Move run-init to under usr/kinit

1 files changed, 214 insertions, 0 deletions

diff --git a/usr/kinit/run-init/runinitlib.c b/usr/kinit/run-init/runinitlib.c
new file mode 100644
index 00000000000000..3edee8c32fd846
--- /dev/null
+++ b/usr/kinit/run-init/runinitlib.c
@@ -0,0 +1,214 @@
+/* ----------------------------------------------------------------------- *
+ *   
+ *   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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * runinitlib.c
+ *
+ * run_init(consoledev, realroot, init, initargs)
+ *
+ * This function should be called as the last thing in kinit,
+ * from initramfs, it does the following:
+ *
+ * - Delete all files in the initramfs;
+ * - Remounts /real-root onto the root filesystem;
+ * - Chroots;
+ * - Opens /dev/console;
+ * - Spawns the specified init program (with arguments.)
+ */
+
+#include <alloca.h>
+#include <assert.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+#include "run-init.h"
+
+/* Make it possible to compile on glibc by including constants that the
+   always-behind shipped glibc headers may not include.  Classic example
+   on why the lack of ABI headers screw us up. */
+#ifndef TMPFS_MAGIC
+# define TMPFS_MAGIC	0x01021994
+#endif
+#ifndef RAMFS_MAGIC
+# define RAMFS_MAGIC	0x858458f6
+#endif
+#ifndef MS_MOVE
+# define MS_MOVE	8192
+#endif
+
+static int nuke(const char *what);
+
+static int nuke_dirent(int len, const char *dir, const char *name, dev_t me)
+{
+  int bytes = len+strlen(name)+2;
+  char path[bytes];
+  int xlen;
+  struct stat st;
+
+  xlen = snprintf(path, bytes, "%s/%s", dir, name);
+  assert(xlen < bytes);
+
+  if ( lstat(path, &st) )
+    return ENOENT;		/* Return 0 since already gone? */
+
+  if ( st.st_dev != me )
+    return 0;			/* DO NOT recurse down mount points!!!!! */
+
+  return nuke(path);
+}
+
+/* Wipe the contents of a directory, but not the directory itself */
+static int nuke_dir(const char *what)
+{
+  int len = strlen(what);
+  DIR *dir;
+  struct dirent *d;
+  int err = 0;
+  struct stat st;
+
+  if ( lstat(what, &st) )
+    return errno;
+  
+  if ( !S_ISDIR(st.st_mode) )
+    return ENOTDIR;
+
+  if ( !(dir = opendir(what)) ) {
+    /* EACCES means we can't read it.  Might be empty and removable;
+       if not, the rmdir() in nuke() will trigger an error. */
+    return (errno == EACCES) ? 0 : errno;
+  }
+  
+  while ( (d = readdir(dir)) ) {
+    /* Skip . and .. */
+    if ( d->d_name[0] == '.' &&
+	 (d->d_name[1] == '\0' ||
+	  (d->d_name[1] == '.' && d->d_name[2] == '\0')) )
+      continue;
+    
+    err = nuke_dirent(len, what, d->d_name, st.st_dev);
+    if ( err ) {
+      closedir(dir);
+      return err;
+    }
+  }
+  
+  closedir(dir);
+
+  return 0;
+}
+
+static int nuke(const char *what)
+{
+  int rv;
+  int err = 0;
+
+  rv = unlink(what);
+  if ( rv < 0 ) {
+    if ( errno == EISDIR ) {
+      /* It's a directory. */
+      err = nuke_dir(what);
+      if ( !err ) err = rmdir(what) ? errno : err;
+    } else {
+      err = errno;
+    }
+  }
+
+  if ( err ) {
+    errno = err;
+    die(what);
+  } else {
+    return 0;
+  }
+}
+
+
+int run_init(const char *realroot, const char *console,
+	     const char *init, char **initargs)
+{
+  struct stat   rst, cst, ist;
+  struct statfs sfs;
+  int confd;
+
+  /* First, change to the new root directory */
+  if ( chdir(realroot) )
+    die("chdir to new root");
+
+  /* This is a potentially highly destructive program.  Take some
+     extra precautions. */
+
+  /* Make sure the current directory is not on the same filesystem
+     as the root directory */
+  if ( stat("/", &rst) || stat(".", &cst) )
+    die("stat");
+
+  if ( rst.st_dev == cst.st_dev )
+    die("current directory on the same filesystem as the root");
+  
+  /* The initramfs should have /init */
+  if ( stat("/init", &ist) || !S_ISREG(ist.st_mode) )
+    die("can't find /init on initramfs");
+
+  /* Make sure we're on a ramfs */
+  if ( statfs("/", &sfs) )
+    die("statfs /");
+  if ( sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC )
+    die("rootfs not a ramfs or tmpfs");
+
+  /* Okay, I think we should be safe... */
+
+  /* Delete rootfs contents */
+  if ( nuke_dir("/") )
+    die("nuking initramfs contents");
+
+  /* Overmount the root */
+  if ( mount(".", "/", NULL, MS_MOVE, NULL) )
+    die("overmounting root");
+  
+  /* chroot, chdir */
+  if ( chroot(".") || chdir("/") )
+    die("chroot");
+
+  /* Open /dev/console */
+  if ( (confd = open(console, O_RDWR)) < 0 )
+    die("opening console");
+  dup2(confd, 0);
+  dup2(confd, 1);
+  dup2(confd, 2);
+  close(confd);
+
+  /* Spawn init */
+  execv(init, initargs);
+  die(init);			/* Failed to spawn init */
+}