bectl: use jail id as the default jail name for a boot environment

By default, bectl is setting the jail 'name' parameter to the boot
environment name, which causes an error when the boot environment name is
not a valid jail name. With the attached fix, when no name is supplied, the
default jail name will be the jail id - this is is the same behavior as the
jail command.

Additionally, this commit addresses two other bugs that prevented unjailing
in scenarios where the jail name does not match the boot environment name:

1. In 'bectl_locate_jail', 'mountpoint' is used to resolve the boot
  environment path, but really 'mounted' should be used. 'mountpoint' is the
  path where the zfs dataset will be mounted. 'mounted' is the path where
  the dataset is actually mounted.

2. in 'bectl_search_jail_paths', 'jail_getv' would fail after the first
  call. Which is fine, if the boot environment you're unjailing is the next
  one up. According to 'man jail_getv', it's expecting name and value
  strings. 'jail_getv' is being passed an integer for the lastjid, so amend
  that to use a string instead.

Test cases have been amended to reflect the bugs found.

PR:		233637
Submitted by:	Rob <rob.fx907_gmail.com>
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D18607

1 files changed, 3 insertions, 8 deletions

diff --git a/sbin/bectl/bectl.8 b/sbin/bectl/bectl.8
index 575091613a12..daff7306b0dd 100644
--- a/sbin/bectl/bectl.8
+++ b/sbin/bectl/bectl.8
@@ -18,7 +18,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 21, 2018
+.Dd December 25, 2018
 .Dt BECTL 8
 .Os
 .Sh NAME
@@ -52,7 +52,6 @@
 .Cm jail
 .Brq Fl b | Fl U
 .Oo Bro Fl o Ar key Ns = Ns Ar value | Fl u Ar key Brc Oc Ns ...
-.Brq Ar jailID | jailName
 .Ar bootenv
 .Op Ar utility Op Ar argument ...
 .Nm
@@ -153,7 +152,6 @@ from
 .Cm jail
 .Brq Fl b | Fl U
 .Oo Bro Fl o Ar key Ns = Ns Ar value | Fl u Ar key Brc Oc Ns ...
-.Brq Ar jailID | jailName
 .Ao Ar bootenv Ac
 .Op Ar utility Op Ar argument ...
 .Xc
@@ -193,10 +191,7 @@ The
 .Va host.hostname ,
 and
 .Va path
-may not actually be unset.
-Attempts to unset any of these will revert them to the default values specified
-below, if they have been overwritten by
-.Fl o .
+must be set, the default values are specified below.
 .Pp
 All
 .Ar key Ns = Ns Ar value
@@ -207,7 +202,7 @@ The following default parameters are provided:
 .It Va allow.mount Ta Cm true
 .It Va allow.mount.devfs Ta Cm true
 .It Va enforce_statfs Ta Cm 1
-.It Va name Ta Va bootenv
+.It Va name Ta jail id
 .It Va host.hostname Ta Va bootenv
 .It Va path Ta Set to a path in /tmp generated by
 .Xr libbe 3 .