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Annotation of 43BSD/usr.bin/uucp/LIBNDIR/ndir.h, revision 1.1.1.1

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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