From b58cb9f72b1bc17da7ee98c78024a904c0730022 Mon Sep 17 00:00:00 2001
From: Eshan Kelkar <eshankelkar@galorithm.com>
Date: Tue, 13 Aug 2024 11:52:21 +0530
Subject: [PATCH] misc.c, priv.h: Add support for localtime_r() on Windows

Windows supports localtime_s() instead of POSIX's localtime_r()
and the function prototype of localtime_s() is different as compared
to localtime_r().

This commit introduces ssh_localtime() (having same prototype as localtime_r())
for Windows which acts as a wrapper for localtime_s(), and defines localtime_r
as a macro which expands to ssh_localtime for Windows.

As a result, libssh can now use localtime_r() on Windows in the same manner
as localtime_r() can be used on POSIX systems.

Signed-off-by: Eshan Kelkar <eshankelkar@galorithm.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
---
 include/libssh/priv.h |  4 ++++
 src/misc.c            | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/libssh/priv.h b/include/libssh/priv.h
index 35fd8506..e164154b 100644
--- a/include/libssh/priv.h
+++ b/include/libssh/priv.h
@@ -34,6 +34,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
+#include <time.h>
 
 #if !defined(HAVE_STRTOULL)
 # if defined(HAVE___STRTOULL)
@@ -164,6 +165,9 @@ int ssh_gettimeofday(struct timeval *__p, void *__t);
 
 #define gettimeofday ssh_gettimeofday
 
+struct tm *ssh_localtime(const time_t *timer, struct tm *result);
+# define localtime_r ssh_localtime
+
 #define _XCLOSESOCKET closesocket
 
 # ifdef HAVE_IO_H
diff --git a/src/misc.c b/src/misc.c
index 7fe243f5..349f407a 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -178,6 +178,35 @@ int ssh_gettimeofday(struct timeval *__p, void *__t)
   return (0);
 }
 
+/**
+ * @internal
+ *
+ * @brief Convert time in seconds since the Epoch to broken-down local time
+ *
+ * This is a helper used to provide localtime_r() like function interface
+ * on Windows.
+ *
+ * @param timer    Pointer to a location storing the time_t which
+ *                 represents the time in seconds since the Epoch.
+ *
+ * @param result   Pointer to a location where the broken-down time
+ *                 (expressed as local time) should be stored.
+ *
+ * @returns        A pointer to the structure pointed to by the parameter
+ *                 <tt>result</tt> on success, NULL on error with the errno
+ *                 set to indicate the error.
+ */
+struct tm *ssh_localtime(const time_t *timer, struct tm *result)
+{
+    errno_t rc;
+    rc = localtime_s(result, timer);
+    if (rc != 0) {
+        return NULL;
+    }
+
+    return result;
+}
+
 char *ssh_get_local_username(void)
 {
     DWORD size = 0;