X-Git-Url: http://git.ipfire.org/?p=people%2Fteissler%2Fipfire-2.x.git;a=blobdiff_plain;f=src%2Fdracut%2Fswitch_root.c;fp=src%2Fdracut%2Fswitch_root.c;h=1520387239e1d8d0ac797f57ae08d474be4a7e8d;hp=0000000000000000000000000000000000000000;hb=41c0d0cab7d24d6bf2fa1f3ada1c86da79aaa762;hpb=6f21706ddaf26fbae1d3118bef93e25db90aef29

diff --git a/src/dracut/switch_root.c b/src/dracut/switch_root.c
new file mode 100644
index 000000000..152038723
--- /dev/null
+++ b/src/dracut/switch_root.c
@@ -0,0 +1,188 @@
+/*
+ * switchroot.c - switch to new root directory and start init.
+ *
+ * Copyright 2002-2008 Red Hat, Inc.  All rights reserved.
+ *
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *	Peter Jones <pjones@redhat.com>
+ *	Jeremy Katz <katzj@redhat.com>
+ */
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <dirent.h>
+
+#ifndef MS_MOVE
+#define MS_MOVE 8192
+#endif
+
+enum {
+	ok,
+	err_no_directory,
+	err_usage,
+};
+
+/* remove all files/directories below dirName -- don't cross mountpoints */
+static int
+recursiveRemove(char * dirName)
+{
+	struct stat sb,rb;
+	DIR * dir;
+	struct dirent * d;
+	char * strBuf = alloca(strlen(dirName) + 1024);
+
+	if (!(dir = opendir(dirName))) {
+		printf("error opening %s: %m\n", dirName);
+		return 0;
+	}
+
+	if (fstat(dirfd(dir),&rb)) {
+		printf("unable to stat %s: %m\n", dirName);
+		closedir(dir);
+		return 0;
+	}
+
+	errno = 0;
+
+	while ((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) {
+		closedir(dir);
+		printf("error reading from %s: %m\n", dirName);
+		return 1;
+	}
+
+	closedir(dir);
+	return 0;
+}
+
+static int switchroot(const char *newroot)
+{
+	/*  Don't try to unmount the old "/", there's no way to do it. */
+	const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
+	int errnum;
+	int i;
+
+	for (i = 0; umounts[i] != NULL; i++) {
+		char newmount[PATH_MAX];
+		strcpy(newmount, newroot);
+		strcat(newmount, umounts[i]);
+		if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
+			fprintf(stderr, "Error mount moving old %s %s %m\n",
+				umounts[i], newmount);
+			fprintf(stderr, "Forcing unmount of %s\n", umounts[i]);
+			umount2(umounts[i], MNT_FORCE);
+		}
+	}
+
+	if (chdir(newroot) < 0) {
+		errnum=errno;
+		fprintf(stderr, "switchroot: chdir failed: %m\n");
+		errno=errnum;
+		return -1;
+	}
+	recursiveRemove("/");
+	if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
+		errnum = errno;
+		fprintf(stderr, "switchroot: mount failed: %m\n");
+		errno = errnum;
+		return -1;
+	}
+
+	if (chroot(".")) {
+		errnum = errno;
+		fprintf(stderr, "switchroot: chroot failed: %m\n");
+		errno = errnum;
+		return -2;
+	}
+	return 1;
+}
+
+static void usage(FILE *output)
+{
+	fprintf(output, "usage: switchroot <newrootdir> <init> <args to init>\n");
+	if (output == stderr)
+		exit(err_usage);
+	exit(ok);
+}
+
+int main(int argc, char *argv[])
+{
+	char *newroot = argv[1];
+	char *init = argv[2];
+	char **initargs = &argv[2];
+
+	if (newroot == NULL || newroot[0] == '\0' ||
+	    init == NULL || init[0] == '\0' ) {
+		usage(stderr);
+	}
+
+	if (switchroot(newroot) < 0) {
+		fprintf(stderr, "switchroot has failed.  Sorry.\n");
+		return 1;
+	}
+	if (access(initargs[0], X_OK))
+		fprintf(stderr, "WARNING: can't access %s\n", initargs[0]);
+
+	/* get session leader */
+	setsid();
+	/* set controlling terminal */
+	ioctl (0, TIOCSCTTY, 1);
+
+	execv(initargs[0], initargs);
+}
+