core/fs/fat/fat_fs.h

   1 #ifndef FAT_FS_H
   2 #define FAT_FS_H
   3
   4 #include <stdint.h>
   5
   6 #define FAT_DIR_ENTRY_SIZE 32
   7 #define DIRENT_SHIFT 5
   8
   9 #define FAT_ATTR_READ_ONLY 0x01
  10 #define FAT_ATTR_HIDDEN    0x02
  11 #define FAT_ATTR_SYSTEM    0x04
  12 #define FAT_ATTR_VOLUME_ID 0x08
  13 #define FAT_ATTR_DIRECTORY 0x10
  14 #define FAT_ATTR_ARCHIVE   0x20
  15
  16 #define FAT_MAXFILE        256
  17
  18 #define FAT_ATTR_LONG_NAME (FAT_ATTR_READ_ONLY             \
  19                             | FAT_ATTR_HIDDEN              \
  20                             | FAT_ATTR_SYSTEM              \
  21                             | FAT_ATTR_VOLUME_ID)
  22
  23 #define FAT_ATTR_VALID     (FAT_ATTR_READ_ONLY             \
  24                             | FAT_ATTR_HIDDEN              \
  25                             | FAT_ATTR_SYSTEM              \
  26                             | FAT_ATTR_DIRECTORY           \
  27                             | FAT_ATTR_ARCHIVE)
  28
  29 enum fat_type{ FAT12, FAT16, FAT32 };
  30
  31 /*
  32  * The fat file system structures
  33  */
  34
  35 struct fat_bpb {
  36         uint8_t  jmp_boot[3];
  37         uint8_t  oem_name[8];
  38         uint16_t sector_size;
  39         uint8_t  bxSecPerClust;
  40         uint16_t bxResSectors;
  41         uint8_t  bxFATs;
  42         uint16_t bxRootDirEnts;
  43         uint16_t bxSectors;
  44         uint8_t  media;
  45         uint16_t bxFATsecs;
  46         uint16_t sectors_per_track;
  47         uint16_t num_heads;
  48         uint32_t num_hidden_sectors;
  49         uint32_t bsHugeSectors;
  50
  51         union {
  52                 struct {
  53                         uint8_t  num_ph_drive;
  54                         uint8_t  reserved;
  55                         uint8_t  boot_sig;
  56                         uint32_t num_serial;
  57                         uint8_t  label[11];
  58                         uint8_t  fstype[8];
  59                 } __attribute__ ((packed)) fat12_16;
  60
  61                 struct {
  62                         uint32_t bxFATsecs_32;
  63                         uint16_t extended_flags;
  64                         uint16_t fs_version;
  65                         uint32_t root_cluster;
  66                         uint16_t fs_info;
  67                         uint16_t backup_boot_sector;
  68                         uint8_t  reserved[12];
  69                         uint8_t  num_ph_drive;
  70                         uint8_t  reserved1;
  71                         uint8_t  boot_sig;
  72                         uint32_t num_serial;
  73                         uint8_t  label[11];
  74                         uint8_t  fstype[8];
  75                 } __attribute__ ((packed)) fat32;
  76
  77         } __attribute__ ((packed));
  78
  79         uint8_t pad[422];  /* padding to 512 Bytes (one sector) */
  80
  81 } __attribute__ ((packed));
  82
  83 /*
  84  * The fat file system info in memory
  85  */
  86 struct fat_sb_info {
  87         sector_t fat;             /* The FAT region */
  88         sector_t root;            /* The root dir region */
  89         sector_t data;            /* The data region */
  90
  91         uint32_t clusters;        /* Total number of clusters */
  92         uint32_t root_cluster;    /* Cluster number for (FAT32) root dir */
  93         int      root_size;       /* The root dir size in sectors */
  94
  95         int      clust_shift;      /* based on sectors */
  96         int      clust_byte_shift; /* based on bytes   */
  97         int      clust_mask;       /* sectors per cluster mask */
  98         int      clust_size;
  99
 100         int      fat_type;
 101 } __attribute__ ((packed));
 102
 103 struct fat_dir_entry {
 104         char     name[11];
 105         uint8_t  attr;
 106         uint8_t  lcase;
 107         uint8_t  c_time_tenth;
 108         uint16_t c_time;
 109         uint16_t c_date;
 110         uint16_t a_date;
 111         uint16_t first_cluster_high;
 112         uint16_t w_time;
 113         uint16_t w_date;
 114         uint16_t first_cluster_low;
 115         uint32_t file_size;
 116 } __attribute__ ((packed));
 117
 118 #define LCASE_BASE 8       /* basename is lower case */
 119 #define LCASE_EXT  16      /* extension is lower case */
 120
 121 struct fat_long_name_entry {
 122         uint8_t  id;
 123         uint16_t name1[5];
 124         uint8_t  attr;
 125         uint8_t  reserved;
 126         uint8_t  checksum;
 127         uint16_t name2[6];
 128         uint16_t first_cluster;
 129         uint16_t name3[2];
 130 } __attribute__ ((packed));
 131
 132 static inline struct fat_sb_info *FAT_SB(struct fs_info *fs)
 133 {
 134         return fs->fs_info;
 135 }
 136
 137 /*
 138  * Count the root dir size in sectors
 139  */
 140 static inline int root_dir_size(struct fs_info *fs, struct fat_bpb *fat)
 141 {
 142     return (fat->bxRootDirEnts + SECTOR_SIZE(fs)/32 - 1)
 143         >> (SECTOR_SHIFT(fs) - 5);
 144 }
 145
 146 /*
 147  * FAT private inode information
 148  */
 149 struct fat_pvt_inode {
 150     uint32_t start_cluster;     /* Starting cluster address */
 151     sector_t start;             /* Starting sector */
 152     sector_t offset;            /* Current sector offset */
 153     sector_t here;              /* Sector corresponding to offset */
 154 };
 155
 156 #define PVT(i) ((struct fat_pvt_inode *)((i)->pvt))
 157
 158 #endif /* fat_fs.h */