Document tzgetgmtoff(3)

lib/libc/time/tzset.3

@@ -1,11 +1,12 @@
-.\"	$NetBSD: tzset.3,v 1.32 2015/04/05 08:36:38 pgoyette Exp $
-.Dd October 23, 2014
+.\"	$NetBSD: tzset.3,v 1.33 2015/10/29 17:51:58 christos Exp $
+.Dd October 29, 2015
 .Dt TZSET 3
 .Os
 .Sh NAME
 .Nm tzset ,
 .Nm tzalloc ,
 .Nm tzgetname ,
+.Nm tzgetgmtoff ,
 .Nm tzfree
 .Nd initialize time conversion information
 .Sh LIBRARY
@@ -18,6 +19,8 @@
 .Fn tzfree "timezone_t restrict tz"
 .Ft const char *
 .Fn tzgetname "timezone_t restrict tz" "int isdst"
+.Ft long
+.Fn tzgetgmtoff "timezone_t restrict tz" "int isdst"
 .Ft void
 .Fn tzset "void"
 .Sh DESCRIPTION
@@ -70,7 +73,7 @@ This invalidates any
 pointers that
 .Fa tz
 was used to set.
-Finally,
+The function
 .Fn tzgetname
 returns the name for the given
 .Fa tz .
@@ -86,6 +89,17 @@ is set to
 .Va 1
 the call is equivalent to
 .Va tzname[1] .
+Finally, the
+.Fn tzgetgmtoff
+function acts like
+.Fn tzgetname
+only it returns the offset in seconds from GMT for the timezone.
+If there is no match, then
+.Dv \-1 
+is returned and 
+.Va errno
+is set to
+.Dv ESRCH .
 The
 .Fn tzset
 function acts like