From: Steve McIntyre <steve@einval.com>
Date: Fri, 15 Apr 2016 14:48:53 +0000 (+0100)
Subject: Change the sanity check on save to use the release date
X-Git-Tag: v0.11^0
X-Git-Url: https://git.einval.com/cgi-bin/gitweb.cgi?p=fake-hwclock.git;a=commitdiff_plain;h=f889fd09f2d8d55819dd53785e8bd895866e6628

Change the sanity check on save to use the release date

Rather than disallowing saving a clock prior to the last saved state,
now compare to a fixed date which corresponds to the release of
fake-hwclock itself. Closes: #819019
---

diff --git a/debian/changelog b/debian/changelog
index eeac978..a410a58 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+fake-hwclock (0.11) unstable; urgency=medium
+
+  * Change the sanity checking behaviour on save. Rather than disallowing
+    saving a clock prior to the last saved state, now compare to a fixed
+    date which corresponds to the release of fake-hwclock itself.
+    Closes: #819019
+
+ -- Steve McIntyre <93sam@debian.org>  Fri, 15 Apr 2016 12:32:30 +0100
+
 fake-hwclock (0.10) unstable; urgency=medium
 
   * Add a save call to the postinst, to make sure that we save working
diff --git a/fake-hwclock b/fake-hwclock
index 5c34775..a8e72fa 100755
--- a/fake-hwclock
+++ b/fake-hwclock
@@ -6,7 +6,7 @@
 # NTP is still recommended on these machines to get to real time sync
 # once more of the system is up and running.
 #
-# Copyright 2012 Steve McIntyre <93sam@debian.org>
+# Copyright 2012-2016 Steve McIntyre <93sam@debian.org>
 #
 # License: GPLv2, see COPYING
 
@@ -14,6 +14,11 @@ if [ "$FILE"x = ""x ] ; then
     FILE=/etc/fake-hwclock.data
 fi
 
+# Midnight on the day of this release, used as a sanity check when
+# saving
+HWCLOCK_EPOCH="2016-04-15 00:00:00"
+HWCLOCK_EPOCH_SEC="1460678400"
+
 COMMAND=$1
 if [ "$COMMAND"x = ""x ] ; then
     COMMAND="save"
@@ -27,15 +32,14 @@ fi
 case $COMMAND in
     save)
         if [ -e $FILE ] ; then
-            SAVED="$(cat $FILE)"
-            SAVED_SEC=$(date -u -d "$SAVED" '+%s')
             NOW_SEC=$(date -u '+%s')
-            if $FORCE || [ $NOW_SEC -ge $SAVED_SEC ] ; then
+            if $FORCE || [ $NOW_SEC -ge $HWCLOCK_EPOCH_SEC ] ; then
                 date -u '+%Y-%m-%d %H:%M:%S' > $FILE
             else
+		echo "Time travel detected!"
+                echo "fake-hwclock release date is in the future: $HWCLOCK_EPOCH"
                 echo "Current system time: $(date -u '+%Y-%m-%d %H:%M:%S')"
-                echo "fake-hwclock saved clock information is in the future: $SAVED"
-                echo "To force the saved system clock backwards anyway, use \"force\""
+                echo "To force the saved system clock backwards in time anyway, use \"force\""
             fi
         else
             date -u '+%Y-%m-%d %H:%M:%S' > $FILE
diff --git a/fake-hwclock.8 b/fake-hwclock.8
index 6090c36..9da62ae 100644
--- a/fake-hwclock.8
+++ b/fake-hwclock.8
@@ -34,9 +34,9 @@ If no command is given then fake-hwclock acts as if the save command was used.
 .SS
 .TP
 \fBsave\fP
-Save the time to the file. If force is specified fake-hwclock will move the
-saved clock either backwards or forwards. Otherwise it will only move
-it forwards.
+Save the time to the file. As a sanity check, fake-hwclock will not
+move the saved clock backwards to a time/date earlier than its own
+release date. Use "force" to over-ride this check.
 .TP
 \fBload\fP
 Load the time from the file. If force is specified fake-hwclock will move the