file.h

struct file {
  enum { FD_NONE, FD_PIPE, FD_INODE } type;
  int ref; // reference count
  char readable;
  char writable;
  struct pipe *pipe;
  struct inode *ip;
  uint off;
};

/* file-system specific functions that are maintained for each
   inode. When a new in-memory inode is allocated using iget(),
   the parent inode is now passed in, and the functions are inherited.

   If no parent is passed in, the standard file-system functions are assigned. 

   WARNING: this list of functions is likely incomplete, meaning that some operation
            may not be supported in new file systems introduced. To improve
            generality, add new file system function pointers here as needed.
*/

struct inode_functions {  
  void (*ipopulate)(struct inode*);                   // fill in inode details
  void (*iupdate)(struct inode*);                     // write inode details back to disk
  int (*readi)(struct inode*, char*, uint, uint);     // read from file contents
  int (*writei)(struct inode*, char*, uint, uint);    // write to file contents
}; 

#define NDIRECT 12

// in-memory copy of an inode
struct inode {
  uint dev;           // Device number
  uint inum;          // Inode number
  int ref;            // Reference count
  int flags;          // I_BUSY, I_VALID

  struct inode_functions *i_func;

  short type;         // copy of disk inode
  short major;
  short minor;
  short nlink;
  uint size;
  uint mounted;    //mounted on non-default file system
  uint addrs[NDIRECT+1];
};
#define I_BUSY 0x1
#define I_VALID 0x2

// table mapping major device number to
// device functions
struct devsw {
  int (*read)(struct inode*, char*, int);
  int (*write)(struct inode*, char*, int);
};

extern struct devsw devsw[];

#define CONSOLE 1

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