We don't want to inherit any FDs in the new namespace
except for the stdio FDs. Explicitly close them all,
just in case some do not have the close-on-exec flag
set.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit b7fcc799)

and wrap some long lines
Signed-off-by: NEric Blake <eblake@redhat.com>

Address a number of code, style and docs issues identified
in review of virt-login-shell after it was merged.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The virLoginShellAllowedUser method must not free the 'groups'
parameter it is given, as that is owned by the caller.

The virLoginShellAllowedUser method should be checking
'!*ptr' (ie empty string) rather than '!ptr' (NULL string)
since the latter cannot be true.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

virt-login-shell.c was failing to compile with

CC       virt_login_shell-virt-login-shell.o
virt-login-shell.c: In function 'main':
virt-login-shell.c:205:5: error: implicit declaration of function 'setlocale' [-Werror=implicit-function-declaration]
virt-login-shell.c:205:5: error: nested extern declaration of 'setlocale' [-Werror=nested-externs]
virt-login-shell.c:205:20: error: 'LC_ALL' undeclared (first use in this function)

Add a virt-login-shell binary that can be set as a user's
shell, such that when they login, it causes them to enter
the LXC container with a name matching their user name.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>