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/* ----------------------------------------------------------------------- *
*
* Copyright 2004-2006 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* Usage: exec run-init [-d caps] [-c /dev/console] [-n] [-p] /real-root /sbin/init "$@"
*
* This program should be called as the last thing in a shell script
* acting as /init in an initramfs; it does the following:
*
* 1. Delete all files in the initramfs;
* 2. Remounts /real-root onto the root filesystem;
* 3. Drops comma-separated list of capabilities;
* 4. Chroots;
* 5. Opens /dev/console;
* 6. Spawns the specified init program (with arguments.)
*
* With the -p option, it skips step 1 in order to allow the initramfs to
* be persisted into the running system.
*
* With the -n option, it skips steps 1, 2 and 6 and can be used to check
* whether the given root and init are likely to work.
*/
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "run-init.h"
static const char *program;
static void __attribute__ ((noreturn)) usage(void)
{
fprintf(stderr,
"Usage: exec %s [-d caps] [-c consoledev] [-n] [-p] /real-root /sbin/init [args]\n",
program);
exit(1);
}
int main(int argc, char *argv[])
{
/* Command-line options and defaults */
const char *console = "/dev/console";
const char *realroot;
const char *init;
const char *error;
const char *drop_caps = NULL;
bool dry_run = false;
bool persist_initramfs = false;
char **initargs;
/* Variables... */
int o;
/* Parse the command line */
program = argv[0];
while ((o = getopt(argc, argv, "c:d:pn")) != -1) {
if (o == 'c') {
console = optarg;
} else if (o == 'd') {
drop_caps = optarg;
} else if (o == 'n') {
dry_run = true;
} else if (o == 'p') {
persist_initramfs = true;
} else {
usage();
}
}
if (argc - optind < 2)
usage();
realroot = argv[optind];
init = argv[optind + 1];
initargs = argv + optind + 1;
error = run_init(realroot, console, drop_caps, dry_run, persist_initramfs, init, initargs);
if (error) {
fprintf(stderr, "%s: %s: %s\n", program, error, strerror(errno));
return 1;
} else {
/* Must have been a dry run */
return 0;
}
}
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