(MAYBE_SET_TZ_UTC0): New macro.

(set_tz): New function.
(batch_convert): If necessary, save the initial value of TZ and
for each date in the file, restore it before each call to get_date,
then set it to UTC0 before each show_date call.
(main): Don't set TZ before calling get_date.
Set TZ after get_date call and before show_date call.
Reported by Matthew Braun.

diff --git a/src/date.c b/src/date.c
index b94853a..36bc01f 100644 (file)
--- a/src/date.c
+++ b/src/date.c
@@ -37,6 +37,9 @@ int putenv ();
 int stime ();
 
 char *xrealloc ();
+char *xmalloc ();
+char *xstrdup ();
+char *stpcpy ();
 time_t posixtime ();
 
 static void show_date __P ((const char *format, time_t when));
@@ -72,8 +75,29 @@ static struct option const long_options[] =
   {NULL, 0, NULL, 0}
 };
 
-/* Parse each line in INPUT_FILENAME as with --date and display the
-   each resulting time and date.  If the file cannot be opened, tell why
+#define TZ_UTC0 "TZ=UTC0"
+
+#if LOCALTIME_CACHE
+# define TZSET tzset ()
+#else
+# define TZSET /* empty */
+#endif
+
+#define MAYBE_SET_TZ_UTC0 \
+  do { if (universal_time) set_tz (TZ_UTC0); } while (0)
+
+/* Set the TZ environment variable.  */
+
+static void
+set_tz (const char *tz_eq_zone)
+{
+  if (putenv (tz_eq_zone) != 0)
+    error (1, 0, "memory exhausted");
+  TZSET;
+}
+
+/* Parse each line in INPUT_FILENAME as with --date and display each
+   resulting time and date.  If the file cannot be opened, tell why
    then exit.  Issue a diagnostic for any lines that cannot be parsed.
    If any line cannot be parsed, return nonzero;  otherwise return zero.  */
 
@@ -86,6 +110,12 @@ batch_convert (const char *input_filename, const char *format)
   int line_length;
   size_t buflen;
   time_t when;
+  char *initial_TZ;
+
+#ifdef lint
+  /* Suppress `may be used before initialized' warning.  */
+  initial_TZ = NULL;
+#endif
 
   if (strcmp (input_filename, "-") == 0)
     {
@@ -104,6 +134,21 @@ batch_convert (const char *input_filename, const char *format)
   line = NULL;
   buflen = 0;
 
+  if (universal_time)
+    {
+      initial_TZ = getenv ("TZ");
+      if (initial_TZ == NULL)
+       {
+         initial_TZ = xstrdup ("TZ=");
+       }
+      else
+       {
+         char *buf = xmalloc (3 + strlen (initial_TZ) + 1);
+         stpcpy (stpcpy (buf, "TZ="), initial_TZ);
+         initial_TZ = buf;
+       }
+    }
+
   status = 0;
   while (1)
     {
@@ -113,7 +158,16 @@ batch_convert (const char *input_filename, const char *format)
          /* FIXME: detect/handle error here.  */
          break;
        }
+
+      if (universal_time)
+       {
+         /* When given a universal time option, restore the initial
+            value of TZ before parsing each string.  */
+         set_tz (initial_TZ);
+       }
+
       when = get_date (line, NULL);
+
       if (when == -1)
        {
          if (line[line_length - 1] == '\n')
@@ -123,10 +177,13 @@ batch_convert (const char *input_filename, const char *format)
        }
       else
        {
+         MAYBE_SET_TZ_UTC0;
          show_date (format, when);
        }
     }
 
+  free (initial_TZ);
+
   if (fclose (in_stream) == EOF)
     error (2, errno, input_filename);
 
@@ -181,11 +238,6 @@ main (int argc, char **argv)
        break;
       case 'u':
        universal_time = 1;
-       if (putenv ("TZ=UTC0") != 0)
-         error (1, 0, "memory exhausted");
-#if LOCALTIME_CACHE
-       tzset ();
-#endif
        break;
       default:
        usage (1);
@@ -278,7 +330,10 @@ argument must be a format string beginning with `+'."),
              when = refstats.st_mtime;
            }
          else
-           when = get_date (datestr, NULL);
+           {
+             when = get_date (datestr, NULL);
+           }
+
          format = (n_args == 1 ? argv[optind] + 1 : NULL);
        }
 
@@ -293,6 +348,10 @@ argument must be a format string beginning with `+'."),
            error (0, errno, _("cannot set date"));
        }
 
+      /* When given a universal time option, set TZ to UTC0 after
+        parsing the specified date, but before printing it.  */
+      MAYBE_SET_TZ_UTC0;
+
       show_date (format, when);
     }