TP(5)TP(5)NAMEtp - DEC/mag tape formats
DESCRIPTION
Tp dumps files to and extracts files from DECtape and magtape. 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
reboot(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
directory; 8 entries per block; 64 bytes per entry. Each entry has the
following format:
struct {
char pathname[32];
unsigned short mode;
char uid;
char gid;
char unused1;
char size[3];
long modtime;
unsigned short tapeaddr;
char unused2[16];
unsigned short 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
fs(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 ALSOfs(5), tp(1)BUGS
The pathname, uid, gid, and size fields are too small.
7th Edition May 15, 1985 TP(5)