// SPDX-License-Identifier: GPL-2.0-only
/*
 * Code for looking up block devices in the early boot code before mounting the
 * root file system.
 */
#include <linux/blkdev.h>
#include <linux/ctype.h>

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 __init match_dev_by_uuid(struct device *dev, const void *data)
{
        struct block_device *bdev = dev_to_bdev(dev);
        const struct uuidcmp *cmp = data;

        if (!bdev->bd_meta_info ||
            strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
                return 0;
        return 1;
}

/**
 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 * @uuid_str:   char array containing ascii UUID
 * @devt:       dev_t result
 *
 * 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 0 on success or a negative error code on failure.
 */
static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt)
{
        struct uuidcmp cmp;
        struct device *dev = NULL;
        int offset = 0;
        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)
                        goto out_invalid;
                cmp.len = slash - uuid_str;
        } else {
                cmp.len = strlen(uuid_str);
        }

        if (!cmp.len)
                goto out_invalid;

        dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
        if (!dev)
                return -ENODEV;

        if (offset) {
                /*
                 * Attempt to find the requested partition by adding an offset
                 * to the partition number found by UUID.
                 */
                *devt = part_devt(dev_to_disk(dev),
                                  bdev_partno(dev_to_bdev(dev)) + offset);
        } else {
                *devt = dev->devt;
        }

        put_device(dev);
        return 0;

out_invalid:
        pr_err("VFS: PARTUUID= is invalid.\n"
               "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
        return -EINVAL;
}

/**
 * match_dev_by_label - callback for finding a partition using its label
 * @dev:        device passed in by the caller
 * @data:       opaque pointer to the label to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int __init match_dev_by_label(struct device *dev, const void *data)
{
        struct block_device *bdev = dev_to_bdev(dev);
        const char *label = data;

        if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
                return 0;
        return 1;
}

static int __init devt_from_partlabel(const char *label, dev_t *devt)
{
        struct device *dev;

        dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
        if (!dev)
                return -ENODEV;
        *devt = dev->devt;
        put_device(dev);
        return 0;
}

static dev_t __init blk_lookup_devt(const char *name, int partno)
{
        dev_t devt = MKDEV(0, 0);
        struct class_dev_iter iter;
        struct device *dev;

        class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
        while ((dev = class_dev_iter_next(&iter))) {
                struct gendisk *disk = dev_to_disk(dev);

                if (strcmp(dev_name(dev), name))
                        continue;

                if (partno < disk->minors) {
                        /* We need to return the right devno, even
                         * if the partition doesn't exist yet.
                         */
                        devt = MKDEV(MAJOR(dev->devt),
                                     MINOR(dev->devt) + partno);
                } else {
                        devt = part_devt(disk, partno);
                        if (devt)
                                break;
                }
        }
        class_dev_iter_exit(&iter);
        return devt;
}

static int __init devt_from_devname(const char *name, dev_t *devt)
{
        int part;
        char s[32];
        char *p;

        if (strlen(name) > 31)
                return -EINVAL;
        strcpy(s, name);
        for (p = s; *p; p++) {
                if (*p == '/')
                        *p = '!';
        }

        *devt = blk_lookup_devt(s, 0);
        if (*devt)
                return 0;

        /*
         * Try non-existent, but valid partition, which may only exist after
         * opening the device, like partitioned md devices.
         */
        while (p > s && isdigit(p[-1]))
                p--;
        if (p == s || !*p || *p == '0')
                return -ENODEV;

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

        /* try disk name without p<part number> */
        if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
                return -ENODEV;
        p[-1] = '\0';
        *devt = blk_lookup_devt(s, part);
        if (*devt)
                return 0;
        return -ENODEV;
}

static int __init devt_from_devnum(const char *name, dev_t *devt)
{
        unsigned maj, min, offset;
        char *p, dummy;

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

        return 0;
}

/*
 *      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.
 *      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.
 *      9) PARTLABEL=<name> with name being the GPT partition label.
 *         MSDOS partitions do not support labels!
 *
 *      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.
 */
int __init early_lookup_bdev(const char *name, dev_t *devt)
{
        if (strncmp(name, "PARTUUID=", 9) == 0)
                return devt_from_partuuid(name + 9, devt);
        if (strncmp(name, "PARTLABEL=", 10) == 0)
                return devt_from_partlabel(name + 10, devt);
        if (strncmp(name, "/dev/", 5) == 0)
                return devt_from_devname(name + 5, devt);
        return devt_from_devnum(name, devt);
}

static char __init *bdevt_str(dev_t devt, char *buf)
{
        if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
                char tbuf[BDEVT_SIZE];
                snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
                snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
        } else
                snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));

        return buf;
}

/*
 * print a full list of all partitions - intended for places where the root
 * filesystem can't be mounted and thus to give the victim some idea of what
 * went wrong
 */
void __init printk_all_partitions(void)
{
        struct class_dev_iter iter;
        struct device *dev;

        class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
        while ((dev = class_dev_iter_next(&iter))) {
                struct gendisk *disk = dev_to_disk(dev);
                struct block_device *part;
                char devt_buf[BDEVT_SIZE];
                unsigned long idx;

                /*
                 * Don't show empty devices or things that have been
                 * suppressed
                 */
                if (get_capacity(disk) == 0 || (disk->flags & GENHD_FL_HIDDEN))
                        continue;

                /*
                 * Note, unlike /proc/partitions, I am showing the numbers in
                 * hex - the same format as the root= option takes.
                 */
                rcu_read_lock();
                xa_for_each(&disk->part_tbl, idx, part) {
                        if (!bdev_nr_sectors(part))
                                continue;
                        printk("%s%s %10llu %pg %s",
                               bdev_is_partition(part) ? "  " : "",
                               bdevt_str(part->bd_dev, devt_buf),
                               bdev_nr_sectors(part) >> 1, part,
                               part->bd_meta_info ?
                                        part->bd_meta_info->uuid : "");
                        if (bdev_is_partition(part))
                                printk("\n");
                        else if (dev->parent && dev->parent->driver)
                                printk(" driver: %s\n",
                                        dev->parent->driver->name);
                        else
                                printk(" (driver?)\n");
                }
                rcu_read_unlock();
        }
        class_dev_iter_exit(&iter);
}