// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2013 HUAWEI
 * Author: Cai Zhiyong <caizhiyong@huawei.com>
 *
 * Read block device partition table from the command line.
 * Typically used for fixed block (eMMC) embedded devices.
 * It has no MBR, so saves storage space. Bootloader can be easily accessed
 * by absolute address of data on the block device.
 * Users can easily change the partition.
 *
 * The format for the command line is just like mtdparts.
 *
 * For further information, see "Documentation/block/cmdline-partition.rst"
 *
 */
#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include "check.h"


/* partition flags */
#define PF_RDONLY                   0x01 /* Device is read only */
#define PF_POWERUP_LOCK             0x02 /* Always locked after reset */

struct cmdline_subpart {
        char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
        sector_t from;
        sector_t size;
        int flags;
        struct cmdline_subpart *next_subpart;
};

struct cmdline_parts {
        char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
        unsigned int nr_subparts;
        struct cmdline_subpart *subpart;
        struct cmdline_parts *next_parts;
};

static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
{
        int ret = 0;
        struct cmdline_subpart *new_subpart;

        *subpart = NULL;

        new_subpart = kzalloc_obj(struct cmdline_subpart);
        if (!new_subpart)
                return -ENOMEM;

        if (*partdef == '-') {
                new_subpart->size = (sector_t)(~0ULL);
                partdef++;
        } else {
                new_subpart->size = (sector_t)memparse(partdef, &partdef);
                if (new_subpart->size < (sector_t)PAGE_SIZE) {
                        pr_warn("cmdline partition size is invalid.");
                        ret = -EINVAL;
                        goto fail;
                }
        }

        if (*partdef == '@') {
                partdef++;
                new_subpart->from = (sector_t)memparse(partdef, &partdef);
        } else {
                new_subpart->from = (sector_t)(~0ULL);
        }

        if (*partdef == '(') {
                partdef++;
                char *next = strsep(&partdef, ")");

                if (!next) {
                        pr_warn("cmdline partition format is invalid.");
                        ret = -EINVAL;
                        goto fail;
                }

                strscpy(new_subpart->name, next, sizeof(new_subpart->name));
        } else
                new_subpart->name[0] = '\0';

        new_subpart->flags = 0;

        if (!strncmp(partdef, "ro", 2)) {
                new_subpart->flags |= PF_RDONLY;
                partdef += 2;
        }

        if (!strncmp(partdef, "lk", 2)) {
                new_subpart->flags |= PF_POWERUP_LOCK;
                partdef += 2;
        }

        *subpart = new_subpart;
        return 0;
fail:
        kfree(new_subpart);
        return ret;
}

static void free_subpart(struct cmdline_parts *parts)
{
        struct cmdline_subpart *subpart;

        while (parts->subpart) {
                subpart = parts->subpart;
                parts->subpart = subpart->next_subpart;
                kfree(subpart);
        }
}

static int parse_parts(struct cmdline_parts **parts, char *bdevdef)
{
        int ret = -EINVAL;
        char *next;
        struct cmdline_subpart **next_subpart;
        struct cmdline_parts *newparts;

        *parts = NULL;

        newparts = kzalloc_obj(struct cmdline_parts);
        if (!newparts)
                return -ENOMEM;

        next = strsep(&bdevdef, ":");
        if (!next) {
                pr_warn("cmdline partition has no block device.");
                goto fail;
        }

        strscpy(newparts->name, next, sizeof(newparts->name));
        newparts->nr_subparts = 0;

        next_subpart = &newparts->subpart;

        while ((next = strsep(&bdevdef, ","))) {
                ret = parse_subpart(next_subpart, next);
                if (ret)
                        goto fail;

                newparts->nr_subparts++;
                next_subpart = &(*next_subpart)->next_subpart;
        }

        if (!newparts->subpart) {
                pr_warn("cmdline partition has no valid partition.");
                ret = -EINVAL;
                goto fail;
        }

        *parts = newparts;

        return 0;
fail:
        free_subpart(newparts);
        kfree(newparts);
        return ret;
}

static void cmdline_parts_free(struct cmdline_parts **parts)
{
        struct cmdline_parts *next_parts;

        while (*parts) {
                next_parts = (*parts)->next_parts;
                free_subpart(*parts);
                kfree(*parts);
                *parts = next_parts;
        }
}

static int cmdline_parts_parse(struct cmdline_parts **parts,
                const char *cmdline)
{
        int ret;
        char *buf;
        char *pbuf;
        char *next;
        struct cmdline_parts **next_parts;

        *parts = NULL;

        pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        next_parts = parts;

        while ((next = strsep(&pbuf, ";"))) {
                ret = parse_parts(next_parts, next);
                if (ret)
                        goto fail;

                next_parts = &(*next_parts)->next_parts;
        }

        if (!*parts) {
                pr_warn("cmdline partition has no valid partition.");
                ret = -EINVAL;
                goto fail;
        }

        ret = 0;
done:
        kfree(buf);
        return ret;

fail:
        cmdline_parts_free(parts);
        goto done;
}

static struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
                                         const char *bdev)
{
        while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
                parts = parts->next_parts;
        return parts;
}

static char *cmdline;
static struct cmdline_parts *bdev_parts;

static int add_part(int slot, struct cmdline_subpart *subpart,
                struct parsed_partitions *state)
{
        struct partition_meta_info *info;
        char tmp[sizeof(info->volname) + 4];

        if (slot >= state->limit)
                return 1;

        put_partition(state, slot, subpart->from >> 9,
                      subpart->size >> 9);

        if (subpart->flags & PF_RDONLY)
                state->parts[slot].flags |= ADDPART_FLAG_READONLY;

        info = &state->parts[slot].info;

        strscpy(info->volname, subpart->name, sizeof(info->volname));

        snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
        strlcat(state->pp_buf, tmp, PAGE_SIZE);

        state->parts[slot].has_info = true;

        return 0;
}

static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
                struct parsed_partitions *state)
{
        sector_t from = 0;
        struct cmdline_subpart *subpart;
        int slot = 1;

        for (subpart = parts->subpart; subpart;
             subpart = subpart->next_subpart, slot++) {
                if (subpart->from == (sector_t)(~0ULL))
                        subpart->from = from;
                else
                        from = subpart->from;

                if (from >= disk_size)
                        break;

                if (subpart->size > (disk_size - from))
                        subpart->size = disk_size - from;

                from += subpart->size;

                if (add_part(slot, subpart, state))
                        break;
        }

        return slot;
}

static int __init cmdline_parts_setup(char *s)
{
        cmdline = s;
        return 1;
}
__setup("blkdevparts=", cmdline_parts_setup);

static bool has_overlaps(sector_t from, sector_t size,
                         sector_t from2, sector_t size2)
{
        sector_t end = from + size;
        sector_t end2 = from2 + size2;

        if (from >= from2 && from < end2)
                return true;

        if (end > from2 && end <= end2)
                return true;

        if (from2 >= from && from2 < end)
                return true;

        if (end2 > from && end2 <= end)
                return true;

        return false;
}

static inline void overlaps_warns_header(void)
{
        pr_warn("Overlapping partitions are used in command line partitions.");
        pr_warn("Don't use filesystems on overlapping partitions:");
}

static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
{
        int i;
        bool header = true;

        for (; slot < state->limit && state->parts[slot].has_info; slot++) {
                for (i = slot+1; i < state->limit && state->parts[i].has_info;
                     i++) {
                        if (has_overlaps(state->parts[slot].from,
                                         state->parts[slot].size,
                                         state->parts[i].from,
                                         state->parts[i].size)) {
                                if (header) {
                                        header = false;
                                        overlaps_warns_header();
                                }
                                pr_warn("%s[%llu,%llu] overlaps with "
                                        "%s[%llu,%llu].",
                                        state->parts[slot].info.volname,
                                        (u64)state->parts[slot].from << 9,
                                        (u64)state->parts[slot].size << 9,
                                        state->parts[i].info.volname,
                                        (u64)state->parts[i].from << 9,
                                        (u64)state->parts[i].size << 9);
                        }
                }
        }
}

/*
 * Purpose: allocate cmdline partitions.
 * Returns:
 * -1 if unable to read the partition table
 *  0 if this isn't our partition table
 *  1 if successful
 */
int cmdline_partition(struct parsed_partitions *state)
{
        sector_t disk_size;
        struct cmdline_parts *parts;

        if (cmdline) {
                if (bdev_parts)
                        cmdline_parts_free(&bdev_parts);

                if (cmdline_parts_parse(&bdev_parts, cmdline)) {
                        cmdline = NULL;
                        return -1;
                }
                cmdline = NULL;
        }

        if (!bdev_parts)
                return 0;

        parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
        if (!parts)
                return 0;

        disk_size = get_capacity(state->disk) << 9;

        cmdline_parts_set(parts, disk_size, state);
        cmdline_parts_verifier(1, state);

        strlcat(state->pp_buf, "\n", PAGE_SIZE);

        return 1;
}