1 /* 2 * Copyright (c) 1982, 1986, 1989 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 * 17 * @(#)dir.h 7.3 (Berkeley) 01/11/89 18 */ 19 20 /* 21 * A directory consists of some number of blocks of DIRBLKSIZ 22 * bytes, where DIRBLKSIZ is chosen such that it can be transferred 23 * to disk in a single atomic operation (e.g. 512 bytes on most machines). 24 * 25 * Each DIRBLKSIZ byte block contains some number of directory entry 26 * structures, which are of variable length. Each directory entry has 27 * a struct direct at the front of it, containing its inode number, 28 * the length of the entry, and the length of the name contained in 29 * the entry. These are followed by the name padded to a 4 byte boundary 30 * with null bytes. All names are guaranteed null terminated. 31 * The maximum length of a name in a directory is MAXNAMLEN. 32 * 33 * The macro DIRSIZ(dp) gives the amount of space required to represent 34 * a directory entry. Free space in a directory is represented by 35 * entries which have dp->d_reclen > DIRSIZ(dp). All DIRBLKSIZ bytes 36 * in a directory block are claimed by the directory entries. This 37 * usually results in the last entry in a directory having a large 38 * dp->d_reclen. When entries are deleted from a directory, the 39 * space is returned to the previous entry in the same directory 40 * block by increasing its dp->d_reclen. If the first entry of 41 * a directory block is free, then its dp->d_ino is set to 0. 42 * Entries other than the first in a directory do not normally have 43 * dp->d_ino set to 0. 44 */ 45 #define DIRBLKSIZ DEV_BSIZE 46 #define MAXNAMLEN 255 47 48 struct direct { 49 u_long d_ino; /* inode number of entry */ 50 u_short d_reclen; /* length of this record */ 51 u_short d_namlen; /* length of string in d_name */ 52 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */ 53 }; 54 55 /* 56 * The DIRSIZ macro gives the minimum record length which will hold 57 * the directory entry. This requires the amount of space in struct direct 58 * without the d_name field, plus enough space for the name with a terminating 59 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary. 60 */ 61 #undef DIRSIZ 62 #define DIRSIZ(dp) \ 63 ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3)) 64 65 #ifdef KERNEL 66 /* 67 * Template for manipulating directories. 68 * Should use struct direct's, but the name field 69 * is MAXNAMLEN - 1, and this just won't do. 70 */ 71 struct dirtemplate { 72 u_long dot_ino; 73 short dot_reclen; 74 short dot_namlen; 75 char dot_name[4]; /* must be multiple of 4 */ 76 u_long dotdot_ino; 77 short dotdot_reclen; 78 short dotdot_namlen; 79 char dotdot_name[4]; /* ditto */ 80 }; 81 #endif 82 83 /* 84 * The following information should be obtained from <dirent.h> 85 * and is provided solely (and temporarily) for backward compatibility. 86 */ 87 #ifndef KERNEL 88 #ifndef DEV_BSIZE 89 #define DEV_BSIZE 512 90 #endif 91 /* 92 * Definitions for library routines operating on directories. 93 */ 94 typedef struct _dirdesc { 95 int dd_fd; 96 long dd_loc; 97 long dd_size; 98 char dd_buf[DIRBLKSIZ]; 99 } DIR; 100 101 #define dirfd(dirp) ((dirp)->dd_fd) 102 103 #ifndef NULL 104 #define NULL 0 105 #endif 106 extern DIR *opendir(); 107 extern struct direct *readdir(); 108 extern long telldir(); 109 extern void seekdir(); 110 #define rewinddir(dirp) seekdir((dirp), (long)0) 111 extern void closedir(); 112 #endif /* not KERNEL */ 113