From 4c32b2dfd204add9a3fed8d5eb100236e276e44a Mon Sep 17 00:00:00 2001
From: Roberto I <roberto@inf.puc-rio.br>
Date: Tue, 15 Sep 2026 09:49:44 -0300
Subject: [PATCH] 'mktime' can return -1

---
 loslib.c         | 25 +++++++++++++++++--------
 testes/files.lua |  7 +++++++
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/loslib.c b/loslib.c
index b7a2b0d1..fe9295c7 100644
--- a/loslib.c
+++ b/loslib.c
@@ -345,11 +345,22 @@ static int os_date (lua_State *L) {
 }
 
 
+static int os_time_aux (lua_State *L, time_t t, int err) {
+  if (err || t != (time_t)(l_timet)t)
+    return luaL_error(L,
+                  "time result cannot be represented in this installation");
+  l_pushtime(L, t);
+  return 1;
+}
+
+
 static int os_time (lua_State *L) {
-  time_t t;
-  if (lua_isnoneornil(L, 1))  /* called without args? */
-    t = time(NULL);  /* get current time */
+  if (lua_isnoneornil(L, 1)) {  /* called without args? */
+    time_t t = time(NULL);  /* get current time; error if it is -1 */
+    return os_time_aux(L, t, (t == (time_t)(-1)));
+  }
   else {
+    time_t t;
     struct tm ts;
     luaL_checktype(L, 1, LUA_TTABLE);
     lua_settop(L, 1);  /* make sure table is at the top */
@@ -360,14 +371,12 @@ static int os_time (lua_State *L) {
     ts.tm_min = getfield(L, "min", 0, 0);
     ts.tm_sec = getfield(L, "sec", 0, 0);
     ts.tm_isdst = getboolfield(L, "isdst");
+    ts.tm_wday = -1;  /* if call succeeds, it will set this value */
     t = mktime(&ts);
     setallfields(L, &ts);  /* update fields with normalized values */
+    /* error if tm_wday was not set */
+    return os_time_aux(L, t, ts.tm_wday == -1);
   }
-  if (t != (time_t)(l_timet)t || t == (time_t)(-1))
-    return luaL_error(L,
-                  "time result cannot be represented in this installation");
-  l_pushtime(L, t);
-  return 1;
 }
 
 
diff --git a/testes/files.lua b/testes/files.lua
index 7146ac7c..04936565 100644
--- a/testes/files.lua
+++ b/testes/files.lua
@@ -854,6 +854,13 @@ local function checkDateTable (t)
   _G.D = nil
 end
 
+
+do   -- testing mktime returning -1
+  local t = os.date("*t", -1)
+  assert(os.time(t) == -1)
+end
+
+
 checkDateTable(os.time())
 if not _port then
   -- assume that time_t can represent these values