From 590f4062ab5733f517fcbfac63cbfee1659f5239 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henning=20P=C3=B6ttker?=
 <25299532+hpoettker@users.noreply.github.com>
Date: Sun, 20 Sep 2026 20:41:16 +0200
Subject: [PATCH] Fix build in Windows C Runtime

In the Windows C Runtime, the POSIX function `localtime_r`, which
is a thread-safe alternative to `localtime`, is not available.

It offers the function `localtime_s` instead, which differs from
the C11 function of that name in both parameter order and return
value.
---
 src/stata/readstat_dta_write.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/stata/readstat_dta_write.c b/src/stata/readstat_dta_write.c
index e30a96c3..4a3a84ef 100644
--- a/src/stata/readstat_dta_write.c
+++ b/src/stata/readstat_dta_write.c
@@ -155,7 +155,12 @@ static readstat_error_t dta_emit_header_time_stamp(readstat_writer_t *writer, dt
     if (writer->timestamp != 0) {
         time_t now = writer->timestamp;
         struct tm time_buf;
+#if !defined _MSC_VER
         struct tm *time_s = localtime_r(&now, &time_buf);
+#else
+        errno_t time_err = localtime_s(&time_buf, &now);
+        struct tm *time_s = (time_err == 0) ? &time_buf : NULL;
+#endif
 
         if (!time_s || time_s->tm_mon < 0 || time_s->tm_mon > 11) {
             error = READSTAT_ERROR_BAD_TIMESTAMP_VALUE;