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Path: utzoo!utcsri!utegc!utai!garfield!dalcs!david
From: david@dalcs.UUCP
Newsgroups: comp.bugs.4bsd
Subject: mt(1) doesn't flag ambiguous commands
Message-ID: <2452@dalcs.UUCP>
Date: Mon, 16-Mar-87 15:08:37 EST
Article-I.D.: dalcs.2452
Posted: Mon Mar 16 15:08:37 1987
Date-Received: Tue, 17-Mar-87 05:44:55 EST
Organization: Dept. of Math., Stats & C.S., Dalhousie University, Halifax, N.S., Canada
Lines: 100

Index:	bin/mt.c 4.3BSD

Description:
	mt(1) is documented to recognize the minimal unambiguous
	prefix for each of its commands.  In fact, it selects the first
	matching command in its internal table of commands, and fails
	to warn the user that other commands matched.
Repeat-By:
	Run the command:
		mt fs
	and watch the tape spin forward, even though "fs" might have
	been intended to mean "fsr".
Fix:
	Change mt to search the whole table of commands, and exit if more
	than one matches.  A diff of the changes follows.

RCS file: RCS/mt.c,v
retrieving revision 1.1
diff -c -r1.1 mt.c
*** /tmp/,RCSt1000487	Mon Mar 16 13:20:52 1987
--- mt.c	Mon Mar 16 13:01:17 1987
***************
*** 54,60 ****
  {
  	char line[80], *getenv();
  	register char *cp;
! 	register struct commands *comp;
  
  	if (argc > 2 && (equal(argv[1], "-t") || equal(argv[1], "-f"))) {
  		argc -= 2;
--- 54,60 ----
  {
  	char line[80], *getenv();
  	register char *cp;
! 	register struct commands *comp, *found = NULL;
  
  	if (argc > 2 && (equal(argv[1], "-t") || equal(argv[1], "-f"))) {
  		argc -= 2;
***************
*** 70,86 ****
  	cp = argv[1];
  	for (comp = com; comp->c_name != NULL; comp++)
  		if (strncmp(cp, comp->c_name, strlen(cp)) == 0)
! 			break;
! 	if (comp->c_name == NULL) {
  		fprintf(stderr, "mt: don't grok \"%s\"\n", cp);
  		exit(1);
  	}
! 	if ((mtfd = open(tape, comp->c_ronly ? 0 : 2)) < 0) {
  		perror(tape);
  		exit(1);
  	}
! 	if (comp->c_code != MTNOP) {
! 		mt_com.mt_op = comp->c_code;
  		mt_com.mt_count = (argc > 2 ? atoi(argv[2]) : 1);
  		if (mt_com.mt_count < 0) {
  			fprintf(stderr, "mt: negative repeat count\n");
--- 70,91 ----
  	cp = argv[1];
  	for (comp = com; comp->c_name != NULL; comp++)
  		if (strncmp(cp, comp->c_name, strlen(cp)) == 0)
! 			if (found == NULL)
! 				found = comp;
! 			else {
! 				fprintf(stderr, "mt: ambiguous command\n");
! 				exit(1);
! 			}
! 	if (found == NULL) {
  		fprintf(stderr, "mt: don't grok \"%s\"\n", cp);
  		exit(1);
  	}
! 	if ((mtfd = open(tape, found->c_ronly ? 0 : 2)) < 0) {
  		perror(tape);
  		exit(1);
  	}
! 	if (found->c_code != MTNOP) {
! 		mt_com.mt_op = found->c_code;
  		mt_com.mt_count = (argc > 2 ? atoi(argv[2]) : 1);
  		if (mt_com.mt_count < 0) {
  			fprintf(stderr, "mt: negative repeat count\n");
***************
*** 87,93 ****
  			exit(1);
  		}
  		if (ioctl(mtfd, MTIOCTOP, &mt_com) < 0) {
! 			fprintf(stderr, "%s %s %d ", tape, comp->c_name,
  				mt_com.mt_count);
  			perror("failed");
  			exit(2);
--- 92,98 ----
  			exit(1);
  		}
  		if (ioctl(mtfd, MTIOCTOP, &mt_com) < 0) {
! 			fprintf(stderr, "%s %s %d ", tape, found->c_name,
  				mt_com.mt_count);
  			perror("failed");
  			exit(2);
-- 
David Trueman

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