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>

diff --git a/AUTHORS b/AUTHORS
index c6843486b25fa5d2b0f28259611ee9e43e6d234e..93fb841271e87fec30e6c735f513bbc7b0cc0742 100644 (file)
--- a/AUTHORS
+++ b/AUTHORS
@@ -29,6 +29,8 @@ AUTHORS (merged projects & commands):
       setarch:         Elliot Lee <sopwith@redhat.com>
                        Jindrich Novy <jnovy@redhat.com>
       simpleinit:      Richard Gooch <rgooch@atnf.csiro.au>
+      switch_root:     Peter Jones <pjones@redhat.com>
+                       Jeremy Katz <katzj@redhat.com>
 
 
 CONTRIBUTORS:

diff --git a/po/POTFILES.in b/po/POTFILES.in
index 2ca79c60e4fe738914333edd75933f41dad04665..334b8e5e7f4c3a02b7d23c957c62a7a66bbf081a 100644 (file)
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -180,6 +180,7 @@ sys-utils/renice.c
 sys-utils/rtcwake.c
 sys-utils/setarch.c
 sys-utils/setsid.c
+sys-utils/switch_root.c
 sys-utils/tunelp.c
 text-utils/col.c
 text-utils/colcrt.c

diff --git a/sys-utils/.gitignore b/sys-utils/.gitignore
index c47cd077a9047b4c93d8cc214b51a463dd865c4e..6f0be710f682fa11060e675b5433bfa4c15f9103 100644 (file)
--- a/sys-utils/.gitignore
+++ b/sys-utils/.gitignore
@@ -36,6 +36,7 @@ sparc32.8
 sparc32bash.8
 sparc64.8
 sparc.8
+switch_root
 tunelp
 vidmode.8
 x86_64.8

diff --git a/sys-utils/Makefile.am b/sys-utils/Makefile.am
index b4c6ac601ac0ae1617e7c8926d1057aa2c87ccae..856d6a1f980850b75f2c689b4f175274d1103ccf 100644 (file)
--- a/sys-utils/Makefile.am
+++ b/sys-utils/Makefile.am
@@ -1,7 +1,7 @@
 include $(top_srcdir)/config/include-Makefile.am
 
 bin_PROGRAMS =
-sbin_PROGRAMS =
+sbin_PROGRAMS = switch_root
 usrbinexec_PROGRAMS = flock ipcrm ipcs ipcmk renice setsid
 usrsbinexec_PROGRAMS = readprofile
 

diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
new file mode 100644 (file)
index 0000000..9188006
--- /dev/null
+++ b/sys-utils/switch_root.c
@@ -0,0 +1,198 @@
+/*
+ * switchroot.c - switch to new root directory and start init.
+ *
+ * Copyright 2002-2008 Red Hat, Inc.  All rights reserved.
+ *
+ * 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/>.
+ *
+ * Authors:
+ *     Peter Jones <pjones@redhat.com>
+ *     Jeremy Katz <katzj@redhat.com>
+ */
+
+#define _GNU_SOURCE 1
+
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <dirent.h>
+
+#ifndef MS_MOVE
+#define MS_MOVE 8192
+#endif
+
+#ifndef MNT_DETACH
+#define MNT_DETACH 0x2
+#endif
+
+enum {
+       ok,
+       err_no_directory,
+       err_usage,
+};
+
+/* remove all files/directories below dirName -- don't cross mountpoints */
+static int
+recursiveRemove(char * dirName)
+ {
+    struct stat sb,rb;
+    DIR * dir;
+    struct dirent * d;
+    char * strBuf = alloca(strlen(dirName) + 1024);
+
+    if (!(dir = opendir(dirName))) {
+        printf("error opening %s: %m\n", dirName);
+        return 0;
+    }
+
+    if (fstat(dirfd(dir),&rb)) {
+        printf("unable to stat %s: %m\n", dirName);
+        closedir(dir);
+        return 0;
+    }
+
+    errno = 0;
+    while ((d = readdir(dir))) {
+        errno = 0;
+
+        if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, "..")) {
+            errno = 0;
+            continue;
+        }
+
+        strcpy(strBuf, dirName);
+        strcat(strBuf, "/");
+        strcat(strBuf, d->d_name);
+
+        if (lstat(strBuf, &sb)) {
+            printf("failed to stat %s: %m\n", strBuf);
+            errno = 0;
+            continue;
+        }
+
+        /* only descend into subdirectories if device is same as dir */
+        if (S_ISDIR(sb.st_mode)) {
+            if (sb.st_dev == rb.st_dev) {
+               recursiveRemove(strBuf);
+                if (rmdir(strBuf))
+                    printf("failed to rmdir %s: %m\n", strBuf);
+            }
+            errno = 0;
+            continue;
+        }
+        if (unlink(strBuf)) {
+            printf("failed to remove %s: %m\n", strBuf);
+            errno = 0;
+            continue;
+        }
+    }
+
+    if (errno) {
+        closedir(dir);
+        printf("error reading from %s: %m\n", dirName);
+        return 1;
+    }
+
+    closedir(dir);
+
+    return 0;
+ }
+
+static int switchroot(const char *newroot)
+{
+       /*  Don't try to unmount the old "/", there's no way to do it. */
+       const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
+       int errnum;
+       int i;
+
+       for (i = 0; umounts[i] != NULL; i++) {
+               char newmount[PATH_MAX];
+               strcpy(newmount, newroot);
+               strcat(newmount, umounts[i]);
+               if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
+                       fprintf(stderr, "Error mount moving old %s %s %m\n",
+                               umounts[i], newmount);
+                       fprintf(stderr, "Forcing unmount of %s\n", umounts[i]);
+                       umount2(umounts[i], MNT_FORCE);
+               }
+       }
+
+       if (chdir(newroot) < 0) {
+         errnum=errno;
+         fprintf(stderr, "switchroot: chdir failed: %m\n");
+         errno=errnum;
+         return -1;
+       }
+       recursiveRemove("/");
+       if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
+               errnum = errno;
+               fprintf(stderr, "switchroot: mount failed: %m\n");
+               errno = errnum;
+               return -1;
+       }
+
+       if (chroot(".")) {
+               errnum = errno;
+               fprintf(stderr, "switchroot: chroot failed: %m\n");
+               errno = errnum;
+               return -2;
+       }
+       return 1;
+}
+
+static void usage(FILE *output)
+{
+       fprintf(output, "usage: switchroot <newrootdir> <init> <args to init>\n");
+       if (output == stderr)
+               exit(err_usage);
+       exit(ok);
+}
+
+int main(int argc, char *argv[])
+{
+       char *newroot = argv[1];
+       char *init = argv[2];
+       char **initargs = &argv[2];
+
+       if (newroot == NULL || newroot[0] == '\0' ||
+           init == NULL || init[0] == '\0' ) {
+               usage(stderr);
+       }
+
+       if (switchroot(newroot) < 0) {
+         fprintf(stderr, "switchroot has failed.  Sorry.\n");
+         return 1;
+       }
+       if (access(initargs[0], X_OK))
+         fprintf(stderr, "WARNING: can't access %s\n", initargs[0]);
+
+       /* get session leader */
+       setsid();
+       /* set controlling terminal */
+       ioctl (0, TIOCSCTTY, 1);
+
+       execv(initargs[0], initargs);
+}
+
+/*
+ * vim:noet:ts=8:sw=8:sts=8
+ */