vfs.h

#ifndef VFS_H
#define VFS_H

#include <stdint.h>

#define FS_FILE        0x01
#define FS_DIRECTORY   0x02
#define FS_CHARDEVICE  0x03
#define FS_BLOCKDEVICE 0x04
#define FS_PIPE        0x05
#define FS_SYMLINK     0x06
#define FS_MOUNTPOINT  0x08 // Is the file an active mountpoint?

struct fs_node;

typedef uint32_t (*read_type_t)(struct fs_node*,uint32_t,uint32_t,uint8_t*);
typedef uint32_t (*write_type_t)(struct fs_node*,uint32_t,uint32_t,uint8_t*);
typedef void (*open_type_t)(struct fs_node*,uint32_t,uint32_t);
typedef void (*close_type_t)(struct fs_node*);
typedef struct dirent * (*readdir_type_t)(struct fs_node*,uint32_t);
typedef struct fs_node * (*finddir_type_t)(struct fs_node*,char *name);

struct dirent // One of these is returned by the readdir call, according to POSIX.
{
  char name[128]; // Filename.
  uint32_t ino;     // Inode number. Required by POSIX.
};

typedef struct fs_node
{
   char name[128];     // The filename.
   uint32_t type;       // Includes the node type. See #defines above.
   uint32_t inode;       // This is device-specific - provides a way for a filesystem to identify files.
   uint32_t length;      // Size of the file, in bytes.
   uint32_t flags;
   read_type_t read;
   write_type_t write;
   open_type_t open;
   close_type_t close;
   readdir_type_t readdir;
   finddir_type_t finddir;
   struct fs_node *ptr; // Used by mountpoints and symlinks.
} fs_node_t;

extern fs_node_t *fs_root; // The root of the filesystem.

// Standard read/write/open/close functions. Note that these are all suffixed with
// _fs to distinguish them from the read/write/open/close which deal with file descriptors
// not file nodes.
extern uint32_t read_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
extern uint32_t write_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
extern void open_fs(fs_node_t *node, uint8_t read, uint8_t write);
extern void close_fs(fs_node_t *node);
struct dirent *readdir_fs(fs_node_t *node, uint32_t index);
fs_node_t *finddir_fs(fs_node_t *node, char *name);

#endif