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/***
This file is part of eudev, forked from systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include "util.h"
#include "virt.h"
#include "fileio.h"
int detect_container(const char **id) {
static thread_local int cached_found = -1;
static thread_local const char *cached_id = NULL;
_cleanup_free_ char *m = NULL;
const char *_id = NULL, *e = NULL;
int r;
if (_likely_(cached_found >= 0)) {
if (id)
*id = cached_id;
return cached_found;
}
/* /proc/vz exists in container and outside of the container,
* /proc/bc only outside of the container. */
if (access("/proc/vz", F_OK) >= 0 &&
access("/proc/bc", F_OK) < 0) {
_id = "openvz";
r = 1;
goto finish;
}
if (getpid() == 1) {
/* If we are PID 1 we can just check our own
* environment variable */
e = getenv("container");
if (isempty(e)) {
r = 0;
goto finish;
}
} else {
/* Otherwise, PID 1 dropped this information into a
* file in /run. This is better than accessing
* /proc/1/environ, since we don't need CAP_SYS_PTRACE
* for that. */
r = read_one_line_file("/run/systemd/container", &m);
if (r == -ENOENT) {
r = 0;
goto finish;
}
if (r < 0)
return r;
e = m;
}
/* We only recognize a selected few here, since we want to
* enforce a redacted namespace */
if (streq(e, "lxc"))
_id ="lxc";
else if (streq(e, "lxc-libvirt"))
_id = "lxc-libvirt";
else if (streq(e, "systemd-nspawn"))
_id = "systemd-nspawn";
else if (streq(e, "docker"))
_id = "docker";
else
_id = "other";
r = 1;
finish:
cached_found = r;
cached_id = _id;
if (id)
*id = _id;
return r;
}
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