glibc/support/support_can_chroot.c

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/* Return true if the process can perform a chroot operation.
Copyright (C) 2017-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C Library 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stdio.h>
#include <support/check.h>
#include <support/namespace.h>
#include <support/support.h>
#include <support/xunistd.h>
#include <sys/stat.h>
#include <unistd.h>
static void
callback (void *closure)
{
int *result = closure;
struct stat64 before;
xstat ("/dev", &before);
if (chroot ("/dev") != 0)
{
*result = errno;
return;
}
struct stat64 after;
xstat ("/", &after);
TEST_VERIFY (before.st_dev == after.st_dev);
TEST_VERIFY (before.st_ino == after.st_ino);
*result = 0;
}
bool
support_can_chroot (void)
{
int *result = support_shared_allocate (sizeof (*result));
*result = 0;
support_isolate_in_subprocess (callback, result);
bool ok = *result == 0;
if (!ok)
{
static bool already_warned;
if (!already_warned)
{
already_warned = true;
errno = *result;
printf ("warning: this process does not support chroot: %m\n");
}
}
support_shared_free (result);
return ok;
}