// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/hfsplus/wrapper.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handling of HFS wrappers around HFS+ volumes
 */

#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/cdrom.h>
#include <linux/unaligned.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

struct hfsplus_wd {
        u32 ablk_size;
        u16 ablk_start;
        u16 embed_start;
        u16 embed_count;
};

/**
 * hfsplus_submit_bio - Perform block I/O
 * @sb: super block of volume for I/O
 * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
 * @buf: buffer for I/O
 * @data: output pointer for location of requested data
 * @opf: I/O operation type and flags
 *
 * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
 * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
 * @data will return a pointer to the start of the requested sector,
 * which may not be the same location as @buf.
 *
 * If @sector is not aligned to the bdev logical block size it will
 * be rounded down. For writes this means that @buf should contain data
 * that starts at the rounded-down address. As long as the data was
 * read using hfsplus_submit_bio() and the same buffer is used things
 * will work correctly.
 *
 * Returns: %0 on success else -errno code
 */
int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
                       void *buf, void **data, blk_opf_t opf)
{
        u64 io_size = hfsplus_min_io_size(sb);
        loff_t start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
        int offset = start & (io_size - 1);

        if ((opf & REQ_OP_MASK) != REQ_OP_WRITE && data)
                *data = (u8 *)buf + offset;

        /*
         * Align sector to hardware sector size and find offset. We assume that
         * io_size is a power of two, which _should_ be true.
         */
        sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
        return bdev_rw_virt(sb->s_bdev, sector, buf, io_size, opf);
}

static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
{
        u32 extent;
        u16 attrib;
        __be16 sig;

        sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
        if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
            sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
                return 0;

        attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
        if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
           !(attrib & HFSP_WRAP_ATTRIB_SPARED))
                return 0;

        wd->ablk_size =
                be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
        if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
                return 0;
        if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
                return 0;
        wd->ablk_start =
                be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));

        extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
        wd->embed_start = (extent >> 16) & 0xFFFF;
        wd->embed_count = extent & 0xFFFF;

        return 1;
}

static int hfsplus_get_last_session(struct super_block *sb,
                                    sector_t *start, sector_t *size)
{
        struct cdrom_device_info *cdi = disk_to_cdi(sb->s_bdev->bd_disk);

        /* default values */
        *start = 0;
        *size = bdev_nr_sectors(sb->s_bdev);

        if (HFSPLUS_SB(sb)->session >= 0) {
                struct cdrom_tocentry te;

                if (!cdi)
                        return -EINVAL;

                te.cdte_track = HFSPLUS_SB(sb)->session;
                te.cdte_format = CDROM_LBA;
                if (cdrom_read_tocentry(cdi, &te) ||
                    (te.cdte_ctrl & CDROM_DATA_TRACK) != 4) {
                        pr_err("invalid session number or type of track\n");
                        return -EINVAL;
                }
                *start = (sector_t)te.cdte_addr.lba << 2;
        } else if (cdi) {
                struct cdrom_multisession ms_info;

                ms_info.addr_format = CDROM_LBA;
                if (cdrom_multisession(cdi, &ms_info) == 0 && ms_info.xa_flag)
                        *start = (sector_t)ms_info.addr.lba << 2;
        }

        return 0;
}

/* Find the volume header and fill in some minimum bits in superblock */
/* Takes in super block, returns true if good data read */
int hfsplus_read_wrapper(struct super_block *sb)
{
        struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
        struct hfsplus_wd wd;
        sector_t part_start, part_size;
        u32 blocksize;
        int error = 0;

        error = -EINVAL;
        blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
        if (!blocksize)
                goto out;

        sbi->min_io_size = blocksize;

        if (hfsplus_get_last_session(sb, &part_start, &part_size))
                goto out;

        error = -ENOMEM;
        sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
        if (!sbi->s_vhdr_buf)
                goto out;
        sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
        if (!sbi->s_backup_vhdr_buf)
                goto out_free_vhdr;

reread:
        error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
                                   sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
                                   REQ_OP_READ);
        if (error)
                goto out_free_backup_vhdr;

        error = -EINVAL;
        switch (sbi->s_vhdr->signature) {
        case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
                set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
                fallthrough;
        case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
                break;
        case cpu_to_be16(HFSP_WRAP_MAGIC):
                if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
                        goto out_free_backup_vhdr;
                wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
                part_start += (sector_t)wd.ablk_start +
                               (sector_t)wd.embed_start * wd.ablk_size;
                part_size = (sector_t)wd.embed_count * wd.ablk_size;
                goto reread;
        default:
                /*
                 * Check for a partition block.
                 *
                 * (should do this only for cdrom/loop though)
                 */
                if (hfs_part_find(sb, &part_start, &part_size))
                        goto out_free_backup_vhdr;
                goto reread;
        }

        error = hfsplus_submit_bio(sb, part_start + part_size - 2,
                                   sbi->s_backup_vhdr_buf,
                                   (void **)&sbi->s_backup_vhdr, REQ_OP_READ);
        if (error)
                goto out_free_backup_vhdr;

        error = -EINVAL;
        if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
                pr_warn("invalid secondary volume header\n");
                goto out_free_backup_vhdr;
        }

        blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);

        /*
         * Block size must be at least as large as a sector and a multiple of 2.
         */
        if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
                goto out_free_backup_vhdr;
        sbi->alloc_blksz = blocksize;
        sbi->alloc_blksz_shift = ilog2(blocksize);
        blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);

        /*
         * Align block size to block offset.
         */
        while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
                blocksize >>= 1;

        if (sb_set_blocksize(sb, blocksize) != blocksize) {
                pr_err("unable to set blocksize to %u!\n", blocksize);
                goto out_free_backup_vhdr;
        }

        sbi->blockoffset =
                part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
        sbi->part_start = part_start;
        sbi->sect_count = part_size;
        sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
        return 0;

out_free_backup_vhdr:
        kfree(sbi->s_backup_vhdr_buf);
out_free_vhdr:
        kfree(sbi->s_vhdr_buf);
out:
        return error;
}