TP(5)TP(5)NAMEtp - DEC/mag tape formats
DESCRIPTION
The command tp dumps files to and extracts files from DECtape and mag‐
tape. The formats of these tapes are the same except that magtapes
have larger directories.
Block zero contains a copy of a stand-alone bootstrap program. See
bproc(8).
Blocks 1 through 24 for DECtape (1 through 62 for magtape) contain a
directory of the tape. There are 192 (resp. 496) entries in the direc‐
tory; 8 entries per block; 64 bytes per entry. Each entry has the fol‐
lowing format:
struct {
char pathname[32];
int mode;
char uid;
char gid;
char unused1;
char size[3];
long modtime;
int tapeaddr;
char unused2[16];
int checksum;
};
The path name entry is the path name of the file when put on the tape.
If the pathname starts with a zero word, the entry is empty. It is at
most 32 bytes long and ends in a null byte. Mode, uid, gid, size and
time modified are the same as described under i-nodes (see file system
filsys(5)). The tape address is the tape block number of the start of
the contents of the file. Every file starts on a block boundary. The
file occupies (size+511)/512 blocks of continuous tape. The checksum
entry has a value such that the sum of the 32 words of the directory
entry is zero.
Blocks above 25 (resp. 63) are available for file storage.
A fake entry has a size of zero.
SEE ALSOfilsys(5), tp(1)BUGS
The pathname, uid, gid, and size fields are too small.
TP(5)
