ast@cs.vu.nl (Andy Tanenbaum) (06/06/88)
Since I still haven't got a PD tar that actually works on MINIX, I decided to
fix up Michiel Huisjes tar. In particular, what I wanted was a way to handle
tar files larger than 1 diskette. I accomplished this by writing a program
vol, which accepts an input stream from stdin and writes it on diskette, pausing
when the diskette is full to prompt for a new diskette. To write the current
directory and its subdirectories on a seequence of diskettes, type:
tar c - . | vol 360 /dev/fd0
To restore the file system later, type:
vol -u 360 /dev/fd0 | tar x -
To make this work, I had to modify tar slightly. The diff listing (relative
to V1.3 tar) is enclosed below. Comments, improvements etc. should be posted
to this group.
Andy Tanenbaum (ast@cs.vu.nl)
: This is a shar archive. Extract with sh, not csh.
: This archive ends with exit, so do not worry about trailing junk.
: --------------------------- cut here --------------------------
PATH=/bin:/usr/bin
echo Extracting \v\o\l\.\c
sed 's/^X//' > \v\o\l\.\c << '+ END-OF-FILE '\v\o\l\.\c
X/* vol - break stdin into volumes Author: Andy Tanenbaum */
X
X/* This program reads standard input and writes it onto diskettes, pausing
X * at the start of each one. It's main use is for saving files that are
X * larger than a single diskette. Vol just writes its standard input onto
X * a diskette, and prompts for a new one when it is full. This mechanism
X * is transparent to the process producing vol's standard input. For example,
X * tar c - . | vol 360 /dev/fd0
X * puts the tar output as as many diskettes as needed. To read them back in,
X * use
X * vol -u 360 /dev/fd0 | tar x -
X *
X */
X
X#include <sys/stat.h>
X#include <minix/blocksize.h>
X#include <signal.h>
X
Xextern int errno;
Xextern char *itoa();
X
Xchar buffer[BLOCK_SIZE];
X
Xmain(argc, argv)
Xint argc;
Xchar *argv[];
X{
X int volume = 1, size, reading, fd, tty;
X char *p, *name;
X struct stat stb;
X
X signal(SIGPIPE, SIG_IGN);
X
X /* Fetch and verify the arguments. */
X if (argc != 3 && argc != 4)
X message("Usage: vol [-u] size block-special\n", "");
X p = argv[1];
X reading = (*p == '-' && *(p+1) == 'u' ? 1 : 0);
X size = atoi(argv[reading + 1]);
X name = argv[reading + 2];
X tty = open("/dev/tty", 0);
X
X if (size <= 0)
X message("vol: bad volume size\n", argv[reading+1]);
X if (stat(name, &stb) < 0)
X message("vol: cannot stat %s\n", name);
X if ( (stb.st_mode & S_IFMT) != S_IFBLK)
X message("vol: %s is not a block special file\n", name);
X if (tty < 0)
X message("vol: cannot open /dev/tty\n", "");
X
X while (1) {
X /* Open the special file. */
X fd = open(name, 1 - reading);
X if (fd < 0)
X message("vol: cannot open %s\n", name);
X
X std_err("Please insert volume ");
X num(volume);
X std_err(" and hit return\n");
X read(tty, buffer, BLOCK_SIZE);
X volume++;
X
X /* Read or write the requisite number of blocks. */
X if (reading)
X diskio(size, fd, 1, name, "stdout"); /* vol -u | tar xf -*/
X else
X diskio(size, 0, fd, "stdin", name); /* tar cf - | vol */
X
X close(fd);
X }
X}
X
Xdiskio(size, fd1, fd2, errstr1, errstr2)
Xint size, fd1, fd2;
Xchar *errstr1, *errstr2;
X{
X/* Read 'size' blocks from 'fd1' and write them on 'fd2'. Watch out for
X * the fact that reads on pipes can return less than the desired data.
X */
X
X int n, m, count;
X long needed;
X
X needed = (long) BLOCK_SIZE * (long) size; /* # bytes to read */
X while (needed > 0L) {
X count = (needed > (long) BLOCK_SIZE ? BLOCK_SIZE : (int) needed);
X n = read(fd1, buffer, count);
X if (n == 0) exit(0);
X if (n < 0) message("Error encountered while reading %s\n", errstr1);
X m = write(fd2, buffer, n);
X if (m < 0 && errno == SIGPIPE) exit(0);
X if (m > 0 && m != n) message("Output error on %s\n", errstr2);
X if (m < 0) message("Error encountered while writing %s\n", errstr2);
X needed -= n;
X }
X}
X
X
X
Xmessage(s1, s2)
Xchar *s1, *s2;
X{
X printf(s1, s2);
X exit(1);
X}
X
Xnum(n)
Xint n;
X{
X char out[3];
X
X out[0] = ' ';
X out[1] = '0';
X out[2] = 0;
X if (n < 10) {
X out[1] += n;
X } else {
X out[1] += (n%10);
X out[2] = '0' + (n/10);
X }
X std_err(out);
X}
+ END-OF-FILE vol.c
chmod 'u=rw,g=r,o=r' \v\o\l\.\c
set `sum \v\o\l\.\c`
sum=$1
case $sum in
56099) :;;
*) echo 'Bad sum in '\v\o\l\.\c >&2
esac
echo Extracting \t\a\r\.\d\i\f\f
sed 's/^X//' > \t\a\r\.\d\i\f\f << '+ END-OF-FILE '\t\a\r\.\d\i\f\f
X3c3
X< /* Usage: tar [cxt][v] tapefile [files]
X---
X> /* Usage: tar [cxt] tapefile [files]
X59a60
X> extern printf();
X104c105,109
X< tar_fd = creat_fl ? creat(argv[2], 0644) : open(argv[2], 0);
X---
X> if (strcmp(argv[2], "-") != 0) {
X> tar_fd = creat_fl ? creat(argv[2], 0644) : open(argv[2], 0);
X> } else {
X> tar_fd = (creat_fl ? 1 : 0);
X> }
X427c432
X< write(1, output, index);
X---
X> write(2, output, index);
X435c440
X< write(1, output, BLOCK_SIZE);
X---
X> write(2, output, BLOCK_SIZE);
+ END-OF-FILE tar.diff
chmod 'u=rw,g=r,o=r' \t\a\r\.\d\i\f\f
set `sum \t\a\r\.\d\i\f\f`
sum=$1
case $sum in
59831) :;;
*) echo 'Bad sum in '\t\a\r\.\d\i\f\f >&2
esac
exit 0