[ostree] Add ostree-switch-root here

[Colin Walters <walters src gnome org>]

commit a904c9693b12fecfa1b07ce368313f38872c2a6e
Author: Colin Walters <walters verbum org>
Date:   Sun Feb 5 16:02:44 2012 -0500

    Add ostree-switch-root here
    
    Merge the code from ostree-init; now that we're back to targeting an
    initramfs (dracut), we don't need to statically link the binary, so
    there's no strong reason to have a separate module.

 Makefile-switchroot.am              |   22 ++++
 Makefile.am                         |    2 +
 src/switchroot/ostree-switch-root.c |  183 +++++++++++++++++++++++++++++++++++
 3 files changed, 207 insertions(+), 0 deletions(-)
---
diff --git a/Makefile-switchroot.am b/Makefile-switchroot.am
new file mode 100644
index 0000000..3400057
--- /dev/null
+++ b/Makefile-switchroot.am
@@ -0,0 +1,22 @@
+# Copyright (C) 2011 Colin Walters <walters verbum org>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+sbin_PROGRAMS += ostree-switch-root
+
+ostree_switch_root_SOURCES = src/switchroot/ostree-switch-root.c
+
+ostree_switch_root_CFLAGS = $(AM_CFLAGS)
diff --git a/Makefile.am b/Makefile.am
index ddcf078..c300c89 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -25,6 +25,7 @@ MANPAGES =
 CLEANFILES =
 EXTRA_DIST =
 bin_PROGRAMS =
+sbin_PROGRAMS =
 bin_SCRIPTS =
 libexec_PROGRAMS =
 noinst_LTLIBRARIES =
@@ -36,6 +37,7 @@ include Makefile-daemon.am
 include Makefile-otutil.am
 include Makefile-libostree.am
 include Makefile-ostree.am
+include Makefile-switchroot.am
 include Makefile-ostbuild.am
 include Makefile-triggers.am
 
diff --git a/src/switchroot/ostree-switch-root.c b/src/switchroot/ostree-switch-root.c
new file mode 100644
index 0000000..16be2b8
--- /dev/null
+++ b/src/switchroot/ostree-switch-root.c
@@ -0,0 +1,183 @@
+/* -*- c-file-style: "gnu" -*-
+ * Switch to new root directory and start init.
+ * Copyright 2011,2012 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>
+
+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[])
+{
+  const char *initramfs_move_mounts[] = { "/dev", "/proc", "/sys", "/run", NULL };
+  const char *toproot_bind_mounts[] = { "/home", "/root", "/tmp", NULL };
+  const char *ostree_bind_mounts[] = { "/var", NULL };
+  const char *readonly_bind_mounts[] = { "/bin", "/etc", "/lib", "/sbin", "/usr",
+					 NULL };
+  const char *ostree_root = NULL;
+  const char *ostree_subinit = NULL;
+  char srcpath[PATH_MAX];
+  char destpath[PATH_MAX];
+  struct stat stbuf;
+  char **init_argv = NULL;
+  int i;
+  int before_init_argc = 0;
+
+  if (argc < 3)
+    {
+      fprintf (stderr, "usage: ostree-switch-root NEWROOT INIT [ARGS...]\n");
+      exit (1);
+    }
+
+  before_init_argc++;
+  ostree_root = argv[1];
+  before_init_argc++;
+  ostree_subinit = argv[2];
+  before_init_argc++;
+
+  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/var", ostree_root);
+  if (mount ("/ostree/var", destpath, NULL, MS_BIND, NULL) < 0)
+    {
+      perrorv ("Failed to bind mount / to '%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);
+    }
+
+  for (i = 0; initramfs_move_mounts[i] != NULL; i++)
+    {
+      const char *path = initramfs_move_mounts[i];
+      snprintf (srcpath, sizeof(srcpath), path);
+      snprintf (destpath, sizeof(destpath), "/ostree/%s%s", ostree_root, path);
+      if (mount (srcpath, destpath, NULL, MS_MOVE, NULL) < 0)
+	{
+	  perrorv ("failed to move mount of %s to %s", srcpath, destpath);
+	  exit (1);
+	}
+    }
+
+  for (i = 0; toproot_bind_mounts[i] != NULL; i++)
+    {
+      snprintf (destpath, sizeof(destpath), "/ostree/%s%s", ostree_root, toproot_bind_mounts[i]);
+      if (mount (toproot_bind_mounts[i], destpath, NULL, MS_BIND & ~MS_RDONLY, NULL) < 0)
+	{
+	  perrorv ("failed to bind mount (class:toproot) %s to %s", toproot_bind_mounts[i], destpath);
+	  exit (1);
+	}
+    }
+
+  for (i = 0; ostree_bind_mounts[i] != NULL; i++)
+    {
+      snprintf (srcpath, sizeof(srcpath), "/ostree/%s", ostree_bind_mounts[i]);
+      snprintf (destpath, sizeof(destpath), "/ostree/%s%s", ostree_root, ostree_bind_mounts[i]);
+      if (mount (srcpath, destpath, NULL, MS_MGC_VAL|MS_BIND, NULL) < 0)
+	{
+	  perrorv ("failed to bind mount (class:bind) %s to %s", srcpath, destpath);
+	  exit (1);
+	}
+    }
+
+  for (i = 0; readonly_bind_mounts[i] != NULL; i++)
+    {
+      snprintf (destpath, sizeof(destpath), "/ostree/%s%s", ostree_root, readonly_bind_mounts[i]);
+      if (mount (destpath, destpath, NULL, MS_BIND, NULL) < 0)
+	{
+	  perrorv ("failed to bind mount (class:readonly) %s", destpath);
+	  exit (1);
+	}
+      if (mount (destpath, destpath, NULL, MS_BIND | MS_REMOUNT | MS_RDONLY, NULL) < 0)
+	{
+	  perrorv ("failed to bind mount (class:readonly) %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);
+    }
+
+  init_argv = malloc (sizeof (char*)*((argc-before_init_argc)+2));
+  init_argv[0] = (char*)ostree_subinit;
+  for (i = 0; i < argc-before_init_argc; i++)
+    init_argv[i+1] = argv[i+before_init_argc];
+  init_argv[i+1] = NULL;
+  
+  fprintf (stderr, "ostree-init: Running real init %s (argc=%d)\n", init_argv[0], argc-before_init_argc);
+  fflush (stderr);
+  execv (init_argv[0], init_argv);
+  perrorv ("Failed to exec init '%s'", init_argv[0]);
+  exit (1);
+}
+