/*
- * switch_root.c
+ * switchroot.c - switch to new root directory and start init.
*
- * Code to switch from initramfs to system root.
- * Based on nash.c from mkinitrd
- *
- * Copyright 2002-2009 Red Hat, Inc. All rights reserved.
+ * 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
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
- * Author(s): Erik Troan <ewt@redhat.com>
- * Jeremy Katz <katzj@redhat.com>
- * Peter Jones <pjones@redhat.com>
- * Harald Hoyer <harald@redhat.com>
+ * Authors:
+ * Peter Jones <pjones@redhat.com>
+ * Jeremy Katz <katzj@redhat.com>
*/
#define _GNU_SOURCE 1
+
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
-#include <unistd.h>
+#include <fcntl.h>
#include <stdio.h>
-#include <dirent.h>
-#include <alloca.h>
+#include <stdlib.h>
+#include <unistd.h>
#include <string.h>
#include <errno.h>
-#include <mntent.h>
-#include <stdlib.h>
#include <ctype.h>
-#include <sys/mount.h>
-#include <fcntl.h>
-#include <linux/fs.h>
-#ifndef MNT_FORCE
-#define MNT_FORCE 0x1
+#ifndef MS_MOVE
+#define MS_MOVE 8192
#endif
#ifndef MNT_DETACH
#define MNT_DETACH 0x2
#endif
+enum {
+ ok,
+ err_no_directory,
+ err_usage,
+};
-#define asprintfa(str, fmt, ...) ({ \
- char *_tmp = NULL; \
- int _rc; \
- _rc = asprintf((str), (fmt), __VA_ARGS__); \
- if (_rc != -1) { \
- _tmp = strdupa(*(str)); \
- if (!_tmp) { \
- _rc = -1; \
- } else { \
- free(*(str)); \
- *(str) = _tmp; \
- } \
- } \
- _rc; \
- })
-
-
-
-static inline int
-setFdCoe(int fd, int enable)
+static int readFD(int fd, char **buf)
{
- int rc;
- long flags = 0;
-
- rc = fcntl(fd, F_GETFD, &flags);
- if (rc < 0)
- return rc;
-
- if (enable)
- flags |= FD_CLOEXEC;
- else
- flags &= ~FD_CLOEXEC;
-
- rc = fcntl(fd, F_SETFD, flags);
- return rc;
+ char *p;
+ size_t size = 16384;
+ int s = 0, filesize = 0;
+
+ if (!(*buf = calloc (16384, sizeof (char))))
+ return -1;
+
+ do {
+ p = *buf + filesize;
+ s = read(fd, p, 16384 - s);
+ if (s < 0)
+ break;
+ filesize += s;
+ /* only exit for empty reads */
+ if (s == 0)
+ break;
+ else if (s == 16384) {
+ *buf = realloc(*buf, size + 16384);
+ memset(*buf + size, '\0', 16384);
+ size += s;
+ s = 0;
+ } else {
+ size += s;
+ }
+ } while (1);
+
+ *buf = realloc(*buf, filesize+1);
+ (*buf)[filesize] = '\0';
+
+ return *buf ? filesize : -1;
}
-static char *
-getArg(char * cmd, char * end, char ** arg)
+static char *getKernelCmdLine(void)
{
- char quote = '\0';
-
- if (!cmd || cmd >= end)
- return NULL;
-
- while (isspace(*cmd) && cmd < end)
- cmd++;
- if (cmd >= end)
- return NULL;
-
- if (*cmd == '"')
- cmd++, quote = '"';
- else if (*cmd == '\'')
- cmd++, quote = '\'';
-
- if (quote) {
- *arg = cmd;
-
- /* This doesn't support \ escapes */
- while (cmd < end && *cmd != quote)
- cmd++;
-
- if (cmd == end) {
- printf("error: quote mismatch for %s\n", *arg);
- return NULL;
- }
-
- *cmd = '\0';
- cmd++;
- } else {
- *arg = cmd;
- while (!isspace(*cmd) && cmd < end)
- cmd++;
- *cmd = '\0';
- if (**arg == '$')
- *arg = getenv(*arg+1);
- if (*arg == NULL)
- *arg = "";
- }
-
- cmd++;
-
- while (isspace(*cmd))
- cmd++;
-
- return cmd;
+ static char *cmdline = NULL;
+ int fd = -1;
+ int errnum;
+
+ fd = open("/proc/cmdline", O_RDONLY);
+ if (fd < 0) {
+ errnum = errno;
+ fprintf(stderr, "Error: Could not open /proc/cmdline: %m\n");
+ errno = errnum;
+ return NULL;
+ }
+
+ if (readFD(fd, &cmdline) < 0) {
+ errnum = errno;
+ fprintf(stderr, "Error: could not read /proc/cmdline: %m\n");
+ close(fd);
+ errno = errnum;
+ return NULL;
+ }
+ close(fd);
+
+ return cmdline;
}
-static int
-mountCommand(char * cmd, char * end)
+/* get the start of a kernel arg "arg". returns everything after it
+ * (useful for things like getting the args to init=). so if you only
+ * want one arg, you need to terminate it at the n */
+static char *getKernelArg(char *arg)
{
- char * fsType = NULL;
- char * device, *spec;
- char * mntPoint;
- char * opts = NULL;
- int rc = 0;
- int flags = MS_MGC_VAL;
- char * newOpts;
-
- if (!(cmd = getArg(cmd, end, &spec))) {
- printf(
- "usage: mount [--ro] [-o <opts>] -t <type> <device> <mntpoint>\n");
- return 1;
- }
-
- while (cmd && *spec == '-') {
- if (!strcmp(spec, "--ro")) {
- flags |= MS_RDONLY;
- } else if (!strcmp(spec, "--bind")) {
- flags = MS_BIND;
- fsType = "none";
- } else if (!strcmp(spec, "--move")) {
- flags = MS_MOVE;
- fsType = "none";
- } else if (!strcmp(spec, "-o")) {
- cmd = getArg(cmd, end, &opts);
- if (!cmd) {
- printf("mount: -o requires arguments\n");
- return 1;
- }
- } else if (!strcmp(spec, "-t")) {
- if (!(cmd = getArg(cmd, end, &fsType))) {
- printf("mount: missing filesystem type\n");
- return 1;
- }
- }
-
- cmd = getArg(cmd, end, &spec);
- }
-
- if (!cmd) {
- printf("mount: missing device or mountpoint\n");
- return 1;
- }
-
- if (!(cmd = getArg(cmd, end, &mntPoint))) {
- struct mntent *mnt;
- FILE *fstab;
-
- fstab = fopen("/etc/fstab", "r");
- if (!fstab) {
- printf("mount: missing mount point\n");
- return 1;
- }
- do {
- if (!(mnt = getmntent(fstab))) {
- printf("mount: missing mount point\n");
- fclose(fstab);
- return 1;
- }
- if (!strcmp(mnt->mnt_dir, spec)) {
- spec = mnt->mnt_fsname;
- mntPoint = mnt->mnt_dir;
-
- if (!strcmp(mnt->mnt_type, "bind")) {
- flags |= MS_BIND;
- fsType = "none";
- } else
- fsType = mnt->mnt_type;
-
- opts = mnt->mnt_opts;
- break;
- }
- } while(1);
-
- fclose(fstab);
- }
-
- if (!fsType) {
- printf("mount: filesystem type expected\n");
- return 1;
- }
-
- if (cmd && cmd < end) {
- printf("mount: unexpected arguments\n");
- return 1;
- }
-
- /* need to deal with options */
- if (opts) {
- char * end;
- char * start = opts;
-
- newOpts = alloca(strlen(opts) + 1);
- *newOpts = '\0';
-
- while (*start) {
- end = strchr(start, ',');
- if (!end) {
- end = start + strlen(start);
- } else {
- *end = '\0';
- end++;
- }
-
- if (!strcmp(start, "ro"))
- flags |= MS_RDONLY;
- else if (!strcmp(start, "rw"))
- flags &= ~MS_RDONLY;
- else if (!strcmp(start, "nosuid"))
- flags |= MS_NOSUID;
- else if (!strcmp(start, "suid"))
- flags &= ~MS_NOSUID;
- else if (!strcmp(start, "nodev"))
- flags |= MS_NODEV;
- else if (!strcmp(start, "dev"))
- flags &= ~MS_NODEV;
- else if (!strcmp(start, "noexec"))
- flags |= MS_NOEXEC;
- else if (!strcmp(start, "exec"))
- flags &= ~MS_NOEXEC;
- else if (!strcmp(start, "sync"))
- flags |= MS_SYNCHRONOUS;
- else if (!strcmp(start, "async"))
- flags &= ~MS_SYNCHRONOUS;
- else if (!strcmp(start, "nodiratime"))
- flags |= MS_NODIRATIME;
- else if (!strcmp(start, "diratime"))
- flags &= ~MS_NODIRATIME;
- else if (!strcmp(start, "noatime"))
- flags |= MS_NOATIME;
- else if (!strcmp(start, "atime"))
- flags &= ~MS_NOATIME;
- else if (!strcmp(start, "relatime"))
- flags |= MS_RELATIME;
- else if (!strcmp(start, "norelatime"))
- flags &= ~MS_RELATIME;
- else if (!strcmp(start, "remount"))
- flags |= MS_REMOUNT;
- else if (!strcmp(start, "bind"))
- flags |= MS_BIND;
- else if (!strcmp(start, "defaults"))
- ;
- else {
- if (*newOpts)
- strcat(newOpts, ",");
- strcat(newOpts, start);
- }
-
- start = end;
- }
-
- opts = newOpts;
- }
-
- device = strdupa(spec);
-
- if (!device) {
- printf("mount: could not find filesystem '%s'\n", spec);
- return 1;
- }
-
- {
- char *mount_opts = NULL;
- mount_opts = opts;
- if (mount(device, mntPoint, fsType, flags, mount_opts) < 0) {
- printf("mount: error mounting %s on %s as %s: %m\n",
- device, mntPoint, fsType);
- rc = 1;
- }
- }
-
- return rc;
+ char *start;
+ char *cmdline;
+ int len;
+
+ cmdline = start = getKernelCmdLine();
+ if (start == NULL)
+ return NULL;
+
+ while (*start) {
+ if (isspace(*start)) {
+ start++;
+ continue;
+ }
+
+ len = strlen(arg);
+ /* don't return if it's a different argument that merely starts
+ * like this one. */
+ if (strncmp(start, arg, len) == 0) {
+ if (start[len] == '=')
+ return start + len + 1;
+ if (!start[len] || isspace(start[len]))
+ return start + len;
+ }
+ while (*++start && !isspace(*start))
+ ;
+ }
+
+ return NULL;
}
-/* remove all files/directories below dirName -- don't cross mountpoints */
-static int
-recursiveRemove(char * dirName)
+#define MAX_INIT_ARGS 32
+static int build_init_args(char **init, char ***initargs_out)
{
- 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;
+ const char *initprogs[] = { "/sbin/init", "/etc/init",
+ "/bin/init", "/bin/sh", NULL };
+ const char *ignoreargs[] = { "console=", "BOOT_IMAGE=", NULL };
+ char *cmdline = NULL;
+ char **initargs;
+
+ int i = 0;
+
+ *init = getKernelArg("init");
+
+ if (*init == NULL) {
+ int j;
+ cmdline = getKernelCmdLine();
+ if (cmdline == NULL)
+ return -1;
+
+ for (j = 0; initprogs[j] != NULL; j++) {
+ if (!access(initprogs[j], X_OK)) {
+ *init = strdup(initprogs[j]);
+ break;
+ }
+ }
+ }
+
+ initargs = (char **)calloc(MAX_INIT_ARGS+1, sizeof (char *));
+ if (initargs == NULL)
+ return -1;
+
+ if (cmdline && *init) {
+ initargs[i++] = *init;
+ } else {
+ cmdline = *init;
+ initargs[0] = NULL;
+ }
+
+ if (cmdline) {
+ char quote = '\0';
+ char *chptr;
+ char *start;
+
+ start = chptr = cmdline;
+ for (; (i < MAX_INIT_ARGS) && (*start != '\0'); i++) {
+ while (*chptr && (*chptr != quote)) {
+ if (isspace(*chptr) && quote == '\0')
+ break;
+ if (*chptr == '"' || *chptr == '\'')
+ quote = *chptr;
+ chptr++;
+ }
+
+ if (quote == '"' || quote == '\'')
+ chptr++;
+ if (*chptr != '\0')
+ *(chptr++) = '\0';
+
+ /* There are some magic parameters added *after*
+ * everything you pass, including a console= from the
+ * x86_64 kernel and BOOT_IMAGE= by syslinux. Bash
+ * doesn't know what they mean, so it then exits, init
+ * gets killed, desaster ensues. *sigh*.
+ */
+ int j;
+ for (j = 0; ignoreargs[j] != NULL; j++) {
+ if (cmdline == *init && !strncmp(start, ignoreargs[j], strlen(ignoreargs[j]))) {
+ if (!*chptr)
+ initargs[i] = NULL;
+ else
+ i--;
+ start = chptr;
+ break;
+ }
+ }
+ if (start == chptr)
+ continue;
+
+ if (start[0] == '\0')
+ i--;
+ else
+ initargs[i] = strdup(start);
+ start = chptr;
+ }
+ }
+
+ if (initargs[i-1] != NULL)
+ initargs[i] = NULL;
+
+ *initargs_out = initargs;
+
+
+ return 0;
}
-static void
-mountMntEnt(const struct mntent *mnt)
+static void switchroot(const char *newroot)
{
- char *start = NULL, *end;
- char *target = NULL;
- struct stat sb;
-
- printf("mounting %s\n", mnt->mnt_dir);
- if (asprintfa(&target, ".%s", mnt->mnt_dir) < 0) {
- printf("setuproot: out of memory while mounting %s\n",
- mnt->mnt_dir);
- return;
- }
-
- if (stat(target, &sb) < 0)
- return;
-
- if (asprintf(&start, "-o %s -t %s %s .%s\n",
- mnt->mnt_opts, mnt->mnt_type, mnt->mnt_fsname,
- mnt->mnt_dir) < 0) {
- printf("setuproot: out of memory while mounting %s\n",
- mnt->mnt_dir);
- return;
- }
-
- end = start + 1;
- while (*end && (*end != '\n'))
- end++;
- /* end points to the \n at the end of the command */
-
- if (mountCommand(start, end) != 0)
- printf("setuproot: mount returned error\n");
+ /* Don't try to unmount the old "/", there's no way to do it. */
+ const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
+ char *init, **initargs;
+ int errnum;
+ int rc;
+ int i;
+
+ rc = build_init_args(&init, &initargs);
+ if (rc < 0)
+ return;
+
+ for (i = 0; umounts[i] != NULL; i++) {
+ if (umount2(umounts[i], MNT_DETACH) < 0) {
+ fprintf(stderr, "Error unmounting old %s: %m\n",
+ umounts[i]);
+ fprintf(stderr, "Forcing unmount of %s\n", umounts[i]);
+ umount2(umounts[i], MNT_FORCE);
+ }
+ }
+
+ chdir(newroot);
+
+ if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
+ errnum = errno;
+ fprintf(stderr, "switchroot: mount failed: %m\n");
+ errno = errnum;
+ return;
+ }
+
+ if (chroot(".")) {
+ errnum = errno;
+ fprintf(stderr, "switchroot: chroot failed: %m\n");
+ errno = errnum;
+ return;
+ }
+
+ if (access(initargs[0], X_OK))
+ fprintf(stderr, "WARNING: can't access %s\n", initargs[0]);
+
+ execv(initargs[0], initargs);
+ return;
}
-static int
-setuprootCommand(char *new)
+static void usage(FILE *output)
{
- FILE *fp;
-
- printf("Setting up new root fs\n");
-
- if (chdir(new)) {
- printf("setuproot: chdir(%s) failed: %m\n", new);
- return 1;
- }
-
- if (mount("/dev", "./dev", NULL, MS_BIND, NULL) < 0)
- printf("setuproot: moving /dev failed: %m\n");
-
- fp = setmntent("./etc/fstab.sys", "r");
- if (fp)
- printf("using fstab.sys from mounted FS\n");
- else {
- fp = setmntent("/etc/fstab.sys", "r");
- if (fp)
- printf("using fstab.sys from initrd\n");
- }
- if (fp) {
- struct mntent *mnt;
-
- while((mnt = getmntent(fp)))
- mountMntEnt(mnt);
- endmntent(fp);
- } else {
- struct {
- char *source;
- char *target;
- char *type;
- int flags;
- void *data;
- int raise;
- } fstab[] = {
- { "/proc", "./proc", "proc", 0, NULL },
- { "/sys", "./sys", "sysfs", 0, NULL },
-#if 0
- { "/dev/pts", "./dev/pts", "devpts", 0, "gid=5,mode=620" },
- { "/dev/shm", "./dev/shm", "tmpfs", 0, NULL },
- { "/selinux", "/selinux", "selinuxfs", 0, NULL },
-#endif
- { NULL, }
- };
- int i = 0;
-
- printf("no fstab.sys, mounting internal defaults\n");
- for (; fstab[i].source != NULL; i++) {
- if (mount(fstab[i].source, fstab[i].target, fstab[i].type,
- fstab[i].flags, fstab[i].data) < 0)
- printf("setuproot: error mounting %s: %m\n",
- fstab[i].source);
- }
- }
-
- chdir("/");
- return 0;
+ fprintf(output, "usage: switchroot {-n|--newroot} <newrootdir>\n");
+ if (output == stderr)
+ exit(err_usage);
+ exit(ok);
}
-int main(int argc, char **argv)
+int main(int argc, char *argv[])
{
- /* Don't try to unmount the old "/", there's no way to do it. */
- const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
- char *new = NULL;
- int fd, i = 0;
-
- argv++;
- new = argv[0];
- argv++;
- printf("Switching to root: %s\n", new);
-
- setuprootCommand(new);
-
- fd = open("/", O_RDONLY);
- for (; umounts[i] != NULL; i++) {
- printf("unmounting old %s\n", umounts[i]);
- if (umount2(umounts[i], MNT_DETACH) < 0) {
- printf("ERROR unmounting old %s: %m\n",umounts[i]);
- printf("forcing unmount of %s\n", umounts[i]);
- umount2(umounts[i], MNT_FORCE);
- }
- }
- i=0;
-
- chdir(new);
-
- recursiveRemove("/");
-
- if (mount(new, "/", NULL, MS_MOVE, NULL) < 0) {
- printf("switchroot: mount failed: %m\n");
- close(fd);
- return 1;
- }
-
- if (chroot(".")) {
- printf("switchroot: chroot() failed: %m\n");
- close(fd);
- return 1;
- }
-
- /* release the old "/" */
- close(fd);
-
- close(3);
- if ((fd = open("/dev/console", O_RDWR)) < 0) {
- printf("ERROR opening /dev/console: %m\n");
- printf("Trying to use fd 0 instead.\n");
- fd = dup2(0, 3);
- } else {
- setFdCoe(fd, 0);
- if (fd != 3) {
- dup2(fd, 3);
- close(fd);
- fd = 3;
- }
- }
- close(0);
- dup2(fd, 0);
- close(1);
- dup2(fd, 1);
- close(2);
- dup2(fd, 2);
- close(fd);
-
- if (access(argv[0], X_OK)) {
- printf("WARNING: can't access %s\n", argv[0]);
- }
-
- execv(argv[0], argv);
-
- printf("exec of init (%s) failed!!!: %m\n", argv[0]);
- return 1;
+ int i;
+ char *newroot = NULL;
+
+ for (i = 1; i < argc; i++) {
+ if (!strcmp(argv[i], "--help")
+ || !strcmp(argv[i], "-h")
+ || !strcmp(argv[i], "--usage")) {
+ usage(stdout);
+ } else if (!strcmp(argv[i], "-n")
+ || !strcmp(argv[i], "--newroot")) {
+ newroot = argv[++i];
+ } else if (!strncmp(argv[i], "--newroot=", 10)) {
+ newroot = argv[i] + 10;
+ } else {
+ usage(stderr);
+ }
+ }
+
+ if (newroot == NULL || newroot[0] == '\0') {
+ usage(stderr);
+ }
+
+ switchroot(newroot);
+
+ fprintf(stderr, "switchroot has failed. Sorry.\n");
+ return 1;
}
+
+/*
+ * vim:noet:ts=8:sw=8:sts=8
+ */
projects / thirdparty / dracut.git / commitdiff
