bug: os.date throws error when result is the empty string

bugs

@@ -1142,6 +1142,15 @@ patch = [[
 }
 
 
+Bug{
+what = [[os.date throws an error when result is the empty string]],
+report = [[  ]],
+since = [[4.0]],
+example = [[print(os.date(""))]],
+patch = [[  ]],
+}
+
+
 Bug{
 what = [[  ]],
 report = [[  ]],

loslib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: loslib.c,v 1.18 2006/03/09 18:08:22 roberto Exp roberto $
+** $Id: loslib.c,v 1.19 2006/04/26 18:19:49 roberto Exp roberto $
 ** Standard Operating System library
 ** See Copyright Notice in lua.h
 */
@@ -146,11 +146,22 @@ static int os_date (lua_State *L) {
     setboolfield(L, "isdst", stm->tm_isdst);
   }
   else {
-    char b[256];
-    if (strftime(b, sizeof(b), s, stm))
-      lua_pushstring(L, b);
-    else
-      return luaL_error(L, LUA_QL("date") " format too long");
+    char cc[3];
+    luaL_Buffer b;
+    cc[0] = '%'; cc[2] = '\0';
+    luaL_buffinit(L, &b);
+    for (; *s; s++) {
+      if (*s != '%' || *(s + 1) == '\0')  /* no conversion specifier? */
+        luaL_addchar(&b, *s);
+      else {
+        size_t reslen;
+        char buff[200];  /* should be big enough for any conversion result */
+        cc[1] = *(++s);
+        reslen = strftime(buff, sizeof(buff), cc, stm);
+        luaL_addlstring(&b, buff, reslen);
+      }
+    }
+    luaL_pushresult(&b);
   }
   return 1;
 }