mdev: Rob's #if forest removal

[oweals/busybox.git] / util-linux / switch_root.c

diff --git a/util-linux/switch_root.c b/util-linux/switch_root.c
index 1ba374076c200402285f5d9df71f437896bacb9a..21cc99229752368d41db367976997411f8ba49dd 100644 (file)
--- a/util-linux/switch_root.c
+++ b/util-linux/switch_root.c
@@ -1,57 +1,53 @@
-/* vi:set ts=4:*/
-
-#include <dirent.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <sys/mount.h>
-#include <sys/stat.h>
-#include <sys/types.h>
+/* vi: set sw=4 ts=4: */
+/* Copyright 2005 Rob Landley <rob@landley.net>
+ *
+ * Switch from rootfs to another filesystem as the root of the mount tree.
+ *
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
 #include <sys/vfs.h>
-#include <unistd.h>
-
-#include "busybox.h"
 
 // Make up for header deficiencies.
-
 #ifndef RAMFS_MAGIC
-#define RAMFS_MAGIC            0x858458f6
+#define RAMFS_MAGIC ((unsigned)0x858458f6)
 #endif
 
 #ifndef TMPFS_MAGIC
-#define TMPFS_MAGIC            0x01021994
+#define TMPFS_MAGIC ((unsigned)0x01021994)
 #endif
 
 #ifndef MS_MOVE
-#define MS_MOVE                        8192
+#define MS_MOVE     8192
 #endif
 
-dev_t rootdev;
-
 // Recursively delete contents of rootfs.
-
-static void delete_contents(char *directory)
+static void delete_contents(const char *directory, dev_t rootdev)
 {
        DIR *dir;
        struct dirent *d;
        struct stat st;
 
        // Don't descend into other filesystems
-       if (stat(directory,&st) || st.st_dev != rootdev) return;
+       if (lstat(directory, &st) || st.st_dev != rootdev)
+               return;
 
        // Recursively delete the contents of directories.
        if (S_ISDIR(st.st_mode)) {
-               if((dir = opendir(directory))) {
+               dir = opendir(directory);
+               if (dir) {
                        while ((d = readdir(dir))) {
-                               char *newdir=d->d_name;
+                               char *newdir = d->d_name;
 
                                // Skip . and ..
-                               if(*newdir=='.' && (!newdir[1] || (newdir[1]=='.' && !newdir[2])))
+                               if (DOT_OR_DOTDOT(newdir))
                                        continue;
 
                                // Recurse to delete contents
-                               newdir = alloca(strlen(directory) + strlen(d->d_name) + 2);
-                               sprintf(newdir, "%s/%s", directory, d->d_name);
-                               delete_contents(newdir);
+                               newdir = concat_path_file(directory, newdir);
+                               delete_contents(newdir, rootdev);
+                               free(newdir);
                        }
                        closedir(dir);
 
@@ -60,64 +56,60 @@ static void delete_contents(char *directory)
                }
 
        // It wasn't a directory.  Zap it.
-
        } else unlink(directory);
 }
 
-int switch_root_main(int argc, char *argv[])
+int switch_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int switch_root_main(int argc UNUSED_PARAM, char **argv)
 {
-       char *newroot, *console=NULL;
+       char *newroot, *console = NULL;
        struct stat st1, st2;
        struct statfs stfs;
+       dev_t rootdev;
 
        // Parse args (-c console)
-
-       bb_opt_complementally="-2";
-       bb_getopt_ulflags(argc,argv,"c:",&console);
+       opt_complementary = "-2"; // minimum 2 params
+       getopt32(argv, "+c:", &console); // '+': stop parsing at first non-option
+       argv += optind;
 
        // Change to new root directory and verify it's a different fs.
+       newroot = *argv++;
 
-       newroot=argv[optind++];
-
-       if (chdir(newroot) || stat(".", &st1) || stat("/", &st2) ||
-               st1.st_dev == st2.st_dev)
-       {
-               bb_error_msg_and_die("bad newroot %s",newroot);
+       xchdir(newroot);
+       if (lstat(".", &st1) || lstat("/", &st2) || st1.st_dev == st2.st_dev) {
+               bb_error_msg_and_die("bad newroot %s", newroot);
        }
-       rootdev=st2.st_dev;
+       rootdev = st2.st_dev;
 
        // Additional sanity checks: we're about to rm -rf /,  so be REALLY SURE
        // we mean it.  (I could make this a CONFIG option, but I would get email
-       // from all the people who WILL eat their filesystemss.)
-
-       if (stat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs) ||
-               (stfs.f_type != RAMFS_MAGIC && stfs.f_type != TMPFS_MAGIC) ||
-               getpid() != 1)
-       {
+       // from all the people who WILL eat their filesystems.)
+       if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs)
+        || (((unsigned)stfs.f_type != RAMFS_MAGIC) && ((unsigned)stfs.f_type != TMPFS_MAGIC))
+        || (getpid() != 1)
+       ) {
                bb_error_msg_and_die("not rootfs");
        }
 
        // Zap everything out of rootdev
-
-       delete_contents("/");
+       delete_contents("/", rootdev);
 
        // Overmount / with newdir and chroot into it.  The chdir is needed to
        // recalculate "." and ".." links.
-
-       if (mount(".", "/", NULL, MS_MOVE, NULL) || chroot(".") || chdir("/"))
-               bb_error_msg_and_die("moving root");
+       if (mount(".", "/", NULL, MS_MOVE, NULL))
+               bb_error_msg_and_die("error moving root");
+       xchroot(".");
+       xchdir("/");
 
        // If a new console specified, redirect stdin/stdout/stderr to that.
-
        if (console) {
                close(0);
-               if(open(console, O_RDWR) < 0)
-                       bb_error_msg_and_die("Bad console '%s'",console);
-               dup2(0, 1);
-               dup2(0, 2);
+               xopen(console, O_RDWR);
+               xdup2(0, 1);
+               xdup2(0, 2);
        }
 
        // Exec real init.  (This is why we must be pid 1.)
-       execv(argv[optind],argv+optind);
-       bb_error_msg_and_die("Bad init '%s'",argv[optind]);
+       execv(argv[0], argv);
+       bb_perror_msg_and_die("bad init %s", argv[0]);
 }