dirent.h

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/*      dirent.h - Declarations for directory reading routines.
 *                                                      Author: Kees J. Bot
 *                                                              24 Apr 1989
 * 
 * Note: The V7 format directory entries used under Minix must be transformed
 * into a struct dirent with a d_name of at least 15 characters.  Given that
 * we have to transform V7 entries anyhow it is little trouble to let the
 * routines understand the so-called "flex" directory format too.
 */

#ifndef _DIRENT_H
#define _DIRENT_H

#ifndef _TYPES_H
#include <sys/types.h>
#endif

#include <sys/dir.h>

/* _fl_direct is a flexible directory entry.  Actually it's a union of 8
 * characters and the 3 fields defined below. 
 */

/* Flexible directory entry: */
struct _fl_direct {             /* First slot in an entry */
        ino_t           d_ino;
        unsigned char   d_extent;
        char            d_name[3];  /* two characters for the shortest name */
};

        /* Name of length len needs _EXTENT(len) extra slots. */
#define _EXTENT(len)    (((len) + 5) >> 3)

/* Version 7 directory entry: */
struct _v7_direct {             
        ino_t           d_ino;
        char            d_name[DIRSIZ];
};

/* The block size must be at least 1024 bytes, because otherwise
 * the superblock (at 1024 bytes) overlaps with other filesystem data.
 */
#define _MIN_BLOCK_SIZE          1024

/* The below is allocated in some parts of the system as the largest
 * a filesystem block can be. For instance, the boot monitor allocates
 * 3 of these blocks and has to fit within 64kB, so this can't be
 * increased without taking that into account.
 */
#define _MAX_BLOCK_SIZE          4096

/* This is the block size for the fixed versions of the filesystem (V1/V2) */
#define _STATIC_BLOCK_SIZE      1024

#define _STATIC_FLEX_PER_BLOCK (_STATIC_BLOCK_SIZE/sizeof(struct _fl_direct))
#define _FLEX_PER_V7 (_EXTENT(DIRSIZ) + 1)
#define _FLEX_PER_BLOCK (_STATIC_BLOCK_SIZE/sizeof(struct _fl_direct))

/* Definitions for the directory(3) routines: */
typedef struct {
        char            _fd;    /* Filedescriptor of open directory */
        char            _v7;    /* Directory is Version 7 */
        short           _count; /* This many objects in buf */
        off_t           _pos;   /* Position in directory file */
        struct _fl_direct  *_ptr;       /* Next slot in buf */
        struct _fl_direct  _buf[_FLEX_PER_BLOCK]; /* One block of a directory file */
        struct _fl_direct  _v7f[_FLEX_PER_V7];   /* V7 entry transformed to flex */
} DIR;

#define _DIRENT_NAME_LEN 61

struct dirent {         /* Largest entry (8 slots) */
        ino_t           d_ino;          /* I-node number */
        unsigned char   d_extent;       /* Extended with this many slots */
        char            d_name[_DIRENT_NAME_LEN];       /* Null terminated name */
};

/* Function Prototypes. */
_PROTOTYPE( int closedir, (DIR *_dirp)                                  );
_PROTOTYPE( DIR *opendir, (const char *_dirname)                        );
_PROTOTYPE( struct dirent *readdir, (DIR *_dirp)                        );
_PROTOTYPE( void rewinddir, (DIR *_dirp)                                );

#ifdef _MINIX
_PROTOTYPE( int seekdir, (DIR *_dirp, off_t _loc)                       );
_PROTOTYPE( off_t telldir, (DIR *_dirp)                                 );

#define   dirfd(dirp)     ((dirp)->_fd)

#endif

#endif /* _DIRENT_H */

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