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/* -*- c-file-style: "gnu" -*-
* ostree-init.c - switch to new root directory and start init.
* Copyright 2011 Colin Walters <walters@verbum.org>
*
* 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, see <http://www.gnu.org/licenses/>.
*
*/
#define _GNU_SOURCE
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <fcntl.h>
#include <assert.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <dirent.h>
#define INIT_PATH "/sbin/init"
static int
perrorv (const char *format, ...) __attribute__ ((format (printf, 1, 2)));
static int
perrorv (const char *format, ...)
{
va_list args;
char buf[PATH_MAX];
char *p;
p = strerror_r (errno, buf, sizeof (buf));
va_start (args, format);
vfprintf (stderr, format, args);
fprintf (stderr, ": %s\n", p);
fflush (stderr);
va_end (args);
sleep (3);
return 0;
}
int main(int argc, char *argv[])
{
FILE *cmdline_f = NULL;
const char *ostree_root = NULL;
const char *p = NULL;
size_t bytes_read;
size_t buf_size;
size_t buf_used;
char destpath[PATH_MAX];
char *buf;
struct stat stbuf;
char **init_argv = NULL;
int i;
cmdline_f = fopen ("/proc/cmdline", "r");
if (!cmdline_f)
{
perrorv ("Failed to open /proc/cmdline");
return 1;
}
buf_size = 8;
buf_used = 0;
buf = malloc (buf_size);
assert (buf);
while ((bytes_read = fread (buf + buf_used, 1, buf_size - buf_used, cmdline_f)) > 0)
{
buf_used += bytes_read;
if (buf_size == buf_used)
{
buf_size *= 2;
buf = realloc (buf, buf_size);
assert (buf);
}
}
if (bytes_read < 0)
{
perrorv ("Failed to read from /proc/cmdline");
exit (1);
}
for (p = buf; *p; p += strlen (p) + 1)
{
if (!strcmp (p, "ostree="))
{
ostree_root = p + strlen ("ostree=");
break;
}
}
if (ostree_root)
{
snprintf (destpath, sizeof(destpath), "/ostree/%s", ostree_root);
if (stat (destpath, &stbuf) < 0)
{
perrorv ("Invalid ostree root '%s'", destpath);
exit (1);
}
snprintf (destpath, sizeof(destpath), "/ostree/%s/sysroot", ostree_root);
if (mount ("/", destpath, NULL, MS_BIND, NULL) < 0)
{
perrorv ("Failed to bind mount / to '%s'", destpath);
exit (1);
}
snprintf (destpath, sizeof(destpath), "/ostree/%s", ostree_root);
if (chroot (destpath) < 0)
{
perrorv ("failed to change root to '%s'", destpath);
exit (1);
}
if (chdir ("/") < 0)
{
perrorv ("failed to chdir to subroot");
exit (1);
}
}
else
{
fprintf (stderr, "No ostree= argument specified\n");
exit (1);
}
init_argv = malloc (sizeof (char*)*(argc+1));
init_argv[0] = INIT_PATH;
for (i = 1; i < argc; i++)
init_argv[i] = argv[i];
init_argv[i] = NULL;
execv (INIT_PATH, init_argv);
perrorv ("Failed to exec init '%s'", INIT_PATH);
exit (1);
}
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