/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _FAT_H
#define _FAT_H

#include <linux/buffer_head.h>
#include <linux/nls.h>
#include <linux/hash.h>
#include <linux/ratelimit.h>
#include <linux/msdos_fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>

/*
 * vfat shortname flags
 */
#define VFAT_SFN_DISPLAY_LOWER  0x0001 /* convert to lowercase for display */
#define VFAT_SFN_DISPLAY_WIN95  0x0002 /* emulate win95 rule for display */
#define VFAT_SFN_DISPLAY_WINNT  0x0004 /* emulate winnt rule for display */
#define VFAT_SFN_CREATE_WIN95   0x0100 /* emulate win95 rule for create */
#define VFAT_SFN_CREATE_WINNT   0x0200 /* emulate winnt rule for create */

#define FAT_ERRORS_CONT         1      /* ignore error and continue */
#define FAT_ERRORS_PANIC        2      /* panic on error */
#define FAT_ERRORS_RO           3      /* remount r/o on error */

#define FAT_NFS_STALE_RW        1      /* NFS RW support, can cause ESTALE */
#define FAT_NFS_NOSTALE_RO      2      /* NFS RO support, no ESTALE issue */

struct fat_mount_options {
        kuid_t fs_uid;
        kgid_t fs_gid;
        unsigned short fs_fmask;
        unsigned short fs_dmask;
        unsigned short codepage;   /* Codepage for shortname conversions */
        int time_offset;           /* Offset of timestamps from UTC (in minutes) */
        char *iocharset;           /* Charset used for filename input/display */
        unsigned short shortname;  /* flags for shortname display/create rule */
        unsigned char name_check;  /* r = relaxed, n = normal, s = strict */
        unsigned char errors;      /* On error: continue, panic, remount-ro */
        unsigned char nfs;        /* NFS support: nostale_ro, stale_rw */
        unsigned short allow_utime;/* permission for setting the [am]time */
        unsigned quiet:1,          /* set = fake successful chmods and chowns */
                 showexec:1,       /* set = only set x bit for com/exe/bat */
                 sys_immutable:1,  /* set = system files are immutable */
                 dotsOK:1,         /* set = hidden and system files are named '.filename' */
                 isvfat:1,         /* 0=no vfat long filename support, 1=vfat support */
                 utf8:1,           /* Use of UTF-8 character set (Default) */
                 unicode_xlate:1,  /* create escape sequences for unhandled Unicode */
                 numtail:1,        /* Does first alias have a numeric '~1' type tail? */
                 flush:1,          /* write things quickly */
                 nocase:1,         /* Does this need case conversion? 0=need case conversion*/
                 usefree:1,        /* Use free_clusters for FAT32 */
                 tz_set:1,         /* Filesystem timestamps' offset set */
                 rodir:1,          /* allow ATTR_RO for directory */
                 discard:1,        /* Issue discard requests on deletions */
                 dos1xfloppy:1,    /* Assume default BPB for DOS 1.x floppies */
                 debug:1;          /* Not currently used */
};

#define FAT_HASH_BITS   8
#define FAT_HASH_SIZE   (1UL << FAT_HASH_BITS)

/*
 * MS-DOS file system in-core superblock data
 */
struct msdos_sb_info {
        unsigned short sec_per_clus;  /* sectors/cluster */
        unsigned short cluster_bits;  /* log2(cluster_size) */
        unsigned int cluster_size;    /* cluster size */
        unsigned char fats, fat_bits; /* number of FATs, FAT bits (12,16 or 32) */
        unsigned short fat_start;
        unsigned long fat_length;     /* FAT start & length (sec.) */
        unsigned long dir_start;
        unsigned short dir_entries;   /* root dir start & entries */
        unsigned long data_start;     /* first data sector */
        unsigned long max_cluster;    /* maximum cluster number */
        unsigned long root_cluster;   /* first cluster of the root directory */
        unsigned long fsinfo_sector;  /* sector number of FAT32 fsinfo */
        struct mutex fat_lock;
        struct mutex nfs_build_inode_lock;
        struct mutex s_lock;
        unsigned int prev_free;      /* previously allocated cluster number */
        unsigned int free_clusters;  /* -1 if undefined */
        unsigned int free_clus_valid; /* is free_clusters valid? */
        struct fat_mount_options options;
        struct nls_table *nls_disk;   /* Codepage used on disk */
        struct nls_table *nls_io;     /* Charset used for input and display */
        const void *dir_ops;          /* Opaque; default directory operations */
        int dir_per_block;            /* dir entries per block */
        int dir_per_block_bits;       /* log2(dir_per_block) */
        unsigned int vol_id;            /*volume ID*/

        int fatent_shift;
        const struct fatent_operations *fatent_ops;
        struct inode *fat_inode;
        struct inode *fsinfo_inode;

        struct ratelimit_state ratelimit;

        spinlock_t inode_hash_lock;
        struct hlist_head inode_hashtable[FAT_HASH_SIZE];

        spinlock_t dir_hash_lock;
        struct hlist_head dir_hashtable[FAT_HASH_SIZE];

        unsigned int dirty;           /* fs state before mount */
        struct rcu_head rcu;
};

#define FAT_CACHE_VALID 0       /* special case for valid cache */

/*
 * MS-DOS file system inode data in memory
 */
struct msdos_inode_info {
        spinlock_t cache_lru_lock;
        struct list_head cache_lru;
        int nr_caches;
        /* for avoiding the race between fat_free() and fat_get_cluster() */
        unsigned int cache_valid_id;

        /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
        loff_t mmu_private;     /* physically allocated size */

        int i_start;            /* first cluster or 0 */
        int i_logstart;         /* logical first cluster */
        int i_attrs;            /* unused attribute bits */
        loff_t i_pos;           /* on-disk position of directory entry or 0 */
        struct hlist_node i_fat_hash;   /* hash by i_location */
        struct hlist_node i_dir_hash;   /* hash by i_logstart */
        struct rw_semaphore truncate_lock; /* protect bmap against truncate */
        struct timespec64 i_crtime;     /* File creation (birth) time */
        struct inode vfs_inode;
};

struct fat_slot_info {
        loff_t i_pos;           /* on-disk position of directory entry */
        loff_t slot_off;        /* offset for slot or de start */
        int nr_slots;           /* number of slots + 1(de) in filename */
        struct msdos_dir_entry *de;
        struct buffer_head *bh;
};

static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
{
        return sb->s_fs_info;
}

/*
 * Functions that determine the variant of the FAT file system (i.e.,
 * whether this is FAT12, FAT16 or FAT32.
 */
static inline bool is_fat12(const struct msdos_sb_info *sbi)
{
        return sbi->fat_bits == 12;
}

static inline bool is_fat16(const struct msdos_sb_info *sbi)
{
        return sbi->fat_bits == 16;
}

static inline bool is_fat32(const struct msdos_sb_info *sbi)
{
        return sbi->fat_bits == 32;
}

/* Maximum number of clusters */
static inline u32 max_fat(struct super_block *sb)
{
        struct msdos_sb_info *sbi = MSDOS_SB(sb);

        return is_fat32(sbi) ? MAX_FAT32 :
                is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
}

static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
{
        return container_of(inode, struct msdos_inode_info, vfs_inode);
}

/*
 * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
 * save ATTR_RO instead of ->i_mode.
 *
 * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
 * bit, it's just used as flag for app.
 */
static inline int fat_mode_can_hold_ro(struct inode *inode)
{
        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
        umode_t mask;

        if (S_ISDIR(inode->i_mode)) {
                if (!sbi->options.rodir)
                        return 0;
                mask = ~sbi->options.fs_dmask;
        } else
                mask = ~sbi->options.fs_fmask;

        if (!(mask & S_IWUGO))
                return 0;
        return 1;
}

/* Convert attribute bits and a mask to the UNIX mode. */
static inline umode_t fat_make_mode(struct msdos_sb_info *sbi,
                                   u8 attrs, umode_t mode)
{
        if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
                mode &= ~S_IWUGO;

        if (attrs & ATTR_DIR)
                return (mode & ~sbi->options.fs_dmask) | S_IFDIR;
        else
                return (mode & ~sbi->options.fs_fmask) | S_IFREG;
}

/* Return the FAT attribute byte for this inode */
static inline u8 fat_make_attrs(struct inode *inode)
{
        u8 attrs = MSDOS_I(inode)->i_attrs;
        if (S_ISDIR(inode->i_mode))
                attrs |= ATTR_DIR;
        if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
                attrs |= ATTR_RO;
        return attrs;
}

static inline void fat_save_attrs(struct inode *inode, u8 attrs)
{
        if (fat_mode_can_hold_ro(inode))
                MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
        else
                MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
}

static inline unsigned char fat_checksum(const __u8 *name)
{
        unsigned char s = name[0];
        s = (s<<7) + (s>>1) + name[1];  s = (s<<7) + (s>>1) + name[2];
        s = (s<<7) + (s>>1) + name[3];  s = (s<<7) + (s>>1) + name[4];
        s = (s<<7) + (s>>1) + name[5];  s = (s<<7) + (s>>1) + name[6];
        s = (s<<7) + (s>>1) + name[7];  s = (s<<7) + (s>>1) + name[8];
        s = (s<<7) + (s>>1) + name[9];  s = (s<<7) + (s>>1) + name[10];
        return s;
}

static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
{
        return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
                + sbi->data_start;
}

static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
                                loff_t i_pos, sector_t *blknr, int *offset)
{
        *blknr = i_pos >> sbi->dir_per_block_bits;
        *offset = i_pos & (sbi->dir_per_block - 1);
}

static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
                                        struct inode *inode)
{
        loff_t i_pos;
#if BITS_PER_LONG == 32
        spin_lock(&sbi->inode_hash_lock);
#endif
        i_pos = MSDOS_I(inode)->i_pos;
#if BITS_PER_LONG == 32
        spin_unlock(&sbi->inode_hash_lock);
#endif
        return i_pos;
}

static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len)
{
#ifdef __BIG_ENDIAN
        while (len--) {
                *dst++ = src[0] | (src[1] << 8);
                src += 2;
        }
#else
        memcpy(dst, src, len * 2);
#endif
}

static inline int fat_get_start(const struct msdos_sb_info *sbi,
                                const struct msdos_dir_entry *de)
{
        int cluster = le16_to_cpu(de->start);
        if (is_fat32(sbi))
                cluster |= (le16_to_cpu(de->starthi) << 16);
        return cluster;
}

static inline void fat_set_start(struct msdos_dir_entry *de, int cluster)
{
        de->start   = cpu_to_le16(cluster);
        de->starthi = cpu_to_le16(cluster >> 16);
}

static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
{
#ifdef __BIG_ENDIAN
        while (len--) {
                dst[0] = *src & 0x00FF;
                dst[1] = (*src & 0xFF00) >> 8;
                dst += 2;
                src++;
        }
#else
        memcpy(dst, src, len * 2);
#endif
}

/* fat/cache.c */
extern void fat_cache_inval_inode(struct inode *inode);
extern int fat_get_cluster(struct inode *inode, int cluster,
                           int *fclus, int *dclus);
extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
                                  sector_t last_block,
                                  unsigned long *mapped_blocks, sector_t *bmap);
extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
                    unsigned long *mapped_blocks, int create, bool from_bmap);

/* fat/dir.c */
extern const struct file_operations fat_dir_operations;
extern int fat_search_long(struct inode *inode, const unsigned char *name,
                           int name_len, struct fat_slot_info *sinfo);
extern int fat_dir_empty(struct inode *dir);
extern int fat_subdirs(struct inode *dir);
extern int fat_scan(struct inode *dir, const unsigned char *name,
                    struct fat_slot_info *sinfo);
extern int fat_scan_logstart(struct inode *dir, int i_logstart,
                             struct fat_slot_info *sinfo);
extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
                                struct msdos_dir_entry **de);
extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
                           struct fat_slot_info *sinfo);
extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);

/* fat/fatent.c */
struct fat_entry {
        int entry;
        union {
                u8 *ent12_p[2];
                __le16 *ent16_p;
                __le32 *ent32_p;
        } u;
        int nr_bhs;
        struct buffer_head *bhs[2];
        struct inode *fat_inode;
};

static inline void fatent_init(struct fat_entry *fatent)
{
        fatent->nr_bhs = 0;
        fatent->entry = 0;
        fatent->u.ent32_p = NULL;
        fatent->bhs[0] = fatent->bhs[1] = NULL;
        fatent->fat_inode = NULL;
}

static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
{
        fatent->entry = entry;
        fatent->u.ent32_p = NULL;
}

static inline void fatent_brelse(struct fat_entry *fatent)
{
        int i;
        fatent->u.ent32_p = NULL;
        for (i = 0; i < fatent->nr_bhs; i++)
                brelse(fatent->bhs[i]);
        fatent->nr_bhs = 0;
        fatent->bhs[0] = fatent->bhs[1] = NULL;
        fatent->fat_inode = NULL;
}

static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
{
        return FAT_START_ENT <= entry && entry < sbi->max_cluster;
}

extern void fat_ent_access_init(struct super_block *sb);
extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
                        int entry);
extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
                         int new, int wait);
extern int fat_alloc_clusters(struct inode *inode, int *cluster,
                              int nr_cluster);
extern int fat_free_clusters(struct inode *inode, int cluster);
extern int fat_count_free_clusters(struct super_block *sb);
extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);

/* fat/file.c */
extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
                              unsigned long arg);
extern const struct file_operations fat_file_operations;
extern const struct inode_operations fat_file_inode_operations;
extern int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                       struct iattr *attr);
extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
extern int fat_getattr(struct mnt_idmap *idmap,
                       const struct path *path, struct kstat *stat,
                       u32 request_mask, unsigned int flags);
extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
                          int datasync);

/* fat/inode.c */
extern int fat_block_truncate_page(struct inode *inode, loff_t from);
extern void fat_attach(struct inode *inode, loff_t i_pos);
extern void fat_detach(struct inode *inode);
extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
extern struct inode *fat_build_inode(struct super_block *sb,
                        struct msdos_dir_entry *de, loff_t i_pos);
extern int fat_sync_inode(struct inode *inode);
extern int fat_fill_super(struct super_block *sb, struct fs_context *fc,
                          void (*setup)(struct super_block *));
extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);

extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
                            struct inode *i2);

extern const struct fs_parameter_spec fat_param_spec[];
int fat_init_fs_context(struct fs_context *fc, bool is_vfat);
void fat_free_fc(struct fs_context *fc);

int fat_parse_param(struct fs_context *fc, struct fs_parameter *param,
                    bool is_vfat);
int fat_reconfigure(struct fs_context *fc);

static inline unsigned long fat_dir_hash(int logstart)
{
        return hash_32(logstart, FAT_HASH_BITS);
}
extern int fat_add_cluster(struct inode *inode);

/* fat/misc.c */
extern __printf(3, 4) __cold
void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
#define fat_fs_error(sb, fmt, args...)          \
        __fat_fs_error(sb, 1, fmt , ## args)
#define fat_fs_error_ratelimit(sb, fmt, args...) \
        __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)

#define FAT_PRINTK_PREFIX "%sFAT-fs (%s): "
#define fat_msg(sb, level, fmt, args...)                                \
do {                                                                    \
        printk_index_subsys_emit(FAT_PRINTK_PREFIX, level, fmt, ##args);\
        _fat_msg(sb, level, fmt, ##args);                               \
} while (0)
__printf(3, 4) __cold
void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
#define fat_msg_ratelimit(sb, level, fmt, args...)      \
        do {    \
                        if (__ratelimit(&MSDOS_SB(sb)->ratelimit))      \
                                fat_msg(sb, level, fmt, ## args);       \
         } while (0)
extern int fat_clusters_flush(struct super_block *sb);
extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
                              __le16 __time, __le16 __date, u8 time_cs);
extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
                              __le16 *time, __le16 *date, u8 *time_cs);
extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
                                            const struct timespec64 *ts);
#define FAT_UPDATE_ATIME        (1u << 0)
#define FAT_UPDATE_CMTIME       (1u << 1)
void fat_truncate_time(struct inode *inode, struct timespec64 *now,
                unsigned int flags);
int fat_update_time(struct inode *inode, enum fs_update_time type,
                unsigned int flags);
extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);

int fat_cache_init(void);
void fat_cache_destroy(void);

/* fat/nfs.c */
extern const struct export_operations fat_export_ops;
extern const struct export_operations fat_export_ops_nostale;

/* helper for printk */
typedef unsigned long long      llu;

#endif /* !_FAT_H */