PR_CAP_BE))
+						WILL_LJMP(luaL_argerror(L, first + idx, "Mandatory argument expected"));
+					argp[idx].data.prx = p;
+					argp[idx].type = ARGT_BE;
+					argp[idx+1].type = ARGT_STOP;
+					break;
+
+				case ARGT_TAB:
+					argp[idx].data.prx = p;
+					argp[idx].type = ARGT_TAB;
+					argp[idx+1].type = ARGT_STOP;
+					break;
+
+				default:
+					WILL_LJMP(luaL_argerror(L, first + idx, "Mandatory argument expected"));
+					break;
+				}
+			}
 			return 0;
 		}