| 1 | /* dir.h 6.1 83/07/29 */ |
| 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 | /* so user programs can just include dir.h */ |
| 29 | #if !defined(KERNEL) && !defined(DEV_BSIZE) |
| 30 | #define DEV_BSIZE 512 |
| 31 | #endif |
| 32 | #define DIRBLKSIZ DEV_BSIZE |
| 33 | #define MAXNAMLEN 255 |
| 34 | |
| 35 | struct direct { |
| 36 | u_long d_ino; /* inode number of entry */ |
| 37 | u_short d_reclen; /* length of this record */ |
| 38 | u_short d_namlen; /* length of string in d_name */ |
| 39 | char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */ |
| 40 | }; |
| 41 | |
| 42 | /* |
| 43 | * The DIRSIZ macro gives the minimum record length which will hold |
| 44 | * the directory entry. This requires the amount of space in struct direct |
| 45 | * without the d_name field, plus enough space for the name with a terminating |
| 46 | * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary. |
| 47 | */ |
| 48 | #undef DIRSIZ |
| 49 | #define DIRSIZ(dp) \ |
| 50 | ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3)) |
| 51 | |
| 52 | #ifndef KERNEL |
| 53 | /* |
| 54 | * Definitions for library routines operating on directories. |
| 55 | */ |
| 56 | typedef struct _dirdesc { |
| 57 | int dd_fd; |
| 58 | long dd_loc; |
| 59 | long dd_size; |
| 60 | char dd_buf[DIRBLKSIZ]; |
| 61 | } DIR; |
| 62 | #ifndef NULL |
| 63 | #define NULL 0 |
| 64 | #endif |
| 65 | extern DIR *opendir(); |
| 66 | extern struct direct *readdir(); |
| 67 | extern long telldir(); |
| 68 | extern void seekdir(); |
| 69 | #define rewinddir(dirp) seekdir((dirp), (long)0) |
| 70 | extern void closedir(); |
| 71 | #endif |
| 72 | |
| 73 | #ifdef KERNEL |
| 74 | /* |
| 75 | * Template for manipulating directories. |
| 76 | * Should use struct direct's, but the name field |
| 77 | * is MAXNAMLEN - 1, and this just won't do. |
| 78 | */ |
| 79 | struct dirtemplate { |
| 80 | u_long dot_ino; |
| 81 | short dot_reclen; |
| 82 | short dot_namlen; |
| 83 | char dot_name[4]; /* must be multiple of 4 */ |
| 84 | u_long dotdot_ino; |
| 85 | short dotdot_reclen; |
| 86 | short dotdot_namlen; |
| 87 | char dotdot_name[4]; /* ditto */ |
| 88 | }; |
| 89 | #endif |