// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/affs/amigaffs.c
 *
 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
 *
 *  (C) 1993  Ray Burr - Amiga FFS filesystem.
 *
 *  Please send bug reports to: hjw@zvw.de
 */

#include <linux/math64.h>
#include <linux/iversion.h>
#include "affs.h"

/*
 * Functions for accessing Amiga-FFS structures.
 */


/* Insert a header block bh into the directory dir
 * caller must hold AFFS_DIR->i_hash_lock!
 */

int
affs_insert_hash(struct inode *dir, struct buffer_head *bh)
{
        struct super_block *sb = dir->i_sb;
        struct buffer_head *dir_bh;
        u32 ino, hash_ino;
        int offset;

        ino = bh->b_blocknr;
        offset = affs_hash_name(sb, AFFS_TAIL(sb, bh)->name + 1, AFFS_TAIL(sb, bh)->name[0]);

        pr_debug("%s(dir=%lu, ino=%d)\n", __func__, dir->i_ino, ino);

        dir_bh = affs_bread(sb, dir->i_ino);
        if (!dir_bh)
                return -EIO;

        hash_ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[offset]);
        while (hash_ino) {
                affs_brelse(dir_bh);
                dir_bh = affs_bread(sb, hash_ino);
                if (!dir_bh)
                        return -EIO;
                hash_ino = be32_to_cpu(AFFS_TAIL(sb, dir_bh)->hash_chain);
        }
        AFFS_TAIL(sb, bh)->parent = cpu_to_be32(dir->i_ino);
        AFFS_TAIL(sb, bh)->hash_chain = 0;
        affs_fix_checksum(sb, bh);

        if (dir->i_ino == dir_bh->b_blocknr)
                AFFS_HEAD(dir_bh)->table[offset] = cpu_to_be32(ino);
        else
                AFFS_TAIL(sb, dir_bh)->hash_chain = cpu_to_be32(ino);

        affs_adjust_checksum(dir_bh, ino);
        mark_buffer_dirty_inode(dir_bh, dir);
        affs_brelse(dir_bh);

        dir->i_mtime = dir->i_ctime = current_time(dir);
        inode_inc_iversion(dir);
        mark_inode_dirty(dir);

        return 0;
}

/* Remove a header block from its directory.
 * caller must hold AFFS_DIR->i_hash_lock!
 */

int
affs_remove_hash(struct inode *dir, struct buffer_head *rem_bh)
{
        struct super_block *sb;
        struct buffer_head *bh;
        u32 rem_ino, hash_ino;
        __be32 ino;
        int offset, retval;

        sb = dir->i_sb;
        rem_ino = rem_bh->b_blocknr;
        offset = affs_hash_name(sb, AFFS_TAIL(sb, rem_bh)->name+1, AFFS_TAIL(sb, rem_bh)->name[0]);
        pr_debug("%s(dir=%lu, ino=%d, hashval=%d)\n", __func__, dir->i_ino,
                 rem_ino, offset);

        bh = affs_bread(sb, dir->i_ino);
        if (!bh)
                return -EIO;

        retval = -ENOENT;
        hash_ino = be32_to_cpu(AFFS_HEAD(bh)->table[offset]);
        while (hash_ino) {
                if (hash_ino == rem_ino) {
                        ino = AFFS_TAIL(sb, rem_bh)->hash_chain;
                        if (dir->i_ino == bh->b_blocknr)
                                AFFS_HEAD(bh)->table[offset] = ino;
                        else
                                AFFS_TAIL(sb, bh)->hash_chain = ino;
                        affs_adjust_checksum(bh, be32_to_cpu(ino) - hash_ino);
                        mark_buffer_dirty_inode(bh, dir);
                        AFFS_TAIL(sb, rem_bh)->parent = 0;
                        retval = 0;
                        break;
                }
                affs_brelse(bh);
                bh = affs_bread(sb, hash_ino);
                if (!bh)
                        return -EIO;
                hash_ino = be32_to_cpu(AFFS_TAIL(sb, bh)->hash_chain);
        }

        affs_brelse(bh);

        dir->i_mtime = dir->i_ctime = current_time(dir);
        inode_inc_iversion(dir);
        mark_inode_dirty(dir);

        return retval;
}

static void
affs_fix_dcache(struct inode *inode, u32 entry_ino)
{
        struct dentry *dentry;
        spin_lock(&inode->i_lock);
        hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
                if (entry_ino == (u32)(long)dentry->d_fsdata) {
                        dentry->d_fsdata = (void *)inode->i_ino;
                        break;
                }
        }
        spin_unlock(&inode->i_lock);
}


/* Remove header from link chain */

static int
affs_remove_link(struct dentry *dentry)
{
        struct inode *dir, *inode = d_inode(dentry);
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh, *link_bh = NULL;
        u32 link_ino, ino;
        int retval;

        pr_debug("%s(key=%ld)\n", __func__, inode->i_ino);
        retval = -EIO;
        bh = affs_bread(sb, inode->i_ino);
        if (!bh)
                goto done;

        link_ino = (u32)(long)dentry->d_fsdata;
        if (inode->i_ino == link_ino) {
                /* we can't remove the head of the link, as its blocknr is still used as ino,
                 * so we remove the block of the first link instead.
                 */ 
                link_ino = be32_to_cpu(AFFS_TAIL(sb, bh)->link_chain);
                link_bh = affs_bread(sb, link_ino);
                if (!link_bh)
                        goto done;

                dir = affs_iget(sb, be32_to_cpu(AFFS_TAIL(sb, link_bh)->parent));
                if (IS_ERR(dir)) {
                        retval = PTR_ERR(dir);
                        goto done;
                }

                affs_lock_dir(dir);
                /*
                 * if there's a dentry for that block, make it
                 * refer to inode itself.
                 */
                affs_fix_dcache(inode, link_ino);
                retval = affs_remove_hash(dir, link_bh);
                if (retval) {
                        affs_unlock_dir(dir);
                        goto done;
                }
                mark_buffer_dirty_inode(link_bh, inode);

                memcpy(AFFS_TAIL(sb, bh)->name, AFFS_TAIL(sb, link_bh)->name, 32);
                retval = affs_insert_hash(dir, bh);
                if (retval) {
                        affs_unlock_dir(dir);
                        goto done;
                }
                mark_buffer_dirty_inode(bh, inode);

                affs_unlock_dir(dir);
                iput(dir);
        } else {
                link_bh = affs_bread(sb, link_ino);
                if (!link_bh)
                        goto done;
        }

        while ((ino = be32_to_cpu(AFFS_TAIL(sb, bh)->link_chain)) != 0) {
                if (ino == link_ino) {
                        __be32 ino2 = AFFS_TAIL(sb, link_bh)->link_chain;
                        AFFS_TAIL(sb, bh)->link_chain = ino2;
                        affs_adjust_checksum(bh, be32_to_cpu(ino2) - link_ino);
                        mark_buffer_dirty_inode(bh, inode);
                        retval = 0;
                        /* Fix the link count, if bh is a normal header block without links */
                        switch (be32_to_cpu(AFFS_TAIL(sb, bh)->stype)) {
                        case ST_LINKDIR:
                        case ST_LINKFILE:
                                break;
                        default:
                                if (!AFFS_TAIL(sb, bh)->link_chain)
                                        set_nlink(inode, 1);
                        }
                        affs_free_block(sb, link_ino);
                        goto done;
                }
                affs_brelse(bh);
                bh = affs_bread(sb, ino);
                if (!bh)
                        goto done;
        }
        retval = -ENOENT;
done:
        affs_brelse(link_bh);
        affs_brelse(bh);
        return retval;
}


static int
affs_empty_dir(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh;
        int retval, size;

        retval = -EIO;
        bh = affs_bread(sb, inode->i_ino);
        if (!bh)
                goto done;

        retval = -ENOTEMPTY;
        for (size = AFFS_SB(sb)->s_hashsize - 1; size >= 0; size--)
                if (AFFS_HEAD(bh)->table[size])
                        goto not_empty;
        retval = 0;
not_empty:
        affs_brelse(bh);
done:
        return retval;
}


/* Remove a filesystem object. If the object to be removed has
 * links to it, one of the links must be changed to inherit
 * the file or directory. As above, any inode will do.
 * The buffer will not be freed. If the header is a link, the
 * block will be marked as free.
 * This function returns a negative error number in case of
 * an error, else 0 if the inode is to be deleted or 1 if not.
 */

int
affs_remove_header(struct dentry *dentry)
{
        struct super_block *sb;
        struct inode *inode, *dir;
        struct buffer_head *bh = NULL;
        int retval;

        dir = d_inode(dentry->d_parent);
        sb = dir->i_sb;

        retval = -ENOENT;
        inode = d_inode(dentry);
        if (!inode)
                goto done;

        pr_debug("%s(key=%ld)\n", __func__, inode->i_ino);
        retval = -EIO;
        bh = affs_bread(sb, (u32)(long)dentry->d_fsdata);
        if (!bh)
                goto done;

        affs_lock_link(inode);
        affs_lock_dir(dir);
        switch (be32_to_cpu(AFFS_TAIL(sb, bh)->stype)) {
        case ST_USERDIR:
                /* if we ever want to support links to dirs
                 * i_hash_lock of the inode must only be
                 * taken after some checks
                 */
                affs_lock_dir(inode);
                retval = affs_empty_dir(inode);
                affs_unlock_dir(inode);
                if (retval)
                        goto done_unlock;
                break;
        default:
                break;
        }

        retval = affs_remove_hash(dir, bh);
        if (retval)
                goto done_unlock;
        mark_buffer_dirty_inode(bh, inode);

        affs_unlock_dir(dir);

        if (inode->i_nlink > 1)
                retval = affs_remove_link(dentry);
        else
                clear_nlink(inode);
        affs_unlock_link(inode);
        inode->i_ctime = current_time(inode);
        mark_inode_dirty(inode);

done:
        affs_brelse(bh);
        return retval;

done_unlock:
        affs_unlock_dir(dir);
        affs_unlock_link(inode);
        goto done;
}

/* Checksum a block, do various consistency checks and optionally return
   the blocks type number.  DATA points to the block.  If their pointers
   are non-null, *PTYPE and *STYPE are set to the primary and secondary
   block types respectively, *HASHSIZE is set to the size of the hashtable
   (which lets us calculate the block size).
   Returns non-zero if the block is not consistent. */

u32
affs_checksum_block(struct super_block *sb, struct buffer_head *bh)
{
        __be32 *ptr = (__be32 *)bh->b_data;
        u32 sum;
        int bsize;

        sum = 0;
        for (bsize = sb->s_blocksize / sizeof(__be32); bsize > 0; bsize--)
                sum += be32_to_cpu(*ptr++);
        return sum;
}

/*
 * Calculate the checksum of a disk block and store it
 * at the indicated position.
 */

void
affs_fix_checksum(struct super_block *sb, struct buffer_head *bh)
{
        int cnt = sb->s_blocksize / sizeof(__be32);
        __be32 *ptr = (__be32 *)bh->b_data;
        u32 checksum;
        __be32 *checksumptr;

        checksumptr = ptr + 5;
        *checksumptr = 0;
        for (checksum = 0; cnt > 0; ptr++, cnt--)
                checksum += be32_to_cpu(*ptr);
        *checksumptr = cpu_to_be32(-checksum);
}

void
affs_secs_to_datestamp(time64_t secs, struct affs_date *ds)
{
        u32      days;
        u32      minute;
        s32      rem;

        secs -= sys_tz.tz_minuteswest * 60 + AFFS_EPOCH_DELTA;
        if (secs < 0)
                secs = 0;
        days    = div_s64_rem(secs, 86400, &rem);
        minute  = rem / 60;
        rem    -= minute * 60;

        ds->days = cpu_to_be32(days);
        ds->mins = cpu_to_be32(minute);
        ds->ticks = cpu_to_be32(rem * 50);
}

umode_t
affs_prot_to_mode(u32 prot)
{
        umode_t mode = 0;

        if (!(prot & FIBF_NOWRITE))
                mode |= 0200;
        if (!(prot & FIBF_NOREAD))
                mode |= 0400;
        if (!(prot & FIBF_NOEXECUTE))
                mode |= 0100;
        if (prot & FIBF_GRP_WRITE)
                mode |= 0020;
        if (prot & FIBF_GRP_READ)
                mode |= 0040;
        if (prot & FIBF_GRP_EXECUTE)
                mode |= 0010;
        if (prot & FIBF_OTR_WRITE)
                mode |= 0002;
        if (prot & FIBF_OTR_READ)
                mode |= 0004;
        if (prot & FIBF_OTR_EXECUTE)
                mode |= 0001;

        return mode;
}

void
affs_mode_to_prot(struct inode *inode)
{
        u32 prot = AFFS_I(inode)->i_protect;
        umode_t mode = inode->i_mode;

        /*
         * First, clear all RWED bits for owner, group, other.
         * Then, recalculate them afresh.
         *
         * We'll always clear the delete-inhibit bit for the owner, as that is
         * the classic single-user mode AmigaOS protection bit and we need to
         * stay compatible with all scenarios.
         *
         * Since multi-user AmigaOS is an extension, we'll only set the
         * delete-allow bit if any of the other bits in the same user class
         * (group/other) are used.
         */
        prot &= ~(FIBF_NOEXECUTE | FIBF_NOREAD
                  | FIBF_NOWRITE | FIBF_NODELETE
                  | FIBF_GRP_EXECUTE | FIBF_GRP_READ
                  | FIBF_GRP_WRITE   | FIBF_GRP_DELETE
                  | FIBF_OTR_EXECUTE | FIBF_OTR_READ
                  | FIBF_OTR_WRITE   | FIBF_OTR_DELETE);

        /* Classic single-user AmigaOS flags. These are inverted. */
        if (!(mode & 0100))
                prot |= FIBF_NOEXECUTE;
        if (!(mode & 0400))
                prot |= FIBF_NOREAD;
        if (!(mode & 0200))
                prot |= FIBF_NOWRITE;

        /* Multi-user extended flags. Not inverted. */
        if (mode & 0010)
                prot |= FIBF_GRP_EXECUTE;
        if (mode & 0040)
                prot |= FIBF_GRP_READ;
        if (mode & 0020)
                prot |= FIBF_GRP_WRITE;
        if (mode & 0070)
                prot |= FIBF_GRP_DELETE;

        if (mode & 0001)
                prot |= FIBF_OTR_EXECUTE;
        if (mode & 0004)
                prot |= FIBF_OTR_READ;
        if (mode & 0002)
                prot |= FIBF_OTR_WRITE;
        if (mode & 0007)
                prot |= FIBF_OTR_DELETE;

        AFFS_I(inode)->i_protect = prot;
}

void
affs_error(struct super_block *sb, const char *function, const char *fmt, ...)
{
        struct va_format vaf;
        va_list args;

        va_start(args, fmt);
        vaf.fmt = fmt;
        vaf.va = &args;
        pr_crit("error (device %s): %s(): %pV\n", sb->s_id, function, &vaf);
        if (!sb_rdonly(sb))
                pr_warn("Remounting filesystem read-only\n");
        sb->s_flags |= SB_RDONLY;
        va_end(args);
}

void
affs_warning(struct super_block *sb, const char *function, const char *fmt, ...)
{
        struct va_format vaf;
        va_list args;

        va_start(args, fmt);
        vaf.fmt = fmt;
        vaf.va = &args;
        pr_warn("(device %s): %s(): %pV\n", sb->s_id, function, &vaf);
        va_end(args);
}

bool
affs_nofilenametruncate(const struct dentry *dentry)
{
        return affs_test_opt(AFFS_SB(dentry->d_sb)->s_flags, SF_NO_TRUNCATE);
}

/* Check if the name is valid for a affs object. */

int
affs_check_name(const unsigned char *name, int len, bool notruncate)
{
        int      i;

        if (len > AFFSNAMEMAX) {
                if (notruncate)
                        return -ENAMETOOLONG;
                len = AFFSNAMEMAX;
        }
        for (i = 0; i < len; i++) {
                if (name[i] < ' ' || name[i] == ':'
                    || (name[i] > 0x7e && name[i] < 0xa0))
                        return -EINVAL;
        }

        return 0;
}

/* This function copies name to bstr, with at most 30
 * characters length. The bstr will be prepended by
 * a length byte.
 * NOTE: The name will must be already checked by
 *       affs_check_name()!
 */

int
affs_copy_name(unsigned char *bstr, struct dentry *dentry)
{
        u32 len = min(dentry->d_name.len, AFFSNAMEMAX);

        *bstr++ = len;
        memcpy(bstr, dentry->d_name.name, len);
        return len;
}