New optional ZONE arg for format-time-string etc.

This simplifies time conversions in other time zones.
It also prevents display-time-world tampering with TZ (Bug#21020).
* admin/admin.el (add-release-logs):
Use improved add-log-time-format API.
* admin/merge-gnulib (GNULIB_MODULES): Add time_rz, timegm.
(GNULIB_TOOL_FLAGS): Avoid flexmember, setenv, unsetenv.
* configure.ac (tzalloc): Remove test for this, since
Emacs no longer uses HAVE_TZALLOC directly.
* doc/lispref/os.texi (Time of Day, Time Conversion)
(Time Parsing):
* etc/NEWS: Document the new behavior.
Merge from gnulib, incorporating:
2015-07-25 strftime: fix newly-introduced bug on Solaris
2015-07-23 fprintftime, strftime: use timezone_t args
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/strftime.c, lib/strftime.h, lib/time.in.h, m4/sys_time_h.m4:
* m4/time_h.m4:
Update from gnulib.
* lib/time_rz.c, lib/timegm.c, m4/time_rz.m4, m4/timegm.m4:
New files from gnulib.
* lisp/time-stamp.el (time-stamp-string):
* lisp/time.el (display-time-world-list)
(display-time-world-display):
Use new API, with time zone arg.
* lisp/time.el (display-time-world-display):
Fix race when current-time advances while we're running.
* lisp/vc/add-log.el (add-log-iso8601-time-zone)
(add-log-iso8601-time-string): Accept optional time zone arg.
* lisp/vc/add-log.el (add-change-log-entry):
* lisp/vc/log-edit.el (log-edit-changelog-ours-p): Use new arg.
* nt/gnulib.mk: Propagate lib/gnulib.mk changes here.
Add rules for the time module, since they're now needed
for tzalloc etc.
* src/conf_post.h (getenv_TZ, setenv_TZ): New macros.
(emacs_getenv_TZ, emacs_setenv_TZ): New decls.
* src/editfns.c: Include errno.h.
(set_time_zone_rule): Omit unnecessary forward decl.
(initial_tz): Remove, replacing with ...
(local_tz, wall_clock_tz, utc_tz): New static vars and constants.
(tzeqlen): New constant; prefer it to (sizeof "TZ=" - 1).
(emacs_localtime_rz, emacs_mktime_z, xtzalloc, xtzfree)
(tzlookup): New static functions.
(init_editfns): New arg DUMPING.  All uses changed.
(init_editfns): Omit most initialization if dumping, not if
!initialized.  Initialize wall_clock_tz and local_tz.
(emacs_nmemftime, format_time_string): Time zone argument can now
be any time zone, not just a boolean for UTC or local time.  All
callers changed.
(Fformat_time_string, Fencode_time, Fcurrent_time_string)
(Fcurrent_time_zone): New optional arg ZONE.
(Fdecode_time, Fset_time_zone_rule): ZONE arg can now also take
the same form as with the other new additions.
(decode_time_zone): Remove; no longer needed.
(tzvalbuf): Now file-scope.
(emacs_getenv_TZ, emacs_setenv_TZ): New functions.
(syms_of_editfns): Define Qwall.
* src/editfns.c (mktime_z) [!HAVE_TZALLOC]:
* src/systime.h (mktime_z, timezone_t, tzalloc, tzfree)
[!HAVE_TZALLOC]:
Remove; now supplied by gnulib.
* src/emacs.c (main):
* src/lisp.h (init_editfns): Adjust to init_editfns API change.

4 files changed, 24 insertions, 47 deletions

diff --git a/lisp/time-stamp.el b/lisp/time-stamp.el
index 24e5ef47d29..1e0fe9919d2 100644
--- a/lisp/time-stamp.el
+++ b/lisp/time-stamp.el
@@ -420,16 +420,8 @@ format the string."
   (or ts-format
       (setq ts-format time-stamp-format))
   (if (stringp ts-format)
-      (if (stringp time-stamp-time-zone)
-	  (let ((ts-real-time-zone (getenv "TZ")))
-	    (unwind-protect
-		(progn
-		  (setenv "TZ" time-stamp-time-zone)
-		  (format-time-string
-		   (time-stamp-string-preprocess ts-format)))
-	      (setenv "TZ" ts-real-time-zone)))
-	(format-time-string
-	 (time-stamp-string-preprocess ts-format)))
+      (format-time-string (time-stamp-string-preprocess ts-format)
+                          nil time-stamp-time-zone)
     ;; handle version 1 compatibility
     (cond ((or (eq time-stamp-old-format-warn 'error)
 	       (and (eq time-stamp-old-format-warn 'ask)
diff --git a/lisp/time.el b/lisp/time.el
index ae0e598b64c..d35f5b93964 100644
--- a/lisp/time.el
+++ b/lisp/time.el
@@ -160,15 +160,8 @@ LABEL is a string to display as the label of that TIMEZONE's time."
 (defcustom display-time-world-list
   ;; Determine if zoneinfo style timezones are supported by testing that
   ;; America/New York and Europe/London return different timezones.
-  (let ((old-tz (getenv "TZ"))
-	gmt nyt)
-    (unwind-protect
-	(progn
-	  (setenv "TZ" "America/New_York")
-	  (setq nyt (format-time-string "%z"))
-	  (setenv "TZ" "Europe/London")
-	  (setq gmt (format-time-string "%z")))
-      (setenv "TZ" old-tz))
+  (let ((nyt (format-time-string "%z" nil "America/New_York"))
+        (gmt (format-time-string "%z" nil "Europe/London")))
     (if (string-equal nyt gmt)
         legacy-style-world-list
       zoneinfo-style-world-list))
@@ -523,21 +516,19 @@ See `display-time-world'."
   "Replace current buffer text with times in various zones, based on ALIST."
   (let ((inhibit-read-only t)
 	(buffer-undo-list t)
-	(old-tz (getenv "TZ"))
+	(now (current-time))
 	(max-width 0)
 	result fmt)
     (erase-buffer)
-    (unwind-protect
-	(dolist (zone alist)
-	  (let* ((label (cadr zone))
-		 (width (string-width label)))
-	    (setenv "TZ" (car zone))
-	    (push (cons label
-			(format-time-string display-time-world-time-format))
-		  result)
-	    (when (> width max-width)
-	      (setq max-width width))))
-      (setenv "TZ" old-tz))
+    (dolist (zone alist)
+      (let* ((label (cadr zone))
+	     (width (string-width label)))
+	(push (cons label
+		    (format-time-string display-time-world-time-format
+					now (car zone)))
+	      result)
+	(when (> width max-width)
+	  (setq max-width width))))
     (setq fmt (concat "%-" (int-to-string max-width) "s %s\n"))
     (dolist (timedata (nreverse result))
       (insert (format fmt (car timedata) (cdr timedata))))
diff --git a/lisp/vc/add-log.el b/lisp/vc/add-log.el
index eb7e5bfdfad..c90413c42c2 100644
--- a/lisp/vc/add-log.el
+++ b/lisp/vc/add-log.el
@@ -581,8 +581,8 @@ If t, use universal time.")
 (put 'add-log-time-zone-rule 'safe-local-variable
      (lambda (x) (or (booleanp x) (stringp x))))
 
-(defun add-log-iso8601-time-zone (&optional time)
-  (let* ((utc-offset (or (car (current-time-zone time)) 0))
+(defun add-log-iso8601-time-zone (&optional time zone)
+  (let* ((utc-offset (or (car (current-time-zone time zone)) 0))
 	 (sign (if (< utc-offset 0) ?- ?+))
 	 (sec (abs utc-offset))
 	 (ss (% sec 60))
@@ -596,12 +596,11 @@ If t, use universal time.")
 
 (defvar add-log-iso8601-with-time-zone nil)
 
-(defun add-log-iso8601-time-string ()
-  (let ((time (format-time-string "%Y-%m-%d"
-                                  nil (eq t add-log-time-zone-rule))))
+(defun add-log-iso8601-time-string (&optional time zone)
+  (let ((date (format-time-string "%Y-%m-%d" time zone)))
     (if add-log-iso8601-with-time-zone
-        (concat time " " (add-log-iso8601-time-zone))
-      time)))
+        (concat date " " (add-log-iso8601-time-zone time zone))
+      date)))
 
 (defun change-log-name ()
   "Return (system-dependent) default name for a change log file."
@@ -848,14 +847,8 @@ non-nil, otherwise in local time."
       (let ((new-entries
              (mapcar (lambda (addr)
                        (concat
-                        (if (stringp add-log-time-zone-rule)
-                            (let ((tz (getenv "TZ")))
-                              (unwind-protect
-                                  (progn
-                                    (setenv "TZ" add-log-time-zone-rule)
-                                    (funcall add-log-time-format))
-                                (setenv "TZ" tz)))
-                          (funcall add-log-time-format))
+                        (funcall add-log-time-format
+                                 nil add-log-time-zone-rule)
                         "  " full-name
                         "  <" addr ">"))
                      (if (consp mailing-address)
diff --git a/lisp/vc/log-edit.el b/lisp/vc/log-edit.el
index d59549772c0..acbd9c0cd9f 100644
--- a/lisp/vc/log-edit.el
+++ b/lisp/vc/log-edit.el
@@ -872,7 +872,8 @@ Return non-nil if it is."
 		  (and (boundp 'user-mail-address) user-mail-address)))
 	(time (or (and (boundp 'add-log-time-format)
 		       (functionp add-log-time-format)
-		       (funcall add-log-time-format))
+		       (funcall add-log-time-format
+				nil add-log-time-zone-rule))
 		  (format-time-string "%Y-%m-%d"))))
     (if (null log-edit-changelog-use-first)
         (looking-at (regexp-quote (format "%s  %s  <%s>" time name mail)))