From 34c44c01e93645c52101eff2e63559a0b2365ba1 Mon Sep 17 00:00:00 2001
From: Bruce Allen <bruce.allen@aei.mpg.de>
Date: Thu, 5 May 2005 04:26:52 +0000
Subject: [PATCH] Bug fix so that Unix hosts report their timezones correctly.
 NOTE: hosts that lack a gmt offset in the tm structure (System V with no BSD
 extensions) will have the WRONG SIGN for the timezone. This can be fixed by
 changing the signs of __timezone, _timezone and timezone in get_timezone(),
 but I won't do it until David signs off.

Note that with this change we adopt the convention that the database
timezone value is the (Local Standard Time) - (UTC time).  This
quantity only depends upon spatial location on the earth's surface and
is NOT a function of time.

svn path=/trunk/boinc/; revision=6027
---
 checkin_notes          | 16 ++++++++++++++++
 client/hostinfo_unix.C | 14 ++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/checkin_notes b/checkin_notes
index e5c95521c8..5943637372 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -6055,3 +6055,19 @@ David  4 May 2005
         boinc_api.C
     db/
         schema.sql
+
+Bruce 4 May 2005
+    - bug fix so that Unix hosts report their timezones correctly.
+      NOTE: hosts that lack a gmt offset in the tm structure (System V
+      with no BSD extensions) will have the WRONG SIGN for the timezone.
+      This can be fixed by changing the signs of __timezone, _timezone and
+      timezone in get_timezone(), but I won't do it until David signs
+      off.
+    - Note that with this change we adopt the convention that the database
+      timezone value is the (Local Standard Time) - (UTC time).  This
+      quantity only depends upon spatial location on the earth's surface and
+      is NOT a function of time.
+
+    client/
+        hostinfo_unix.C
+ 
diff --git a/client/hostinfo_unix.C b/client/hostinfo_unix.C
index b2af285915..0655eb2eff 100644
--- a/client/hostinfo_unix.C
+++ b/client/hostinfo_unix.C
@@ -98,7 +98,8 @@ char* ip_addr_string(int ip_addr) {
 }
 #endif
 
-// Returns the number of seconds difference from UTC
+// Returns the offset between LOCAL STANDARD TIME and UTC.
+// LOCAL_STANDARD_TIME = UTC_TIME + get_timezone().
 //
 int get_timezone() {
     tzset();
@@ -109,13 +110,22 @@ int get_timezone() {
 
     cur_time = time(NULL);
     time_data = localtime( &cur_time );
-    return time_data->tm_gmtoff;
+    if (time_data->tm_isdst>0) {
+        // daylight savings in effect
+        return (time_data->tm_gmtoff)-3600;
+    } else {
+        // no daylight savings in effect
+        return time_data->tm_gmtoff;
+    }
 #elif defined(linux)
     return __timezone;
+    // SHOULD BE -1*__timezone;
 #elif defined(__CYGWIN32__)
     return _timezone;
+    // SHOULD BE -1*_timezone;
 #elif defined(unix)
     return timezone;
+    // SHOULD BE -1*timezone;
 #else
 #error timezone
 #endif