2004-05-14 Kevin B. Kenny <kennykb@acm.org>

	* generic/tclInt.decls:      Promoted TclpLocaltime and TclpGmtime
	* generic/tclIntDecls.h:     from Unix-specific stubs to the generic
	* generic/tclIntPlatDecls.h: internal Stubs table.  Reran 'genstubs'
	* generic/tclStubInit.c:
	* unix/tclUnixPort.h:

	* generic/tclClock.c: Changed a buggy 'GMT' timezone specification
	                      to the correct 'GMT0'. [Bug #922848]
	
	* unix/tclUnixThrd.c: Moved TclpGmtime and TclpLocaltime to
	                      unix/tclUnixTime.c where they belong.

	* unix/tclUnixTime.c (TclpGmtime, TclpLocaltime, TclpGetTimeZone,
	                      ThreadSafeGMTime [removed],
	                      ThreadSafeLocalTime [removed],
	                      SetTZIfNecessary, CleanupMemory):
	    Restructured to make sure that the same mutex protects
	    all calls to localtime, gmtime, and tzset.  Added a check
	    in front of those calls to make sure that the TZ env var
	    hasn't changed since the last call to tzset, and repeat
	    tzset if necessary. [Bug #942078]  Removed a buggy test
	    of the Daylight Saving Time information in 'gettimeofday'
	    in favor of applying 'localtime' to a known value.
	    [Bug #922848]

	* tests/clock.test (clock-3.14): Added test to make sure that
	    changes to $env(TZ) take effect immediately.
	
	* win/tclWinTime.c (TclpLocaltime, TclpGmtime):
	    Added porting layer for 'localtime' and 'gmtime' calls.

11 files changed, 343 insertions, 168 deletions

diff --git a/ChangeLog b/ChangeLog
index c0bb25b..66885c4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,36 @@
+2004-05-14  Kevin B. Kenny  <kennykb@acm.org>
+
+	* generic/tclInt.decls:      Promoted TclpLocaltime and TclpGmtime
+	* generic/tclIntDecls.h:     from Unix-specific stubs to the generic
+	* generic/tclIntPlatDecls.h: internal Stubs table.  Reran 'genstubs'
+	* generic/tclStubInit.c:
+	* unix/tclUnixPort.h:
+
+	* generic/tclClock.c: Changed a buggy 'GMT' timezone specification
+	                      to the correct 'GMT0'. [Bug #922848]
+	
+	* unix/tclUnixThrd.c: Moved TclpGmtime and TclpLocaltime to
+	                      unix/tclUnixTime.c where they belong.
+
+	* unix/tclUnixTime.c (TclpGmtime, TclpLocaltime, TclpGetTimeZone,
+	                      ThreadSafeGMTime [removed],
+	                      ThreadSafeLocalTime [removed],
+	                      SetTZIfNecessary, CleanupMemory):
+	    Restructured to make sure that the same mutex protects
+	    all calls to localtime, gmtime, and tzset.  Added a check
+	    in front of those calls to make sure that the TZ env var
+	    hasn't changed since the last call to tzset, and repeat
+	    tzset if necessary. [Bug #942078]  Removed a buggy test
+	    of the Daylight Saving Time information in 'gettimeofday'
+	    in favor of applying 'localtime' to a known value.
+	    [Bug #922848]
+
+	* tests/clock.test (clock-3.14): Added test to make sure that
+	    changes to $env(TZ) take effect immediately.
+	
+	* win/tclWinTime.c (TclpLocaltime, TclpGmtime):
+	    Added porting layer for 'localtime' and 'gmtime' calls.
+
 2004-05-14  Miguel Sofer <msofer@users.sf.net>
 
 	* generic/tclExecute.h:
diff --git a/generic/tclClock.c b/generic/tclClock.c
index 6d23006..67570df 100644
--- a/generic/tclClock.c
+++ b/generic/tclClock.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclClock.c,v 1.27 2004/04/15 21:06:39 dkf Exp $
+ * RCS: @(#) $Id: tclClock.c,v 1.28 2004/05/14 21:43:28 kennykb Exp $
  */
 
 #include "tclInt.h"
@@ -313,7 +313,7 @@ FormatClock(interp, clockVal, useGMT, format)
         } else {
             savedTZEnv = NULL;
 	}
-        Tcl_SetVar2(interp, "env", "TZ", "GMT", TCL_GLOBAL_ONLY);
+        Tcl_SetVar2(interp, "env", "TZ", "GMT0", TCL_GLOBAL_ONLY);
         savedTimeZone = timezone;
         timezone = 0;
         tzset();
diff --git a/generic/tclInt.decls b/generic/tclInt.decls
index 6a98616..4a7e787 100644
--- a/generic/tclInt.decls
+++ b/generic/tclInt.decls
@@ -12,7 +12,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 # 
-# RCS: @(#) $Id: tclInt.decls,v 1.72 2004/05/13 20:31:07 dkf Exp $
+# RCS: @(#) $Id: tclInt.decls,v 1.73 2004/05/14 21:43:29 kennykb Exp $
 
 library tcl
 
@@ -736,6 +736,15 @@ declare 181 generic {
 	    CONST char *file, int line)
 }
 
+# TclpGmtime and TclpLocaltime promoted to the generic interface from unix
+
+declare 182 generic {
+     struct tm *TclpLocaltime(CONST time_t *clock)
+}
+declare 183 generic {
+     struct tm *TclpGmtime(CONST time_t *clock)
+}
+
 ##############################################################################
 
 # Define the platform specific internal Tcl interface. These functions are
@@ -904,11 +913,13 @@ declare 9 unix {
 declare 10 unix {
     Tcl_DirEntry *TclpReaddir(DIR *dir)
 }
+# Slots 11 and 12 are forwarders for functions that were promoted to
+# generic Stubs
 declare 11 unix {
-    struct tm *TclpLocaltime(time_t *clock)
+    struct tm *TclpLocaltime_unix(CONST time_t *clock)
 }
 declare 12 unix {
-    struct tm *TclpGmtime(time_t *clock)
+    struct tm *TclpGmtime_unix(CONST time_t *clock)
 }
 declare 13 unix {
     char *TclpInetNtoa(struct in_addr addr)
diff --git a/generic/tclIntDecls.h b/generic/tclIntDecls.h
index 09e193d..3b6fbfb 100644
--- a/generic/tclIntDecls.h
+++ b/generic/tclIntDecls.h
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclIntDecls.h,v 1.61 2004/03/19 18:43:15 dgp Exp $
+ * RCS: @(#) $Id: tclIntDecls.h,v 1.62 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #ifndef _TCLINTDECLS
@@ -959,6 +959,16 @@ EXTERN Tcl_Obj *	TclNewListObjDirect _ANSI_ARGS_((int objc,
 EXTERN Tcl_Obj *	TclDbNewListObjDirect _ANSI_ARGS_((int objc, 
 				Tcl_Obj ** objv, CONST char * file, int line));
 #endif
+#ifndef TclpLocaltime_TCL_DECLARED
+#define TclpLocaltime_TCL_DECLARED
+/* 182 */
+EXTERN struct tm *	TclpLocaltime _ANSI_ARGS_((CONST time_t * clock));
+#endif
+#ifndef TclpGmtime_TCL_DECLARED
+#define TclpGmtime_TCL_DECLARED
+/* 183 */
+EXTERN struct tm *	TclpGmtime _ANSI_ARGS_((CONST time_t * clock));
+#endif
 
 typedef struct TclIntStubs {
     int magic;
@@ -1161,6 +1171,8 @@ typedef struct TclIntStubs {
     Tcl_Obj * (*tcl_GetStartupScript) _ANSI_ARGS_((CONST char ** encodingNamePtr)); /* 179 */
     Tcl_Obj * (*tclNewListObjDirect) _ANSI_ARGS_((int objc, Tcl_Obj ** objv)); /* 180 */
     Tcl_Obj * (*tclDbNewListObjDirect) _ANSI_ARGS_((int objc, Tcl_Obj ** objv, CONST char * file, int line)); /* 181 */
+    struct tm * (*tclpLocaltime) _ANSI_ARGS_((CONST time_t * clock)); /* 182 */
+    struct tm * (*tclpGmtime) _ANSI_ARGS_((CONST time_t * clock)); /* 183 */
 } TclIntStubs;
 
 #ifdef __cplusplus
@@ -1797,6 +1809,14 @@ extern TclIntStubs *tclIntStubsPtr;
 #define TclDbNewListObjDirect \
 	(tclIntStubsPtr->tclDbNewListObjDirect) /* 181 */
 #endif
+#ifndef TclpLocaltime
+#define TclpLocaltime \
+	(tclIntStubsPtr->tclpLocaltime) /* 182 */
+#endif
+#ifndef TclpGmtime
+#define TclpGmtime \
+	(tclIntStubsPtr->tclpGmtime) /* 183 */
+#endif
 
 #endif /* defined(USE_TCL_STUBS) && !defined(USE_TCL_STUB_PROCS) */
 
diff --git a/generic/tclIntPlatDecls.h b/generic/tclIntPlatDecls.h
index 0d5bf30..3477646 100644
--- a/generic/tclIntPlatDecls.h
+++ b/generic/tclIntPlatDecls.h
@@ -9,7 +9,7 @@
  * Copyright (c) 1998-1999 by Scriptics Corporation.
  * All rights reserved.
  *
- * RCS: @(#) $Id: tclIntPlatDecls.h,v 1.22 2004/03/17 18:14:13 das Exp $
+ * RCS: @(#) $Id: tclIntPlatDecls.h,v 1.23 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #ifndef _TCLINTPLATDECLS
@@ -91,15 +91,15 @@ EXTERN TclFile		TclpCreateTempFile _ANSI_ARGS_((
 /* 10 */
 EXTERN Tcl_DirEntry *	TclpReaddir _ANSI_ARGS_((DIR * dir));
 #endif
-#ifndef TclpLocaltime_TCL_DECLARED
-#define TclpLocaltime_TCL_DECLARED
+#ifndef TclpLocaltime_unix_TCL_DECLARED
+#define TclpLocaltime_unix_TCL_DECLARED
 /* 11 */
-EXTERN struct tm *	TclpLocaltime _ANSI_ARGS_((time_t * clock));
+EXTERN struct tm *	TclpLocaltime_unix _ANSI_ARGS_((CONST time_t * clock));
 #endif
-#ifndef TclpGmtime_TCL_DECLARED
-#define TclpGmtime_TCL_DECLARED
+#ifndef TclpGmtime_unix_TCL_DECLARED
+#define TclpGmtime_unix_TCL_DECLARED
 /* 12 */
-EXTERN struct tm *	TclpGmtime _ANSI_ARGS_((time_t * clock));
+EXTERN struct tm *	TclpGmtime_unix _ANSI_ARGS_((CONST time_t * clock));
 #endif
 #ifndef TclpInetNtoa_TCL_DECLARED
 #define TclpInetNtoa_TCL_DECLARED
@@ -300,8 +300,8 @@ typedef struct TclIntPlatStubs {
     int (*tclUnixWaitForFile) _ANSI_ARGS_((int fd, int mask, int timeout)); /* 8 */
     TclFile (*tclpCreateTempFile) _ANSI_ARGS_((CONST char * contents)); /* 9 */
     Tcl_DirEntry * (*tclpReaddir) _ANSI_ARGS_((DIR * dir)); /* 10 */
-    struct tm * (*tclpLocaltime) _ANSI_ARGS_((time_t * clock)); /* 11 */
-    struct tm * (*tclpGmtime) _ANSI_ARGS_((time_t * clock)); /* 12 */
+    struct tm * (*tclpLocaltime_unix) _ANSI_ARGS_((CONST time_t * clock)); /* 11 */
+    struct tm * (*tclpGmtime_unix) _ANSI_ARGS_((CONST time_t * clock)); /* 12 */
     char * (*tclpInetNtoa) _ANSI_ARGS_((struct in_addr addr)); /* 13 */
     int (*tclUnixCopyFile) _ANSI_ARGS_((CONST char * src, CONST char * dst, CONST Tcl_StatBuf * statBufPtr, int dontCopyAtts)); /* 14 */
 #endif /* UNIX */
@@ -399,13 +399,13 @@ extern TclIntPlatStubs *tclIntPlatStubsPtr;
 #define TclpReaddir \
 	(tclIntPlatStubsPtr->tclpReaddir) /* 10 */
 #endif
-#ifndef TclpLocaltime
-#define TclpLocaltime \
-	(tclIntPlatStubsPtr->tclpLocaltime) /* 11 */
+#ifndef TclpLocaltime_unix
+#define TclpLocaltime_unix \
+	(tclIntPlatStubsPtr->tclpLocaltime_unix) /* 11 */
 #endif
-#ifndef TclpGmtime
-#define TclpGmtime \
-	(tclIntPlatStubsPtr->tclpGmtime) /* 12 */
+#ifndef TclpGmtime_unix
+#define TclpGmtime_unix \
+	(tclIntPlatStubsPtr->tclpGmtime_unix) /* 12 */
 #endif
 #ifndef TclpInetNtoa
 #define TclpInetNtoa \
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 19266e0..8f6e4c2 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclStubInit.c,v 1.95 2004/05/13 13:00:20 dkf Exp $
+ * RCS: @(#) $Id: tclStubInit.c,v 1.96 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #include "tclInt.h"
@@ -266,6 +266,8 @@ TclIntStubs tclIntStubs = {
     Tcl_GetStartupScript, /* 179 */
     TclNewListObjDirect, /* 180 */
     TclDbNewListObjDirect, /* 181 */
+    TclpLocaltime, /* 182 */
+    TclpGmtime, /* 183 */
 };
 
 TclIntPlatStubs tclIntPlatStubs = {
@@ -283,8 +285,8 @@ TclIntPlatStubs tclIntPlatStubs = {
     TclUnixWaitForFile, /* 8 */
     TclpCreateTempFile, /* 9 */
     TclpReaddir, /* 10 */
-    TclpLocaltime, /* 11 */
-    TclpGmtime, /* 12 */
+    TclpLocaltime_unix, /* 11 */
+    TclpGmtime_unix, /* 12 */
     TclpInetNtoa, /* 13 */
     TclUnixCopyFile, /* 14 */
 #endif /* UNIX */
diff --git a/tests/clock.test b/tests/clock.test
index ea7310e..5f1b028 100644
--- a/tests/clock.test
+++ b/tests/clock.test
@@ -10,7 +10,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: clock.test,v 1.25 2004/04/15 21:06:39 dkf Exp $
+# RCS: @(#) $Id: clock.test,v 1.26 2004/05/14 21:43:29 kennykb Exp $
 
 set env(LC_TIME) POSIX
 
@@ -173,6 +173,27 @@ test clock-3.13 {clock format with non-ASCII character in the format string} {
     set res
 } "\u00c4"
 
+# Bug 942078
+
+test clock-3.14 {change of time zone} -setup {
+    catch { unset oldTZ }
+    if { [info exists env(TZ)] } {
+	set oldTZ $env(TZ)
+    }
+} -body {
+    set env(TZ) PST8PDT
+    set s [clock format 0 -format %H%M]
+    set env(TZ) GMT0
+    append s -[clock format 0 -format %H%M]
+} -cleanup {
+    if { [info exists oldTZ] } {
+	set env(TZ) $oldTZ
+	unset oldTZ
+    } else {
+	unset env(TZ)
+    }
+} -result {1600-0000}
+
 # clock scan
 test clock-4.1 {clock scan tests} {
     list [catch {clock scan} msg] $msg
diff --git a/unix/tclUnixPort.h b/unix/tclUnixPort.h
index e1b2fc4..8bb93bf 100644
--- a/unix/tclUnixPort.h
+++ b/unix/tclUnixPort.h
@@ -19,7 +19,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclUnixPort.h,v 1.35 2004/04/06 22:25:57 dgp Exp $
+ * RCS: @(#) $Id: tclUnixPort.h,v 1.36 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #ifndef _TCLUNIXPORT
@@ -557,12 +557,12 @@ EXTERN void	TclpMutexInit _ANSI_ARGS_((TclpMutex *mPtr));
 EXTERN void	TclpMutexLock _ANSI_ARGS_((TclpMutex *mPtr));
 EXTERN void	TclpMutexUnlock _ANSI_ARGS_((TclpMutex *mPtr));
 EXTERN Tcl_DirEntry * 	TclpReaddir(DIR *);
-EXTERN struct tm *     	TclpLocaltime(time_t *);
-EXTERN struct tm *     	TclpGmtime(time_t *);
+EXTERN struct tm *     	TclpLocaltime(CONST time_t *);
+EXTERN struct tm *     	TclpGmtime(CONST time_t *);
 EXTERN char *          	TclpInetNtoa(struct in_addr);
 #define readdir(x)	TclpReaddir(x)
-#define localtime(x)	TclpLocaltime(x)
-#define gmtime(x)	TclpGmtime(x)
+/* #define localtime(x)	TclpLocaltime(x)
+ * #define gmtime(x)	TclpGmtime(x)    */
 #undef inet_ntoa
 #define inet_ntoa(x)	TclpInetNtoa(x)
 #undef TclOSreaddir
diff --git a/unix/tclUnixThrd.c b/unix/tclUnixThrd.c
index c087423..3de2319 100644
--- a/unix/tclUnixThrd.c
+++ b/unix/tclUnixThrd.c
@@ -20,8 +20,6 @@
 
 typedef struct ThreadSpecificData {
     char	    	nabuf[16];
-    struct tm   	gtbuf;
-    struct tm   	ltbuf;
     struct {
 	Tcl_DirEntry ent;
 	char name[MAXNAMLEN+1];
@@ -863,51 +861,6 @@ TclpReaddir(DIR * dir)
 #endif
     return ent;
 }
-
-#if defined(TCL_THREADS) && (!defined(HAVE_GMTIME_R) || !defined(HAVE_LOCALTIME_R))
-TCL_DECLARE_MUTEX( tmMutex )
-#undef localtime
-#undef gmtime
-#endif
-
-struct tm *
-TclpLocaltime(time_t * clock)
-{
-#ifdef TCL_THREADS
-    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
-
-#ifdef HAVE_LOCALTIME_R
-    return localtime_r(clock, &tsdPtr->ltbuf);
-#else
-    Tcl_MutexLock( &tmMutex );
-    memcpy( (VOID *) &tsdPtr->ltbuf, (VOID *) localtime( clock ), sizeof (struct tm) );
-    Tcl_MutexUnlock( &tmMutex );
-    return &tsdPtr->ltbuf;
-#endif    
-#else
-    return localtime(clock);
-#endif
-}
-
-struct tm *
-TclpGmtime(time_t * clock)
-{
-#ifdef TCL_THREADS
-    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
-
-#ifdef HAVE_GMTIME_R
-    return gmtime_r(clock, &tsdPtr->gtbuf);
-#else
-    Tcl_MutexLock( &tmMutex );
-    memcpy( (VOID *) &tsdPtr->gtbuf, (VOID *) gmtime( clock ), sizeof (struct tm) );
-    Tcl_MutexUnlock( &tmMutex );
-    return &tsdPtr->gtbuf;
-#endif    
-#else
-    return gmtime(clock);
-#endif
-}
-
 char *
 TclpInetNtoa(struct in_addr addr)
 {
diff --git a/unix/tclUnixTime.c b/unix/tclUnixTime.c
index 37c16bc..6def210 100644
--- a/unix/tclUnixTime.c
+++ b/unix/tclUnixTime.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclUnixTime.c,v 1.20 2004/04/06 22:25:57 dgp Exp $
+ * RCS: @(#) $Id: tclUnixTime.c,v 1.21 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #include "tclInt.h"
@@ -24,22 +24,27 @@
  */
 
 static Tcl_ThreadDataKey tmKey;
+typedef struct ThreadSpecificData {
+    struct tm gmtime_buf;
+    struct tm localtime_buf;
+} ThreadSpecificData;
 
 /*
  * If we fall back on the thread-unsafe versions of gmtime and localtime,
  * use this mutex to try to protect them.
  */
 
-#if !defined(HAVE_GMTIME_R) || !defined(HAVE_LOCALTIME_R)
 TCL_DECLARE_MUTEX(tmMutex)
-#endif
 
-/*
- * Forward declarations for procedures defined later in this file.
- */
+static char* lastTZ = NULL;	/* Holds the last setting of the
+				 * TZ environment variable, or an
+				 * empty string if the variable was
+				 * not set. */
+
+/* Static functions declared in this file */
 
-static struct tm *ThreadSafeGMTime _ANSI_ARGS_(( CONST time_t* ));
-static struct tm *ThreadSafeLocalTime _ANSI_ARGS_(( CONST time_t* ));
+static void SetTZIfNecessary _ANSI_ARGS_((void));
+static void CleanupMemory _ANSI_ARGS_((ClientData));
 
 /*
  *-----------------------------------------------------------------------------
@@ -128,18 +133,22 @@ TclpGetTimeZone (currentTime)
     unsigned long  currentTime;
 {
     /*
-     * Determine how a timezone is obtained from "struct tm".  If there is no
-     * time zone in this struct (very lame) then use the timezone variable.
-     * This is done in a way to make the timezone variable the method of last
-     * resort, as some systems have it in addition to a field in "struct tm".
-     * The gettimeofday system call can also be used to determine the time
-     * zone.
+     * We prefer first to use the time zone in "struct tm" if the
+     * structure contains such a member.  Following that, we try
+     * to locate the external 'timezone' variable and use its value.
+     * If both of those methods fail, we attempt to convert a known
+     * time to local time and use the difference from UTC as the local
+     * time zone.  In all cases, we need to undo any Daylight Saving Time
+     * adjustment.
      */
     
 #if defined(HAVE_TM_TZADJ)
 #   define TCL_GOT_TIMEZONE
+
+    /* Struct tm contains tm_tzadj - that value may be used. */
+
     time_t      curTime = (time_t) currentTime;
-    struct tm  *timeDataPtr = ThreadSafeLocalTime(&curTime);
+    struct tm  *timeDataPtr = TclpLocaltime(&curTime);
     int         timeZone;
 
     timeZone = timeDataPtr->tm_tzadj  / 60;
@@ -148,12 +157,16 @@ TclpGetTimeZone (currentTime)
     }
     
     return timeZone;
+
 #endif
 
 #if defined(HAVE_TM_GMTOFF) && !defined (TCL_GOT_TIMEZONE)
 #   define TCL_GOT_TIMEZONE
+
+    /* Struct tm contains tm_gmtoff - that value may be used. */
+
     time_t     curTime = (time_t) currentTime;
-    struct tm *timeDataPtr = ThreadSafeLocalTime(&curTime);
+    struct tm *timeDataPtr = TclpLocaltime(&curTime);
     int        timeZone;
 
     timeZone = -(timeDataPtr->tm_gmtoff / 60);
@@ -162,46 +175,17 @@ TclpGetTimeZone (currentTime)
     }
     
     return timeZone;
-#endif
-
-#if defined(USE_DELTA_FOR_TZ)
-#define TCL_GOT_TIMEZONE 1
-    /*
-     * This hack replaces using global var timezone or gettimeofday
-     * in situations where they are buggy such as on AIX when libbsd.a
-     * is linked in.
-     */
 
-    int timeZone;
-    time_t tt;
-    struct tm *stm;
-    tt = 849268800L;      /*    1996-11-29 12:00:00  GMT */
-    stm = ThreadSafeLocalTime(&tt); /* eg 1996-11-29  6:00:00  CST6CDT */
-    /* The calculation below assumes a max of +12 or -12 hours from GMT */
-    timeZone = (12 - stm->tm_hour)*60 + (0 - stm->tm_min);
-    return timeZone;  /* eg +360 for CST6CDT */
 #endif
 
-    /*
-     * Must prefer timezone variable over gettimeofday, as gettimeofday does
-     * not return timezone information on many systems that have moved this
-     * information outside of the kernel.
-     */
-    
-#if defined(HAVE_TIMEZONE_VAR) && !defined (TCL_GOT_TIMEZONE)
+#if defined(HAVE_TIMEZONE_VAR) && !defined(TCL_GOT_TIMEZONE) && !defined(USE_DELTA_FOR_TZ)
 #   define TCL_GOT_TIMEZONE
-    static int setTZ = 0;
-#ifdef TCL_THREADS
-    static Tcl_Mutex tzMutex;
-#endif
-    int        timeZone;
 
-    Tcl_MutexLock(&tzMutex);
-    if (!setTZ) {
-        tzset();
-        setTZ = 1;
-    }
-    Tcl_MutexUnlock(&tzMutex);
+    int         timeZone;
+
+    /* The 'timezone' external var is present and may be used. */
+
+    SetTZIfNecessary();
 
     /*
      * Note: this is not a typo in "timezone" below!  See tzset
@@ -209,30 +193,36 @@ TclpGetTimeZone (currentTime)
      */
 
     timeZone = timezone / 60;
-
     return timeZone;
+
 #endif
 
-#if !defined(NO_GETTOD) && !defined (TCL_GOT_TIMEZONE)
-#   define TCL_GOT_TIMEZONE
-    struct timeval  tv;
-    struct timezone tz;
-    int timeZone;
+#if !defined(TCL_GOT_TIMEZONE) 
+#define TCL_GOT_TIMEZONE 1
+    /*
+     * Fallback - determine time zone with a known reference time.
+     */
 
-    gettimeofday(&tv, &tz);
-    timeZone = tz.tz_minuteswest;
-    if (tz.tz_dsttime) {
-        timeZone += 60;
+    int timeZone;
+    time_t tt;
+    struct tm *stm;
+    tt = 849268800L;      /*    1996-11-29 12:00:00  GMT */
+    stm = TclpLocaltime(&tt); /* eg 1996-11-29  6:00:00  CST6CDT */
+    /* The calculation below assumes a max of +12 or -12 hours from GMT */
+    timeZone = (12 - stm->tm_hour)*60 + (0 - stm->tm_min);
+    if ( stm -> tm_isdst ) {
+	timeZone += 60;
     }
-    
-    return timeZone;
+    return timeZone;  /* eg +360 for CST6CDT */
 #endif
 
 #ifndef TCL_GOT_TIMEZONE
     /*
      * Cause compile error, we don't know how to get timezone.
      */
-    error: autoconf did not figure out how to determine the timezone. 
+
+#error autoconf did not figure out how to determine the timezone. 
+
 #endif
 
 }
@@ -290,9 +280,9 @@ TclpGetDate(time, useGMT)
     int useGMT;
 {
     if (useGMT) {
-	return ThreadSafeGMTime(time);
+	return TclpGmtime(time);
     } else {
-	return ThreadSafeLocalTime(time);
+	return TclpLocaltime(time);
     }
 }
 
@@ -354,7 +344,7 @@ TclpStrftime(s, maxsize, format, t, useGMT)
 /*
  *----------------------------------------------------------------------
  *
- * ThreadSafeGMTime --
+ * TclpGmtime --
  *
  *	Wrapper around the 'gmtime' library function to make it thread
  *	safe.
@@ -368,33 +358,42 @@ TclpStrftime(s, maxsize, format, t, useGMT)
  *----------------------------------------------------------------------
  */
 
-static struct tm *
-ThreadSafeGMTime(timePtr)
+struct tm *
+TclpGmtime( timePtr )
     CONST time_t *timePtr;	/* Pointer to the number of seconds
-				 * since the local system's epoch
-				 */
+				 * since the local system's epoch */
 
 {
     /*
      * Get a thread-local buffer to hold the returned time.
      */
 
-    struct tm *tmPtr = (struct tm *)
-	    Tcl_GetThreadData(&tmKey, sizeof(struct tm));
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT( &tmKey );
 #ifdef HAVE_GMTIME_R
-    gmtime_r(timePtr, tmPtr);
+    gmtime_r(timePtr, &( tsdPtr->gmtime_buf ));
 #else
-    Tcl_MutexLock(&tmMutex);
-    memcpy((VOID *) tmPtr, (VOID *) gmtime(timePtr), sizeof(struct tm));
-    Tcl_MutexUnlock(&tmMutex);
+    Tcl_MutexLock( &tmMutex );
+    memcpy( (VOID *) &( tsdPtr->gmtime_buf ),
+	    (VOID *) gmtime( timePtr ),
+	    sizeof( struct tm ) );
+    Tcl_MutexUnlock( &tmMutex );
 #endif    
-    return tmPtr;
+    return &( tsdPtr->gmtime_buf );
+}
+/*
+ * Forwarder for obsolete item in Stubs
+ */
+struct tm*
+TclpGmtime_unix( timePtr )
+    CONST time_t* timePtr;
+{
+    return TclpGmtime( timePtr );
 }
 
 /*
  *----------------------------------------------------------------------
  *
- * ThreadSafeLocalTime --
+ * TclpLocaltime --
  *
  *	Wrapper around the 'localtime' library function to make it thread
  *	safe.
@@ -408,25 +407,99 @@ ThreadSafeGMTime(timePtr)
  *----------------------------------------------------------------------
  */
 
-static struct tm *
-ThreadSafeLocalTime(timePtr)
+struct tm *
+TclpLocaltime(timePtr)
     CONST time_t *timePtr;	/* Pointer to the number of seconds
-				 * since the local system's epoch
-				 */
+				 * since the local system's epoch */
 
 {
     /*
      * Get a thread-local buffer to hold the returned time.
      */
 
-    struct tm *tmPtr = (struct tm *)
-	    Tcl_GetThreadData(&tmKey, sizeof(struct tm));
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT( &tmKey );
+    SetTZIfNecessary();
 #ifdef HAVE_LOCALTIME_R
-    localtime_r(timePtr, tmPtr);
+    localtime_r( timePtr, &( tsdPtr->localtime_buf ) );
 #else
+    Tcl_MutexLock( &tmMutex );
+    memcpy( (VOID *) &( tsdPtr -> localtime_buf ),
+	    (VOID *) localtime( timePtr ),
+	    sizeof( struct tm ) );
+    Tcl_MutexUnlock( &tmMutex );
+#endif    
+    return &( tsdPtr->localtime_buf );
+}
+/*
+ * Forwarder for obsolete item in Stubs
+ */
+struct tm*
+TclpLocaltime_unix( timePtr )
+    CONST time_t* timePtr;
+{
+    return TclpLocaltime( timePtr );
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SetTZIfNecessary --
+ *
+ *	Determines whether a call to 'tzset' is needed prior to the
+ *	next call to 'localtime' or examination of the 'timezone' variable.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	If 'tzset' has never been called in the current process, or if
+ *	the value of the environment variable TZ has changed since the
+ *	last call to 'tzset', then 'tzset' is called again.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+SetTZIfNecessary() {
+
+    CONST char* newTZ = getenv( "TZ" );
     Tcl_MutexLock(&tmMutex);
-    memcpy((VOID *) tmPtr, (VOID *) localtime(timePtr), sizeof(struct tm));
+    if ( newTZ == NULL ) {
+	newTZ = "";
+    }
+    if ( lastTZ == NULL || strcmp( lastTZ, newTZ ) ) {
+        tzset();
+	if ( lastTZ == NULL ) {
+	    Tcl_CreateExitHandler( CleanupMemory, (ClientData) NULL );
+	} else {
+	    Tcl_Free( lastTZ );
+	}
+	lastTZ = Tcl_Alloc( strlen( newTZ ) + 1 );
+	strcpy( lastTZ, newTZ );
+    }
     Tcl_MutexUnlock(&tmMutex);
-#endif    
-    return tmPtr;
+
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * CleanupMemory --
+ *
+ *	Releases the private copy of the TZ environment variable
+ *	upon exit from Tcl.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Frees allocated memory.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+CleanupMemory( ClientData ignored )
+{
+    Tcl_Free( lastTZ );
 }
diff --git a/win/tclWinTime.c b/win/tclWinTime.c
index 2c10978..38523b2 100644
--- a/win/tclWinTime.c
+++ b/win/tclWinTime.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclWinTime.c,v 1.25 2004/04/23 07:12:08 davygrvy Exp $
+ * RCS: @(#) $Id: tclWinTime.c,v 1.26 2004/05/14 21:43:29 kennykb Exp $
  */
 
 #include "tclInt.h"
@@ -578,7 +578,7 @@ TclpGetDate(t, useGMT)
 #else
 	if (*t >= 0) {
 #endif
-	    return localtime(t);
+	    return TclpLocaltime(t);
 	}
 
 	time = *t - timezone;
@@ -1084,3 +1084,65 @@ AccumulateSample( Tcl_WideInt perfCounter,
 	return estFreq;
     }
 }
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpGmtime --
+ *
+ *	Wrapper around the 'gmtime' library function to make it thread
+ *	safe.
+ *
+ * Results:
+ *	Returns a pointer to a 'struct tm' in thread-specific data.
+ *
+ * Side effects:
+ *	Invokes gmtime or gmtime_r as appropriate.
+ *
+ *----------------------------------------------------------------------
+ */
+
+struct tm *
+TclpGmtime( timePtr )
+    CONST time_t *timePtr;	/* Pointer to the number of seconds
+				 * since the local system's epoch */
+
+{
+    /*
+     * The MS implementation of gmtime is thread safe because
+     * it returns the time in a block of thread-local storage,
+     * and Windows does not provide a Posix gmtime_r function.
+     */
+    return gmtime( timePtr );
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpLocaltime --
+ *
+ *	Wrapper around the 'localtime' library function to make it thread
+ *	safe.
+ *
+ * Results:
+ *	Returns a pointer to a 'struct tm' in thread-specific data.
+ *
+ * Side effects:
+ *	Invokes localtime or localtime_r as appropriate.
+ *
+ *----------------------------------------------------------------------
+ */
+
+struct tm *
+TclpLocaltime( timePtr )
+    CONST time_t *timePtr;	/* Pointer to the number of seconds
+				 * since the local system's epoch */
+
+{
+    /*
+     * The MS implementation of localtime is thread safe because
+     * it returns the time in a block of thread-local storage,
+     * and Windows does not provide a Posix localtime_r function.
+     */
+    return localtime( timePtr );
+}