lib: Add decoder functions

Split existing lua_to* functions into two functions:
 - lua_decode_*: unmarshall Lua values into an existing C data structure
 - lua_to*: allocate *and* unmarshall Lua values into C data structure
This allows us to mutate C data structures passed into frrscript_call,
without allocation

Signed-off-by: Donald Lee <dlqs@gmx.com>

lib/frrlua.c

@@ -71,14 +71,17 @@ void lua_pushprefix(lua_State *L, const struct prefix *prefix)
 	lua_setfield(L, -2, "family");
 }
 
+void lua_decode_prefix(lua_State *L, int idx, struct prefix *prefix)
+{
+	lua_getfield(L, idx, "network");
+	(void)str2prefix(lua_tostring(L, -1), prefix);
+	lua_pop(L, 1);
+}
+
 void *lua_toprefix(lua_State *L, int idx)
 {
 	struct prefix *p = XCALLOC(MTYPE_TMP, sizeof(struct prefix));
-
-	lua_getfield(L, idx, "network");
-	(void)str2prefix(lua_tostring(L, -1), p);
-	lua_pop(L, 1);
-
+	lua_decode_prefix(L, idx, p);
 	return p;
 }
 
@@ -109,10 +112,8 @@ void lua_pushinterface(lua_State *L, const struct interface *ifp)
 	lua_setfield(L, -2, "linklayer_type");
 }
 
-void *lua_tointerface(lua_State *L, int idx)
+void lua_decode_interface(lua_State *L, int idx, struct interface *ifp)
 {
-	struct interface *ifp = XCALLOC(MTYPE_TMP, sizeof(struct interface));
-
 	lua_getfield(L, idx, "name");
 	strlcpy(ifp->name, lua_tostring(L, -1), sizeof(ifp->name));
 	lua_pop(L, 1);
@@ -146,13 +147,19 @@ void *lua_tointerface(lua_State *L, int idx)
 	lua_getfield(L, idx, "linklayer_type");
 	ifp->ll_type = lua_tointeger(L, -1);
 	lua_pop(L, 1);
+}
+void *lua_tointerface(lua_State *L, int idx)
+{
+	struct interface *ifp = XCALLOC(MTYPE_TMP, sizeof(struct interface));
 
+	lua_decode_interface(L, idx, ifp);
 	return ifp;
 }
 
 void lua_pushinaddr(lua_State *L, const struct in_addr *addr)
 {
 	char buf[INET_ADDRSTRLEN];
+
 	inet_ntop(AF_INET, addr, buf, sizeof(buf));
 
 	lua_newtable(L);
@@ -162,14 +169,17 @@ void lua_pushinaddr(lua_State *L, const struct in_addr *addr)
 	lua_setfield(L, -2, "string");
 }
 
-void *lua_toinaddr(lua_State *L, int idx)
+void lua_decode_inaddr(lua_State *L, int idx, struct in_addr *inaddr)
 {
-	struct in_addr *inaddr = XCALLOC(MTYPE_TMP, sizeof(struct in_addr));
-
 	lua_getfield(L, idx, "value");
 	inaddr->s_addr = lua_tointeger(L, -1);
 	lua_pop(L, 1);
+}
 
+void *lua_toinaddr(lua_State *L, int idx)
+{
+	struct in_addr *inaddr = XCALLOC(MTYPE_TMP, sizeof(struct in_addr));
+	lua_decode_inaddr(L, idx, inaddr);
 	return inaddr;
 }
 
@@ -177,6 +187,7 @@ void *lua_toinaddr(lua_State *L, int idx)
 void lua_pushin6addr(lua_State *L, const struct in6_addr *addr)
 {
 	char buf[INET6_ADDRSTRLEN];
+
 	inet_ntop(AF_INET6, addr, buf, sizeof(buf));
 
 	lua_newtable(L);
@@ -186,20 +197,24 @@ void lua_pushin6addr(lua_State *L, const struct in6_addr *addr)
 	lua_setfield(L, -2, "string");
 }
 
-void *lua_toin6addr(lua_State *L, int idx)
+void lua_decode_in6addr(lua_State *L, int idx, struct in6_addr *in6addr)
 {
-	struct in6_addr *in6addr = XCALLOC(MTYPE_TMP, sizeof(struct in6_addr));
-
 	lua_getfield(L, idx, "string");
 	inet_pton(AF_INET6, lua_tostring(L, -1), in6addr);
 	lua_pop(L, 1);
+}
 
+void *lua_toin6addr(lua_State *L, int idx)
+{
+	struct in6_addr *in6addr = XCALLOC(MTYPE_TMP, sizeof(struct in6_addr));
+	lua_decode_in6addr(L, idx, in6addr);
 	return in6addr;
 }
 
 void lua_pushsockunion(lua_State *L, const union sockunion *su)
 {
 	char buf[SU_ADDRSTRLEN];
+
 	sockunion2str(su, buf, sizeof(buf));
 
 	lua_newtable(L);
@@ -210,13 +225,17 @@ void lua_pushsockunion(lua_State *L, const union sockunion *su)
 	lua_setfield(L, -2, "string");
 }
 
+void lua_decode_sockunion(lua_State *L, int idx, union sockunion *su)
+{
+	lua_getfield(L, idx, "string");
+	str2sockunion(lua_tostring(L, -1), su);
+}
+
 void *lua_tosockunion(lua_State *L, int idx)
 {
 	union sockunion *su = XCALLOC(MTYPE_TMP, sizeof(union sockunion));
 
-	lua_getfield(L, idx, "string");
-	str2sockunion(lua_tostring(L, -1), su);
-
+	lua_decode_sockunion(L, idx, su);
 	return su;
 }
 
@@ -225,12 +244,16 @@ void lua_pushtimet(lua_State *L, const time_t *time)
 	lua_pushinteger(L, *time);
 }
 
+void lua_decode_timet(lua_State *L, int idx, time_t *t)
+{
+	*t = lua_tointeger(L, idx);
+}
+
 void *lua_totimet(lua_State *L, int idx)
 {
 	time_t *t = XCALLOC(MTYPE_TMP, sizeof(time_t));
 
-	*t = lua_tointeger(L, idx);
-
+	lua_decode_timet(L, idx, t);
 	return t;
 }
 
@@ -239,17 +262,27 @@ void lua_pushintegerp(lua_State *L, const long long *num)
 	lua_pushinteger(L, *num);
 }
 
-void *lua_tointegerp(lua_State *L, int idx)
+void lua_decode_integerp(lua_State *L, int idx, long long *num)
 {
 	int isnum;
-	long long *num = XCALLOC(MTYPE_TMP, sizeof(long long));
-
 	*num = lua_tonumberx(L, idx, &isnum);
 	assert(isnum);
+}
 
+void *lua_tointegerp(lua_State *L, int idx)
+{
+	long long *num = XCALLOC(MTYPE_TMP, sizeof(long long));
+
+	lua_decode_integerp(L, idx, num);
 	return num;
 }
 
+void lua_decode_stringp(lua_State *L, int idx, char *str)
+{
+	strlcpy(str, lua_tostring(L, idx), strlen(str) + 1);
+	lua_pop(L, 1);
+}
+
 void *lua_tostringp(lua_State *L, int idx)
 {
 	char *string = XSTRDUP(MTYPE_TMP, lua_tostring(L, idx));

lib/frrlua.h

@@ -50,6 +50,8 @@ static inline void lua_pushstring_wrapper(lua_State *L, const char *str)
  */
 void lua_pushprefix(lua_State *L, const struct prefix *prefix);
 
+void lua_decode_prefix(lua_State *L, int idx, struct prefix *prefix);
+
 /*
  * Converts the Lua value at idx to a prefix.
  *
@@ -63,6 +65,8 @@ void *lua_toprefix(lua_State *L, int idx);
  */
 void lua_pushinterface(lua_State *L, const struct interface *ifp);
 
+void lua_decode_interface(lua_State *L, int idx, struct interface *ifp);
+
 /*
  * Converts the Lua value at idx to an interface.
  *
@@ -77,6 +81,8 @@ void *lua_tointerface(lua_State *L, int idx);
  */
 void lua_pushinaddr(lua_State *L, const struct in_addr *addr);
 
+void lua_decode_inaddr(lua_State *L, int idx, struct in_addr *addr);
+
 /*
  * Converts the Lua value at idx to an in_addr.
  *
@@ -90,6 +96,8 @@ void *lua_toinaddr(lua_State *L, int idx);
  */
 void lua_pushin6addr(lua_State *L, const struct in6_addr *addr);
 
+void lua_decode_in6addr(lua_State *L, int idx, struct in6_addr *addr);
+
 /*
  * Converts the Lua value at idx to an in6_addr.
  *
@@ -103,6 +111,8 @@ void *lua_toin6addr(lua_State *L, int idx);
  */
 void lua_pushtimet(lua_State *L, const time_t *time);
 
+void lua_decode_timet(lua_State *L, int idx, time_t *time);
+
 /*
  * Converts the Lua value at idx to a time_t.
  *
@@ -116,6 +126,8 @@ void *lua_totimet(lua_State *L, int idx);
  */
 void lua_pushsockunion(lua_State *L, const union sockunion *su);
 
+void lua_decode_sockunion(lua_State *L, int idx, union sockunion *su);
+
 /*
  * Converts the Lua value at idx to a sockunion.
  *
@@ -129,6 +141,8 @@ void *lua_tosockunion(lua_State *L, int idx);
  */
 void lua_pushintegerp(lua_State *L, const long long *num);
 
+void lua_decode_integerp(lua_State *L, int idx, long long *num);
+
 /*
  * Converts the Lua value at idx to an int.
  *
@@ -137,6 +151,8 @@ void lua_pushintegerp(lua_State *L, const long long *num);
  */
 void *lua_tointegerp(lua_State *L, int idx);
 
+void lua_decode_stringp(lua_State *L, int idx, char *str);
+
 /*
  * Pop string.
  *

lib/frrscript.h

@@ -105,7 +105,7 @@ void frrscript_init(const char *scriptdir);
 #define DECODE_ARGS(name, value)                                               \
 	do {                                                                   \
 		lua_getglobal(L, name);                                        \
-		DECODE_ARGS_WITH_STATE(L, value)                               \
+		DECODE_ARGS_WITH_STATE(L, value);                              \
 	} while (0)
 
 #define ENCODE_ARGS_WITH_STATE(L, value)                                       \
@@ -120,7 +120,17 @@ time_t * : lua_pushtimet,                                       \
 char * : lua_pushstring_wrapper                                 \
 )(L, value)
 
-#define DECODE_ARGS_WITH_STATE(L, value) _Generic((value), )(L, value);
+#define DECODE_ARGS_WITH_STATE(L, value)                                       \
+	_Generic((value), \
+long long * : lua_decode_integerp,                              \
+struct prefix * : lua_decode_prefix,                            \
+struct interface * : lua_decode_interface,                      \
+struct in_addr * : lua_decode_inaddr,                           \
+struct in6_addr * : lua_decode_in6addr,                         \
+union sockunion * : lua_decode_sockunion,                       \
+time_t * : lua_decode_timet,                                    \
+char * : lua_decode_stringp                                     \
+)(L, -1, value)
 
 /*
  * Call script.