inc/fs.h

   1 // See COPYRIGHT for copyright information.
   2
   3 #ifndef JOS_INC_FS_H
   4 #define JOS_INC_FS_H
   5
   6 #include <inc/types.h>
   7
   8 // File nodes (both in-memory and on-disk)
   9
  10 // Bytes per file system block - same as page size
  11 #define BLKSIZE         PGSIZE
  12 #define BLKBITSIZE      (BLKSIZE * 8)
  13
  14 // Maximum size of a filename (a single path component), including null
  15 // Must be a multiple of 4
  16 #define MAXNAMELEN      128
  17
  18 // Maximum size of a complete pathname, including null
  19 #define MAXPATHLEN      1024
  20
  21 // Number of block pointers in a File descriptor
  22 #define NDIRECT         10
  23 // Number of direct block pointers in an indirect block
  24 #define NINDIRECT       (BLKSIZE / 4)
  25
  26 #define MAXFILESIZE     (NINDIRECT * BLKSIZE)
  27
  28 struct File {
  29         char f_name[MAXNAMELEN];        // filename
  30         off_t f_size;                   // file size in bytes
  31         uint32_t f_type;                // file type
  32
  33         // Block pointers.
  34         // A block is allocated iff its value is != 0.
  35         uint32_t f_direct[NDIRECT];     // direct blocks
  36         uint32_t f_indirect;            // indirect block
  37
  38         // Points to the directory in which this file lives.
  39         // Meaningful only in memory; the value on disk can be garbage.
  40         // dir_lookup() sets the value when required.
  41         struct File *f_dir;
  42
  43         // Pad out to 256 bytes; must do arithmetic in case we're compiling
  44         // fsformat on a 64-bit machine.
  45         uint8_t f_pad[256 - MAXNAMELEN - 8 - 4*NDIRECT - 4 - sizeof(struct File*)];
  46 } __attribute__((packed));      // required only on some 64-bit machines
  47
  48 // An inode block contains exactly BLKFILES 'struct File's
  49 #define BLKFILES        (BLKSIZE / sizeof(struct File))
  50
  51 // File types
  52 #define FTYPE_REG       0       // Regular file
  53 #define FTYPE_DIR       1       // Directory
  54
  55
  56 // File system super-block (both in-memory and on-disk)
  57
  58 #define FS_MAGIC        0x4A0530AE      // related vaguely to 'J\0S!'
  59
  60 struct Super {
  61         uint32_t s_magic;               // Magic number: FS_MAGIC
  62         uint32_t s_nblocks;             // Total number of blocks on disk
  63         struct File s_root;             // Root directory node
  64 };
  65
  66 // Definitions for requests from clients to file system
  67
  68 #define FSREQ_OPEN      1
  69 #define FSREQ_MAP       2
  70 #define FSREQ_SET_SIZE  3
  71 #define FSREQ_CLOSE     4
  72 #define FSREQ_DIRTY     5
  73 #define FSREQ_REMOVE    6
  74 #define FSREQ_SYNC      7
  75
  76 struct Fsreq_open {
  77         char req_path[MAXPATHLEN];
  78         int req_omode;
  79 };
  80
  81 struct Fsreq_map {
  82         int req_fileid;
  83         off_t req_offset;
  84 };
  85
  86 struct Fsreq_set_size {
  87         int req_fileid;
  88         off_t req_size;
  89 };
  90
  91 struct Fsreq_close {
  92         int req_fileid;
  93 };
  94
  95 struct Fsreq_dirty {
  96         int req_fileid;
  97         off_t req_offset;
  98 };
  99
 100 struct Fsreq_remove {
 101         char req_path[MAXPATHLEN];
 102 };
 103
 104 #endif /* !JOS_INC_FS_H */