Handle edge case for lua_pushlstring(). Add test.

3 files changed, 14 insertions, 1 deletions

diff --git a/c-api/compat-5.3.h b/c-api/compat-5.3.h
index 5c3052b..7dd77c6 100644
--- a/c-api/compat-5.3.h
+++ b/c-api/compat-5.3.h
@@ -123,7 +123,7 @@ COMPAT53_API void lua_len (lua_State *L, int i);
   (lua_pushstring(L, (s)), lua_tostring(L, -1))
 
 #define lua_pushlstring(L, s, len) \
-  (lua_pushlstring(L, (s), (len)), lua_tostring(L, -1))
+  ((((len) == 0) ? lua_pushlstring(L, "", 0) : lua_pushlstring(L, (s), (len))), lua_tostring(L, -1))
 
 #ifndef luaL_newlibtable
 #  define luaL_newlibtable(L, l) \
diff --git a/tests/test.lua b/tests/test.lua
index be16af9..582f55e 100755
--- a/tests/test.lua
+++ b/tests/test.lua
@@ -776,6 +776,9 @@ meta.__name = "XXX"
 print(mod.tolstring(ud):gsub(":.*$", ": yyy"))
 
 ___''
+print(mod.pushstring())
+
+___''
 print(mod.buffer())
 
 ___''
diff --git a/tests/testmod.c b/tests/testmod.c
index 2293064..868136b 100644
--- a/tests/testmod.c
+++ b/tests/testmod.c
@@ -246,6 +246,15 @@ static int test_tolstring (lua_State *L) {
   return 2;
 }
 
+static int test_pushstring (lua_State *L) {
+  lua_pushstring(L, lua_pushliteral(L, "abc"));
+  lua_pushstring(L, lua_pushlstring(L, "abc", 2));
+  lua_pushstring(L, lua_pushlstring(L, NULL, 0));
+  lua_pushstring(L, lua_pushstring(L, "abc"));
+  lua_pushboolean(L, NULL == lua_pushstring(L, NULL));
+  return 10;
+}
+
 static int test_buffer (lua_State *L) {
   luaL_Buffer b;
   char *p = luaL_buffinitsize(L, &b, LUAL_BUFFERSIZE+1);
@@ -285,6 +294,7 @@ static const luaL_Reg funcs[] = {
   { "uservalue", test_uservalue },
   { "globals", test_globals },
   { "tolstring", test_tolstring },
+  { "pushstring", test_pushstring },
   { "buffer", test_buffer },
   { "exec", test_exec },
   { NULL, NULL }