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(* virt-v2v
* Copyright (C) 2009-2016 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.
*)
(** Functions for making files and directories as another user.
[-o rhev] output mode has to write files as UID:GID 36:36,
otherwise RHEV cannot read them. Because the files are located on
NFS (and hence might be root-squashed) we also cannot chown the
files. We cannot setuid the whole process to 36:36 because it
needs to do other root things like mounting and unmounting the NFS
volume.
The solution to this craziness is to fork a subprocess every time
we need to create a file, setuid in the subprocess, and write the
file. The subprocess then exits, leaving the main process still
running as root.
This mini-library encapsulates this tomfoolery into something that
is slightly more sane to use.
NB. We are {b not} dropping permissions for security reasons.
This file has nothing to do with security. *)
type t
(** Abstract handle. *)
val create : ?uid:int -> ?gid:int -> unit -> t
(** Create handle. The optional [?uid] and [?gid] parameters are the
user/group to run as. If omitted, then we don't change user
and/or group (but we still do the forking anyway). *)
val mkdir : t -> string -> int -> unit
(** [mkdir t path perm] creates the directory [path] with mode [perm]. *)
val rmdir : t -> string -> unit
(** [rmdir t path] removes the directory [path]. *)
val make_file : t -> string -> string -> unit
(** [make_file t path content] creates the file [path] with content
[content]. The current umask controls file permissions. *)
val output : t -> string -> (out_channel -> unit) -> unit
(** [output t path f] creates the file [path] with content from
function [f]. The current umask controls file permissions. *)
val unlink : t -> string -> unit
(** [unlink t path] deletes the file [path]. *)
val func : t -> (unit -> unit) -> unit
(** [func t f] runs the arbitrary function [f]. *)
val command : t -> string -> unit
(** [command t cmd] runs [cmd] as the alternate user/group after
forking. *)
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