#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/fd.h>
#include <linux/tty.h>
#include <linux/suspend.h>
#include <linux/root_dev.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <linux/genhd.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/initrd.h>
#include <linux/async.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>

#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>

#include "do_mounts.h"

int __initdata rd_doload;       /* 1 = load RAM disk, 0 = don't load */

int root_mountflags = MS_RDONLY | MS_SILENT;
static char * __initdata root_device_name;
static char __initdata saved_root_name[64];
static int root_wait;

dev_t ROOT_DEV;

static int __init load_ramdisk(char *str)
{
        rd_doload = simple_strtol(str,NULL,0) & 3;
        return 1;
}
__setup("load_ramdisk=", load_ramdisk);

static int __init readonly(char *str)
{
        if (*str)
                return 0;
        root_mountflags |= MS_RDONLY;
        return 1;
}

static int __init readwrite(char *str)
{
        if (*str)
                return 0;
        root_mountflags &= ~MS_RDONLY;
        return 1;
}

__setup("ro", readonly);
__setup("rw", readwrite);

#ifdef CONFIG_BLOCK
struct uuidcmp {
        const char *uuid;
        int len;
};

/**
 * match_dev_by_uuid - callback for finding a partition using its uuid
 * @dev:        device passed in by the caller
 * @data:       opaque pointer to the desired struct uuidcmp to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int match_dev_by_uuid(struct device *dev, const void *data)
{
        const struct uuidcmp *cmp = data;
        struct hd_struct *part = dev_to_part(dev);

        if (!part->info)
                goto no_match;

        if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
                goto no_match;

        return 1;
no_match:
        return 0;
}


/**
 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 * @uuid_str:   char array containing ascii UUID
 *
 * The function will return the first partition which contains a matching
 * UUID value in its partition_meta_info struct.  This does not search
 * by filesystem UUIDs.
 *
 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
 * extracted and used as an offset from the partition identified by the UUID.
 *
 * Returns the matching dev_t on success or 0 on failure.
 */
static dev_t devt_from_partuuid(const char *uuid_str)
{
        dev_t res = 0;
        struct uuidcmp cmp;
        struct device *dev = NULL;
        struct gendisk *disk;
        struct hd_struct *part;
        int offset = 0;
        bool clear_root_wait = false;
        char *slash;

        cmp.uuid = uuid_str;

        slash = strchr(uuid_str, '/');
        /* Check for optional partition number offset attributes. */
        if (slash) {
                char c = 0;
                /* Explicitly fail on poor PARTUUID syntax. */
                if (sscanf(slash + 1,
                           "PARTNROFF=%d%c", &offset, &c) != 1) {
                        clear_root_wait = true;
                        goto done;
                }
                cmp.len = slash - uuid_str;
        } else {
                cmp.len = strlen(uuid_str);
        }

        if (!cmp.len) {
                clear_root_wait = true;
                goto done;
        }

        dev = class_find_device(&block_class, NULL, &cmp,
                                &match_dev_by_uuid);
        if (!dev)
                goto done;

        res = dev->devt;

        /* Attempt to find the partition by offset. */
        if (!offset)
                goto no_offset;

        res = 0;
        disk = part_to_disk(dev_to_part(dev));
        part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
        if (part) {
                res = part_devt(part);
                put_device(part_to_dev(part));
        }

no_offset:
        put_device(dev);
done:
        if (clear_root_wait) {
                pr_err("VFS: PARTUUID= is invalid.\n"
                       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
                if (root_wait)
                        pr_err("Disabling rootwait; root= is invalid.\n");
                root_wait = 0;
        }
        return res;
}
#endif

/*
 *      Convert a name into device number.  We accept the following variants:
 *
 *      1) <hex_major><hex_minor> device number in hexadecimal represents itself
 *         no leading 0x, for example b302.
 *      2) /dev/nfs represents Root_NFS (0xff)
 *      3) /dev/<disk_name> represents the device number of disk
 *      4) /dev/<disk_name><decimal> represents the device number
 *         of partition - device number of disk plus the partition number
 *      5) /dev/<disk_name>p<decimal> - same as the above, that form is
 *         used when disk name of partitioned disk ends on a digit.
 *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 *         unique id of a partition if the partition table provides it.
 *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 *         filled hex representation of the 32-bit "NT disk signature", and PP
 *         is a zero-filled hex representation of the 1-based partition number.
 *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 *         a partition with a known unique id.
 *      8) <major>:<minor> major and minor number of the device separated by
 *         a colon.
 *
 *      If name doesn't have fall into the categories above, we return (0,0).
 *      block_class is used to check if something is a disk name. If the disk
 *      name contains slashes, the device name has them replaced with
 *      bangs.
 */

dev_t name_to_dev_t(const char *name)
{
        char s[32];
        char *p;
        dev_t res = 0;
        int part;

#ifdef CONFIG_BLOCK
        if (strncmp(name, "PARTUUID=", 9) == 0) {
                name += 9;
                res = devt_from_partuuid(name);
                if (!res)
                        goto fail;
                goto done;
        }
#endif

        if (strncmp(name, "/dev/", 5) != 0) {
                unsigned maj, min, offset;
                char dummy;

                if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
                    (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
                        res = MKDEV(maj, min);
                        if (maj != MAJOR(res) || min != MINOR(res))
                                goto fail;
                } else {
                        res = new_decode_dev(simple_strtoul(name, &p, 16));
                        if (*p)
                                goto fail;
                }
                goto done;
        }

        name += 5;
        res = Root_NFS;
        if (strcmp(name, "nfs") == 0)
                goto done;
        res = Root_RAM0;
        if (strcmp(name, "ram") == 0)
                goto done;

        if (strlen(name) > 31)
                goto fail;
        strcpy(s, name);
        for (p = s; *p; p++)
                if (*p == '/')
                        *p = '!';
        res = blk_lookup_devt(s, 0);
        if (res)
                goto done;

        /*
         * try non-existent, but valid partition, which may only exist
         * after revalidating the disk, like partitioned md devices
         */
        while (p > s && isdigit(p[-1]))
                p--;
        if (p == s || !*p || *p == '0')
                goto fail;

        /* try disk name without <part number> */
        part = simple_strtoul(p, NULL, 10);
        *p = '\0';
        res = blk_lookup_devt(s, part);
        if (res)
                goto done;

        /* try disk name without p<part number> */
        if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
                goto fail;
        p[-1] = '\0';
        res = blk_lookup_devt(s, part);
        if (res)
                goto done;

fail:
        return 0;
done:
        return res;
}
EXPORT_SYMBOL_GPL(name_to_dev_t);

static int __init root_dev_setup(char *line)
{
        strlcpy(saved_root_name, line, sizeof(saved_root_name));
        return 1;
}

__setup("root=", root_dev_setup);

static int __init rootwait_setup(char *str)
{
        if (*str)
                return 0;
        root_wait = 1;
        return 1;
}

__setup("rootwait", rootwait_setup);

static char * __initdata root_mount_data;
static int __init root_data_setup(char *str)
{
        root_mount_data = str;
        return 1;
}

static char * __initdata root_fs_names;
static int __init fs_names_setup(char *str)
{
        root_fs_names = str;
        return 1;
}

static unsigned int __initdata root_delay;
static int __init root_delay_setup(char *str)
{
        root_delay = simple_strtoul(str, NULL, 0);
        return 1;
}

__setup("rootflags=", root_data_setup);
__setup("rootfstype=", fs_names_setup);
__setup("rootdelay=", root_delay_setup);

static void __init get_fs_names(char *page)
{
        char *s = page;

        if (root_fs_names) {
                strcpy(page, root_fs_names);
                while (*s++) {
                        if (s[-1] == ',')
                                s[-1] = '\0';
                }
        } else {
                int len = get_filesystem_list(page);
                char *p, *next;

                page[len] = '\0';
                for (p = page-1; p; p = next) {
                        next = strchr(++p, '\n');
                        if (*p++ != '\t')
                                continue;
                        while ((*s++ = *p++) != '\n')
                                ;
                        s[-1] = '\0';
                }
        }
        *s = '\0';
}

static int __init do_mount_root(char *name, char *fs, int flags, void *data)
{
        struct super_block *s;
        int err = ksys_mount(name, "/root", fs, flags, data);
        if (err)
                return err;

        ksys_chdir("/root");
        s = current->fs->pwd.dentry->d_sb;
        ROOT_DEV = s->s_dev;
        printk(KERN_INFO
               "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
               s->s_type->name,
               sb_rdonly(s) ? " readonly" : "",
               MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
        return 0;
}

void __init mount_block_root(char *name, int flags)
{
        struct page *page = alloc_page(GFP_KERNEL);
        char *fs_names = page_address(page);
        char *p;
#ifdef CONFIG_BLOCK
        char b[BDEVNAME_SIZE];
#else
        const char *b = name;
#endif

        get_fs_names(fs_names);
retry:
        for (p = fs_names; *p; p += strlen(p)+1) {
                int err = do_mount_root(name, p, flags, root_mount_data);
                switch (err) {
                        case 0:
                                goto out;
                        case -EACCES:
                        case -EINVAL:
                                continue;
                }
                /*
                 * Allow the user to distinguish between failed sys_open
                 * and bad superblock on root device.
                 * and give them a list of the available devices
                 */
#ifdef CONFIG_BLOCK
                __bdevname(ROOT_DEV, b);
#endif
                printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
                                root_device_name, b, err);
                printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");

                printk_all_partitions();
#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
                printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
                       "explicit textual name for \"root=\" boot option.\n");
#endif
                panic("VFS: Unable to mount root fs on %s", b);
        }
        if (!(flags & SB_RDONLY)) {
                flags |= SB_RDONLY;
                goto retry;
        }

        printk("List of all partitions:\n");
        printk_all_partitions();
        printk("No filesystem could mount root, tried: ");
        for (p = fs_names; *p; p += strlen(p)+1)
                printk(" %s", p);
        printk("\n");
#ifdef CONFIG_BLOCK
        __bdevname(ROOT_DEV, b);
#endif
        panic("VFS: Unable to mount root fs on %s", b);
out:
        put_page(page);
}
 
#ifdef CONFIG_ROOT_NFS

#define NFSROOT_TIMEOUT_MIN     5
#define NFSROOT_TIMEOUT_MAX     30
#define NFSROOT_RETRY_MAX       5

static int __init mount_nfs_root(void)
{
        char *root_dev, *root_data;
        unsigned int timeout;
        int try, err;

        err = nfs_root_data(&root_dev, &root_data);
        if (err != 0)
                return 0;

        /*
         * The server or network may not be ready, so try several
         * times.  Stop after a few tries in case the client wants
         * to fall back to other boot methods.
         */
        timeout = NFSROOT_TIMEOUT_MIN;
        for (try = 1; ; try++) {
                err = do_mount_root(root_dev, "nfs",
                                        root_mountflags, root_data);
                if (err == 0)
                        return 1;
                if (try > NFSROOT_RETRY_MAX)
                        break;

                /* Wait, in case the server refused us immediately */
                ssleep(timeout);
                timeout <<= 1;
                if (timeout > NFSROOT_TIMEOUT_MAX)
                        timeout = NFSROOT_TIMEOUT_MAX;
        }
        return 0;
}
#endif

#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
void __init change_floppy(char *fmt, ...)
{
        struct termios termios;
        char buf[80];
        char c;
        int fd;
        va_list args;
        va_start(args, fmt);
        vsprintf(buf, fmt, args);
        va_end(args);
        fd = ksys_open("/dev/root", O_RDWR | O_NDELAY, 0);
        if (fd >= 0) {
                ksys_ioctl(fd, FDEJECT, 0);
                ksys_close(fd);
        }
        printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
        fd = ksys_open("/dev/console", O_RDWR, 0);
        if (fd >= 0) {
                ksys_ioctl(fd, TCGETS, (long)&termios);
                termios.c_lflag &= ~ICANON;
                ksys_ioctl(fd, TCSETSF, (long)&termios);
                ksys_read(fd, &c, 1);
                termios.c_lflag |= ICANON;
                ksys_ioctl(fd, TCSETSF, (long)&termios);
                ksys_close(fd);
        }
}
#endif

void __init mount_root(void)
{
#ifdef CONFIG_ROOT_NFS
        if (ROOT_DEV == Root_NFS) {
                if (mount_nfs_root())
                        return;

                printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
                ROOT_DEV = Root_FD0;
        }
#endif
#ifdef CONFIG_BLK_DEV_FD
        if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
                /* rd_doload is 2 for a dual initrd/ramload setup */
                if (rd_doload==2) {
                        if (rd_load_disk(1)) {
                                ROOT_DEV = Root_RAM1;
                                root_device_name = NULL;
                        }
                } else
                        change_floppy("root floppy");
        }
#endif
#ifdef CONFIG_BLOCK
        {
                int err = create_dev("/dev/root", ROOT_DEV);

                if (err < 0)
                        pr_emerg("Failed to create /dev/root: %d\n", err);
                mount_block_root("/dev/root", root_mountflags);
        }
#endif
}

/*
 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 */
void __init prepare_namespace(void)
{
        int is_floppy;

        if (root_delay) {
                printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
                       root_delay);
                ssleep(root_delay);
        }

        /*
         * wait for the known devices to complete their probing
         *
         * Note: this is a potential source of long boot delays.
         * For example, it is not atypical to wait 5 seconds here
         * for the touchpad of a laptop to initialize.
         */
        wait_for_device_probe();

        md_run_setup();

        if (saved_root_name[0]) {
                root_device_name = saved_root_name;
                if (!strncmp(root_device_name, "mtd", 3) ||
                    !strncmp(root_device_name, "ubi", 3)) {
                        mount_block_root(root_device_name, root_mountflags);
                        goto out;
                }
                ROOT_DEV = name_to_dev_t(root_device_name);
                if (strncmp(root_device_name, "/dev/", 5) == 0)
                        root_device_name += 5;
        }

        if (initrd_load())
                goto out;

        /* wait for any asynchronous scanning to complete */
        if ((ROOT_DEV == 0) && root_wait) {
                printk(KERN_INFO "Waiting for root device %s...\n",
                        saved_root_name);
                while (driver_probe_done() != 0 ||
                        (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
                        msleep(5);
                async_synchronize_full();
        }

        is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;

        if (is_floppy && rd_doload && rd_load_disk(0))
                ROOT_DEV = Root_RAM0;

        mount_root();
out:
        devtmpfs_mount("dev");
        ksys_mount(".", "/", NULL, MS_MOVE, NULL);
        ksys_chroot(".");
}

static bool is_tmpfs;
static struct dentry *rootfs_mount(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data)
{
        static unsigned long once;
        void *fill = ramfs_fill_super;

        if (test_and_set_bit(0, &once))
                return ERR_PTR(-ENODEV);

        if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
                fill = shmem_fill_super;

        return mount_nodev(fs_type, flags, data, fill);
}

static struct file_system_type rootfs_fs_type = {
        .name           = "rootfs",
        .mount          = rootfs_mount,
        .kill_sb        = kill_litter_super,
};

int __init init_rootfs(void)
{
        int err = register_filesystem(&rootfs_fs_type);

        if (err)
                return err;

        if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
                (!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
                err = shmem_init();
                is_tmpfs = true;
        } else {
                err = init_ramfs_fs();
        }

        if (err)
                unregister_filesystem(&rootfs_fs_type);

        return err;
}