From 636f5e942c8f543e8aea00f83ffbfd1ec2d3fc91 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 26 Aug 2014 12:01:30 -0700
Subject: [PROPOSED PATCH 1/4] tzalloc(NULL) now acts like tzset() does when TZ
 is unset.

Suggested by Jonathan Lennox in:
http://mm.icann.org/pipermail/tz/2014-August/021529.html
* localtime.c (tzalloc): Treat NULL argument like tzsetwall.
(tzsetwall_unlocked): Remove, replacing with ...
(tzsetlcl): New function, which merges the old tzsetwall and
tzset_unlocked.
(zoneinit): Treat a null NAME like tzsetwall.
(tzsetwall, tzset_unlocked): Rewrite to use tzsetlcl.
* NEWS: Document this.
---
 NEWS        |  4 ++--
 localtime.c | 73 ++++++++++++++++++++++++-------------------------------------
 2 files changed, 30 insertions(+), 47 deletions(-)

diff --git a/NEWS b/NEWS
index b8ef455..db9e46f 100644
--- a/NEWS
+++ b/NEWS
@@ -58,8 +58,8 @@ Unreleased, experimental changes
     zones simultaneously, e.g., an application where each thread may be
     in a different time zone.  The new functions are tzalloc, tzfree,
     localtime_rz, mktime_z, and (if STD_INSPIRED is also defined)
-    posix2time_z and time2posix_z.  (Thanks to Alan Barrett for
-    helping to debug this.)
+    posix2time_z and time2posix_z.  (Thanks to Alan Barrett and
+    Jonathan Lennox for helping to debug this.)
 
     The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
     already defined, to make it easier to configure on common platforms.
diff --git a/localtime.c b/localtime.c
index aee343e..e294a9e 100644
--- a/localtime.c
+++ b/localtime.c
@@ -1174,42 +1174,11 @@ gmtload(struct state *const sp)
 		tzparse(gmt, sp, true);
 }
 
-static void
-tzsetwall_unlocked(void)
-{
-  if (lcl_is_set < 0)
-    return;
-#ifdef ALL_STATE
-  if (! lclptr)
-    lclptr = malloc(sizeof *lclptr);
-#endif
-  if (lclptr && ! tzload(NULL, lclptr, true))
-    gmtload(lclptr);
-  settzname();
-  lcl_is_set = -1;
-}
-
-#ifdef STD_INSPIRED
-void
-tzsetwall(void)
-{
-  if (lock() != 0)
-    return;
-  tzsetwall_unlocked();
-  unlock();
-}
-#endif
-
 static struct state *
 zoneinit(struct state *sp, char const *name)
 {
   if (sp) {
-    if (! name
-	|| (name[0]
-	    && ! (tzload(name, sp, true)
-		  || (name[0] != ':' && tzparse(name, sp, false)))))
-      gmtload(sp);
-    else if (! name[0]) {
+    if (name && ! name[0]) {
       /*
       ** User wants it fast rather than right.
       */
@@ -1220,25 +1189,22 @@ zoneinit(struct state *sp, char const *name)
       sp->ttis[0].tt_gmtoff = 0;
       sp->ttis[0].tt_abbrind = 0;
       strcpy(sp->chars, gmt);
-    }
+    } else if (! (tzload(name, sp, true)
+		  || (name && name[0] != ':' && tzparse(name, sp, false))))
+      gmtload(sp);
   }
   return sp;
 }
 
 static void
-tzset_unlocked(void)
+tzsetlcl(char const *name)
 {
-  bool shortname;
-  register char const *name = getenv("TZ");
-
-  if (!name) {
-    tzsetwall_unlocked();
-    return;
-  }
-  shortname = strlen(name) < sizeof lcl_TZname;
-  if (0 < lcl_is_set && strcmp(lcl_TZname, name) == 0)
+  int lcl = name ? strlen(name) < sizeof lcl_TZname : -1;
+  if (lcl < 0
+      ? lcl_is_set < 0
+      : 0 < lcl_is_set && strcmp(lcl_TZname, name) == 0)
     return;
-  if (shortname)
+  if (0 < lcl)
     strcpy(lcl_TZname, name);
 #ifdef ALL_STATE
   if (! lclptr)
@@ -1246,7 +1212,24 @@ tzset_unlocked(void)
 #endif /* defined ALL_STATE */
   zoneinit(lclptr, name);
   settzname();
-  lcl_is_set = shortname;
+  lcl_is_set = lcl;
+}
+
+#ifdef STD_INSPIRED
+void
+tzsetwall(void)
+{
+  if (lock() != 0)
+    return;
+  tzsetlcl(NULL);
+  unlock();
+}
+#endif
+
+static void
+tzset_unlocked(void)
+{
+  return tzsetlcl(getenv("TZ"));
 }
 
 void
-- 
1.9.1