projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 75c01646 C |
1 | .TH DIR 5 "15 January 1983" |
| 2 | .SH NAME | |
| 3 | dir \- format of directories | |
| 4 | .SH SYNOPSIS | |
| 5 | .B #include <sys/types.h> | |
| 6 | .br | |
| 7 | .B #include <sys/dir.h> | |
| 8 | .SH DESCRIPTION | |
| 9 | A directory behaves exactly like an ordinary file, save that no | |
| 10 | user may write into a directory. | |
| 11 | The fact that a file is a directory is indicated by | |
| 12 | a bit in the flag word of its i-node entry; see | |
| 13 | .IR fs (5). | |
| 14 | The structure of a directory entry as given in the include file is: | |
| 15 | .RS | |
| 16 | .ta 8n +10n +10n | |
| 17 | .PP | |
| 18 | .nf | |
| 19 | /* | |
| 20 | * This sets the "page size" for directories. | |
| 21 | * Requirements are DEV_BSIZE <= DIRBLKSIZ <= MINBSIZE with | |
| 22 | * DIRBLKSIZ a power of two. | |
| 23 | * Dennis Ritchie feels that directory pages should be atomic | |
| 24 | * operations to the disk, so we use DEV_BSIZE. | |
| 25 | */ | |
| 26 | #ifdef KERNEL | |
| 27 | #define DIRBLKSIZ DEV_BSIZE | |
| 28 | #else | |
| 29 | #define DIRBLKSIZ 512 | |
| 30 | #endif | |
| 31 | ||
| 32 | /* | |
| 33 | * This limits the directory name length. Its main constraint | |
| 34 | * is that it appears twice in the user structure. (u. area) | |
| 35 | */ | |
| 36 | #define MAXNAMLEN 255 | |
| 37 | ||
| 38 | struct direct { | |
| 39 | u_long d_ino; | |
| 40 | short d_reclen; | |
| 41 | short d_namlen; | |
| 42 | char d_name[MAXNAMLEN + 1]; | |
| 43 | /* typically shorter */ | |
| 44 | }; | |
| 45 | ||
| 46 | struct _dirdesc { | |
| 47 | int dd_fd; | |
| 48 | long dd_loc; | |
| 49 | long dd_size; | |
| 50 | char dd_buf[DIRBLKSIZ]; | |
| 51 | }; | |
| 52 | .fi | |
| 53 | .RE | |
| 54 | .PP | |
| 55 | By convention, the first two entries in each directory | |
| 56 | are for `\fB.\fR' and `\fB..\fR'. The first is an entry for the | |
| 57 | directory itself. The second is for the parent directory. | |
| 58 | The meaning of `\fB..\fR' is modified for the root directory | |
| 59 | of the master file system | |
| 60 | .RB (\*(lq / \*(rq), | |
| 61 | where `\fB..\fR' has the same meaning as `\fB.\fR'. | |
| 62 | .SH "SEE ALSO" | |
| 63 | fs(5) |