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Annotation of 42BSD/usr.bin/uucp/LIBNDIR/ndir.h, revision 1.1

1.1     ! root        1: /*     ndir.h  4.4     82/07/25        */
        !             2: 
        !             3: /*
        !             4:  * Change notice (rti!trt):  To be compatible with non-bsd systems:
        !             5:  * #defines for u_short, u_long, and void added.
        !             6:  */
        !             7: 
        !             8: #define        u_short unsigned short
        !             9: #define        u_long  long
        !            10: #define        void
        !            11: 
        !            12: /*
        !            13:  * A directory consists of some number of blocks of DIRBLKSIZ
        !            14:  * bytes, where DIRBLKSIZ is chosen such that it can be transferred
        !            15:  * to disk in a single atomic operation (e.g. 512 bytes on most machines).
        !            16:  *
        !            17:  * Each DIRBLKSIZ byte block contains some number of directory entry
        !            18:  * structures, which are of variable length.  Each directory entry has
        !            19:  * a struct direct at the front of it, containing its inode number,
        !            20:  * the length of the entry, and the length of the name contained in
        !            21:  * the entry.  These are followed by the name padded to a 4 byte boundary
        !            22:  * with null bytes.  All names are guaranteed null terminated.
        !            23:  * The maximum length of a name in a directory is MAXNAMLEN.
        !            24:  *
        !            25:  * The macro DIRSIZ(dp) gives the amount of space required to represent
        !            26:  * a directory entry.  Free space in a directory is represented by
        !            27:  * entries which have dp->d_reclen >= DIRSIZ(dp).  All DIRBLKSIZ bytes
        !            28:  * in a directory block are claimed by the directory entries.  This
        !            29:  * usually results in the last entry in a directory having a large
        !            30:  * dp->d_reclen.  When entries are deleted from a directory, the
        !            31:  * space is returned to the previous entry in the same directory
        !            32:  * block by increasing its dp->d_reclen.  If the first entry of
        !            33:  * a directory block is free, then its dp->d_ino is set to 0.
        !            34:  * Entries other than the first in a directory do not normally have
        !            35:  * dp->d_ino set to 0.
        !            36:  */
        !            37: #define DIRBLKSIZ      512
        !            38: #define        MAXNAMLEN       255
        !            39: 
        !            40: struct direct {
        !            41:        u_long  d_ino;                  /* inode number of entry */
        !            42:        u_short d_reclen;               /* length of this record */
        !            43:        u_short d_namlen;               /* length of string in d_name */
        !            44:        char    d_name[MAXNAMLEN + 1];  /* name must be no longer than this */
        !            45: };
        !            46: 
        !            47: /*
        !            48:  * The DIRSIZ macro gives the minimum record length which will hold
        !            49:  * the directory entry.  This requires the amount of space in struct direct
        !            50:  * without the d_name field, plus enough space for the name with a terminating
        !            51:  * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
        !            52:  */
        !            53: #undef DIRSIZ
        !            54: #define DIRSIZ(dp) \
        !            55:     ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
        !            56: 
        !            57: #ifndef KERNEL
        !            58: /*
        !            59:  * Definitions for library routines operating on directories.
        !            60:  */
        !            61: typedef struct _dirdesc {
        !            62:        int     dd_fd;
        !            63:        long    dd_loc;
        !            64:        long    dd_size;
        !            65:        char    dd_buf[DIRBLKSIZ];
        !            66: } DIR;
        !            67: #ifndef NULL
        !            68: #define NULL 0
        !            69: #endif
        !            70: extern DIR *opendir();
        !            71: extern struct direct *readdir();
        !            72: extern long telldir();
        !            73: extern void seekdir();
        !            74: #define rewinddir(dirp)        seekdir((dirp), (long)0)
        !            75: extern void closedir();
        !            76: #endif KERNEL

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