Commit | Line | Data |
---|---|---|
61a00120 C |
1 | .TH TP 5 "15 January 1983" |
2 | .SH NAME | |
3 | tp \- DEC/mag tape formats | |
4 | .SH DESCRIPTION | |
5 | .I Tp | |
6 | dumps files to and extracts files from | |
7 | DECtape and magtape. | |
8 | The formats of these tapes are the same except | |
9 | that magtapes have larger directories. | |
10 | .PP | |
11 | Block zero contains a | |
12 | copy of a stand-alone bootstrap program. | |
13 | See | |
14 | .IR reboot (8). | |
15 | .PP | |
16 | Blocks 1 through 24 | |
17 | for DECtape (1 through 62 for magtape) | |
18 | contain a directory of the tape. | |
19 | There are 192 (resp. 496) entries in the directory; | |
20 | 8 entries per block; | |
21 | 64 bytes per entry. | |
22 | Each entry has the following format: | |
23 | .nf | |
24 | .IP "" | |
25 | .ta 8n +\w'unsigned short 'u | |
26 | struct { | |
27 | char pathname[32]; | |
28 | unsigned short mode; | |
29 | char uid; | |
30 | char gid; | |
31 | char unused1; | |
32 | char size[3]; | |
33 | long modtime; | |
34 | unsigned short tapeaddr; | |
35 | char unused2[16]; | |
36 | unsigned short checksum; | |
37 | }; | |
38 | .fi | |
39 | .DT | |
40 | .PP | |
41 | The path name entry is the path name of the | |
42 | file when put on the tape. | |
43 | If the pathname starts with a zero word, | |
44 | the entry is empty. | |
45 | It is at most 32 bytes long and ends in a null byte. | |
46 | Mode, uid, gid, size and time modified | |
47 | are the same as described under i-nodes | |
48 | (see file system | |
49 | .IR fs (5)). | |
50 | The tape address is the tape block number of the start of | |
51 | the contents of the file. | |
52 | Every file | |
53 | starts on a block boundary. | |
54 | The file occupies (size+511)/512 blocks | |
55 | of continuous tape. | |
56 | The checksum entry has a value such that | |
57 | the sum of the 32 words of the directory entry is zero. | |
58 | .PP | |
59 | Blocks above 25 (resp. 63) are available for file storage. | |
60 | .PP | |
61 | A fake entry | |
62 | has a size of zero. | |
63 | .SH "SEE ALSO" | |
64 | fs(5), tp(1) | |
65 | .SH BUGS | |
66 | The | |
67 | .I pathname, uid, gid, | |
68 | and | |
69 | .I size | |
70 | fields are too small. |