[Libguestfs] [PATCH RFC] sysprep: remove user accounts

[Richard W.M. Jones]

On Wed, Apr 18, 2012 at 05:14:39PM +0800, Wanlong Gao wrote:
> Hi Rich,
> This patch attends to remove the user accounts in the guest,
> I send this out to request your comments, if the concept
> is correct and you can point out some syntax error for me.

One thought I have is:

Should we only enable a "core" of functions by default, and let the
user enable other ones?  That would allow us to put experimental
functions in, disabled by default, without too much risk.

Other comments inline below.

> +let user_account_perform g root =
> +  let typ = g#inspect_get_type root in
> +  if typ <> "windows" then (
> +    let login_def = "/etc/login.defs" in
> +    let lines = Array.to_list (g#read_lines login_def) in
> +    let line_min = Array.filter (
> +      fun line -> (string_prefix line "UID_MIN")
> +    ) lines in
> +    let _,min_uid = sscanf line_min "%s %d" (fun a b -> a,b) in
> +    let line_max = Array.filter (
> +      fun line -> (string_prefix line "UID_MAX")
> +    ) lines in
> +    let _,max_uid = sscanf line_max "%s %d" (fun a b -> a,b) in

Augeas has lenses for login.defs, passwd, shadow and group.  The
Augeas API is exposed through libguestfs, and it's relatively easy to
use.  Easier than parsing files ...

For example:

  $ guestfish --ro -a /dev/vg_pin/RHEL60x64 -i
  
  Welcome to guestfish, the libguestfs filesystem interactive shell for
  editing virtual machine filesystems.
  
  Type: 'help' for help on commands
        'man' to read the manual
        'quit' to quit the shell
  
  Operating system: Red Hat Enterprise Linux Server release 6.0 (Santiago)
  /dev/mapper/vg_rhel6brewx64-lv_root mounted on /
  /dev/vda1 mounted on /boot
  
  ><fs> aug-init / 0
  ><fs> aug-ls /files/etc/login.defs
  /files/etc/login.defs/#comment[10]
  /files/etc/login.defs/#comment[11]
  /files/etc/login.defs/#comment[12]
  /files/etc/login.defs/#comment[13]
  /files/etc/login.defs/#comment[14]
  /files/etc/login.defs/#comment[15]
  /files/etc/login.defs/#comment[16]
  /files/etc/login.defs/#comment[17]
  /files/etc/login.defs/#comment[18]
  /files/etc/login.defs/#comment[19]
  /files/etc/login.defs/#comment[1]
  /files/etc/login.defs/#comment[20]
  /files/etc/login.defs/#comment[21]
  /files/etc/login.defs/#comment[22]
  /files/etc/login.defs/#comment[23]
  /files/etc/login.defs/#comment[24]
  /files/etc/login.defs/#comment[2]
  /files/etc/login.defs/#comment[3]
  /files/etc/login.defs/#comment[4]
  /files/etc/login.defs/#comment[5]
  /files/etc/login.defs/#comment[6]
  /files/etc/login.defs/#comment[7]
  /files/etc/login.defs/#comment[8]
  /files/etc/login.defs/#comment[9]
  /files/etc/login.defs/CREATE_HOME
  /files/etc/login.defs/ENCRYPT_METHOD
  /files/etc/login.defs/GID_MAX
  /files/etc/login.defs/GID_MIN
  /files/etc/login.defs/MAIL_DIR
  /files/etc/login.defs/PASS_MAX_DAYS
  /files/etc/login.defs/PASS_MIN_DAYS
  /files/etc/login.defs/PASS_MIN_LEN
  /files/etc/login.defs/PASS_WARN_AGE
  /files/etc/login.defs/UID_MAX
  /files/etc/login.defs/UID_MIN
  /files/etc/login.defs/UMASK
  /files/etc/login.defs/USERGROUPS_ENAB
  ><fs> aug-get /files/etc/login.defs/UID_MAX
  60000
  ><fs> aug-get /files/etc/login.defs/UID_MIN
  500

It might make things easier if we used Augeas here.

But the general idea is good.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org