/*
 *  linux/fs/msdos/namei.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
 *  Rewritten for constant inumbers 1999 by Al Viro
 */


#define __NO_VERSION__
#include <linux/module.h>

#include <linux/sched.h>
#include <linux/msdos_fs.h>
#include <linux/errno.h>
#include <linux/string.h>

#include <asm/uaccess.h>

#define MSDOS_DEBUG 0
#define PRINTK(x)

/* MS-DOS "device special files" */

static const char *reserved_names[] = {
    "CON     ","PRN     ","NUL     ","AUX     ",
    "LPT1    ","LPT2    ","LPT3    ","LPT4    ",
    "COM1    ","COM2    ","COM3    ","COM4    ",
    NULL };


/* Characters that are undesirable in an MS-DOS file name */
  
static char bad_chars[] = "*?<>|\"";
static char bad_if_strict_pc[] = "+=,; ";
static char bad_if_strict_atari[] = " "; /* GEMDOS is less restrictive */
#define bad_if_strict(opts) ((opts)->atari ? bad_if_strict_atari : bad_if_strict_pc)

/* Must die */
void msdos_put_super(struct super_block *sb)
{
        fat_put_super(sb);
}

/***** Formats an MS-DOS file name. Rejects invalid names. */
static int msdos_format_name(const char *name,int len,
        char *res,struct fat_mount_options *opts)
        /* name is the proposed name, len is its length, res is
         * the resulting name, opts->name_check is either (r)elaxed,
         * (n)ormal or (s)trict, opts->dotsOK allows dots at the
         * beginning of name (for hidden files)
         */
{
        char *walk;
        const char **reserved;
        unsigned char c;
        int space;

        if (name[0] == '.') {  /* dotfile because . and .. already done */
                if (opts->dotsOK) {
                        /* Get rid of dot - test for it elsewhere */
                        name++; len--;
                }
                else if (!opts->atari) return -EINVAL;
        }
        /* disallow names that _really_ start with a dot for MS-DOS, GEMDOS does
         * not care */
        space = !opts->atari;
        c = 0;
        for (walk = res; len && walk-res < 8; walk++) {
                c = *name++;
                len--;
                if (opts->name_check != 'r' && strchr(bad_chars,c))
                        return -EINVAL;
                if (opts->name_check == 's' && strchr(bad_if_strict(opts),c))
                        return -EINVAL;
                if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
                        return -EINVAL;
                if (c < ' ' || c == ':' || c == '\\') return -EINVAL;
/*  0xE5 is legal as a first character, but we must substitute 0x05     */
/*  because 0xE5 marks deleted files.  Yes, DOS really does this.       */
/*  It seems that Microsoft hacked DOS to support non-US characters     */
/*  after the 0xE5 character was already in use to mark deleted files.  */
                if((res==walk) && (c==0xE5)) c=0x05;
                if (c == '.') break;
                space = (c == ' ');
                *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c-32 : c;
        }
        if (space) return -EINVAL;
        if (opts->name_check == 's' && len && c != '.') {
                c = *name++;
                len--;
                if (c != '.') return -EINVAL;
        }
        while (c != '.' && len--) c = *name++;
        if (c == '.') {
                while (walk-res < 8) *walk++ = ' ';
                while (len > 0 && walk-res < MSDOS_NAME) {
                        c = *name++;
                        len--;
                        if (opts->name_check != 'r' && strchr(bad_chars,c))
                                return -EINVAL;
                        if (opts->name_check == 's' &&
                            strchr(bad_if_strict(opts),c))
                                return -EINVAL;
                        if (c < ' ' || c == ':' || c == '\\')
                                return -EINVAL;
                        if (c == '.') {
                                if (opts->name_check == 's')
                                        return -EINVAL;
                                break;
                        }
                        if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
                                return -EINVAL;
                        space = c == ' ';
                        *walk++ = (!opts->nocase && c >= 'a' && c <= 'z') ? c-32 : c;
                }
                if (space) return -EINVAL;
                if (opts->name_check == 's' && len) return -EINVAL;
        }
        while (walk-res < MSDOS_NAME) *walk++ = ' ';
        if (!opts->atari)
                /* GEMDOS is less stupid and has no reserved names */
                for (reserved = reserved_names; *reserved; reserved++)
                        if (!strncmp(res,*reserved,8)) return -EINVAL;
        return 0;
}

/***** Locates a directory entry.  Uses unformatted name. */
static int msdos_find(struct inode *dir, const char *name, int len,
                      struct buffer_head **bh, struct msdos_dir_entry **de,
                      loff_t *i_pos)
{
        int res;
        char dotsOK;
        char msdos_name[MSDOS_NAME];

        dotsOK = MSDOS_SB(dir->i_sb)->options.dotsOK;
        res = msdos_format_name(name,len, msdos_name,&MSDOS_SB(dir->i_sb)->options);
        if (res < 0)
                return -ENOENT;
        res = fat_scan(dir, msdos_name, bh, de, i_pos);
        if (!res && dotsOK) {
                if (name[0]=='.') {
                        if (!((*de)->attr & ATTR_HIDDEN))
                                res = -ENOENT;
                } else {
                        if ((*de)->attr & ATTR_HIDDEN)
                                res = -ENOENT;
                }
        }
        return res;
}

/*
 * Compute the hash for the msdos name corresponding to the dentry.
 * Note: if the name is invalid, we leave the hash code unchanged so
 * that the existing dentry can be used. The msdos fs routines will
 * return ENOENT or EINVAL as appropriate.
 */
static int msdos_hash(struct dentry *dentry, struct qstr *qstr)
{
        struct fat_mount_options *options = & (MSDOS_SB(dentry->d_sb)->options);
        int error;
        char msdos_name[MSDOS_NAME];
        
        error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
        if (!error)
                qstr->hash = full_name_hash(msdos_name, MSDOS_NAME);
        return 0;
}

/*
 * Compare two msdos names. If either of the names are invalid,
 * we fall back to doing the standard name comparison.
 */
static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
{
        struct fat_mount_options *options = & (MSDOS_SB(dentry->d_sb)->options);
        int error;
        char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];

        error = msdos_format_name(a->name, a->len, a_msdos_name, options);
        if (error)
                goto old_compare;
        error = msdos_format_name(b->name, b->len, b_msdos_name, options);
        if (error)
                goto old_compare;
        error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
out:
        return error;

old_compare:
        error = 1;
        if (a->len == b->len)
                error = memcmp(a->name, b->name, a->len);
        goto out;
}


static struct dentry_operations msdos_dentry_operations = {
        d_hash:         msdos_hash,
        d_compare:      msdos_cmp,
};

/*
 * AV. Wrappers for FAT sb operations. Is it wise?
 */

/***** Get inode using directory and name */
struct dentry *msdos_lookup(struct inode *dir,struct dentry *dentry)
{
        struct super_block *sb = dir->i_sb;
        struct inode *inode = NULL;
        struct msdos_dir_entry *de;
        struct buffer_head *bh = NULL;
        loff_t i_pos;
        int res;
        
        PRINTK (("msdos_lookup\n"));

        dentry->d_op = &msdos_dentry_operations;

        res = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &bh,
                         &de, &i_pos);
        if (res == -ENOENT)
                goto add;
        if (res < 0)
                goto out;
        inode = fat_build_inode(sb, de, i_pos, &res);
        if (res)
                goto out;
add:
        d_add(dentry, inode);
        res = 0;
out:
        if (bh)
                fat_brelse(sb, bh);
        return ERR_PTR(res);
}

/***** Creates a directory entry (name is already formatted). */
static int msdos_add_entry(struct inode *dir, const char *name,
                           struct buffer_head **bh,
                           struct msdos_dir_entry **de,
                           loff_t *i_pos, int is_dir, int is_hid)
{
        struct super_block *sb = dir->i_sb;
        int res;

        res = fat_add_entries(dir, 1, bh, de, i_pos);
        if (res < 0)
                return res;
        /*
         * XXX all times should be set by caller upon successful completion.
         */
        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        mark_inode_dirty(dir);
        memcpy((*de)->name,name,MSDOS_NAME);
        (*de)->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
        if (is_hid)
                (*de)->attr |= ATTR_HIDDEN;
        (*de)->start = 0;
        (*de)->starthi = 0;
        fat_date_unix2dos(dir->i_mtime,&(*de)->time,&(*de)->date);
        (*de)->size = 0;
        fat_mark_buffer_dirty(sb, *bh);
        return 0;
}

/*
 * AV. Huh??? It's exported. Oughtta check usage.
 */

/***** Create a file */
int msdos_create(struct inode *dir,struct dentry *dentry,int mode)
{
        struct super_block *sb = dir->i_sb;
        struct buffer_head *bh;
        struct msdos_dir_entry *de;
        struct inode *inode;
        loff_t i_pos;
        int res, is_hid;
        char msdos_name[MSDOS_NAME];

        res = msdos_format_name(dentry->d_name.name,dentry->d_name.len,
                                msdos_name, &MSDOS_SB(sb)->options);
        if (res < 0)
                return res;
        is_hid = (dentry->d_name.name[0]=='.') && (msdos_name[0]!='.');
        /* Have to do it due to foo vs. .foo conflicts */
        if (fat_scan(dir, msdos_name, &bh, &de, &i_pos) >= 0) {
                fat_brelse(sb, bh);
                return -EINVAL;
        }
        inode = NULL;
        res = msdos_add_entry(dir, msdos_name, &bh, &de, &i_pos, 0, is_hid);
        if (res)
                return res;
        inode = fat_build_inode(dir->i_sb, de, i_pos, &res);
        fat_brelse(sb, bh);
        if (!inode)
                return res;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
        mark_inode_dirty(inode);
        d_instantiate(dentry, inode);
        return 0;
}

/***** Remove a directory */
int msdos_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct super_block *sb = dir->i_sb;
        struct inode *inode = dentry->d_inode;
        loff_t i_pos;
        int res;
        struct buffer_head *bh;
        struct msdos_dir_entry *de;

        bh = NULL;
        res = msdos_find(dir, dentry->d_name.name, dentry->d_name.len,
                         &bh, &de, &i_pos);
        if (res < 0)
                goto rmdir_done;
        /*
         * Check whether the directory is not in use, then check
         * whether it is empty.
         */
        res = fat_dir_empty(inode);
        if (res)
                goto rmdir_done;

        de->name[0] = DELETED_FLAG;
        fat_mark_buffer_dirty(sb, bh);
        fat_detach(inode);
        inode->i_nlink = 0;
        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        dir->i_nlink--;
        mark_inode_dirty(inode);
        mark_inode_dirty(dir);
        res = 0;

rmdir_done:
        fat_brelse(sb, bh);
        return res;
}

/***** Make a directory */
int msdos_mkdir(struct inode *dir,struct dentry *dentry,int mode)
{
        struct super_block *sb = dir->i_sb;
        struct buffer_head *bh;
        struct msdos_dir_entry *de;
        struct inode *inode;
        int res,is_hid;
        char msdos_name[MSDOS_NAME];
        loff_t i_pos;

        res = msdos_format_name(dentry->d_name.name,dentry->d_name.len,
                                msdos_name, &MSDOS_SB(sb)->options);
        if (res < 0)
                return res;
        is_hid = (dentry->d_name.name[0]=='.') && (msdos_name[0]!='.');
        /* foo vs .foo situation */
        if (fat_scan(dir, msdos_name, &bh, &de, &i_pos) >= 0)
                goto out_exist;

        res = msdos_add_entry(dir, msdos_name, &bh, &de, &i_pos, 1, is_hid);
        if (res)
                goto out_unlock;
        inode = fat_build_inode(dir->i_sb, de, i_pos, &res);
        if (!inode) {
                fat_brelse(sb, bh);
                goto out_unlock;
        }
        res = 0;

        dir->i_nlink++;
        inode->i_nlink = 2; /* no need to mark them dirty */

        res = fat_new_dir(inode, dir, 0);
        if (res)
                goto mkdir_error;

        fat_brelse(sb, bh);
        d_instantiate(dentry, inode);
        res = 0;

out_unlock:
        return res;

mkdir_error:
        printk(KERN_WARNING "msdos_mkdir: error=%d, attempting cleanup\n", res);
        inode->i_nlink = 0;
        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        dir->i_nlink--;
        mark_inode_dirty(inode);
        mark_inode_dirty(dir);
        de->name[0] = DELETED_FLAG;
        fat_mark_buffer_dirty(sb, bh);
        fat_brelse(sb, bh);
        fat_detach(inode);
        iput(inode);
        goto out_unlock;

out_exist:
        fat_brelse(sb, bh);
        res = -EINVAL;
        goto out_unlock;
}

/***** Unlink a file */
int msdos_unlink( struct inode *dir, struct dentry *dentry)
{
        struct super_block *sb = dir->i_sb;
        struct inode *inode = dentry->d_inode;
        loff_t i_pos;
        int res;
        struct buffer_head *bh;
        struct msdos_dir_entry *de;

        bh = NULL;
        res = msdos_find(dir, dentry->d_name.name, dentry->d_name.len,
                         &bh, &de, &i_pos);
        if (res < 0)
                goto unlink_done;

        de->name[0] = DELETED_FLAG;
        fat_mark_buffer_dirty(sb, bh);
        fat_detach(inode);
        fat_brelse(sb, bh);
        inode->i_nlink = 0;
        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        mark_inode_dirty(inode);
        mark_inode_dirty(dir);
        res = 0;
unlink_done:
        return res;
}

static int do_msdos_rename(struct inode *old_dir, char *old_name,
    struct dentry *old_dentry,
    struct inode *new_dir,char *new_name, struct dentry *new_dentry,
    struct buffer_head *old_bh,
    struct msdos_dir_entry *old_de, loff_t old_i_pos, int is_hid)
{
        struct super_block *sb = old_dir->i_sb;
        struct buffer_head *new_bh=NULL,*dotdot_bh=NULL;
        struct msdos_dir_entry *new_de,*dotdot_de;
        struct inode *old_inode,*new_inode;
        loff_t new_i_pos, dotdot_i_pos;
        int error;
        int is_dir;

        old_inode = old_dentry->d_inode;
        new_inode = new_dentry->d_inode;
        is_dir = S_ISDIR(old_inode->i_mode);

        if (fat_scan(new_dir, new_name, &new_bh, &new_de, &new_i_pos) >= 0
            && !new_inode)
                goto degenerate_case;
        if (is_dir) {
                if (new_inode) {
                        error = fat_dir_empty(new_inode);
                        if (error)
                                goto out;
                }
                error = fat_scan(old_inode, MSDOS_DOTDOT, &dotdot_bh,
                                &dotdot_de, &dotdot_i_pos);
                if (error < 0) {
                        printk(KERN_WARNING
                                "MSDOS: %s/%s, get dotdot failed, ret=%d\n",
                                old_dentry->d_parent->d_name.name,
                                old_dentry->d_name.name, error);
                        goto out;
                }
        }
        if (!new_bh) {
                error = msdos_add_entry(new_dir, new_name, &new_bh, &new_de,
                                        &new_i_pos, is_dir, is_hid);
                if (error)
                        goto out;
        }
        new_dir->i_version = ++event;

        /* There we go */

        if (new_inode)
                fat_detach(new_inode);
        old_de->name[0] = DELETED_FLAG;
        fat_mark_buffer_dirty(sb, old_bh);
        fat_detach(old_inode);
        fat_attach(old_inode, new_i_pos);
        if (is_hid)
                MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
        else
                MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
        mark_inode_dirty(old_inode);
        old_dir->i_version = ++event;
        old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
        mark_inode_dirty(old_dir);
        if (new_inode) {
                new_inode->i_nlink--;
                new_inode->i_ctime = CURRENT_TIME;
                mark_inode_dirty(new_inode);
        }
        if (dotdot_bh) {
                dotdot_de->start = CT_LE_W(MSDOS_I(new_dir)->i_logstart);
                dotdot_de->starthi = CT_LE_W((MSDOS_I(new_dir)->i_logstart) >> 16);
                fat_mark_buffer_dirty(sb, dotdot_bh);
                old_dir->i_nlink--;
                mark_inode_dirty(old_dir);
                if (new_inode) {
                        new_inode->i_nlink--;
                        mark_inode_dirty(new_inode);
                } else {
                        new_dir->i_nlink++;
                        mark_inode_dirty(new_dir);
                }
        }
        error = 0;
out:
        fat_brelse(sb, new_bh);
        fat_brelse(sb, dotdot_bh);
        return error;

degenerate_case:
        error = -EINVAL;
        if (new_de!=old_de)
                goto out;
        if (is_hid)
                MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
        else
                MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
        mark_inode_dirty(old_inode);
        old_dir->i_version = ++event;
        old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
        mark_inode_dirty(old_dir);
        return 0;
}

/***** Rename, a wrapper for rename_same_dir & rename_diff_dir */
int msdos_rename(struct inode *old_dir,struct dentry *old_dentry,
                 struct inode *new_dir,struct dentry *new_dentry)
{
        struct super_block *sb = old_dir->i_sb;
        struct buffer_head *old_bh;
        struct msdos_dir_entry *old_de;
        loff_t old_i_pos;
        int error, is_hid, old_hid; /* if new file and old file are hidden */
        char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];

        error = msdos_format_name(old_dentry->d_name.name,
                                  old_dentry->d_name.len,old_msdos_name,
                                  &MSDOS_SB(old_dir->i_sb)->options);
        if (error < 0)
                goto rename_done;
        error = msdos_format_name(new_dentry->d_name.name,
                                  new_dentry->d_name.len,new_msdos_name,
                                  &MSDOS_SB(new_dir->i_sb)->options);
        if (error < 0)
                goto rename_done;

        is_hid  = (new_dentry->d_name.name[0]=='.') && (new_msdos_name[0]!='.');
        old_hid = (old_dentry->d_name.name[0]=='.') && (old_msdos_name[0]!='.');
        error = fat_scan(old_dir, old_msdos_name, &old_bh, &old_de, &old_i_pos);
        if (error < 0)
                goto rename_done;

        error = do_msdos_rename(old_dir, old_msdos_name, old_dentry,
                                new_dir, new_msdos_name, new_dentry,
                                old_bh, old_de, old_i_pos, is_hid);
        fat_brelse(sb, old_bh);

rename_done:
        return error;
}


/* The public inode operations for the msdos fs */
struct inode_operations msdos_dir_inode_operations = {
        create:         msdos_create,
        lookup:         msdos_lookup,
        unlink:         msdos_unlink,
        mkdir:          msdos_mkdir,
        rmdir:          msdos_rmdir,
        rename:         msdos_rename,
        setattr:        fat_notify_change,
};

struct super_block *msdos_read_super(struct super_block *sb,void *data, int silent)
{
        struct super_block *res;

        MSDOS_SB(sb)->options.isvfat = 0;
        res = fat_read_super(sb, data, silent, &msdos_dir_inode_operations);
        if (res)
                sb->s_root->d_op = &msdos_dentry_operations;
        return res;
}