[Bug 1707645] [NEW] system with high numbered uids has huge sparse /var/log/lastlog

[Jamie Strandboge]

Public bug reported:

I was investigating the use of a single high UID user (ie, 2000000000)
and discovered that /var/log/lastlog grew to an enormously large sparse
file:

$ ls -lh /var/log/lastlog 
-rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

The file is actually quite small though:
$ ls -lh --size /var/log/lastlog 
56K -rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

On a standalone system, this is possibly not a problem since it is
highly unlikely that a system will have 2 billion users, but this is
confirmed to wreak havoc on rsync backups.

** Affects: util-linux (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  system with high numbered uids has huge sparse /var/log/lastlog

Status in util-linux package in Ubuntu:
  New

Bug description:
  I was investigating the use of a single high UID user (ie, 2000000000)
  and discovered that /var/log/lastlog grew to an enormously large
  sparse file:

  $ ls -lh /var/log/lastlog 
  -rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

  The file is actually quite small though:
  $ ls -lh --size /var/log/lastlog 
  56K -rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

  On a standalone system, this is possibly not a problem since it is
  highly unlikely that a system will have 2 billion users, but this is
  confirmed to wreak havoc on rsync backups.

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