From b8a1b29b90108dda98e6d1a086e9f63f4e7ff673 Mon Sep 17 00:00:00 2001
From: Gary Houston <ghouston@arglist.com>
Date: Sun, 14 May 2000 22:15:59 +0000
Subject: [PATCH] 2000-05-14  Gary Houston  <ghouston@arglist.com>

	* stime.c (scm_strftime): if HAVE_TM_ZONE is not defined, hack the
	TZ environment variable so that the %Z format returns the zone
	from the input vector instead of the system default.
---
 libguile/stime.c | 44 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/libguile/stime.c b/libguile/stime.c
index 5f57b40cc..601191d33 100644
--- a/libguile/stime.c
+++ b/libguile/stime.c
@@ -572,15 +572,45 @@ SCM_DEFINE (scm_strftime, "strftime", 2, 0, 0,
   len = SCM_ROLENGTH (format);
 
   tbuf = SCM_MUST_MALLOC (size);
-#ifdef LOCALTIME_CACHE
-  tzset ();
+  {
+#if !defined (HAVE_TM_ZONE)
+    /* it seems the only way to tell non-GNU versions of strftime what
+       zone to use (for the %Z format) is to set TZ in the
+       environment.  interrupts and thread switching must be deferred
+       until TZ is restored.  */
+    char **oldenv = NULL;
+    SCM *velts = SCM_VELTS (stime);
+
+    if (SCM_NFALSEP (velts[10]))
+      {
+	/* it's not required that the TZ setting be correct, just that
+	   it has the right name.  so try something like TZ=EST.
+	   possibly TZ=EST0 would be better.  */
+	SCM_DEFER_INTS;
+	oldenv = setzone (velts[10], SCM_ARG2, FUNC_NAME);
+      }
+#endif
+
+#ifdef LOCALTIME_CACHE
+    tzset ();
+#endif
+
+    while ((len = strftime (tbuf, size, fmt, &t)) == size)
+      {
+	scm_must_free (tbuf);
+	size *= 2;
+	tbuf = SCM_MUST_MALLOC (size);
+      }
+
+#if !defined (HAVE_TM_ZONE)
+    if (SCM_NFALSEP (velts[10]))
+      {
+	restorezone (velts[10], oldenv, FUNC_NAME);
+	SCM_ALLOW_INTS;
+      }
 #endif
-  while ((len = strftime (tbuf, size, fmt, &t)) == size)
-    {
-      scm_must_free (tbuf);
-      size *= 2;
-      tbuf = SCM_MUST_MALLOC (size);
     }
+
   result = scm_makfromstr (tbuf, len, 0);
   scm_must_free (tbuf);
   return result;