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68404f13d4
function old new delta procps_scan 1265 1298 +33 aliascmd 278 283 +5 parse_file_cmd 116 120 +4 dname_enc 373 377 +4 setcmd 90 93 +3 execcmd 57 60 +3 count_lines 72 74 +2 process_command_subs 340 339 -1 test_main 409 407 -2 mknod_main 179 177 -2 handle_incoming_and_exit 2653 2651 -2 argstr 1312 1310 -2 shiftcmd 131 128 -3 exitcmd 46 43 -3 dotcmd 297 294 -3 breakcmd 86 83 -3 evalpipe 353 349 -4 evalcommand 1180 1176 -4 evalcmd 109 105 -4 send_tree 374 369 -5 mkfifo_main 82 77 -5 evalsubshell 152 147 -5 typecmd 75 69 -6 letcmd 61 55 -6 add_cmd 1190 1183 -7 main 891 883 -8 ash_main 1415 1407 -8 parse_stream 1377 1367 -10 alloc_procps_scan 55 - -55 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 7/21 up/down: 54/-148) Total: -94 bytes text data bss dec hex filename 797195 658 7428 805281 c49a1 busybox_old 797101 658 7428 805187 c4943 busybox_unstripped
126 lines
2.9 KiB
C
126 lines
2.9 KiB
C
/* vi: set sw=4 ts=4: */
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/* Copyright 2005 Rob Landley <rob@landley.net>
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*
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* Switch from rootfs to another filesystem as the root of the mount tree.
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*
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* Licensed under GPL version 2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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#include <sys/vfs.h>
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// Make up for header deficiencies.
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#ifndef RAMFS_MAGIC
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#define RAMFS_MAGIC 0x858458f6
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#endif
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#ifndef TMPFS_MAGIC
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#define TMPFS_MAGIC 0x01021994
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#endif
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#ifndef MS_MOVE
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#define MS_MOVE 8192
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#endif
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static dev_t rootdev;
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// Recursively delete contents of rootfs.
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static void delete_contents(const char *directory)
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{
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DIR *dir;
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struct dirent *d;
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struct stat st;
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// Don't descend into other filesystems
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if (lstat(directory, &st) || st.st_dev != rootdev) return;
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// Recursively delete the contents of directories.
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if (S_ISDIR(st.st_mode)) {
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dir = opendir(directory);
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if (dir) {
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while ((d = readdir(dir))) {
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char *newdir = d->d_name;
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// Skip . and ..
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if (*newdir=='.' && (!newdir[1] || (newdir[1]=='.' && !newdir[2])))
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continue;
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// Recurse to delete contents
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newdir = alloca(strlen(directory) + strlen(d->d_name) + 2);
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sprintf(newdir, "%s/%s", directory, d->d_name);
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delete_contents(newdir);
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}
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closedir(dir);
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// Directory should now be empty. Zap it.
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rmdir(directory);
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}
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// It wasn't a directory. Zap it.
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} else unlink(directory);
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}
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int switch_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int switch_root_main(int argc ATTRIBUTE_UNUSED, char **argv)
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{
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char *newroot, *console = NULL;
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struct stat st1, st2;
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struct statfs stfs;
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// Parse args (-c console)
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opt_complementary = "-2"; // minimum 2 params
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getopt32(argv, "+c:", &console); // '+': stop parsing at first non-option
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argv += optind;
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// Change to new root directory and verify it's a different fs.
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newroot = *argv++;
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xchdir(newroot);
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if (lstat(".", &st1) || lstat("/", &st2) || st1.st_dev == st2.st_dev) {
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bb_error_msg_and_die("bad newroot %s", newroot);
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}
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rootdev = st2.st_dev;
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// Additional sanity checks: we're about to rm -rf /, so be REALLY SURE
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// we mean it. (I could make this a CONFIG option, but I would get email
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// from all the people who WILL eat their filesystems.)
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if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs) ||
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(stfs.f_type != RAMFS_MAGIC && stfs.f_type != TMPFS_MAGIC) ||
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getpid() != 1)
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{
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bb_error_msg_and_die("not rootfs");
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}
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// Zap everything out of rootdev
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delete_contents("/");
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// Overmount / with newdir and chroot into it. The chdir is needed to
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// recalculate "." and ".." links.
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if (mount(".", "/", NULL, MS_MOVE, NULL))
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bb_error_msg_and_die("error moving root");
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xchroot(".");
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xchdir("/");
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// If a new console specified, redirect stdin/stdout/stderr to that.
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if (console) {
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close(0);
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xopen(console, O_RDWR);
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dup2(0, 1);
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dup2(0, 2);
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}
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// Exec real init. (This is why we must be pid 1.)
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execv(argv[0], argv);
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bb_perror_msg_and_die("bad init %s", argv[0]);
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}
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