Return to dir.h CVS log

Up to [CSRG BSD Unix] / 42BSD / usr.lib / sendmail / lib / libndir

Annotation of 42BSD/usr.lib/sendmail/lib/libndir/dir.h, revision 1.1.1.1

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

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.