[svn] Check for timegm and use it where available.

configure.in

@@ -204,7 +204,7 @@ dnl
 AC_FUNC_ALLOCA
 AC_FUNC_MMAP
 AC_FUNC_FSEEKO
-AC_CHECK_FUNCS(strptime snprintf vsnprintf)
+AC_CHECK_FUNCS(strptime timegm snprintf vsnprintf)
 AC_CHECK_FUNCS(usleep ftello sigblock sigsetjmp symlink)
 
 dnl We expect to have these functions on Unix-like systems configure

src/ChangeLog

@@ -1,3 +1,9 @@
+2005-06-27  Hrvoje Niksic  <hniksic@xemacs.org>
+
+	* http.c (mktime_from_utc): Renamed to timegm and moved to cmpt.c.
+	Don't compile it if GNU timegm is available.
+	(http_atotm): Use timegm.
+
 2005-06-27  Hrvoje Niksic  <hniksic@xemacs.org>
 
 	* http.c (http_atotm): Correctly query the old locale value.

src/cmpt.c

@@ -1222,3 +1222,71 @@ fnmatch (const char *pattern, const char *string, int flags)
 }
 
 #endif /* not SYSTEM_FNMATCH */
+
+#ifndef HAVE_TIMEGM
+/* timegm is a GNU extension typically unavailable on non-glibc-based
+   platforms. */
+
+/* Inverse of gmtime: converts struct tm to time_t, assuming the data
+   in tm is UTC rather than local timezone.
+
+   mktime is similar but assumes struct tm, also known as the
+   "broken-down" form of time, is in local time zone.  This
+   implementation of timegm uses mktime to make the conversion
+   understanding that an offset will be introduced by the local time
+   assumption.
+
+   timegm then measures the introduced offset by applying gmtime to
+   the initial result and applying mktime to the resulting
+   "broken-down" form.  The difference between the two mktime results
+   is the measured offset which is then subtracted from the initial
+   mktime result to yield a calendar time which is the value returned.
+
+   tm_isdst in struct tm is set to 0 to force mktime to introduce a
+   consistent offset (the non DST offset) since tm and tm+o might be
+   on opposite sides of a DST change.
+
+   Some implementations of mktime return -1 for the nonexistent
+   localtime hour at the beginning of DST.  In this event, use
+   mktime(tm - 1hr) + 3600.
+
+   Schematically
+     mktime(tm)   --> t+o
+     gmtime(t+o)  --> tm+o
+     mktime(tm+o) --> t+2o
+     t+o - (t+2o - t+o) = t
+
+   Contributed by Roger Beeman <beeman@cisco.com>, with the help of
+   Mark Baushke <mdb@cisco.com> and other experts at CISCO.  Further
+   improved by Roger with assistance from Edward J. Sabol based on
+   input by Jamie Zawinski.  */
+
+time_t
+timegm (struct tm *t)
+{
+  time_t tl, tb;
+  struct tm *tg;
+
+  tl = mktime (t);
+  if (tl == -1)
+    {
+      t->tm_hour--;
+      tl = mktime (t);
+      if (tl == -1)
+	return -1; /* can't deal with contents of T */
+      tl += 3600;
+    }
+  tg = gmtime (&tl);
+  tg->tm_isdst = 0;
+  tb = mktime (tg);
+  if (tb == -1)
+    {
+      tg->tm_hour--;
+      tb = mktime (tg);
+      if (tb == -1)
+	return -1; /* can't deal with output from gmtime */
+      tb += 3600;
+    }
+  return (tl - (tb - tl));
+}
+#endif /* HAVE_TIMEGM */

src/http.c

@@ -2501,74 +2501,6 @@ The sizes do not match (local %s) -- retrieving.\n"),
   return TRYLIMEXC;
 }
 
-/* Converts struct tm to time_t, assuming the data in tm is UTC rather
-   than local timezone.
-
-   mktime is similar but assumes struct tm, also known as the
-   "broken-down" form of time, is in local time zone.  mktime_from_utc
-   uses mktime to make the conversion understanding that an offset
-   will be introduced by the local time assumption.
-
-   mktime_from_utc then measures the introduced offset by applying
-   gmtime to the initial result and applying mktime to the resulting
-   "broken-down" form.  The difference between the two mktime results
-   is the measured offset which is then subtracted from the initial
-   mktime result to yield a calendar time which is the value returned.
-
-   tm_isdst in struct tm is set to 0 to force mktime to introduce a
-   consistent offset (the non DST offset) since tm and tm+o might be
-   on opposite sides of a DST change.
-
-   Some implementations of mktime return -1 for the nonexistent
-   localtime hour at the beginning of DST.  In this event, use
-   mktime(tm - 1hr) + 3600.
-
-   Schematically
-     mktime(tm)   --> t+o
-     gmtime(t+o)  --> tm+o
-     mktime(tm+o) --> t+2o
-     t+o - (t+2o - t+o) = t
-
-   Note that glibc contains a function of the same purpose named
-   `timegm' (reverse of gmtime).  But obviously, it is not universally
-   available, and unfortunately it is not straightforwardly
-   extractable for use here.  Perhaps configure should detect timegm
-   and use it where available.
-
-   Contributed by Roger Beeman <beeman@cisco.com>, with the help of
-   Mark Baushke <mdb@cisco.com> and the rest of the Gurus at CISCO.
-   Further improved by Roger with assistance from Edward J. Sabol
-   based on input by Jamie Zawinski.  */
-
-static time_t
-mktime_from_utc (struct tm *t)
-{
-  time_t tl, tb;
-  struct tm *tg;
-
-  tl = mktime (t);
-  if (tl == -1)
-    {
-      t->tm_hour--;
-      tl = mktime (t);
-      if (tl == -1)
-	return -1; /* can't deal with output from strptime */
-      tl += 3600;
-    }
-  tg = gmtime (&tl);
-  tg->tm_isdst = 0;
-  tb = mktime (tg);
-  if (tb == -1)
-    {
-      tg->tm_hour--;
-      tb = mktime (tg);
-      if (tb == -1)
-	return -1; /* can't deal with output from gmtime */
-      tb += 3600;
-    }
-  return (tl - (tb - tl));
-}
-
 /* Check whether the result of strptime() indicates success.
    strptime() returns the pointer to how far it got to in the string.
    The processing has been successful if the string is at `GMT' or
@@ -2652,12 +2584,12 @@ http_atotm (const char *time_string)
 
       /* Some versions of strptime use the existing contents of struct
 	 tm to recalculate the date according to format.  Zero it out
-	 to prevent garbage from the stack influencing strptime.  */
+	 to prevent stack garbage from influencing strptime.  */
       xzero (t);
 
       if (check_end (strptime (time_string, time_formats[i], &t)))
 	{
-	  ret = mktime_from_utc (&t);
+	  ret = timegm (&t);
 	  break;
 	}
     }

src/sysdep.h

@@ -131,6 +131,10 @@ int strncasecmp ();
 #ifndef HAVE_STRPTIME
 char *strptime ();
 #endif
+#ifndef HAVE_TIMEGM
+# include <time.h>
+time_t timegm (struct tm *);
+#endif
 
 /* These are defined in snprintf.c.  It would be nice to have an
    snprintf.h, though.  */