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/*
* Copyright (C) 2014 John Crispin <blogic@openwrt.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation
*
* 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.
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <libgen.h>
#include "libfstools.h"
char const *extroot_prefix = NULL;
/*
* This will execute "block extroot" and make use of mounted extroot or return
* an error.
*/
int mount_extroot(void)
{
char ldlib_path[32];
char block_path[32];
char kmod_loader[64];
struct stat s;
pid_t pid;
if (!extroot_prefix)
return -1;
/* try finding the library directory */
snprintf(ldlib_path, sizeof(ldlib_path), "%s/upper/lib", extroot_prefix);
if (stat(ldlib_path, &s) || !S_ISDIR(s.st_mode))
snprintf(ldlib_path, sizeof(ldlib_path), "%s/lib", extroot_prefix);
/* try finding the block executable */
snprintf(block_path, sizeof(block_path), "%s/upper/sbin/block", extroot_prefix);
if (stat(block_path, &s) || !S_ISREG(s.st_mode))
snprintf(block_path, sizeof(block_path), "%s/sbin/block", extroot_prefix);
if (stat(block_path, &s) || !S_ISREG(s.st_mode))
snprintf(block_path, sizeof(block_path), "/sbin/block");
if (stat(block_path, &s) || !S_ISREG(s.st_mode))
return -1;
/* set LD_LIBRARY_PATH env var and load kmods from overlay if we found a lib directory there */
if (!stat(ldlib_path, &s) && S_ISDIR(s.st_mode)) {
ULOG_INFO("loading kmods from internal overlay\n");
setenv("LD_LIBRARY_PATH", ldlib_path, 1);
snprintf(kmod_loader, sizeof(kmod_loader),
"/sbin/kmodloader %s/etc/modules-boot.d/", dirname(ldlib_path));
if (system(kmod_loader))
ULOG_ERR("failed to launch kmodloader from internal overlay\n");
}
pid = fork();
if (!pid) {
mkdir("/tmp/extroot", 0755);
execl(block_path, block_path, "extroot", NULL);
exit(-1);
} else if (pid > 0) {
int status;
waitpid(pid, &status, 0);
if (!WEXITSTATUS(status)) {
if (find_mount("/tmp/extroot/mnt")) {
mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT | MS_RDONLY, 0);
mkdir("/tmp/extroot/mnt/proc", 0755);
mkdir("/tmp/extroot/mnt/dev", 0755);
mkdir("/tmp/extroot/mnt/sys", 0755);
mkdir("/tmp/extroot/mnt/tmp", 0755);
mkdir("/tmp/extroot/mnt/rom", 0755);
if (mount_move("/tmp/extroot", "", "/mnt")) {
ULOG_ERR("moving pivotroot failed - continue normal boot\n");
umount("/tmp/extroot/mnt");
} else if (pivot("/mnt", "/rom")) {
ULOG_ERR("switching to pivotroot failed - continue normal boot\n");
umount("/mnt");
} else {
umount("/tmp/overlay");
rmdir("/tmp/overlay");
rmdir("/tmp/extroot/mnt");
rmdir("/tmp/extroot");
return 0;
}
} else if (find_mount("/tmp/extroot/overlay")) {
if (mount_move("/tmp/extroot", "", "/overlay")) {
ULOG_ERR("moving extroot failed - continue normal boot\n");
umount("/tmp/extroot/overlay");
} else if (fopivot("/overlay", "/rom")) {
ULOG_ERR("switching to extroot failed - continue normal boot\n");
umount("/overlay");
} else {
umount("/tmp/overlay");
rmdir("/tmp/overlay");
rmdir("/tmp/extroot/overlay");
rmdir("/tmp/extroot");
return 0;
}
}
}
}
return -1;
}
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