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updated switch_root.c 

matches the version, which will go to util-linux-ng
master
Harald Hoyer 2009-06-19 12:09:14 +02:00
parent 30f9bb2cb1
commit d49449cd4e
2 changed files with 107 additions and 111 deletions
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2
Makefile
View File

@ -9,7 +9,7 @@ sbindir = ${prefix}/sbin
mandir = ${prefix}/share/man mandir = ${prefix}/share/man


modules.d/99base/switch_root: switch_root.c modules.d/99base/switch_root: switch_root.c
gcc -o modules.d/99base/switch_root switch_root.c gcc -D _GNU_SOURCE -D 'PACKAGE_STRING="dracut"' -std=gnu99 -fsigned-char -g -O2 -o modules.d/99base/switch_root switch_root.c


all: modules.d/99base/switch_root all: modules.d/99base/switch_root



204
switch_root.c
View File

@ -1,7 +1,7 @@
/* /*
* switchroot.c - switch to new root directory and start init. * switchroot.c - switch to new root directory and start init.
* *
* Copyright 2002-2008 Red Hat, Inc. All rights reserved. * Copyright 2002-2009 Red Hat, Inc. All rights reserved.
* *
* This program is free software; you can redistribute it and/or modify * 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 * it under the terms of the GNU General Public License as published by
@ -20,9 +20,6 @@
* Peter Jones <pjones@redhat.com> * Peter Jones <pjones@redhat.com>
* Jeremy Katz <katzj@redhat.com> * Jeremy Katz <katzj@redhat.com>
*/ */

#define _GNU_SOURCE 1

#include <sys/mount.h> #include <sys/mount.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/stat.h> #include <sys/stat.h>
@ -35,164 +32,163 @@
#include <errno.h> #include <errno.h>
#include <ctype.h> #include <ctype.h>
#include <dirent.h> #include <dirent.h>
#include <err.h>


#ifndef MS_MOVE #ifndef MS_MOVE
#define MS_MOVE 8192 #define MS_MOVE 8192
#endif #endif


#ifndef MNT_DETACH
#define MNT_DETACH 0x2
#endif

enum {
ok,
err_no_directory,
err_usage,
};

/* remove all files/directories below dirName -- don't cross mountpoints */ /* remove all files/directories below dirName -- don't cross mountpoints */
static int static int recursiveRemove(char *dirName)
recursiveRemove(char * dirName)
{ {
struct stat sb,rb; struct stat rb;
DIR *dir; DIR *dir;
struct dirent * d; int rc = -1;
char * strBuf = alloca(strlen(dirName) + 1024); int dfd;


if (!(dir = opendir(dirName))) { if (!(dir = opendir(dirName))) {
printf("error opening %s: %m\n", dirName); warn("failed to open %s", dirName);
return 0; goto done;
} }


if (fstat(dirfd(dir),&rb)) { dfd = dirfd(dir);
printf("unable to stat %s: %m\n", dirName);
closedir(dir); if (fstat(dfd, &rb)) {
return 0; warn("failed to stat %s", dirName);
goto done;
} }


while(1) {
struct dirent *d;

errno = 0; errno = 0;
while ((d = readdir(dir))) { if (!(d = readdir(dir))) {
errno = 0;

if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, "..")) {
errno = 0;
continue;
}

strcpy(strBuf, dirName);
strcat(strBuf, "/");
strcat(strBuf, d->d_name);

if (lstat(strBuf, &sb)) {
printf("failed to stat %s: %m\n", strBuf);
errno = 0;
continue;
}

/* only descend into subdirectories if device is same as dir */
if (S_ISDIR(sb.st_mode)) {
if (sb.st_dev == rb.st_dev) {
recursiveRemove(strBuf);
if (rmdir(strBuf))
printf("failed to rmdir %s: %m\n", strBuf);
}
errno = 0;
continue;
}
if (unlink(strBuf)) {
printf("failed to remove %s: %m\n", strBuf);
errno = 0;
continue;
}
}

if (errno) { if (errno) {
closedir(dir); warn("failed to read %s", dirName);
printf("error reading from %s: %m\n", dirName); goto done;
return 1; }
break; /* end of directory */
} }


closedir(dir); if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
continue;


return 0; if (d->d_type == DT_DIR) {
struct stat sb;

if (fstatat(dfd, d->d_name, &sb, AT_SYMLINK_NOFOLLOW)) {
warn("failed to stat %s/%s", dirName, d->d_name);
continue;
}

/* remove subdirectories if device is same as dir */
if (sb.st_dev == rb.st_dev) {
char subdir[ strlen(dirName) +
strlen(d->d_name) + 2 ];

sprintf(subdir, "%s/%s", dirName, d->d_name);
recursiveRemove(subdir);
} else
continue;
}

if (unlinkat(dfd, d->d_name,
d->d_type == DT_DIR ? AT_REMOVEDIR : 0))
warn("failed to unlink %s/%s", dirName, d->d_name);
}

rc = 0; /* success */

done:
if (dir)
closedir(dir);
return rc;
} }


static int switchroot(const char *newroot) static int switchroot(const char *newroot)
{ {
/* Don't try to unmount the old "/", there's no way to do it. */ /* Don't try to unmount the old "/", there's no way to do it. */
const char *umounts[] = { "/dev", "/proc", "/sys", NULL }; const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
int errnum;
int i; int i;


for (i = 0; umounts[i] != NULL; i++) { for (i = 0; umounts[i] != NULL; i++) {
char newmount[PATH_MAX]; char newmount[PATH_MAX];
strcpy(newmount, newroot);
strcat(newmount, umounts[i]); snprintf(newmount, sizeof(newmount), "%s%s", newroot, umounts[i]);

if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) { if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
fprintf(stderr, "Error mount moving old %s %s %m\n", warn("failed to mount moving %s to %s",
umounts[i], newmount); umounts[i], newmount);
fprintf(stderr, "Forcing unmount of %s\n", umounts[i]); warnx("forcing unmount of %s", umounts[i]);
umount2(umounts[i], MNT_FORCE); umount2(umounts[i], MNT_FORCE);
} }
} }


if (chdir(newroot) < 0) { if (chdir(newroot)) {
errnum=errno; warn("failed to change directory to %s", newroot);
fprintf(stderr, "switchroot: chdir failed: %m\n");
errno=errnum;
return -1; return -1;
} }

recursiveRemove("/"); recursiveRemove("/");

if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) { if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
errnum = errno; warn("failed to mount moving %s to /", newroot);
fprintf(stderr, "switchroot: mount failed: %m\n");
errno = errnum;
return -1; return -1;
} }


if (chroot(".")) { if (chroot(".")) {
errnum = errno; warn("failed to change root");
fprintf(stderr, "switchroot: chroot failed: %m\n"); return -1;
errno = errnum;
return -2;
} }
return 1; return 0;
} }


static void usage(FILE *output) static void usage(FILE *output)
{ {
fprintf(output, "usage: switchroot <newrootdir> <init> <args to init>\n"); fprintf(output, "usage: %s <newrootdir> <init> <args to init>\n",
if (output == stderr) program_invocation_short_name);
exit(err_usage); exit(output == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
exit(ok); }

static void version(void)
{
fprintf(stdout, "%s from %s\n", program_invocation_short_name,
PACKAGE_STRING);
exit(EXIT_SUCCESS);
} }


int main(int argc, char *argv[]) int main(int argc, char *argv[])
{ {
char *newroot = argv[1]; char *newroot, *init, **initargs;
char *init = argv[2];
char **initargs = &argv[2];


if (newroot == NULL || newroot[0] == '\0' || if (argv[1] && (!strcmp(argv[1], "--help") || !strcmp(argv[1], "-h")))
init == NULL || init[0] == '\0' ) { usage(stdout);
if (argv[1] && (!strcmp(argv[1], "--version") || !strcmp(argv[1], "-V")))
version();
if (argc < 3)
usage(stderr); usage(stderr);
}


if (switchroot(newroot) < 0) { newroot = argv[1];
fprintf(stderr, "switchroot has failed. Sorry.\n"); init = argv[2];
return 1; initargs = &argv[2];
}
if (access(initargs[0], X_OK)) if (!*newroot || !*init)
fprintf(stderr, "WARNING: can't access %s\n", initargs[0]); usage(stderr);

if (switchroot(newroot))
errx(EXIT_FAILURE, "failed. Sorry.");

if (access(init, X_OK))
warn("cannot access %s", init);


/* get session leader */ /* get session leader */
setsid(); setsid();
/* set controlling terminal */
ioctl (0, TIOCSCTTY, 1);


execv(initargs[0], initargs); /* set controlling terminal */
if (ioctl (0, TIOCSCTTY, 1))
warn("failed to TIOCSCTTY");

execv(init, initargs);
err(EXIT_FAILURE, "failed to execute %s", init);
} }


/*
* vim:noet:ts=8:sw=8:sts=8
*/