switch_root: new command
Copied from Dracut project: git://dracut.git.sourceforge.net/gitroot/dracut switch_root history in dracut.git repository: $ git shortlog switch_root.c Harald Hoyer (5): replace switch_root shell script with binary add \n to switch_root use switch_root code from http://pjones.fedorapeople.org/mkstart/usr/lib/mkstart/switchroot.c mount move instead of umount and fix the search for fallback inits setsid() and set controlling terminal for real /sbin/init Victor Lowther (2): Simplify switch_root.c a bit Remove all files on the initramfs before switching root Signed-off-by: Peter Jones <pjones@redhat.com> Signed-off-by: Karel Zak <kzak@redhat.com>
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AUTHORS
2
AUTHORS
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@ -29,6 +29,8 @@ AUTHORS (merged projects & commands):
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setarch: Elliot Lee <sopwith@redhat.com>
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Jindrich Novy <jnovy@redhat.com>
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simpleinit: Richard Gooch <rgooch@atnf.csiro.au>
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switch_root: Peter Jones <pjones@redhat.com>
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Jeremy Katz <katzj@redhat.com>
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CONTRIBUTORS:
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@ -180,6 +180,7 @@ sys-utils/renice.c
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sys-utils/rtcwake.c
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sys-utils/setarch.c
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sys-utils/setsid.c
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sys-utils/switch_root.c
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sys-utils/tunelp.c
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text-utils/col.c
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text-utils/colcrt.c
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@ -36,6 +36,7 @@ sparc32.8
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sparc32bash.8
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sparc64.8
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sparc.8
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switch_root
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tunelp
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vidmode.8
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x86_64.8
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@ -1,7 +1,7 @@
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include $(top_srcdir)/config/include-Makefile.am
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bin_PROGRAMS =
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sbin_PROGRAMS =
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sbin_PROGRAMS = switch_root
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usrbinexec_PROGRAMS = flock ipcrm ipcs ipcmk renice setsid
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usrsbinexec_PROGRAMS = readprofile
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@ -0,0 +1,198 @@
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/*
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* switchroot.c - switch to new root directory and start init.
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*
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* Copyright 2002-2008 Red Hat, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Authors:
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* Peter Jones <pjones@redhat.com>
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* Jeremy Katz <katzj@redhat.com>
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*/
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#define _GNU_SOURCE 1
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#include <sys/mount.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/param.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <ctype.h>
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#include <dirent.h>
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#ifndef MS_MOVE
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#define MS_MOVE 8192
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#endif
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#ifndef MNT_DETACH
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#define MNT_DETACH 0x2
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#endif
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enum {
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ok,
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err_no_directory,
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err_usage,
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};
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/* remove all files/directories below dirName -- don't cross mountpoints */
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static int
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recursiveRemove(char * dirName)
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{
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struct stat sb,rb;
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DIR * dir;
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struct dirent * d;
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char * strBuf = alloca(strlen(dirName) + 1024);
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if (!(dir = opendir(dirName))) {
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printf("error opening %s: %m\n", dirName);
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return 0;
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}
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if (fstat(dirfd(dir),&rb)) {
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printf("unable to stat %s: %m\n", dirName);
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closedir(dir);
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return 0;
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}
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errno = 0;
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while ((d = readdir(dir))) {
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errno = 0;
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if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, "..")) {
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errno = 0;
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continue;
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}
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strcpy(strBuf, dirName);
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strcat(strBuf, "/");
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strcat(strBuf, d->d_name);
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if (lstat(strBuf, &sb)) {
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printf("failed to stat %s: %m\n", strBuf);
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errno = 0;
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continue;
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}
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/* only descend into subdirectories if device is same as dir */
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if (S_ISDIR(sb.st_mode)) {
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if (sb.st_dev == rb.st_dev) {
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recursiveRemove(strBuf);
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if (rmdir(strBuf))
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printf("failed to rmdir %s: %m\n", strBuf);
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}
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errno = 0;
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continue;
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}
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if (unlink(strBuf)) {
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printf("failed to remove %s: %m\n", strBuf);
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errno = 0;
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continue;
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}
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}
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if (errno) {
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closedir(dir);
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printf("error reading from %s: %m\n", dirName);
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return 1;
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}
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closedir(dir);
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return 0;
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}
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static int switchroot(const char *newroot)
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{
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/* Don't try to unmount the old "/", there's no way to do it. */
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const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
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int errnum;
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int i;
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for (i = 0; umounts[i] != NULL; i++) {
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char newmount[PATH_MAX];
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strcpy(newmount, newroot);
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strcat(newmount, umounts[i]);
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if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
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fprintf(stderr, "Error mount moving old %s %s %m\n",
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umounts[i], newmount);
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fprintf(stderr, "Forcing unmount of %s\n", umounts[i]);
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umount2(umounts[i], MNT_FORCE);
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}
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}
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if (chdir(newroot) < 0) {
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errnum=errno;
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fprintf(stderr, "switchroot: chdir failed: %m\n");
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errno=errnum;
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return -1;
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}
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recursiveRemove("/");
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if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
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errnum = errno;
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fprintf(stderr, "switchroot: mount failed: %m\n");
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errno = errnum;
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return -1;
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}
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if (chroot(".")) {
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errnum = errno;
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fprintf(stderr, "switchroot: chroot failed: %m\n");
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errno = errnum;
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return -2;
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}
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return 1;
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}
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static void usage(FILE *output)
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{
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fprintf(output, "usage: switchroot <newrootdir> <init> <args to init>\n");
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if (output == stderr)
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exit(err_usage);
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exit(ok);
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}
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int main(int argc, char *argv[])
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{
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char *newroot = argv[1];
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char *init = argv[2];
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char **initargs = &argv[2];
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if (newroot == NULL || newroot[0] == '\0' ||
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init == NULL || init[0] == '\0' ) {
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usage(stderr);
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}
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if (switchroot(newroot) < 0) {
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fprintf(stderr, "switchroot has failed. Sorry.\n");
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return 1;
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}
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if (access(initargs[0], X_OK))
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fprintf(stderr, "WARNING: can't access %s\n", initargs[0]);
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/* get session leader */
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setsid();
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/* set controlling terminal */
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ioctl (0, TIOCSCTTY, 1);
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execv(initargs[0], initargs);
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}
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/*
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* vim:noet:ts=8:sw=8:sts=8
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*/
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