mail-big-homedirs: add sanity check for lastlog parsing

If we find a negative timestamp, something's gone wrong, abort.

Signed-off-by: Julien Cristau <jcristau@debian.org>

diff --git a/modules/porterbox/files/mail-big-homedirs b/modules/porterbox/files/mail-big-homedirs
index 9f86801..fc9ad45 100755 (executable)
--- a/modules/porterbox/files/mail-big-homedirs
+++ b/modules/porterbox/files/mail-big-homedirs
@@ -139,6 +139,9 @@ class LastlogTimes(dict):
                                % (len(record), record_size))
         uid += 1 # so keep incrementing uid for each record read
         lastlog_time, _, _ = list(struct.unpack(self.LASTLOG_STRUCT, record))
+        if lastlog_time < 0:
+            raise RuntimeError('unexpected last login time %d for user %s'
+                               % (lastlog_time, pwd.getpwuid(uid).pw_name))
         try:
           self[pwd.getpwuid(uid).pw_name] = lastlog_time
         except KeyError: