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From: rer@hpfcdc.HP.COM (Rob Robason)
Newsgroups: comp.sys.hp
Subject: Re: Re: Need Help Reading 9-Track Tapes written on a VAX. (LONG answer)
Message-ID: <5570481@hpfcdc.HP.COM>
Date: 27 Aug 90 18:41:53 GMT
References: <4180@pikes.Colorado.EDU>
Organization: HP Fort Collins, Co.
Lines: 105

If the other suggestions don't pan out, you may wish to use the mtdump
utility attached below to figure out the format of the tape, then use a
combination of the mt and dd commands to retrieve what you need.  mtdump
is on the HP contrib tape.

Rob Robason

/* @(#) $Revision: 29.2 $ */   
/* 1/2 inch mag tape dump utility .... Oct 25, 1984, Rob Robason */
/* Last modified 1/86 to use 8192 Byte buffer and /dev/rmt/0m  */
/* Usage: mtdump [-t special_file] [-b max_rec_size ] */
/* Default maximum record size is BUFSIZE */

#include <fcntl.h>	/* required for read(2) */
#include <stdio.h>
#include <signal.h>
#define BUFSIZE 8192	/*default buffer size used by malloc(3c) */
#define DFLT_TAPE "/dev/rmt/0m"
#define WIDTH 16	/* width of data fields on output */
int done = 0;		/* set if 'more' dies */
char *malloc();

main(argc,argv)
int argc;
char *argv[];
{
	int filedes, size, recno, pos;
	unsigned bufsize = BUFSIZE;
	char *tape_name = DFLT_TAPE;
	union {
		char *sign;
		unsigned char *unsign;
	} buf;		/* data buffer for mag tape record */
	unsigned char tmp[WIDTH];	/* display buffer for ascii */
	FILE *pfp;
	int moredead();
	int c;
	extern char *optarg;
	extern int optind;

	while ((c = getopt(argc, argv, "t:b:")) != EOF)
		switch (c) {
		case 't':
			tape_name = optarg;
			break;
		case 'b':
			if ((bufsize = atoi(optarg)) == 0) {
				perror(optarg);
				exit (-1);
				}
			break;
		default:
			fprintf(stderr,"Usage: %s [-t special_file] [-b max_rec_size ]\n",argv[0]);
			exit(-1);
		}
	if ((filedes = open(tape_name, O_RDONLY | O_NDELAY)) == -1) {
		perror(tape_name);
		exit(-1);
		}
	if ((buf.sign = malloc(bufsize)) == NULL) {
		perror("malloc");
		exit(-1);
		}
	signal(SIGPIPE, moredead);
	pfp = popen("/usr/bin/more", "w");
	fprintf(pfp,"device to be dumped: %s\n",tape_name);
	recno=1;
	/* read the file, record at a time */
	while ((size = read(filedes,buf.unsign,bufsize)) && !done) {
		fprintf(pfp,"Record #%d, Size=%d bytes\n",recno,size);
		for (pos=0;pos<size;pos++){
			/* print buf out in hex and ascii */
			if ( !( pos % WIDTH ))
				/* print decimal pos in record at SOL*/
				fprintf(pfp,"%.6d  ",pos);
			fprintf(pfp," %.2X",buf.unsign[pos]);
				/* print hex char */
			if(buf.unsign[pos] >= 32 & buf.unsign[pos] <= 127)
				/* put display-able char into display buffer */
				tmp[pos % WIDTH] = buf.unsign[pos];
			else
				/* put '.' into display buffer */
				tmp[pos % WIDTH] = '.';
			if (!((pos+1) % WIDTH))
				/* print ascii buffer at EOL */
				fprintf(pfp,"  %16s\n",tmp);
		}
		if ( size % WIDTH ) {
			/* print the last partial buffer */
			tmp[pos % WIDTH] = 0;
			fprintf(pfp,"\r\t\t\t\t\t\t\t  %s",tmp);
		}
		fprintf(pfp,"\n");
		recno++;
	}
	fprintf(pfp,"end of file\n");
	pclose(pfp);
	close(filedes);
}

moredead()
{
	done++;
	exit(0);
}