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(* guestfs-inspection
* Copyright (C) 2009-2020 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*)
(** This is a generic module for running functions in a chroot directory.
It is normally used where we want to run a function on files mounted
under [Sysroot.sysroot ()] (normally [/sysroot]), ie. in the
libguestfs namespace.
The function runs in a forked subprocess, ensuring that the main
daemon process does not chroot so everything is restored properly
afterwards. (Note this is different from how the legacy
C [CHROOT_IN] and [CHROOT_OUT] macros work).
Basic usage is:
{v
let chroot = Chroot.create ~name:(sprintf "lstat: %s" path) () in
let statbuf = Chroot.f chroot lstat path in
...
v}
After this runs, [statbuf] will contain the results of [lstat]
on [Sysroot.sysroot () // path]. (Any exception thrown by [lstat]
will be rethrown in the main process.)
This module handles passing the parameter, forking, running the
function and marshalling the result or any exceptions. *)
type t
val create : ?name:string -> ?chroot:string -> unit -> t
(** Create a chroot handle.
[?name] is an optional name used in debugging and error messages.
[?chroot] is the optional chroot directory. This parameter
defaults to [Sysroot.sysroot ()]. *)
val f : t -> ('a -> 'b) -> 'a -> 'b
(** Run a function in the chroot, returning the result or re-raising
any exception thrown. *)
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