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 88bb9db2a67e92ff9c36028ee2c36209fc6cefa6..21cc99229752368d41db367976997411f8ba49dd 100644 (file)
--- a/util-linux/switch_root.c
+++ b/util-linux/switch_root.c
@@ -6,36 +6,32 @@
  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  */
 
-#include "busybox.h"
+#include "libbb.h"
 #include <sys/vfs.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
 
-static dev_t rootdev;
-
 // Recursively delete contents of rootfs.
-
-static void delete_contents(const 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 (lstat(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)) {
@@ -45,13 +41,13 @@ static void delete_contents(const char *directory)
                                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);
 
@@ -60,25 +56,23 @@ static void delete_contents(const 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)
+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;
        struct stat st1, st2;
        struct statfs stfs;
+       dev_t rootdev;
 
        // Parse args (-c console)
-
-       opt_complementary = "-2";
-       getopt32(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++;
 
        xchdir(newroot);
@@ -90,32 +84,29 @@ int switch_root_main(int argc, char **argv)
        // 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 filesystems.)
-
-       if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs) ||
-               (stfs.f_type != RAMFS_MAGIC && stfs.f_type != TMPFS_MAGIC) ||
-               getpid() != 1)
-       {
+       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("."))
+       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);
                xopen(console, O_RDWR);
-               dup2(0, 1);
-               dup2(0, 2);
+               xdup2(0, 1);
+               xdup2(0, 2);
        }
 
        // Exec real init.  (This is why we must be pid 1.)